Author Topic: Big stroke 55 cc one cylinder ICE  (Read 8332 times)

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 »

Offline AlexS

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Re: Big stroke 55 cc one cylinder ICE
« Reply #57 on: October 08, 2019, 09:23:26 PM »
Long time ago. Times flies when you're having fun/bussy/working??


Quick update. Last Juni a upgrade to the engine and a start and tune.



First pics view of piston and cylinder before update run. So after rebuild with steel crankshaft. Running fuel + 2t oil.


I added a extra support block with bearing to prevent bending of the camshaft. This allows to add more tension to the timing belt.

As you can guess, the previous camshaft was broken after add some pressure to the timing belt when the engine was running. So this stiffen the camshaft drive train some bit.

When remaking the stock shaft to mount both cams, I did changed the lobe degree between the two camshafts to get some 'better' valve timing. I did checked the timing on opening and closing degrees. The intake duration is okay, some ~200+ degree and exhaust ~180, I don't have my notes here.
So I did add some lobe degree to get the opening timing of the exhaust some bit sooner.

In the video you can see that the engine is now equipped with transparent poly carbonate plates. This allowed the crankcase to be filled with 300cc of 10W40 oil. Added a crank ventilation and filling holes.

Next time I will make a new exhaust and maybe intake cam with more duration(now with consideration of the difference between theoretical and measured duration). , And make no mistake with to small diameter and so sharp exhaust cam, I really don't know how I did make the exhaust diameter of stock material smaller  :-[ :-X
Also I will build the support shaft of the cams out of round bar without retaining groves to prevent axial movement of this shaft. I think these groves again caused a break in the described support shaft.

Offline AlexS

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Re: Big stroke 55 cc one cylinder ICE
« Reply #58 on: October 08, 2019, 09:24:05 PM »
Video of run Juni


Offline Roger B

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Re: Big stroke 55 cc one cylinder ICE
« Reply #59 on: October 09, 2019, 10:07:13 AM »
Good to see you back on this one  :) There was less splashing in the crankcase than I expected.

Did you reduce the base circle in your cam design to allow for the valve clearance? This can be responsible for some loss of opening angle.
Best regards

Roger