Author Topic: Big stroke 55 cc one cylinder ICE  (Read 6871 times)

Offline AlexS

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Big stroke 55 cc one cylinder ICE
« on: January 21, 2018, 12:12:43 PM »
Hello, this is my building log of first and own design combustion engine. For several months I am busy with building of the engine.

My goal is to make the engine block as solid as possible. So that is one of the reasons that it is big stroker. The engine should have the possibilities to be able to easily adjust.

The swept-volume is 55 cc, with a boring of 39 mm and 46 mm stroke. I want it to run at low to mid range. So let's say 750-3000 rpm.
Intake valve diameter 18 mm with a max lift of 4.5 mm, exhaust valve diameter 14 mm and a max lift of 3.5 mm.
One camshaft fitted two cams that are adjustable. The duration of the cams would be around 200 degrees, I have to go into this further.

I want to make most of the parts by myself. But given that this is my first engine, I also use existing components. Such as piston, valve springs and a spark plug.


Feel free to give comments!

Offline AlexS

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Re: Big stroke 55 cc one cylinder ICE
« Reply #1 on: January 21, 2018, 12:29:54 PM »
First I had to turn a new flange to mount a four claw chuck for my lathe. With my current three-claw I can not turn large diameters of rod material.


Offline AlexS

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Re: Big stroke 55 cc one cylinder ICE
« Reply #2 on: January 21, 2018, 12:37:20 PM »
Start building with some raw material. First part, crankshaft crank cheeks.

Offline AlexS

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Re: Big stroke 55 cc one cylinder ICE
« Reply #3 on: January 21, 2018, 12:43:15 PM »
Cylinder head. I try to upload photos chronologically as possible, but as wel all of one part.

Offline AlexS

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Re: Big stroke 55 cc one cylinder ICE
« Reply #4 on: January 21, 2018, 12:49:11 PM »
The diameter for the valve seat of the inlet has unfortunately been larger to 20 mm. Due to a measurement error (x-as movement). :-X

Offline AlexS

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Re: Big stroke 55 cc one cylinder ICE
« Reply #5 on: January 21, 2018, 12:53:07 PM »
Cylinder

Offline AlexS

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Re: Big stroke 55 cc one cylinder ICE
« Reply #6 on: January 21, 2018, 12:56:23 PM »
Drill holes for mounting on cylinder head and crankcase.

Offline Ramon

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Re: Big stroke 55 cc one cylinder ICE
« Reply #7 on: January 21, 2018, 01:37:40 PM »
By my engine building standards Alex that's one big engine - ten times bigger in fact  :o

That's some nice machining you are doing there - I'll look forward to seeing it progress in coming days

Regards - Tug
"I ain't here for the long time but I am here for a good time"
(a very apt phrase - thanks to a well meaning MEM friend)

Offline AlexS

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Re: Big stroke 55 cc one cylinder ICE
« Reply #8 on: January 21, 2018, 01:43:56 PM »
Thank you Tug, yeah the reason I want to make a bigger one is the diameter of a standard piston. And the ability to use some larger parts for valve stems etc (round 5 mm). The photos that now are uploaded are from a month of two ago. Recently I had solder the exhaust valve.

I want to upload more, but for some reason it didn't work. Maybe I had to wait some time ;)

Offline scc

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Re: Big stroke 55 cc one cylinder ICE
« Reply #9 on: January 21, 2018, 01:47:08 PM »
Looks an interesting engine. I'm following along too :popcorn:   Keep posting.    Regards       Terry

Offline b.lindsey

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Re: Big stroke 55 cc one cylinder ICE
« Reply #10 on: January 21, 2018, 06:57:24 PM »
Also following your progress Alex.  Nice documentation of the parts so far.

Bill

Offline Plani

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Re: Big stroke 55 cc one cylinder ICE
« Reply #11 on: January 21, 2018, 08:07:06 PM »
Interesting Build! Keep the pictures comig  ;) :popcorn:

Plani

Offline AlexS

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Re: Big stroke 55 cc one cylinder ICE
« Reply #12 on: January 21, 2018, 10:03:57 PM »
Connecting rod and small-end assembly. I had the idea to fit a 15 mm outside diameter for the small-end bearing. But unfortunately there are no 15 mm drill or cutter. :noidea:

Because of that, I have made a part of material C45 to fit the bearing.

