2003 Yamaha Warrior 350 YFM350XR

calypsoaz · June 10, 2010

Ok this is a new thread, but I posted an old thread a few months back, i will link it, and the ones that recognize the thread, that is me.

UPDATE: Okay so I got a new carb (well used carb that I rebuilt) and got a new pilot screw, turned it two turns out, got a new stator, it starts up IMMEDIATELY!! I installed an Oil Cooler Mod with the Hayden 401 Transmission cooler, and couple of Fragola 90 degree -6an swivel fittings, yadda yadda so on, so forth. I put 3.3 Quarts of Valvoline Racing 20w50 oil in it. The clutch seemed to be slipping (it was sitting for 8 months (or more) doing nothing). Once it got warm and the clutch got wet (hehe sounds dirty) it seemed to shift fine, so everything is good in that department.

Here is my question... I took the Stock Airbox off of it. I built an aluminum housing that holds my electronics and battery (some cutting of the plastics was done) and I'm running straight UNI Carb Filter and crankcase breather. It seems to be running lean at the current moment, do I need to re-jet the quad? Has anyone removed their stock airbox and run straight filter? If so what jet kit did you use? OR did you just adjust the pilot screw out (or in) to compensate for the lean fuel mixture?

One other thing, my Haynes Warrior manual is right next to me, I'm just to lazy to hunt down the illusive instructions as to the correct way to turn the pilot screw in order to make it more rich/lean, does anyone know which is which?

Click Here to get to my old post

DirtDemon · June 10, 2010

You will want to run bigger pilot and main jets, and maybe move the needle clip down a notch. Buy an assortment of jets starting from the next sizes up from what you are running. I would keep the next 5 sizes of each around.

calypsoaz · June 10, 2010

Thank you DirtDemon!

One other question, my Warrior smokes white when you start it, but when it gets warms it stops smoking, should I be concerned? Are my piston rings going out/getting worn?

DirtDemon · June 12, 2010

The white smoke is probably oil burning off that has leaked into the cylinder past the valves while the machine sits. Once it burns off and warms up, it goes away because it doesn't leak in fast enough to be noticeable. Also, things expand when the motor gets warmed up and help seal things off, since the piston is alluminum, it expands a bit more, that could also be why the smoke stops after it warms up. Bottom line, a rebuild is in the near future, but for now, the most important thing would be to keep an eye on the oil level and keep an extra plug on you in case you oil foul the one in the bike. Here is a link to a shop that does some good work on Warriors for good prices.

Yamaha Warrior performance kit.

calypsoaz · June 13, 2010

it hasn't smoked since i first started it, so that's a good thing, someone on yfm350.com forums had mentioned something about that needle clip and moving it one clip down, tuning it, if it still doesn't run right, move it down to the last notch, but said he didn't have to re-jet it.

DirtDemon · June 15, 2010

Moving the clip down will only make the main jet come into play earlier, this will affect the mid throttle range and will not help with full throttle jetting. The only way to richen things up at fulll throttle is to put in a bigger main jet. Dropping the clip may help, but I think it would be best to richen up the both jets too.

calypsoaz · June 15, 2010

Thank you again dirtdemon, you seem like you know your stuff. When I get the time and money to deal with my carburetor again, i will swap jets and tweak my carb. I just hate taking it on and off and on and off, its a pain in the a$$!! I could just take it over to my father in laws. He is the service manager at a station, and they used to be a dealer of Artic Cat and serviced them as needed through his shop, and also knows a lot about other quads. I will see if I can get him to tweak my quad with me. So you said the next 5 sizes? I can tell you what the stock sizes are, because thats whats in it.

Stock jets are as followed

Main Jet: 145

Main Air Jet: 0.6

Jet Needle: 5J18-3

Pilot: 42.5

Pilot Air Jet 1: 1.0

Pilot Air Jet 2: 0.7

Tell me what I need of those jets, and what sizes, I would be more than willing to go to my Yamaha Dealer and buy them.

DirtDemon · June 16, 2010

Those are the stock pilot and main jet sizes, so if you get pilot sizes 45, 48, 50, 52 and 55, and main jet sizes 148, 150, 152, 155 and 158, you should be pretty well covered for any weather or elevetion changes and some future mods. Honestly, unless you really work that thing over, I don't think you will ever need a 55 pilot or 158 main, so to save a few $ you might just go with the next 3 sizes of each for now, I am sure those will be enough for what you have done. If you still need bigger jets, you can always pick them up later.