Hello from dublin

Have a 1990 -91 250 ltr, just bought it and have a problem with the engine reving. It revs to about 4-5000 rpm and will not rev past this, Prob is the same in or out of gear, Once in awhile it revs past this and flys but 99% of the time it sounds like it has a limiter. Anyone with any ideas ?

John F

1990 Lt250R
1999 YZ125
1999 R1
1994 Cherokee 4.0

 

sounds like a jetting problem. does it do this in nutreal? check your reeds they might be cracked or worn

 

check your compresion. also remove the exhaust valve cover and make sure the bearings are moving freely also inspect the spring to make sure it's in good shape. You should be able to pinch the exhast valve stem with your fingers and turn it counter clockwise. It should turn freely as long as spring is good. Just place spring on exhaust stem place cover back on line up the shaft. Then with the screws still loose turn the dial 360 degrees counter clockwise. And tighten screws down. If the compression checks and the exhaust valve is ok. I would have to say change out your cdi box. And check your reeds.

 

its probably a jetting issue if it does it when it's out of gear too. Try leaning it out a couple sizes. Also make sure the pipe isn't cracked.

 

Hi, thanks for the replies, I have been told that it could be the lower windings on the stator plate - does this sound possible ? The quad revs freely when cold for about 30 - 40 seconds and then wont pull into the pwerband. The motor has been rebuilt only about 2 riding hours ago so parts like reeds, powervalve should be o.k. but I will check them. The problem is the same in neutral. It really sounds like the revs are hitting a rev limiter , they rise to about 5000 revs then drop to 4500 then back upto 5000 and so on. Thanks again for the help,

John F

 

i had a very similar problem a while back with a 87 i had. Your looking in the right spot, its def. an electrical problem. Check the wire(s) on the magneto pick up (small black box that sits outside of the magneto- part number 9 here: link). In my case the wire was frayed so badly that only one or two individual strands of wire were connected. This allowed the motor to run but as the rpms gained the signal got more and more delayed due to the resistance of the single strands of wire. This acted exactly as you described even down to it running good for 30 seconds after startup when cold.

 

thanks for your time, I think it is electrical as well but will try anything at this stage, will try your sugg tomorrow and keep you informed,

John f

 

sounds like an air leak. check and replace the crank seal behind the flywheel. i doubt it is electrical. but don't let me stop you from changing your stator.

 

i had the exact same problem, it was a loose wire under the fuel tank, any loose connection in the elec. system will cause a miss , mine ran somewhat ok when cold the got the miss after like 3-4 min. of ridin, like a say any loose conn. in the system will cause the cdi to lose its mind.. good luck

 

Thanks for all the advice, i have been riding crossers for a long time and it dosent sound like the crankshaft oil seal because it runs ok at tickover and low revs and on crossers in the past that have had blown oil seals they would not run at low revs but only at full throttle. It feels electriacal the way once in a while it come to life and hits the powerband but I am far from an expert and could be any of the things you guys have suggested, so I will check the cheap fixs first then work upto the expensive ones if need be. I am really grateful for all your replies, I will let you know how I progress.

John F - Dublin- Ireland