Not KFX Not LTZ

[ifixtheyride]

Sorry guys I have a yamaha warrior question and I asked over there with no replys and you all have been great to me in past. This is a 98 350 warrior it broke an exhaust valve and I had it replaced since then it appears to have some kick back for lack of better words. When you try in start it its hard then gets real easy. When its started it runs good except there is some noise like nylon gears meshing. I have replaced the starter clutch 3 times due to the bearing race cracking. I've checked valve lash several times and replaced cam chain and still have problem. The nylon gear noise is weird its not bearing noise. At idle it kind of surges up and down also. One other thing the damn exhaust caught on fire couple weeks back also been sitten in garage since!
Sorry to bug you all but I know there are some smart dudes in here.

1998 Warrior
Stage 1 Hot Cam
Full FMF Exhaust
Jetted no lid
2003 KFX 400 Loaded!!!

[jonboy]

I have a couple of possibilities to run by. Has it had a complete topend rebuild? Might have wrong placement of piston rings(gaps or chamfers wrong). Do a compression test on it and find out what it should be. Heres the one that I'm leaning towards,it sounds as if you are running way lean. That would be the possibility of the exhaust catching fire and could cause your rings to be hot seizing and causing the hard dry starts. Have you done a plug read on it to see if it is running lean. Does the header glow red while riding? These are some things I would look for.

[bellzbub]

if you are getting kickback then it is more than likely timing. has it been checked? sounds like the piston is hitting tdc before the valves are opened up.

[ifixtheyride]

I really haven't had time to check on your suggestions yet but I was questioning the timing and is why I changed the chain. When I line up the timing marks it wasn't perfect this one you align marks on the cam and sprocket then the "T" mark on flywheel. It was off slight so I rotated a tooth and seamed to help start problem some so I thought chain was stretched. It was a different flywheel cause it came with a starter bearing I replaced thought marks may be off alittle don't know how tight specs are. The quad still has that sound. I am going to do compression tonight then take apart. I did replace piston and ring with valve job but did not take head to shop to have fit. The jug was only a year old. Maybe its tight or I suppose I could have messed the ring alignment up. I'll let you know. The exhaust thing may have happened when son was riding it happened when I looked closer one header nut was gone and the other side the stud was gone so header was not tight to head big leak would that cause fire in muffler?

[bellzbub]

yes a loose exhaust will cause a fire if there is something is there to be burnt. still sounds like timing to me.

[ifixtheyride]

performed compression test last night got 170psi manual calls for 128psi max! I removed the head and the piston is in correct I did not rtemove jug for ring inspection though the thing goes up and down fine and no signs of wear. The top of the piston had some carbon build up kinda suprised being that it basically new maybe 4 tanks of fuel. The valves look ok too. I wonder if somehow I got a different base gasket or head gasket and that would explain the chain not lining up and higher compression. It is a hot cam but I had it in there working for over a year before valve broke this just happened when I replaced valve and piston/ring recent.