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mdrasmussen

05 wr450 jetting question

15 posts in this topic

same old question i know but please help!!!! Ok here it goes.I have a gytr AIS block off kit that came with a needle??? Set it at 4th grove down from the top..Installed the 48 pilot jet that it came with.Then installed a 170 main jet and a sunline air fuel mixture screw set at 2 turns out..And all the free mods have been done.Now the bike has a big bog when you snap the throttle and coolant is dripping from the bottom of the bike.Forgot to mention that i have an yzf 450 pipe from my buddies bike..PLEASE HELP.THANK YOU

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Are you flogging the throttle on the stand? You can first try to ease out the mix screw 1/4 turn and ride it. The coolant drip I'm guessing is you ran it too long sitting still, the rad's need air flow or it will boil over

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You're not jetted right. Read the stickies and consult the jetting database. You have the off-idle bog and need to make some adjustments to your AP circuit...SC

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Well i rode it up the street (pissed off the neighbors) anyway did it every time i grabbed the throttle.....And it was only ideling just a couple minutes???

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First off the leaking antifreeze is not related to the bog unless you did as was said and had it boil over. Its been a while since I fiddled with the water pump so I'll let someone else comment on that.

As far as the bog, I agree with the others.......try setting your fuel screw correctly and see if the bog goes away. If not, try adjusting the AP or change the leak jet to a smaller size. If this doesn't work, you might try a Boyesen Quickshot or Scary Fast Powershot to get rid of the bog....me, I have made my bike run tip top. I have done the BK mod using 0 leak jet (plugged) and use a Quickshot cover. My jetting is in the database.

better luck

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ok..so i should go with a 40 leak jet or maybe solder it off??? before messing with the ap..

I would adjust the AP before doing anything else actually....however the bog comes from a momnetary lean condition when the slide is first openned up (when the throttle is whacked open). It can be hard to get rid of the bog but feel lucky your not messing with a carb on an 07 because you can easily change things and experiment.

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same old question i know but please help!!!! Ok here it goes.I have a gytr AIS block off kit that came with a needle??? Set it at 4th grove down from the top..Installed the 48 pilot jet that it came with.Then installed a 170 main jet and a sunline air fuel mixture screw set at 2 turns out..And all the free mods have been done.Now the bike has a big bog when you snap the throttle and coolant is dripping from the bottom of the bike.Forgot to mention that i have an yzf 450 pipe from my buddies bike..PLEASE HELP.THANK YOU

I have an 05, the same set-up as you except the JD kit red #4. Depending on your temp and altitiude you are probably running too rich. I tried the 170 main 48 pilot jets and I ended up with 168 m, and 45 p with a turn or two on the fuel screw. Are you getting a 1/8- 1/4 throttle stumble?

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I am a California rider with an 05 450 and after much trial and error I ended up with a 45 pilot, 168 main, can't remember the needle setting but I think it is the JD Red#4. The bog is from the accelerator pump. Change the leak jet to a smaller one. I have a #40 leak jet and the Boysen Quickshot but you can probably get the same effect by just changing the leak jet and adjusting the AP duration. I have no bog.

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One more thing, don't fall into the trap that bigger jets are better. Most bikes are way to rich.

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One more thing, don't fall into the trap that bigger jets are better. Most bikes are way to rich.

EXACTLY.....I run a 165 main, and the JD red is still too rich so I use an OEM needle shimmed with 2 small washers. I use a 40 pilot jet but I have the ACV disabled. With ACV enabled, a 45 is plenty big usually. A Boyesen Quickshot will cure the bog I bet.

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Here's something to consider. I have a 05 wr450.. I have been riding all my life and pride my abilities as a well rounded bike mechanic, however, this machine seems to elude my best abilities.

I have all the free mods done, gray wire cut, air box open, yz throttle stop, fmf q2 pipe, rejetted to 168 main, 48 pilot, and a yz needle. Bike runs awesome except for the dreaded off idle bog when you crack the throttle. Everyone says buy the quickshot and problem solved, as this was NOT the case. I put the quickshot on and poo poo went my bog even MORE! It was worse, a LOT worse.

So here's my thought; the quickshot gives thirty-something percent more fuel to the AC pump, and made my bike run worse so logically thinking the pump is too rich. I'm running a 40 leak jet. Now my last shot at getting this stupid bog out is to buy every leak jet from 50-110 and change them out ever so slowly leaning the AC pump out. Other than that, the bike breaths fire.

If that doesn't work, I have heard something about the AC pump jet that squirts the fuel into the ventury should squirt right onto the needle valve but it just shoots straight ahead as the AC pump jet is set to the right of the valve about a half centimeter, and you need security bits to crack the part of the carb that houses the AC pump jet. So who knows?

Tuesday I will order the jets and start the guessing game. If anyone has more info on how to tune this bog out PLEASE post after me as I'm about to pack the gas tank with C4 and blow the damn thing to hell. I love this bike, but I HATE this fudge'n bog! HELP!!

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There's a fine line between a rich and lean bog. Finding the sweet spot is hard to do. You need to pull the carb, set the AP linkage per the manual and then time the AP squirt. The sweet spot is considered to be right around .75 seconds with a good strong shot. It took me about 6 months of tinkering to figure out how to do it with the proper combination of AP diaphragms, leak jets and a video camera. I'm now at .8 seconds and bog-free. However, I still think I can improve so I'll likely send my carb off to Zip-ty to have them do their $100 carb mod...SC

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