Offline AlexS

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Re: Big stroke 55 cc one cylinder ICE
« Reply #13 on: January 21, 2018, 10:12:55 PM »
First (rough) work on the carter. Plates  are 6 mm. The squired profiles are 20x20. On the left and right side there would be a plate of polycarbonate, to look inside the engine (if you can see something with running the engine full of oil ;).

Offline Roger B

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Re: Big stroke 55 cc one cylinder ICE
« Reply #14 on: January 26, 2018, 08:00:56 PM »
An interesting build  :ThumbsUp: Larger than I can do with my machines. There is a lot of experimentation possible with camshafts, valves etc.  :wine1:
Best regards

Roger

Offline Art K

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Re: Big stroke 55 cc one cylinder ICE
« Reply #15 on: January 26, 2018, 09:55:52 PM »
Alex,
Wanted to let you know I'm following along. It's also a bit larger than my Val at 1.125 X 1.1 inch bore & stroke. Are you intending to use splash lube? If so seal it well with silicone and it should be all right. Good progress, look forward to the rest as it progresses.
Art
« Last Edit: January 29, 2018, 04:25:50 PM by Art K »
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Offline Allen Smithee

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Re: Big stroke 55 cc one cylinder ICE
« Reply #16 on: January 27, 2018, 12:18:44 AM »
May I ask why you've chosen to have the exhaust valve smaller than the inlet valve? I would normally expect it to be the other way around.

AS
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Offline AlexS

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Re: Big stroke 55 cc one cylinder ICE
« Reply #17 on: January 28, 2018, 07:19:27 PM »
Thank you all. Roger, my lathe isn't very big one, but with some hint and tricks it is good possible to make a larger engine. I am amazed that the lathe engine continues to rotate larger diameters and harder metals. While the electric motor only has an eighth horsepower of power and some 1.6 Nm torque.

At the moment bottom part is almost finished and I am busy with making valves and seats. Later this week I will upload a little more of the progression.

Art, splash lube is a good idea. But I had in mind to use an existing oil pump. From here I planned to build a pipeline that could lubricate the big end and the cylinder wall as well as possible. But I am open to suggestions. What is the best way to design a splash lube? And yes I want to seal the whole carter with silicone, and add two seals for the axles (15 mm).

Allen, there are two reasons why the exhaust and lift are smaller than the inlet. You want that the engine could breathe easily, that is called the volumetric efficiency. The intake air-fuel mixture is coming in the combustion chamber with a low temperature and pressure. But for the exhaust, the gasses leave the chamber with way more higher temperature and pressure. Because when the exhaust start to open, for a short moment the exhaust gases leave the combustion chamber with tremendous speed. Then the piston moving upward and pushed the rest of the gasses and ensure that the new mixture enter the chamber.
In view of this, the speed and density of intake and exhaust gasses aren't the same. So they needed a different opening to leave the combustion room.

Secondly you don't want a large exhaust valve with also larger mass. The main reason for the size difference is to avoid pre-ignition and knocking. Against that knocking will not be so problematic with a compression ratio of 6:1. But the exhaust valve is the hottest part of the engine. We also know that Q=m Cv dT.
Hence the heat generated is directly proportional to the mass of the substance. Now if the size of the exhaust valve increases, its mass increases. So the heat of the valve increases.

Now after the exhaust stroke, the charge(air and fuel) is sucked in for the next cycle. If the temperature of the exhaust is very high it may cause pre ignition.
Also even if the temperature of the valve is not that high, during compression the charge becomes more volatile. The exhaust valve will ignite the charge creating a flame front which progresses in all directions. Also the spark plug creates a flame front. When these two flame fronts meet, knocking takes place.
To avoid these difficulties the exhaust valve size is kept smaller than the inlet valve. Correct me if I'm wrong.


Offline AlexS

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Re: Big stroke 55 cc one cylinder ICE
« Reply #18 on: January 31, 2018, 01:09:21 PM »
Here some big update from the progress of December-January to today!

Crank pin journals with fitting an big end 20 mm x 14.

Left and right main journals 15. For the journals, I have milled some flattened piece in certain places. This to better fix the flywheel, distribution gear and oil pump later on.

