Air cooled 250R won't rev

[Blown 331]

We just bought an 84 R for $300. The guy just put on a new coil, reed valve and cage, chain and sprockets. He said it needed carb work. It starts and idles fine. If you barely crack the trottle it will rev a little. Maybe 2000 rpm at the most. If you open more than that, even hold it wide open it sounds like it's hitting a rev limiter (kinda like a polaris or 250X in reverse). If you put your hand behind the carb for 30 seconds your hand will have gas on it. I've tried new gas, and 3 different carbs with absolutely no change. Is the ingintion timing adjustable on these things? If so I'm guessing you have to pull the flywheel? Any other idea's?

[4cylinders]

hey, sounds like plugged exhaust. try it, if it is plugged take it to an auto shop with a hot tank, leave it in over night.

[ejc042]

The stator assy can be rotated a small amount. You should be able to loosen the bolts that lock it down without removing the flywheel.

[RideRed250R]

sounds more like a fouled plug to me or a plug with the wrong gap
adam

[ScottZJ]

I would check the exhaust pipe. Cuz getting an R that cheap means its not in perfect shape and might have been left in a shed for awhile. Mice love building nests in pipes. I would take the pipe off and see if you can blow air thru it(with an air hose not your mouth ROFL), then if you cant feel anything, take it to the local car wash and blow it out that way....watch out for flying mice haha.........peace

[Wickedfinger]

At first thoughts ... I think you are way too rich on your main and maybe even the pilot (airscrew adjustment) too from the sounds of it - but you said you tried 3 different carbs - What size carbs did you swap out on it?. That '85 R's 34mm carb you have is too big for it in stock form with its 142 main and 52 pilot ('84's take a 30mm RS with a 130 MJ), if thats what you tried, unless the jug is ported or you are running an open airbox. If its WAY too rich, you wont be able to do a plug check (because of the no reving). After that I would think its not advancing - its not a symptom of a bad CDI but a pulser or exciter coil maybe. One thing I always recommend is check the gas tank vent tube for a blockage, or more likely in this case a partial blockage (since its not completely shutting down when you rev it) - its so simple but it will wreak havoc if you don't know to look for it being clogged. If it was a clogged exhaust you would probably see alot of stove-piping around the header or particularly the stinger joint. I'm assuming you checked the air-filter already.

[Blown 331]

I've tried another stock 84 R carb and a larger flat slide (too big) but all 3 yeilded the same results. As of right now I am starting it with no air box at all. I took the exhaust off and I can blow through it. I even started the engine with no exhaust and that didn't change anything. I also tried 2 different gas tanks and no change. I'm going to work on it some more on Sunday so I'll let you know what happens.

[88 Turbo Coupe]

Check the compression

[TimSr]

I hope you tried a new plug first, before doing anything! That should alwasy be step one on any machine, 2 stroke or 4. Some two strokes you can vary the ignition timing slightly, but not enough to cause anything noticeable. Removing and running it without the airfilter, and without the pipe would be the next logical steps, which you have done. There are some rare electrical problems that only affect high rpm, but I would finish out checking the airflow system first, which pretty much leaves the reeds to be checked.

[timex69]

try replacing the gasket between the carb and the cylinder. It sounds like an air leak.

[70binder]

are your throttle cable isn't stretched?

[Blown 331]

It gets full throttle, sounds like it hits a rev limiter. The previous owner put new reeds, cage and gaskets in it. I took all this apart just to make sure. Compression feels ok when you kick it. I can't really see that being the problem but I'll put a gauge on it. I have another air cooled R that is in pretty bad shape and I hope to fix it but I may try swaping some ignition parts to see what happens.

[Blown 331]

Oh yeah. I dont think it is a rich or lean problem. I've choked it by hand to richen the mixture and I've shut the gas off to see if it ran better just as it ran out of fuel and this has no effect either. That's why I was thinking it was timing. What about bad crankshaft seals?

[twgranger]

Sounds like the main jet is too big but you said it's not?

[CuRt]

Check behind the coil for rust mine would act like it was hitting a rev limiter at silver lake, coulden't figure it out woulden't rev it would just start missing pretty much, when it did that it would start pushing gas back and opening the reeds up to where they would stay open and foul the plug.

Curtis

[Derrick Adams]

Hey Dude, My 83 does the exact same thing. Just ride it around for about 5 minutes and see if it gets better. Mine has done it since I got it, with both carbs. Once it warms up, it only does it at HIGH rpms. Probably just cold blooded.

[trikeman]

My 84 r does the same thing, still havent found out what the problem is.

[Blown 331]

Fixed. It was a bad CDI. Runs GREAT now!