Motorcycle Repair: 1988 vtr250, proper combustion, rear cylinder

Question
A 1988 vtr250, clean and check carburetor (checked float and chock), check for spark to the plugs, will start and idle, low in power when reving and at return throttle rpm is slow to return to idle, removed rear plug and it it wet. rear cylinder is cooler than the front cylinder. Is it valve adjustment?

Frank


Answer
Hi Frank.

How is the mixture setting in the carbs?  Have they been changed from factory at all?  If so, then that is where I would start.  If they have not been touched, then leave them alone.

You have spark, but if the mixture is correct then it could also be weak spark at the affected cylinder.  Check the coil as per the directions in the repair manual.  Make sure that it is within specs.

Valve timing could be an issue, but is not the most likely culprit.  If it were the issue, then you would suffer compression loss as well and still get proper combustion in the cylinder, so check the other things first.

Good luck and ride safe.
FALCON