Last picture shows two extra weights (4.7 gram) for the counterweight. This to fully balanced the rotary forces of the crankshaft and connecting rod assembly.

Offline AlexS

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Re: Big stroke 55 cc one cylinder ICE
« Reply #19 on: January 31, 2018, 01:29:37 PM »
A couple of main bearing 'blocks'. Each fitted with a 6202 bearing.

Then the crankshaft press assembly. Had to make a tool to mount the crank cheeks in parallel. The result was just fine!

Offline AlexS

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Re: Big stroke 55 cc one cylinder ICE
« Reply #20 on: January 31, 2018, 01:43:26 PM »
Crankcase progress to fit crankshaft assembly! Need more adjustment in the future to run it smoother. But it is fine for now;)

Added some spacers for the mounting plate for timing belt rollers and flywheel support bearing. The hole to fit the main journals in the front and rear crankcase plates, are 25 mm. This to put some seals for the journals.

Offline AlexS

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Re: Big stroke 55 cc one cylinder ICE
« Reply #21 on: January 31, 2018, 02:07:34 PM »
Now it is more serious work! Valves and valve seats.

Valve stem of round 5. And the valve dish of staff material round 35 (needed for cams).

Third picture shows the result of solder at my home, but this was not good enough (heat to solder brass). So I had to do this with an autogenous welding machine set. I was lucky they had such a set at school. I thought the result was fine, for the first time I soldered hard (with some nice help tips from the workshop teacher !).

Offline AlexS

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Re: Big stroke 55 cc one cylinder ICE
« Reply #22 on: January 31, 2018, 02:16:43 PM »
Modify valve disks. Before I install the valve seats in the head. I adjust the passage of the inlet in the cylinder head.

The seats and valves fits great so far. What a birth! This was done yesterday. Now need to fit some valve springs, camshaft assembly etc etc.

Alex

Offline AlexS

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Re: Big stroke 55 cc one cylinder ICE
« Reply #23 on: January 31, 2018, 02:38:41 PM »
As an attachment you see a section of the cylinder head with valves assembly.

In red the connection between cylinder head and valve stem is shown. In blue, the connection between cylinder head and valve stem guide bushes is shown.

For the exhaust, the valve stem guide bushes fits nicely. But for the intake they are way to lose.
I had expected the milled hole to be small enough. I thought to make some sort of assembly bus. Where the bearings can be mounted more tightly. Outside diameter 10 and inside 7 mm.

Another thing is that the valve stem and the connection between the cylinder head has some slipstick-effect. Simpel solution would be to make the diameter in the head slightly larger. But I don't want that the exhaust gasses flow directly along the valve stem. Possibly I could make a guide bus for this. Maybe have someone any suggestions?

Offline Roger B

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Re: Big stroke 55 cc one cylinder ICE
« Reply #24 on: January 31, 2018, 03:46:43 PM »
Two thoughts:

1. Are you sure that hard soldering will be sufficient for the valve heads, especially the exhaust valve? I have made my valves in one piece from stainless steel screws.

2. I have used one piece bronze valve guides with the outside diameter the same as the port.

Best regards

Roger

Offline AlexS

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Re: Big stroke 55 cc one cylinder ICE
« Reply #25 on: January 31, 2018, 07:43:29 PM »
Roger, the temperature of soldering is around 900 degrees Celsius. For exhaust valve it might been critical. After some research on the internet, I saw that average the inlet valve would run around with 425-540 degrees Celsius and the exhaust 650-780 degrees Celsius. But this engine is not going to deliver high power and peak temperature.

I saw this method from youtube, so I give it a try. But your way of making a valve of a stainless steel screw is also great idea! I think it will be good enough for the first tests. But thanks! Maybe in the future I will turn out of one piece of material. For now I used material silver steel (115CrV3 I guess?), it can be hardened to 64 HRC.
« Last Edit: January 31, 2018, 07:47:36 PM by AlexS »

Offline Admiral_dk

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Re: Big stroke 55 cc one cylinder ICE
« Reply #26 on: January 31, 2018, 08:02:03 PM »
The red area in your drawing looks like a problem area to me - but you might get away with it in a low power engine.

