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slomo138

jetting

9 posts in this topic

Since I am a new 4stroke rider I am not real sure on the proper way to jet these bikes.When I crack the throttle hard after landing off a jump or out of a corner, sometimes it will hesitate and stall.I do not know if this can be jetted out of it or if it is just the way I am riding it.

I am running 48 pilot,stock needle and clip position,160 main and air screw 1 3/4's out. Thanks

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when i jump i always down shift. you figure when you approach the jump you are at your max speed when you take off. once you land you are goig slower if you don't downshift you will be in too high of a gear and the engine will want to stall.when i am going into a turn i down shift when i go into it and upshift halfway through and crack the throttle .this might not be the best advice but it's what works for me. i'm mostly a trail rider and hill climber. i race and jump occassionaly.just my 2 cents

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Hey Slomo,

I'm having the same probs. Last bike was cr125 and I could open throttle and vary/time the hit with the clutch. My 450 will often bog and i have to back out and slowly open throttle, already having my timing blown for the jump or hill. Unfortunately I'm a four stroke newby too so I have no remedy. Sounds like you've made some jetting changes and I hope they helped. I can't even find the plug on this bike let alone jet it. I may just take it to local dealer to have it jetted. Gearhead buddies of mine say it sounds, smells and looks(glowing header) rich, but everyone on the site says they come lean. I don't feel like I'm going fast on this bike but obviously I am (pulling my buddies like never before). We need to do some tuning but adapting to the 4-strokes idiosyncrasies will take time. Hope you're enjoying your bike as much as I am. Later.

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That sounds like lean on the needle.

Try raising the needle (lowering the clip) one notch and see if that improves things. Since the YZ motor is essentially the same (provided you open the air box and uncork the exhaust ) you might also consider purchasing a YZ 450 needle.

Hope this helps.

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NO OFFENSE BUT YOUR GEARHEAD BUDDIES DON'T KNOW JACK. THESE BIKES ARE VERY LEAN FROM FACTORY. THE GLOWING PIPE IS NORMAL CAUSE THESES BIKES DON'T LIKE TO IDLE. EITHER RIDE IT OR TURN IT OFF. THE SPARK PLUG IS ON TOP OF THE MOTOR UNDER THE GAS TANK. MAKES CHANGING PLUGS A BREEZE!! (THAT WAS SARCASM INCASE YOU DIDN'T NOTICE)

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Hey thumper I went out and looked and there it was just like you said, right on top of the motor(sarcasing also) Changing/checking plugs on this bike seems far from easy having to pull the seat and tank, unless I'm doing it wrong. Anyway I did pull the plug after about 20 miles and "gearheads" said it looked pretty black(they tune rails/cars) and said all the popping was from unburnt gas(rich). Power feels flat on top(aside from bog on cracking trottle- please comment) and I don't know if its jetting or if I've ridden 2-strokes too long. I'm at 5000 ft in Arizona, cool but low humidity

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i don't think they're lean from the factory. not set up right is how i'd call it.

you can make the pipe glow with a #50 PJ and you can stop it glowing with a #35 PJ. depends what else you do. the needles are the only bit that is lean.

Taffy

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hick, saw your post regarding needle. thanks for the help. I'm trying to gather the best settings for all jets so I can get real close the first time around.

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If you do try the YZ needle let us know how it works. This was such an effective swap for the 426, and I can't think of a good reason why it won't apply to the WR 450 (but I've not yet seen a WR 450, or its air box, which I'm beginning to think may be a bit restrictive).

Changing the needle taper (like WR vs. YZ) might be the most significant twelve dollar mod you can make to a four stroke.

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