My brother has a 2001 warrior. he bought it used in about 2003. We both hate the thing now, it seems like its broken all the time. plus it doesn't have enough power for him now. So he wants to fix it up and sell it, and hopefully get a yfz to race. So i've decided to help him and im outlining the major areas, and looking at what we can/cannot do ourselves.

-First off, i think the piston might need an appointment with my garabge can. Not totally sure, but it blows a bit of oil smoke (blue/white) on start up and when the gas is mashed. How can i visually inspect the piston and wrings to determine if they are good? how hard is a piston to change on a 4-stroke and what tools are needed? Could i simply put a high compression piston in it if the stock piston is worn out (to possibly boost resale value)?

-I beleive the valves are far out of spec. How can i check the clearance or if they are sticking? what tools would i need to do this? how would i fix them?

-He tells me the clutch slips sometimes, and sometimes just revs out like its in neatral. So im assuming the clutch is going? I'm not very well breifed in the in parts of a clutch. when i pop the clutch cover off what should i look for? what will most likly need replacing? clutch plates? basket? i dont know.

Thats for the motor/tranny. I dont know how well the electrical system is on the bike. but dont know how i can test it. but i think thats a different story. right now i want to focus on the motor.

if anyone can help, i'll really appreciate it.

 

I'm not much of a motor person, but to inspect the clutch you need to take it apart. The normal wear item for the clutch is the friction pads, but usually the clutch parts some in a kit with the springs, friction pads, and steel discs.

If you want it, I uploaded a service manual for the warrior, which should help you out with your rebuild.
Warrior Service Manual (PDF)

 

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A compression test , will determine how bad the rings or valves have got. You may not get much of a return on your money, to fix the motor, and resell. Especially if you use a high compression piston. Most guys who are looking for a used warrior want a totally stock motor, and if they want to hot rod it, they want to be the ones who do the work. The issue could be worn valves or guides, and the piston and rings could be just fine. If it smokes only a little, and the compression is good, id sell it as is, and that would be the best return on your money. Changing a piston, is a major job, and unless its done correctly, itll actually hurt the value of the quad.

There are lots of guys out there, looking for a fix it upper, to do a father and son project on, youll find a buyer, even in its current condition.

The valves wont 'stick', they are mechanical. You just need to check the valve stem clearance, and if you upload the link, the details are in that manual. Its an easy check.

The clutch slipping could be caused by using the wrong motor oil, its posible itll stop slipping by using the correct oil, but if its gone on too long, the friction plates could be coated with moly, and never provide friction again. So even if you inspect them for size, they still might slip when reinstalled. But the only way to know, is to disassemble and measure them. The instructions for that, are also in that manual.