Good full size practice dictates that the valve guides ends either flush or a few millimetres inside the port / channel and inside the spring at the other end. This gives you a big enough support area for the valve stem. The clearance between the two are measured in um (micro-meters) - most of my bikes has been in the 25-55um for the inlet and 40-70um for the exhaust valve.
The engine will run with a much bigger clearance and I don't expect this kind of tolerance on a model we make - but the size of the tolerance has great influence on oil consumption if you have splash lubrication of the valves ....

The reason I don't like the red areas are heating of the valves and the cylinder head on the exhaust side and more wobble of the valves - but again, probably not a serious problem here.

Best wishes

Per

Offline Perry

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Re: Big stroke 55 cc one cylinder ICE
« Reply #27 on: January 31, 2018, 08:27:06 PM »
Hi Alex, that will be big engine, will you try to power something with it once finished? (bicycle perhaps)

Offline AlexS

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Re: Big stroke 55 cc one cylinder ICE
« Reply #28 on: February 02, 2018, 03:56:36 PM »
Per, indeed the red areas could possibly cause problems if the valves get really hot. But what you said, it won't be a high power en fast running engine. For the inlet, I have fit in some extra tube to fix the guide bushes better(shown pic. 1). And I had to make the red area slightly wider. I didn't measured the clearance between the stem and bushes, but now for both stems moves nicely. Fifth picture shows the valve assembly fit in the head with two springs. Lock the valve spring with a seeger ring 55 mm. I do not expect any serious problems, maybe I should make a firmer clip.

The spring constant is 3.63 N/mm. Reduced mass of valve train would be around 100 grams. So the own frequency of the spring with the mass would be around the 4000 rpm. This is higher than the max rpm what I would be running this engine. The spring length when the valves are closed are 8 mm. And for the intake 8+4.5 mm. Forces are not that high (29 N closed, 45.5 N opened), but I think it would be good enough to run it with low rpm range. The cam followers are carried out with rollers. With this and that it does not have to transfer many forces, I think it would be not that necessary to splash lubrication. Occasional greasing with ball bearing grease seems sufficient. Is not that right?

Perry, I have many this in mind to upgrade and to adjust etc. But first I want it that it run good with as a stationary machine. Later on I would make a hydro dyno (load cell), added some sensors like temperature speed etc. I have ideas to advance a programmable (mechanical interaction) ignition. In addition, maybe a throttle controller. Going to nearby convenience store with powered your own build engine to get some beer would be a dream! Maybe to attach this engine to a gearbox of a chinees motorcycle or a Puch moped engine in the future.
But this will come later! First plan is to start the engine properly;)

Offline AlexS

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Re: Big stroke 55 cc one cylinder ICE
« Reply #29 on: February 02, 2018, 04:01:45 PM »
Yesterday started making the mounting beam of the camshaft composition. Two ball bearings 608 would be mounted in this beam. The intake cam comes to the left of the beam and the exhaust cam on the right. Also, two pairs of adjusting blocks are mounted on this beam where the valve clearance can be adjusted.  :cheers:

Offline AlexS

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Re: Big stroke 55 cc one cylinder ICE
« Reply #30 on: February 15, 2018, 01:15:57 PM »
I am almost ready to start making the camshafts.

Does anyone have hits tips to make these on a milling machine with an indexing table? I was thinking to do it like shown in the first picture (blue square is the cutter)

The camshafts are mounted on an axle. The pics shows the intake and exhaust dimension. For the intake I want a duration of +- 200 degrees. This due to run the engine at low rpm. But as you can see in the first picture, with this geometry there is a duration of 272 degrees (136 *2). And for the exhaust the duration is 238 degrees (119*2). The third picture shows the valve timing. Here you can see that for the intake a late closing angle is chosen (for a small valve overlap with the exhaust).

What is the best way to reduce this duration (especially for the intake)? Increase the diameter of the circular arc to lets say 10-12 mm? Or applying a ridge with hollow flanks?
« Last Edit: February 15, 2018, 01:19:20 PM by AlexS »

Offline Roger B

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Re: Big stroke 55 cc one cylinder ICE
« Reply #31 on: February 15, 2018, 02:38:03 PM »
I have milled my camshafts using a table of lifts at 6 intervals. The tables were generated using the cam calculator on the Model Engine News website:

http://modelenginenews.org/

Go to Resources and then Design Centre. I'm not sure how compatible this is with the latest operating systems. Others on this site have also written similar programs which they are willing to share.

