Ok so i have just got my first ltr, also my first 450 about a month or 2 ago and I've been racing it, taking care of it, everything on it is good except one thing. when the engines cold it runs great and it is fine most of the time when its warm to, but every once in a while (becoming more and more often) usually when i let the rpm's get down coming into a corner, it will only give me about half of my rev range. it actually sounds like a rev limiter but slow. but then all i have to do is pull the clutch, hit the kill switch off then on again, let go of the clutch and its back to normal. i cant figure out what it would possibly be. what do some of you ltr experts think? also, the quad is an 07 engine mods are: 13.5:1 piston, port and polished head, +1mm valves, new valve guides, twin air filter and cage in stock airbox with no lid, full dasa exhaust, and a pim2. the engine was just rebuilt and i bought it with about 5 hours on it. always run 110 unleaded unless i the store i buy it from is closed, then 110 leaded out of a gas station nearby. oil im running is rotella t 15w-40. any help would be awesome!

P.S. i didnt pull the spark plug yet because from the looks of it, you gotta take the just about all the plastics and the gas tank off and havent had time to do it yet with work and school.

 

It seems like an electrical component getting hot and failing. However for cost reasons treat it to a new plug, check valve clearances and check the voltage regulator is producing no more than 15v first. In theory checking the resistance of the coils should show if they are the problem but this does not always work. If that doesn't produce a cure, substituting the coil, trigger coil and CDI in turn should sort it, but it is an expensive way of finding the fault.

 

Thanks. I really appreciate it