Awwwrite, it's happened 3 times. Only does it when I am running fairly hard, decide it's time to stop or slow dramatically & it dies & won't crank. Well, that never happened before I opened the idle mix screw( the one under the brass cap I drilled & pulled). So, it did it today & I stuck it in 5th & ran with it & jumped on it & it turned over but didn't start. It was stopped at TDC on compression. I thought that was what happened the last time, because while I was messing with the sidestand switch the motor rolled over & then the starter worked. How do I make it stop dying & stopping at TDC on comp?

Usually when I start it there's no indication the starter is trying to drag it thru compression unaided. When it's locked down, TDC, I am guessing it is dying after I pull the clutch in & it's stopping at TDC on comp. Then the decomp can't relieve the pressure the piston is under, because the engine wont turn. The decomp is a doohickey thet slips between the rocker & cam & causes the exhaust valve to open earlier, correct? If the engine can't turn at all the decomp won't fix the problem. My guess. No one told me this, but It's how I think it works. Am I off base? I think the decomp is working.I guess I could unplug it & see if it starts differently.

Every time I did the valves I have looked at the decomp. Never adjusted it cuz it always seems okay. I have no reason to suspect the decomp as not working since the bike doesn't seeeem to be draGGING THE OOOps Caplock sorry. The starter winds the motor around fine every time Except when I jump off the gas & on the brakes Hard & Fast. Then IF it dies, Every time it dies it won't start.It doesn't die every time I make an abrupt throttle close, but it's done it 3 times. I will admit my idle speed WAS slow. I jacked it up to the lowest mark on the tach today & it hasn't made me push start it since. ONly after I messed with the idle mixture screw behind the brass cap. Maybe, it's the too low idle speed. Anyone ever see this happen? Sl;ap throttle to ZERO & grab brakes for all yer worth? You spose it was just the low idle?
Thanks for your time folks,,

Regarding the decomp allowing the pressure out of the cylinder. UNless the engine is turning over I don't see how a lever slipping between the cam & the rocker arm can cause a valve to open.

This is on a bike with 13,000 trouble free nmiles. Onl;y after I adjusted the idle mixture has it started this. Will changing the pilot jet change this? What about that "White spacer" will it help? I did idle it up to the point where, with a warm engine, at idle the bike was rolling at the lowest dash mark on the speedo. Earlier I refered to the "Tach" I was Hallucinating! thanks!  
P.S. I have had the bike die when cold, but usually I have the choke on 1/2 till it's warmed up well enough to idle. I did have the idle set ridiculously low, I do think it odd that the UNRULY son of a gun has figured out how to stop @ TDC.. amazing!

Adjust the idle RPM at 1100 RPM, not less.
When the engine dies at low RPM the piston will stop at TDC. The low inertia of the crankshaft is unable to overcome the compression.
You can check the device thats put extra fuel in the carb when the trottle is closed ( can't remember the name) It's fitted left from the idle mixture screw and has a 3 screw cover.  The transient enrichment valve.This can be dirty/stuck or the rubber diafragm punctured.

When you open the front (exhaust) valve adjustment cover you can see how the decrompression solenoid acts on the exhaust valve rocker. Bit difficult to explain.
On my engine (1993) I have installed an electrical device that operates the solenoid also when switching off the engine, not required for engines later than 1996 as the starter gears were changed after that date.

My advice to check the general mass connector behind the LH sidecover still stands and I might add check the sidestand springs, if they are weak the sidestand switch may interupt the ignition momentaraly and the engine dies.

Keep us posted, very interesting in what you find.

Greetz
Kropatchek

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


I think that's the idle enrichener, or choke.

Doesn't the solenoid pull a cable that rotates a shaft that then pushes up on the rocker arm which opens the exhaust valve?

Yea, the low idle speed is a likely candidate.