The cam blank was held in a simple fixture with a 60 tooth gear for indexing. The lift values were set using a DTI under the milling head. I have attached the table I used for the camshaft on my horizontal engine.
Best regards

Roger

Offline Art K

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Re: Big stroke 55 cc one cylinder ICE
« Reply #32 on: February 16, 2018, 01:04:01 AM »
Alex,
My suggestion would be to use this program.
http://www.modelenginenews.org/design/CamTable.html
You use an end mill and a rotary table. You zero the Z axis on the base diameter of the cam, mill across the Y axis then move the table up and down as the table tells you. Just fill out the parameters and it gives you a Z height for every degree increment. I did mine in 2 degree and it was ready to run that way, that also means 180 passes for each cam lobe. But there is no filing sanding ect.
Art
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Offline AlexS

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Re: Big stroke 55 cc one cylinder ICE
« Reply #33 on: February 16, 2018, 09:58:15 AM »
Roger and Art. Thanks for your information and explanation!  :ThumbsUp: Tonight or tomorrow I look after this.

Offline AlexS

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Re: Big stroke 55 cc one cylinder ICE
« Reply #34 on: July 06, 2018, 08:18:42 PM »
Hello guys, it has been a while since I gave an update. But in the meantime, the engine has already made a few plops! I had some 'problems' (challenges ;)) with sealing the valves for example (Now 5 bar pressure when turning the engine, had to say that the theoretical compression ratio has been increased duo to thinner Head gasket, so 1:6->7). But I am currently having a question about the crankshaft.

The crankshaft is currently split up. The cheeks are made of aluminum. This was a guess as to whether this went well with the drive shafts and pigtail pen of C45. I have found out that this is a bit of a success. Provided you turn a smaller diameter on the shaft for 'searching' the hole during pressing. But the squareness I did only afterwards. The squareness of the holes for the drive shafts are not good. Both drive shafts do not run in each other's center line. In other words, no straight crankshaft. You also notice this when you mount the block and turn around. It is a little more difficult with some strokes and you can see the drive axles swinging a little bit.
All in all, I think this is enough to start him.
But in addition, I have found out, as soon as he tries to start, that the drive shaft is rotated in the axle. This was fixed with a reasonable fixed fit. This can of course be remedied by the use of glue / or the installation of locking pins.

I am thinking to tackle the total crank cheek problem. So I want to make the cheeks of steel. At the moment I have a leftover cast iron. I wonder if this is strong enough? Given that the material is brittle. However, the material is easy to machine. And I'm probably going to use glue as a deposit (locktite 4xx, I do not know my number).
Or is it advisable to use another type of steel such as C45?

Soon I would upload some more pics and talk. Greetz Alex
« Last Edit: July 07, 2018, 11:39:00 AM by AlexS »

Offline AlexS

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Re: Big stroke 55 cc one cylinder ICE
« Reply #35 on: July 06, 2018, 08:27:45 PM »
First picture of the first test. It was pointed and quite messy in the R & D section! Here I found out that the engine contains too little compression.

The second photo is recently after disassembling the second test session.

Offline AlexS

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Re: Big stroke 55 cc one cylinder ICE
« Reply #36 on: July 07, 2018, 11:34:09 AM »
Today do some bit of math!  :smokin2: Cast iron can not handle the theoretical bending forces. Gas force is 4.8 Kn (ideal situation of combustion 100% VE). The safety factor is 0.7 ish (compared with 1.3 for aluminum and 2.3 for C45) with taking into account the jump load factor.
Cast iron GG25 is weaker than 2020. C45 would be ideal. But, you will not end up balancing the weight of the crank (rotating balance). It is possible, but then it is necessary to build a steel connecting rod. Maybe for another time.

Now I want to adjust the current crankshaft. The insertion of fitting sleeves to improve the squareness of the fitting of the respective shafts in the crank cheeks.
The new confiscation can be seen in the image below.

