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Discussion Starter #1
New to the Raptors, first time owner, not a certified mechanic but Ive worked on a bunch of various motor driven vehicles/toys. Bought a 01 660 running and riding but as a fixer upper project for $600. It needed a few mechanical and cosmetic issues fixed, tires, wheel bearings, etc but the primary problem was that it didnt run right. It Idled rough and would only run at 1/4 throttle before it cuts out. The guy I bought it from took it on a trade and didn't do any work to it. He was told it was bored out to 700 but was not sure (seems high, could have just been honed), that it has a FMF header and slip on pipe, ebay carbs and k&n air filter in stock sealed box, break away clutch lever. The only obvious problem was that one of the boots between the carbs and jug was torn and it was Jerry rigged and the choke adjuster on the bars was broken.

So, I cleaned the carbs, checked floats, put 2 new boots on, fresh spark plug, and left everything as is. I didn't mess with the jets, slide position or mixture screws. I put it back together with new choke lever & It idled great, revved up to full throttle, hopped on and it and as soon as pulled out it sputtered and died. An internet search later, main result was reverse/parking brake limiter. However, clutch safety switch and p. brake was removed and reverse light doesnt work so Im guessing reverse was bypassed. Plus, I could get it to move ok with the choke on. Took carbs back off b/c i didnt identify jets, fuel screw position, needle position. Found out main jets were 146L/148R, power jet doesnt have a size marking, jet needle has 6 positions and was 3 up from bottom, and Pilot jet is 32.5 (seems too high), left screw was out 7 turns (way to high!) and right was out 3.

So, i adjusted fuel screws both to 3 turns out, messed around between 2 and 3 and forgot where i landed but it idled smooth, revved thru high rpms great but as soon as it was in gear and clutch released, i had to have choke on to prevent a stall. Other odd thing is that after I got rpms and speed up and in 2nd 3rd gear i could turn choke off and it would rip. It is in the winter months here near Pittsburgh, PA (1400' ASL) but when i mess around with the tuning its at least 50 F out and bike is always at running temp. My buddy and I determined if it needs the choke then it needs a richer mix. The pilot jets are already 32.5, the needle is already in mid position, so i thought bumping up the mains may help. So i took everything back apart and cleaned every orifice and installed 155L/160R Mikuni jets, left both screws at 3 out and it didnt improve anything.

I have not checked compression or valve clearance nor have i adjusted the jet needle. The bike did have a small 5lb battery thru most of this experiment but i bumped it up to 14lb and there was no difference. I havent checked the spark plug since i put it in, i guess i should do that. I did spray starter fluid all around the motor looking for vac leaks but didnt find anything. I tried running with the air box lid off but that didnt make a difference. Tried some seafoam and high octane gas but it didnt make a difference.

Am i correct for thinking if i need the choke on, it wants more fuel?
Are the 32.5 pilots too big?
Should i stick with the 155L/160R Mikuni mains?
Am i chasing my tail messing with unbranded ebay carbs? (Im stubborn and want to make these work, just as an ego thing. Plus OEM Yamaha parts are expensive!)
Do i really need to pull the head off to see if previous owner did in fact bore it out and any possible head work?
What would yalls next step be? (I already heard sell it and get a 700 fuel injected raptor) LoL

Thanks in advance!
 

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If you truly have 32.5 pilot jets...that's the problem
22.5 is stock, and 25 is sufficient for most builds.
Search for "Clear tube method", as it is the only way to properly set float height.
And, you will benefit from a Dynojet jet kit, because it is the only way to get their needles, which have a different tip taper, and seat better.
The 155/160 mains may or may not be too big, you'll need to swap pilots firtst, but it IS correct that the right side carb takes one main size bigger than the left.
Both pilots and needle positions should be the same.
4th or 5th needle position is where to start as well.
 

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Discussion Starter #3
Sixpack577: thx for the reply. It definitely has 32.5 pilots in it. The markings are clear. I already ordered a pair of 25s and 27.5s with the intentions of trying 25s first. I considered getting a DJ kit but wasn't sure if the needles were going to work with unbranded carbs and that's why I went with the Mikuni mains first since they were a cheap investment. I found out later mikunis are sized per cc flow not hole size...urs saying use DJ needles and keep 155/160 mikunis? I never heard of needle jets having 6 positions but I will try mine at 4th up too. (Obviously it's best to change one thing at a time). I've heard of the clear tube method but used the measure 13mm off the boat seat to top of float method.
 

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If you have Chinese carbs, that can be an issue in itself.
They are notorious for being bad.
I would buy a used stock pair and rebuild them.
The Dynojet's needles are the best, and the 27.5 pilots will be too big in the chinese or stock carbs.
DO the clear tube method, it really makes a difference.
And yes, Khein and Mikuni use different units of flow/size/measurement, and I always have to look up which is which.
A Dynojet kit in stock carbs with the clear tube method will solve your problems, only leaving trying a couple different sizes of main jets.
 

