Back firing

[Fedor]

Hello,
I just bought a 2005 kfx400. It is starting to backfire and is hard to start up now. Every time I give it gas it backfires bad and shuts off. When it is running and I give it gas it will start to die then kick back up .What could be the problem ? Any help at all would be appreciated.
Thanks

[350ex]

Might just need the carb cleaned.

[Fedor]

I checked the carburetor and it was clean but I still cleaned the jets just in case . Still having the same problem.

[twincat800]

I had a kfx do something similar like that to me, i took the stock carb from my dvx and it fixed the problem.. it was an extra carb i had so i threw the bad one out so i couldnt tell ya exacty what it was. Check the seals/gaskets and especially the vacumm hoses could be a small cut in one maybe??

[Fedor]

Only thing that makes me believe it maybe the carburetor is that once I adjusted the idle it started to backfire or that maybe a coincidence. I would like it to be a simple carburetor issue but I don't think it is since it was clean.

[twincat800]

It could be your valve clearance maybe

[Fedor]

What Ive read is that doing a valve job on this engine isn't bad. Do you have any tips or links on what to do?

[twincat800]

Just search through the forums i know theres some good ones in there somewhere.. or try private messaging cataway im sure he would know the links

[Fedor]

I did the shim job and now the cams are at the right clearance and I still have back firing problem. This is frustrating I dont know what to do next

[fearlessfred]

a leak down test or compression test might be the next thing to do . if u bring the piston to tdc on compression stroke,and use air preasure to fill the cylinder thru the spark plug hole,u can listen thru the exhaust or carb to hear if u have a valve prob.