Offline Roger B

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Re: Big stroke 55 cc one cylinder ICE
« Reply #37 on: July 12, 2018, 05:45:02 PM »
The bending forces on an IC engine crankshaft are quite high. I have made my bigger ones from C45k with the balance weights bolted on. I think that getting a good bond between steel shafts and aluminium webs will be quite difficult. RC in Luxembourg do some useful sizes of C45k

https://www.rc-machines.com/en/materials/steel/flat/c45k

Best regards

Roger

Offline Admiral_dk

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Re: Big stroke 55 cc one cylinder ICE
« Reply #38 on: July 12, 2018, 09:22:43 PM »
Your engine is big enough to get into trouble with the distance between crank webs and the bearings ....
Since it looks like the bearings are in separate holders (might be problematic too) I hope that you just can turn them 180 degrees or swap left with right side and get the bearings almost flush with the webs - this should stiffen the crank quite a bit ....

I got absolutely no experience nor ever seen a crank with alu webs, so my next comment might not be worth much, but ..:
Removing material from alu webs will not give you much, but putting heavy metal into the opposite position should be enough to balance the crank.

Best wishes

Per

Offline AlexS

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Re: Big stroke 55 cc one cylinder ICE
« Reply #39 on: July 18, 2018, 02:39:08 PM »
Thank you gentlemen for your reactions! Meanwhile I have been busy fixing the aluminum handle cheeks on the crankshaft.
For me it was also questionable whether it would work. You can take a gamble anyway! The main reason was that I had no experience of milling harder metals. In addition, the use of aluminum ensures less oscillating vibrations. With an aluminum crankshaft and connecting rod it was possible to balance the crankshaft (rotating balance).

But! Last Monday the engine ran a few minutes !! And still pretty neatly stationary.
But unfortunately the locking(pins) of the cranks has been released. I doesn't have put some fitting sleeves in the crank. Now I intend to make the crutches, and possibly the connecting rod, of C45. I collected this material yesterday at a local machining shop.

First, before I go into detail, I chronologically upload the progress of the past months.

Offline AlexS

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Re: Big stroke 55 cc one cylinder ICE
« Reply #40 on: July 18, 2018, 03:21:36 PM »
In the month of March the components were made for the rocker arm / camshaft assembly.

The first series of images are the assembly and adjustment blocks of the tumblers. Now the valve clearance can be adjusted per valve. The axes on which the tumblers rotate are currently glued(locktite 402). But this can be replaced by a threaded rod by mounting both blocks. The valve stem lengths are almost identical. And the valve stem caps can be adjusted to the play (added later).

The tumblers are equipped with rollers. These are admittedly of softer steel than the silver-steel cams. For now the use of ball bearing grease for lubrication is sufficient.

Offline Ye-Ole Steam Dude

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Re: Big stroke 55 cc one cylinder ICE
« Reply #41 on: July 18, 2018, 03:37:33 PM »
Hi AlexS,

Beautiful design engine, will follow along.

Have a great day,
Thomas

Offline AlexS

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Re: Big stroke 55 cc one cylinder ICE
« Reply #42 on: July 18, 2018, 03:39:01 PM »
Time to make some tools! A mounting block for fixing a three claw on the index table. The indextable is mainly used for milling the cams.

The three-claw is fixed with the 3 original bolts of my lathe. Given that you can only mount bolts on one side. Did I use three imbus bolts as centering on the indextable side. In addition, the whole is mounted by means of a threaded rod that you tighten through the middle.

The whole has done a nice job. However, the span was large. For the milling of the cams it was advisable to also manufacture a countercenter. This naturally resulted in fewer vibrations.
I like to make some useful tools.
« Last Edit: October 09, 2018, 09:16:10 PM by AlexS »

Offline AlexS

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Re: Big stroke 55 cc one cylinder ICE
« Reply #43 on: July 18, 2018, 03:39:52 PM »
Thank you Thomas! I appreciate it.

Offline Roger B

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Re: Big stroke 55 cc one cylinder ICE
« Reply #44 on: July 18, 2018, 07:05:58 PM »
Some nice work there  :ThumbsUp:  :ThumbsUp: I am not sure that the aluminium crankshaft webs will work due to the different stiffness (Youngs Modulus). The webs will less stiff than the shafts which will tend to make the holes in the webs barrel shaped.
Best regards

Roger

Offline AlexS

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Re: Big stroke 55 cc one cylinder ICE
« Reply #45 on: July 19, 2018, 05:39:14 PM »
You are right Roger. I am currently working on making steel crankshaft webs.

