Big stroke 55 cc one cylinder ICE

[AlexS]

I am still alive, busy with side things. Camshaft need to be re manufactured. Did not recognize that the holes through the cams are not fully though. Tried to drill it with hss bit, no good, could use TiAlN coated drill but more expensive than new cams.

Also for second batch printed parts, designed with good motorcycle friend a new set of hydraulic drum pistons for his Colleda 250cc 1965? motorcycle (before Suzuki sell there own batch motorcycles same time Meguro did for Kawasaki). Interesting bike, has hydraulic drum brakes and combined front and rear brake system. cylinders rear 18,5mm front 14mm master 15mm. The original cup seals are gone and replacement very difficult to find, we found a seal for inside the master cylinder luckily! Cylinders are in good state, idea is to 3d print new AISI316 pistons, and machine them to correct tolerance (-0,2mm) and cut x-ring grooves. Already got good sizes x rings to fit the cylinder perfect at x% compression rates. Material X-rings EPDM ready for modern DOT3/4. Printing them with additional thickness and cylinder shaft 20mm length for fixation in chuck and support (picture is old, not finished).
We also look at the O-rings for the T350 these where just to large from what designed in '70 need smaller ones and free volume in o ring groove in the carburetors to seal to the intakes. Now the carbs deform.

[Roger B]

Interesting work   

I like the heart you made for your Grandmother     

[AlexS]

Thank you Roger!

In meantime couple weeks ago continue with development. Calculated and drawn a harmonic intake runner with 50cc additional volume between carburetor and cylinder head. Als an replacement exhaust muffler. Muffler equipped with a J-pipe helix shape around outer surface of 700 mm length.  chamber muffler one for expansion and other with damping material with a with a continuous perforated tube through the second chamber.
I have no photo at the moment on this pc, but is looks strange but technical would do a good job on reducing sound on 1750-2200 rpm range. I aspect cost on printing higher. More when things are final, to be continued.

[AlexS]

Hello, last days continued with machining modifications cylinder head and new cylinder. It is still good temperature in the garage to work with the machines instead of doing work outside.

Cylinder

Outer surface of 2nd cylinder has same amount of cooling fins but now equal positioned, so equal thickness remained on top an bottom side. But the cut is a couple millimeter deeper compared to old cylinder so now the thickness from cylinder bore to cut of fin is 3 mm instead of 6 mm.

The cylinder need on both sides for fixation cylinder head and bottom side to crankcase m5 threaded holes.

Cylinder head

The current old exhaust valve seat does is not fitting with new tight bronze valve guide. Previous I had to re cut the seat when installed to be able that the seat and valve seal. But now there is to much of concentric offset with new valve guide. Previous guides was drilled an a slight angle, something like that the intake does not need replacement only fine grinding to clean valve to seat contact area.

So for that plan was to make new exhaust valve seat of GG25 that laying around of cylinder made of 2017. What I understand is that cast iron is much beter material for exhaust seat than silver steel that I used previously. Resistance to heat and little bit of self lubrication and demping of valve motion.

Fist cut was main 45 degree angle, width of seat area is 2mm. After that I machined a 60 degree angle on inside of the seat to reduce the main sealed seat width to 1mm (Difficult to see in picture 4).

New seat pressed in the cylinder head. And grinding the valve and seat to try to proper sealing. Also did a fine grinding on intake valve. Both valves showed in my eyes proper shiny surfaces for silver steel valves.

I had plan to replace the exhaust valve from silver steel to cut from and Peugeot 206 intake valve laying around on the work bench, but I think it is to difficult to reduce valve stem diameter to good cylindrical shape. These might be hardend, machining the outer diameter of valve head was already tough. I will first run it with new valve seat.

[AlexS]

Cylinder head

Valves installed into the head. First photo, maybe difficult to see, t
the offset intake manifold through the head and at position to entry intake valve runner area.The offset settings of milling 11 mm hole was 2.5mm on x position to the left side an 1 mm y position lower.

Both valves moves smoothly while installed in bronze guides, on top of each valves m5 thread cut for fixation with two thin nuts.

Previously I tried different valve/spring fixation with simple shaft clips or c-clips. But als c-clip of exhaust came loose. I don't know how smaller model engines create for this a solution, but I think double nuts work okay. Additional could use loctite but might not needed.

Other engineering

Past months continued with CAD modeling amd engineerong with last phase of additional modifications. Oil lubrication system is mainly finalized.  Created an pressure relieve valve and paper filter housing with an flow distribution in-one part. Two spray nozzles and two seperate feed lines, both lines printed of PA12 with MFJ methode. Still details needed of connecting oil pump to crankshaft by gears and an belt. Oil sump is almost finished with pump support and oil drain


Currently busy with continue forced air cooling shrouds. Outlet positioned towards additional cooling head of cylinder head, have to come with connection to rest of engine and try to make it a stiff part.

Last parts are back covers with output shaft bearing.

[Roger B]

Still following along 

I have always used what I call E clips (probably the same as your C clips) to retain my valve springs. They sit in a recess in the valve spring support so hopefully they can't escape 

[AlexS]

Thanks for following along Roger.

That is a good solution the e clips does not come loose, would remember for other designs.