It's not that. I've had that happen before. I learned to carefully slide the needle and it's piston down the carb when putting it back together.
Keep the ideas coming though
Engine running FAST or quitting---no in betweenNo I haven't. I sure hope it's that. I could fix it then. Also it fits with the fact that this happened over winter hibernation.
I read on the web a similar condition can happen with lawnmower engines. There was some adjustment of valve clearance that was suggested. If the exhaust valve isn't sealing on the intake stroke, that could be the vacuum leak. Does this sound logical? Please say it isn't: I don't know how to adjust valves and can't understand the owner's manual which was written 40 years ago by some Japanese who thought he could speak English. Thanks everyone. Last weekend I was out of ideas. What don't you understand about the valve adjustment.I have faith you can do it..Need to have the piston at TDC("T" mark on rotor) on Compression stroke if I'm not mistaken.Take your tappet covers off and grab the intake or exhaust adjuster on one side and if both have play up and down you should be on the side at TDC.Other sidea adjusters should be tight at this point.If that make sense to you?Also, is the throttle cable seated ok up where it is going thru the frame where the ajuster is?Just thought I'd ask!
Hi Joe
It' nice to hear from you after all this time. You were the one who clued me into the needle position issue that's caused by the after market rebuild kits. MNy bikes wouldn't run at all if it wasn't for you. I hadn't paid much attention to this forum lately, but someone contacted me over this recently reminding me of it. I looked at the bike this weekend. The fuel line isn't clogged and I think I managed to figure out the valve tappet thing---I think. Fortunately, I have another bike that runs fine, so I can look at it. Nothing seemed any different on the two bikes as far as the tappet adjustments. The 0.1mm feeler fit in them all. I guess that doesn't necessarily mean that the valves are sealing, but the bike was running fine last fall, so the problem would seem to point to things that can happen over storage. I doesn't look like the carb is the problem nor are any cables caught in the ON position. The fuel line isn't clogged and a bike engine doesn't have much of an intake manifold where there could be a vacuum leak. I'm back to being out of ideas again. How about the rest of you? I am slightly confused on how you get it started if it only runs if you give it throttle?If you put choke on for a cold start and hit the starter or kick start does it start easily and idle with choke at all till it warms up?Also, did you try the carb. spacer from the running bike when you swapped carbs or did you use the same one?It just seems strange that it is not a carb problem.Not sure where else to go with this one?How do the plugs look when the engine dies?Did you try spraying some starter fluid around the carb spacer when it starts to die and see if it will rev up or do anything at all?Joe
I need to keep the throttle open a bit to get it started. I will start more easily if I turn the key off and give it a couple of pumps with the kick start to fill the piston chambers with gas. When it starts, it starts fast and runs like a rocket. It's scary for an old guy like me to be sitting on something like that so I immediately start trying to get the rpms down. I can do so with either the throttle or the choke, but I can't maintain it at a reasonable idle speed. It's too delicate an adjustment. It will either quit or reeve back up like a rocket.
The vacuum leak thing sounds like the problem although I can't figure out where it could be since swapping carbs didn't help. I'll swap spacers a soon as I can. I had wondered about it but I made sure the carb was screwed on tight and it looked like a tight fit. As to the plugs I can switch them too but I can't figure out why a plug would do this. Thanks for all the help
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