I was messing around on my trx90 today and I decided to test the jetting. I've always known the jetting was bad so today I went full throttle for about 30 seconds. I took out the plug and the tip was white. This means that its running lean doesn't it? And also whats the stock main jet size for my 2000 trx90?


Thanks
RR

 

Its pretty tough to do a good plug chop on a quad that has an auto clutch. The motor needs to be killed, while still holding the throttle steady, and pulling in the clutch, ..if you just shut the spark and it engine brakes, or you shut the throttle, youre not gonna get a good reading. Todays gas has so many additives , it makes getting a good reading very difficult.
The best indicator of correct jetting is going by drivability symptoms.
If your quad is all stock, filter , lid , pipe, and so on, and the jets havent been changed, its most likely good as is.
Heres a good article on jetting, and it has a list of symptoms, for rich and lean.
jetting