I just bought the quad and I love it. It has plenty of power, exhaust seems normal, idle is a little rough but it has a metallic-like knocking sound comming from the engine area. It sounds almost like the engine is actually hitting or tapping on something like a hammer and I can't see what it is. The engine seems secure, the mounts are tight. Now if it was something like piston slap it would have a lot of power loss wouldn't it? The sound seems to be comming from the cylinder area. I won't have money for a while to put it in a shop. Does anyone have any ideas on how I could find out exactly where the sound originates or what the problem is? I have a service manual but has anyone owned one of these scramblers for a while and has some good tips or advice on the operation and maintenance type stuff?

 

Good chance it is the primary clutch buttons wore out.If not it could be piston slap.You dont always loose power.

 

This is the same thing my Xplorer was doing and now it wont run at all turns over very hard *pulls very hard making metal on metal sounds* i'm hoping its the primary clutch.
Will know next week.

 

400's are notorious for piston slap,

if everything seems fine its probably nothing to worry about.

Mine has a sound, that sounds kinda like what you described, since i got it 8 years ago

check your counter balancer oil, and your transmission oil

for the hell of it put fresh stuff in

as far as your idle goes,

try adjusting the carb, cleaning the carb, and or rejetting

check your air filter too

 

I don't know about 2002's, but the earlier ones had more than just a piston slap problem. Over time they usually dropped the piston skirt into the crankcase and ruined everything. My 400 ran for a short while when I bought it, all the while it was grinding the skirt into little chips that screwed all the bearings. 800 bucks later, it's better than new. If I didn't wait so long, it would have been just 200 bucks. Go to Gen3usa and mail Rick Ritter. He's a guru on these engines.

 

Thank you for your quick response. Is there any external evidence that would give me reason to believe that it would be one and not the other. For example, if it was piston slap would I have a much lower compression, richer fuel smell in the exhaust or something like that? If it was the clutch buttons, would it slip while in gear or not go into gear very easily?

 

I don't know. Maybe it's serious or it could be nothing at all, that's why I am asking some people who have been around these quads for a while. I'm just wondering if there are any signs before complete failure that I should pay attention to.

 

Good advice on the fluid changes. If any metal comes out then maybe I can stop a problem before it becomes expensive. I know I need to adjust the carburator and re-jet. The guy I bought it from said he installed the correct jet for his altitude which is a few thousand feet higher than where I am at now and that I would probably need to change the jet when I got it home.

 

See now I hate to hear about the problem that Porider had with the piston falling apart and stuff. I'm wondering if there was any symptoms. Was it overheating really easily or something like that? Looking back, is there any wisdom to pass on to some other poor SOB? I guess that it's possible for the piston to make the sound for a while and then just shatter. Did CSI say it was a stock piston?

 

fluid changes>? its a 2 stroke

only fluids are trans and counter balancer.. change em anyway