4 stroke single

[Roger B]

I have had a private message from a member who was having problems with the CAD drawings so I have put then in pdf format. I couldm't see how to attach anything to a message (Forum Gurus: Am I missing something?) so here they are.

[steamer]

Nope....can't attach to a message....though you could send an email...

In any case...I can see the attachment on your post.

 

Dave

[Roger B]

Thank you Dave. I wondered if I had overlooked a button somewhere. 

[BronxFigs]

Thanks for the PDF file showing the engine drawings.  I was not....probably my fault....able to see the attachment earlier.  Now it's clear.

Thanks for sharing the drawings.



Frank

[BronxFigs]

Sir...

How close are you to getting this engine to run?  Just curious.


Frank

[Roger B]

It is almost at the point that I could try and start it.
I am not completely happy with the compression. I think that the pressure from the chuck may have distorted the cylinder liner when I made it so that the bore is not truly round. As I now have a 20mm collet I may make a new one.
I also suspect that the carburettor I have may be a little too big. From my motor sport days I know that that always make an engine hard to start. Again maybe I will make a new one or try and reduce the venturi size in the one I have.

[Roger B]

Some more of the build sequence.

[Roger B]

Continuing

[vcutajar]

Still following along Roger.  Keep it up.

Vince

[BronxFigs]

Waiting....still....


Frank

[Roger B]

I've been travelling again. Here are a few more parts.

[BronxFigs]

The whole engine build reads like a good novel...can't put it down.

Looking forward to the logical conclusion.



Frank

[b.lindsey]

Nice update Roger...its getting closer now. I can imagine posting from China was a real pain. Still following along here

Bill

[Roger B]

The travelling is really reducing my time in the workshop at present. Unfortunately I don't think I would even be allowed to take a lathe as small as Jo's house lathe on the plane with me , but what a wonderful way it would be to spend a 12 hour flight making swarf

Here are a few more pictures. I only hope that after all the interest and enthusiasm form the other member of the forum that I can get it to run

[Roger B]

The last of the pictures from the build sequence.

I tried to start it at the weekend without too much success. The temporary set up is shown below.

Initially I set the timing around 10° btdc by removing the plug and placing it next too the mark on the flywheel and slowly turning the engine to judge when it sparked. For the first attempts I set the throttle around 1/4 open, turned the engine with an electric drill and slowly opened the needle valve. This resulted in a few pops but then it seemed to flood. Next I tried the same but dabbed my finger over the inlet at each stage. Similar result. The next attempt was with the throttle fully open. This resulted in it kicking away from the starting dog maybe 5 or 6 times in a row but not sustaining. Playing with the timing did not seem to improve things.

During these attempts a lot of oil was blown out of the breather so I think my concerns about the poor compression and possibly out of round cylinder are justified. I will strip it down and look at the rub markings on the piston and cylinder. On a positive note the valves seem to seal as there was no blow back through the carb.