Recently my much loved and cared for/ babied 1990 honda fourtrax has had its first ever serious issue (its got at least 3k miles on it, btw...had to replace all the brakes and bearings, and i run hard)...

At high RPM (Just above operating speed in a gear, say if your cruising in 3rd your okay, but if your planning on shifting up and give it that little extra speed thats where it starts vibration).

I immediately slowed down and went home at a slow speed (half mile)... Ive got no idea what it is...

last year i thought something was wrong but it was just the engine muffler heat guard, the nuts had all fallen out of it so it was vibrating against the engine... Im kind of hoping this is similar, but no, i dont think it is...

Any ideas? im not much of a mechanic, but im thinking needle bearings or valves?

Thanks, anything will be appreciated.. =c)

I've been very proud of how well that machine has held up over the years of hard riding, im sad to see something finally go wrong with it.... the biggest problems ive had is keeping enough gas on hand, and.. oh yeah when i stripped out the oil drain plug.. {yes, its ok, i check it each time i ride, even})..

later

 

From the way you describe it, it would seem to be related to the speed of the 4 wheeler, not the speed(RPM) of the engine. If was caused by the speed of the engine, it shouldn't matter what gear you're in. Can you be more specific in the symtoms?? Maybe I'm not understanding the problem, exactly. Oh, is it 4wd or 2wd?

 

Sorry

its a 4wd
and its not gear specific, it will do it in any gear, and even in neutral. so thats why i think its the engine or something related

 

Don't run the engine anymore. If you're lucky, it will be something loose on one of the clutches - you have 2, a centrifugal clutch & a wet disc clutch, both inside the right side cover. If it's not the clutches then it's probably something that requires further dissassembly of the engine, but either way you need to consult with someone with ATV mechanical experience. And you/they need to get a service manual. Most bike suppliers sell the Clymer brand, which is decent. Dennis Kirk carries them, I know. Good Luck!

 

check all your engine mounts especially the one at the top of the head,before you rip the engine apart eliminate all the simple things.