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Discussion Starter · #1 ·
I apologize for yet another jetting question, but i really could use some advice.

Motor: Stock 660
Header: FMF Powerbomb
Muffler: FMF Powercore
Intake: AirBox Eliminator w/ Dual Banshee Style K&Ns & Outerwears

Needles: GYTR
Needle Clip: 3rd from top
Pilots: GYTR 25
Mains: GYTR 160L/165R
Pilot Screws: 3L/2R Turns Out

Fuel: 87 octane w/ Yamalube Conditioner / Stabalizer
Elevation: 3200 - 3600 ft



Starts easily
Sounds like it's missing / backfiring @ low idle
Raising idle setting smooths it out
Accelerates to Full throttle smoothy and swiftly
Upon Decel, returns to idle VERY SLOWLY
Tends to want to linger at about 1/4 - 1/2 throttle
Lowering idle screw brings back down quickly but idle remains rough

Background:
Quad sat in storage for 3+ years prior to adding intake and exhaust
Less than 100 hours on quad prior to storage
GYTR needles and 25 pilots were installed before storage for old pro-design / k&n filter kit

i removed and cleaned carb and added the 160/165 mains to accomodate the new intake / exhaust

I was seeing a lot of bubbles in my fuel line and fuel seemed to have a hard time reaching the carb. Just pulled the fuel tap out of the gas tank to clean it out. Looked clean, cleaned it anyway, and am reinstalling now.

Am i in the ballpark? What do you guys think?

Any help will be much appreciated.
 

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Master of the Electron
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Hanging idle = lean in pilot circuit. Make both fuel screws 2 3/4 -3 turns out to richen a bit... should take care of it.
 

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Discussion Starter · #3 ·
Since i still have the tank off i am going to pull the carb again and double check to make sure my pilot jets are clean (sat for 3 years with these in it). I will try those pilot screw settings.

Also gonna try these suggestions:

Carb Mods and Clear Tube Method: http://www.raptorforum.com/forums/showthread.php?t=538


Have you tried these extended fuel screws? Are they worth a darn? Seems like they could be helpful, but potentially hard to reach, esp. the right side with the header in the way.

http://www.ebay.com/itm/RAPTOR-660-...ies&vxp=mtr&hash=item43af3572c2#ht_500wt_1180


Thanks for your help.
 

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Master of the Electron
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Some eBay extended fuel screws have caused serious problems for forum members - the only ones I'm SURE work properly are the Vitos screws that come with their jet kit.
 

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I am unique
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Since i still have the tank off i am going to pull the carb again and double check to make sure my pilot jets are clean (sat for 3 years with these in it). I will try those pilot screw settings.

Also gonna try these suggestions:

Carb Mods and Clear Tube Method: http://www.raptorforum.com/forums/showthread.php?t=538


Have you tried these extended fuel screws? Are they worth a darn? Seems like they could be helpful, but potentially hard to reach, esp. the right side with the header in the way.

http://www.ebay.com/itm/RAPTOR-660-BILLET-FUEL-SCREW-KIT-CARBS-JETTING-ENGINE-CARBURETOR-/290702324418?pt=Motors_ATV_Parts_Accessories&vxp=mtr&hash=item43af3572c2#ht_500wt_1180


Thanks for your help.
If you are in doubt with the pilot jets and arent sure they are clean, replace them, the mikuni #25s work the best, GYTR uses mikuni jets, what you are suggesting is indicative of a very lean pilot circuit or a dirty pilot circuit, make sure you remove the fuel screws also since I have seen where these can be dirty and or plugged, another thing to check is that the small tip is still on the fuel screw, I have seen where these when tightened down to far break and jam in to the carb throat........
 

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Discussion Starter · #6 ·
Some eBay extended fuel screws have caused serious problems for forum members - the only ones I'm SURE work properly are the Vitos screws that come with their jet kit.
@QuadManiac: Thanks for the heads up. If i need new pilots i will order that kit. Are these screws "reasonably" accessible when installed? It seems like it would be hard to reach them for adjustment.

If you are in doubt with the pilot jets and arent sure they are clean, replace them, the mikuni #25s work the best, GYTR uses mikuni jets, what you are suggesting is indicative of a very lean pilot circuit or a dirty pilot circuit, make sure you remove the fuel screws also since I have seen where these can be dirty and or plugged, another thing to check is that the small tip is still on the fuel screw, I have seen where these when tightened down to far break and jam in to the carb throat........
@willykiller: i never pulled the fuel screws when i cleaned it out. i hope they are plugged and that solves my problem, but we will see.



I have another carb related question. I have installed a k&n 1/2" crankcase filter on the crankcase vent line (due to airbox elim). What is the preferred method for relocating the middle vent line on the top of the carb (with plastic fitting between the two vents that attach to the intake boots). Also, what is the purpose of this line?


Thanks for all your help, you guys are awesome!!
 

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I am unique
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@QuadManiac: Thanks for the heads up. If i need new pilots i will order that kit. Are these screws "reasonably" accessible when installed? It seems like it would be hard to reach them for adjustment.



@willykiller: i never pulled the fuel screws when i cleaned it out. i hope they are plugged and that solves my problem, but we will see.



I have another carb related question. I have installed a k&n 1/2" crankcase filter on the crankcase vent line (due to airbox elim). What is the preferred method for relocating the middle vent line on the top of the carb (with plastic fitting between the two vents that attach to the intake boots). Also, what is the purpose of this line?


Thanks for all your help, you guys are awesome!!
It is just a vent, I just install a couple feet of hose on it and let it hang down towards the rear of the air box............
 
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