Motorcycle Repair: 400 Big Bear timing, timing chain, shively

Question
Can you tell me how to time my friend's 2002 400 Big Bear? It pops bad at mid range in all gears and i hear what appears to be the timing chain hitting the cover. I've got the chain cover off and the gears seem tight but the chain is loose.  I have not timed a yamaha motor.

Thanks,  Bo  

Answer
Hi Bo,

Do you mean how to time the camsshafts? Ignition is electronic and non-adjustable.

If the cams need timed, you'll need the service manual. I don't have the service manual for this model.

I doubt the cams are the problem. I suspect carburetor air-fuel mixtures need corrected. I recommend thoroughly cleaning the carb and performing a complete tune-up.

Learn about reading the spark plug to know what changes to make to the carburetor, if any. Visit NGK's website to learn about reading plugs:  www.ngk.com  Click "Plug 4-1-1" link and view all the plug images, etc...

Visit "www.atvfrontier.com" This is a very good ATV resource.

Respectfully,
Mark Shively