Offline AlexS

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Re: Big stroke 55 cc one cylinder ICE
« Reply #46 on: October 09, 2018, 09:57:52 PM »
It has been a while since the last update. First a series of photos of the engine components for the first start session (July).

First set of pics shows the milling of the cams on the index table. The cams are locked on an aluminum turned tool (Not so well visible in the photo). This was done by placing a pin. As a guarantee I glued both the cams and the locking pin.
In the small tool, a inbus needed to be fitted on one side. This inbus was mounted against one of the three claws, this prevented the tool and thus also the cam from turning during milling.

I don't have more pics of milling the cams. Sorry.

To fix the cams on the engine, I did have drilled and tapped a hole through the cams and the accompanying shaft. Then the cams are fitted with the use of a set screw and glue. Meanwhile, I started the engine a number of times. And the fixture remains very good.

Also you can see the timing belt assembly. Fitted with four 608 bearings as span and fixed roller. Timing belt T5x10 total length 550 mm. Number of teeth of the pulley are 20 and 40.
« Last Edit: October 09, 2018, 10:03:56 PM by AlexS »

Offline AlexS

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Re: Big stroke 55 cc one cylinder ICE
« Reply #47 on: October 09, 2018, 10:34:40 PM »
After machining the cams it was needed to make a flywheel.

It is desirable that it has a relatively large mass inertia. However, I am limited to the maximum diameter of around 130 mm. In addition, a wider flywheel would take the center of gravity of the total engine too far out of the center.
The flywheel diameter 120 mm, around 1.5 kilogram.
Speed variation is theoretically acceptable for this kind of engine. Starting from the requested torque of 2 Nm, the speed variation at low revolutions (750 rpm) is Cf 0.11 (85 rpm) and at high revs (3k rpm) Cf 0.01 (21 rpm).

I have taken a piece of residual waste from a local turning and milling shop. On both sides of this writing it was sawn off obliquely. This took some time to get this on one side at right angles (1-2 hour ish :D). Then I turned the piece of metal around and turned the actual flywheel. Given that there was already a hole in the metal, I installed an aluminum core. With the core fitted, it was able to support the piece of metal with a center for less vibration for turning.

Offline AlexS

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Re: Big stroke 55 cc one cylinder ICE
« Reply #48 on: October 09, 2018, 11:02:32 PM »
Back to modify the head. Fitting a spark plug. First determine the desired distance and lightly drill with a center drill. Then setup the angle of 45 degree. The use of a center drill and big enough drills works quite well. After that the hole were tapped with M10x1.0.

The fifth photo shows the inlet manifold. In the photo you can see that there is a slot in milled for the carb.
The carburetor is made of orgine for 2t machines (Rc / chainsaws). It concerns a Chinese brother of a zama C1Q. In view of the operation of the carburetor, the intake of fresh petrol through the inlet and the exhaust pulses of the crankcase of the orgine two-stroke engine. However, this appears to work well with a four stroke engine so far. Given this reason, a slot is milled in the intake manifold.

The diameter of the carburetor's passage is 14 inside and 13 mm outside if I'm not mistaken.

Last picture shows the head gasket made of copper-alu alloy. 0.6 mm thick. So th. compression ratio is increased from 6:1 to 6.9:1
« Last Edit: October 09, 2018, 11:06:43 PM by AlexS »

Offline AlexS

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Re: Big stroke 55 cc one cylinder ICE
« Reply #49 on: October 09, 2018, 11:29:55 PM »
Back in June, first ignition sparks flying around! Use a Rcexl set ignition but not with a CM6 spark. Had to add an extra ground for the better spark. Power the ignion system with a usb 230v power supply. Work great for now;)

Next serie of pics shows the modify of the exhaust valve seat. First test session in begin July shows that the engine has low compression. Biggest problem was the seal between the exhaust valve and the seat. The concentrically of both parts was not correct 0.1 mm ish. With adding some water and use of pressed air it was easily shown here it was coming from.
Had to fit the head in the chunk of the lathe. So that said, that done. I did use the tool that I early made for drilling holes in the cylinder. Tapped 4 M6 in it to fix head on it. At the position of the valve stem I used a long threaded end to clamp it in the lathe. I had to use a valve spring to reduce the vibrations of the threaded rod.  ;)

So sealing checked, and it was at the same level as the inlet valve! Use for both valve polishing paste for automotive usage.

