Hi I have a 2002 Yamaha warrior. I just bought a bored cylinder and an 84mm piston and put that in it. I also put in an FMF jet kit, a K&N air filter, and a used camshaft and camshaft flywheel in it since my camshaft broke. I put all of this in and installed everything properly. It wouldn't start so i put the stock jet and needle back in, but it still wont start. It cranks and gets spark but will not start it gets compression and the air filter gets hotter than the exhaust when it backfires. It will only backfire through the carb into the air filter never into the exhaust, can anyone help me??

 

Sounds like you are 180 off on timing, so its firing on intake instead of compression. Make sure of your timing, get the TDC mark lined up, then take the cam cover off, your cam gear should have the dot lined up with the casting pointer on the head, about the 10 oclock positon. In that position, your valves should be closed, you should be able to wiggle the rocker arms on both intake and exhaust, indicating no tension on the valves. Only other thing that can cause that if the timing is on, you sheared the key on the flywheel so the spark is not happening at TDC. Also make sure your cam chain tensioner is working, could have jumped time if the chain is loose.

 

I had to buy a new camshaft because i sheered the key off of my first one, a cam from a 96 warrior with the flywheel. I made sure i lined up the t for tdc and the line with the triangle. I followed the clymer manual. The only thing is that i left one valve a tiny bit open before i put it together.

 

At TDC, there should be NO tension on the valves...even a "tiny bit open" will cause major problems, get your valve lash set up right, and that should cure the carb fires.

 

so should I take the cylinder head off close the valves then time the engine by putting the piston at tdc with the "t" and put the line on the camshaft at the top triangle?

 

The valve is opened and closed by the rocker arm riding on the cam lobe, if you adjust the rocker arm to get a .003-,006 (intake or exhaust) gap, the valve should be shut, if it is stuck open , you got other problems, like a bent valve or a bad valve guide. You dont need to take the head off, just the valve tappet covers in the front and back of the head (will probably need to pull the gas tank to get at intake side).

 

How do i measure the .003-,006??

 

use a feeler gauge between the rocker arm and the valve stem tip, you adjust the gap with the threaded rod, loosen the nut 8mm i believe, get your adjustment, then you need to hold the threaded part stationary while you tighten the jam nut,or your adjustment will change.