1999 yamaha warrior 350

[Warrioryfm1999]

I got a 1999 yamaha warrior fresh rebuild new cam valve and poston, the problem is ever since the rebuild anything past 1/4 throttle it falls on its face and backfires out the exhaust and rarely out the carb, ive tried new coil, new pick up coil new CID, tried the clutch and park brake switch, has bigger jets, its been cleaned several times and i dont know what to do please help.

 

[jimmyde78]

What is your air intake setup? And what kind of exhaust do you have?

 

[Warrioryfm1999]

What is your air intake setup? And what kind of exhaust do you have?

Stock air box k&n filter, and FMF titanium 4 full exhaust

 

[Warrioryfm1999]

And ive already checked the intake boot, valves are adjusted and not too tight i need help

 

[jimmyde78]

Backfiring like that out of the carb is a lean condition. What size jets do you have in there?

 

[Warrioryfm1999]

Backfiring like that out of the carb is a lean condition. What size jets do you have in there?

its a 147.5 main and 45 pilot with closed air box and the choke all the way out does nothing but make it idle like crap

 

[YAMAHAULER]

just for good measure spray the carb boot between carb and head with starting fluid while its idling and see if the idle goes up if so the boot is cracked and will need to be replaced

 

[YAMAHAULER]

also what does the spark plug look like?

 

[Warrioryfm1999]

also what does the spark plug look like?

I just replaced the boot and tried the starting fluid anyway and didnt change the idle and it has a good strong blue spark

 

[YAMAHAULER]

ok but what color is the plug take it out and see what color the porcelain is inside the threads

black=rich
brown=perfect
white or grey=lean

 

[Warrioryfm1999]

ok but what color is the plug take it out and see what color the porcelain is inside the threads

black=rich
brown=perfect
white or grey=lean

Its blackish, never mind sorry its white i had to look at it shoulda did that first lol

 

[YAMAHAULER]

then it's too rich

 

[YAMAHAULER]

how many turns out is the Air/fuel screw? it should be 2 full turns out

 

[jimmyde78]

then it's too rich

Hmmm. Usually backfires thru carb are a cracked boot or a sign of the bike running lean. But Ed is right.

 

[YAMAHAULER]

does it have aftermarket exhaust and filter? or all stock?

 

[jimmyde78]

Its blackish, never mind sorry its white i had to look at it shoulda did that first lol

Wait I'm confused. What color is the plug?

 

[jimmyde78]

If its white then it is running lean. Go up to a 150 main jet

 

[YAMAHAULER]

is it an old plug or a new one?

 

[Warrioryfm1999]

Its got stock air box and k&n filter and FMF titanium 4 full exhaust, and yes the air fuel screw is two full turns out its a brand new plug and its white at the end, and im gonna get a 150 main jet and give that try

 

[YAMAHAULER]

:tup:grab a 152.5 and 155 too just in case