Offline AlexS

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Re: Big stroke 55 cc one cylinder ICE
« Reply #50 on: October 10, 2018, 10:41:23 AM »
Adjusting the aluminum crankshaft (try to safe it). Use of an additional fitting bush and fixing the crank pin. This job also done for make the crankshaft more concentric and straight.
These changes I applied for the first start of the engine.
But at the end it did not help for long, given this reason I started to make a steel crank.


Offline AlexS

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Re: Big stroke 55 cc one cylinder ICE
« Reply #51 on: October 10, 2018, 10:41:46 AM »
Video shows the first real run of the engine! :D This was when the engine run with the aluminium crank webs.


Offline AlexS

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Re: Big stroke 55 cc one cylinder ICE
« Reply #52 on: October 10, 2018, 10:57:12 AM »
Creating a new set of crackwebs made of C45. No need to make a steel connecting rod to compromise the extra weight of the webs. Images shows the section view of the engine and two of the theoretical rotating mass balancing. One part of the connecting rod would be defined as 'rotated mass' and the other half as 'oscillating' mass. For this reason, about half a conrod has been drawn.
The different between center of mass and the center of the crankwebs are minimal.

Maybe I will add once two or four balance shafts to balance the whole together (for compensation the oscillating mass).

Offline AlexS

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Re: Big stroke 55 cc one cylinder ICE
« Reply #53 on: October 10, 2018, 11:31:55 AM »
The next series of photos shows the making of the steel crankshaft. The milling of the handle cheeks took the most time. The milling machine became hot quite quickly. Matter of manufacturing with an occasional break.

For one of the crank web I have turned to the final size of the diameter of the driveshaft, so that I can fit driveshaft of the flywheel side. And also modify the diameter of the driveshaft and crank pin, ready to fit in together.
The last thing to do is to eventually turn the diameter of the other drive shaft. The crankshaft is already mounted with the connecting rod. It was important that the connecting rod with an elastic was mounted on a fixed place (wall of the shop), to prevent the connecting rod from swinging around in the lathe.   ::)

Last step was pressing the last drive shaft in the crank cheek and welding the entire crankshaft. This is to prevent the drive shafts from turning in the crank webs. It was necessary to align the entire crankshaft after welding. It was a bit exciting, but after my say, it succeeded.  :DrinkPint:


Offline AlexS

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Re: Big stroke 55 cc one cylinder ICE
« Reply #54 on: October 10, 2018, 12:02:56 PM »
Second test session with the new steel crankshaft. Engine looks solid, and need some more love for ignition/fuel tuning!  :DrinkPint:

Pics shows build up. Add some liquid gasket on the bottom crankcase and two shaft seals on the drive shafts to prepare for the use of an oil in the crankcase.



Things I want to do are:

Add a left and right crankcase plates, a crankcase blend nipple for adding oil in the engine. First I try to use splash lube, I had some ideas about a oil pump, but that can be done later.

Make a better mounting block for the ignition pickup, so changing time would be easier to do.

An extra support block of the camshaft assembly (for less deflection of the camshaft by tightening the distribution belt).

Exhaust manifold and exhaust pipe/muffler. Thing is 'pretty' loud! (On the advice of the neighbors)

Making plans and sketches for the dynamo meter / sensors. Later on I would start an different topic about this.

And other stuff to modify / adjust.


« Last Edit: October 10, 2018, 12:07:37 PM by AlexS »

Offline Roger B

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Re: Big stroke 55 cc one cylinder ICE
« Reply #55 on: October 10, 2018, 12:14:07 PM »
You've made a lot of progress  :praise2:  :praise2: It runs well  :ThumbsUp: Are you triggering the ignition from the crankshaft? The RCxcel units have a built in advance curve which is designed for this.
Best regards

Roger

Offline AlexS

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Re: Big stroke 55 cc one cylinder ICE
« Reply #56 on: October 10, 2018, 10:55:22 PM »
Thank you Roger. Yes the ignition is triggering from the crankshaft (mouthing a magnet on the flywheel). Don't know of the advance curve is acceptable for the engine. Maybe good to mount a stroboscope between ignition and plug!
« Last Edit: October 10, 2018, 11:14:20 PM by AlexS »