Put a vaccum gauge on what vac.reading do you get running vs. going to stall? Is the needle steady or jumping arround? You may have a valve sticking 1 of tne intakes or exhaust. Try a cylinder leak tester If at tdc @ 80psi you get air out intake valve is leaking out the tail pipe it's exhaust valve out of oil fill plug it's rings or piston. Yes it could be electrical but usually elect. will not cause oil copm. Just thought.
Ride Safe
Viper

Rings??  ??? Rings?  ???

There's supposed to be rings in there somewhere??  

smokin_blue wrote on 12/31/69 at 16:00:11:

Yep.  Just like the rings around yur a nus.

I assume that you have tried replacing the spark plug.  I had a situation recently with a 125cc 4-stroke single.  I had replaced the spark plug with a new one during a routine service.  Next day I rode it to work and back - about 20 miles.  (My Savage is currently off-road being rebuilt).  It ran perfectly.  The next day I rode it to work again with no problems.  On the way back it began to rain.  Then the bike began misfiring and cutting out.  It stalled several times but each time I eventually managed to re-start it. Eventually I nursed it back home.

Because of the rain I thought of problems wih HT lead, spark plug cap, coil etc. I examined the plug which was sooty but giving a good, big, bright blue/white spark so I cleaned it and put it back in.  I replaced the coil and HT lead and it ran fine again.  

I rode it to work again the next day.  On the way back it began to rain.  The bike began missing and cutting out again.  When I got home I cleaned out the carb but it made no difference.  I was thinking about replacing the CDI unit, when, in a flash of inspiration I put the old plug back in it (I had kept it as an emergency spare).  It then ran fine and hasn't had a problem since.

The rain was probably just coincidence.  What I had was a brand new but defective plug. It sparked well out of the bike but kept breaking down under the stress of running in the engine.

My advice is stick to simple explanations.  Even if the oil ring is defective you would be more likely to get oil smoke than the engine stalling.  Carburation would have to be way off for such a problem to occur. My guess is that the problem is electrical but not showing up under non-running condidtions.  

Since this began, I've been kinda PO'd and haven't been back to it until today.  But this afternoon I cleaned my plug, disconnected the vacuum line, plugged the carb nipple, turned it to PRI and started the bike.

Seemed like it took a few more turns than normal to start, but it fired right up.  Nice and smooth, and I thought things might be okay.  After 10 seconds or so, I gave the throttle a couple little blips to see how the exhaust looked in the bright sunlight.  Sounded good with the baffle out of the Raask, but that shotgun blast of gray smoke looked like $hit....

The bike ran about 20 seconds total and I couldn't keep it from dying...it sputtered out quickly.

(Now mind ya, it took me a few minutes to put the plug in the vise and get my camera and tripod...)


What you see on that almost new iridium plug has got to be oil.  The exhaust was gray and my carb is not flooding.  I don't really know how to wipe off a small sample like that and know for sure without one of those spectrography thingies.  After all, a spark plug smells like gas and oil anyway.

I decided to try something else...I turned the piston to TDC, grabbed a small piece of tubing, and a Q-tip.  With the Q-tip in the tubing, I dabbed at the top of my piston.  What I got on the Q-tip was black and liquid.  It didn't rub off the piston like a powdery carbon.  It soaked into the cotton.

My engine is screwed, and it's my own damm fault.  I bet that should have bought those new rings.

More later...

T Mack 1 - FSO wrote on 12/31/69 at 16:00:11:

I know...the new rings were in my wish list at Ron Ayers, but I took the gamble because I didn't want to wait another week or so to get them.  

I figured that I had reinstalled them twice before without a problem....but 3's a charm

Funny too the plug fouled even faster yesterday, than it did last time...must be getting worse.

been a long while since ive been that deep into a cylinder..if i member corectly the cyl wall should be cross hatched and new rings are "broke in"(ride it like you stoled it)then you are assured of max seal= compression=power...set this ol dog straight..

thumperclone wrote on 12/31/69 at 16:00:11:


You are right.

Unfortunately, the cylinder is nicely cross hatched and the rings are old.  They have been reinstalled 3 times...

That's why I'm posting this.  Don't do what I did