I have a yamaha Warrior 350 and i am pretty sure it has two vales and i was wondering what i would have to do to make it four valves and if that would make a difference. I was also wondering what other engine upgrades i could do to make it have more power, torque etc. I am not going to get a new bike so don't say 'get a new bike' because i'm not. now i now it is a very good bike and all but you know when we all get a bike its awesome but after some time you know you want that little extra power, torque, take off, etc. And that is what i am looking for.

oh and i put a new HMF pipe and rejeted the carb, and a K&N air filter.

Thanks.

 

The only way to add two valves is to get a new engine! You have already done well with the bolt on parts. To get more power at this point you are looking at going to a big bore and or stroker kit, higher compression, different cams, possibly head work.

Problem is, by the time you dump THAT much coin into your Warrior, you are still stuck with the handling and suspension of a Warrior. You could have put that money plus the proceeds from selling it and gotten a bigger used quad. I can respect that you don't intend to do that, so it may be best to just appreciate it for what it is.

 

I would also suggest to leave it like it is, there is no reason to waste any money on trying to make a Warrior go "fast" when you can go out and buy another ATV that is faster for the same amount of money. The Warrior's engine is a good, reliable engine, but it's just not designed to make alot of power.

I don't know of any head that would bolt up to a Warrior engine to give it 4 valves, that would require milling a new head out of a chunk of billett aluminum or something. I'm not an engineer by any means, but i'm sure there is more to the equasion than more valves to give an engine more power, like stroke, bore, compression, etc, etc, etc.

If you have plenty of money to waste, an aftermarket cam will really wake that engine up, I would recommend the Webcam 84 grind (Webcamshafts.com), also you would have to get the heavy duty valve springs. You could always get larger valves (+1mm) from Kibblewhite to help out, and get the head ported. All this will essentially do the same thing more valves would do, which is get more fuel/air in faster and get exhaust gases out faster. You would still spend at least $700 to get all this work done but it's cheaper than another engine or new head. As for the piston, I like the 366cc 10.5:1 compression kit from JE. This piston weighs less than a Wiseco which will help get the revs up faster. I would not recommend going with a "big bore" any bigger than that because you lose the reliability of the engine. Just remember that anytime you modify an engine at all it's not going to be as reliable as the way Yamaha made it.