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Master of the Electron
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32.5 is not recommended but you can make them work... but with them you should be down at, perhaps, 1 - 1.5 turns out on the screws. The pilot jet sets the MAX flow through the idle circuit, the screws act as valves on that flow.

The main jets you are running (DJ 146/148) require the airbox lid to be off or holed and you will also need DJ needles for this. Are you open or closed? BTW, the 155/160 Mikuni mains are actually SMALLER than the DJs you had originally.

I also suggest that your pilot jets or the passages from pilot jets thru the screws may be partially clogged - gotta clean them very carefully with sprat cleaner and fine copper wire.

Are you open airbox or stock, unmolested airbox? Tell us and we'll tell you what you need. Also, you need to have the box and snorkel in their final, jetted configuration while testing - you can't jet for closed airbox and have the lid or snorkel off for tests!
 

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Discussion Starter #7
QuadManiac: it has sealed unmolested air box with k&n filter. I prefer to run sealed box if I can. Carbs have been off, disassembled, cleaned, sprayed like 2 or 3 times. I thot mikuni 160 was equivalent to dj 170 and 155 mikuni was dj 166.
 

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Master of the Electron
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Okay, you then need Mikuni 145L/150R mains - you are WAY TOO rich.

You need stock needles in the middle/

You need 25 pilots with the screws about 2 to 2.5 turns out.

DJ 146/148 is equivalent to Mikuni 160/165 !
 

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Master of the Electron
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Did you remove all jets and screws and spray THROUGH all passages in the body and jets?
 

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Discussion Starter #10
QuadManiac: yes...disassembled/cleaned/sprayedmeaning everything possible removed. I have 145/150/155/160 mikuni mains...i ordered 22.5 & 25 pilots...so I planned on trying multiple tunes. Thanks for advice. Will update the forum when its tuned and running right
 

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Master of the Electron
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Great! Good luck.
 

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Just a quick observation....like QM said you already had DJ mains in it (146\148),and the needles having 6 positions means you already have the DJ needles as well,as stock only has 5 positions,the DJ's have 6.Also like QM said,those mains that were in there were too big for still having an airbox lid. If you go to the dynojet site you will be able to download their instructions for the kit.

Good Luck.
 

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Discussion Starter #13
So, Im still running the ebay carbs with closed air box. I put the 25 pilot jets in along side 145L/150R mikuni jets. I put the needles on the 3rd clip up from the bottom and both of the fuel screws out 3 turns with a fresh plug. After all that, it still needed the choke to run good enough pulling out without stalling unless I revved up the rpms.

So I raised the needles to the highest setting and the quad ran better but still not perfect. It would then have enough umph to move w/o the choke but still stuttered.

I bumped the main jets to 150L/155R mikunis, left screws at 3 turns out and the needles all the way up and it improved but not entirely.

I got it on TDC compression and checked the valve lash but it was set to damn near if not 0. So I set valves to what I thot was intake .004" & exhaust. 006". Bumped up to 155L/160R mikunis mains, screws 3 turns out and needles all the way up and it's running much better.

However, my valve adjustment was off and now it has quite the loud tick. I didnt replace plug during all this adjustment but I pulled the plug & it was blacker than night and was not from oil.

So I'm curious, are these off brand carbs that big of junk that they need a ton of gas to run right or have I just not found the sweet spot???
 

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Master of the Electron
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If your box is open - Mikuni 160L/165R or DJ 146L/148R mains, DJ needles... closed - 140L/145R mains (don't know DJ numbers),stock needles. (drop 1 jet step - 5 in Mikuni, 2 in DJ - every 2000 ft rise in elevation)

If these aren't in the ballpark at sea level then there is something else wrong unrelated to jet size! Ebay Chinese carbs are famous for being nearly un-tunable. I'd go back to OEM or plan on spending WAY, WAY more time trying to get the junk to work... no guarantees!

One major word of warning: ONLY change one thing at a time. You will never figure out what's working and what's not if you make multiple 'fixes' between tests!
 

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Not sure about your elevation or temp your are riding at but I use all makuni. And I'm in PHX arizona. Full Yoshi slip on and open proflow intake

Needle on the 4th spot
Mains at 175/180
Pilots 25

It rings great! You would probably be same on pilots, needle POS.
But with a sealed airbox.... Probably 155-160 just my opinion.
Did you try taking off the lid (more air) and see how it ran?

Also when it's idling, spray starter fluid all around the carbs. Make sure it's not sucking air where it shouldn't be
 

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Discussion Starter #16
Not sure about your elevation or temp your are riding at but I use all makuni. And I'm in PHX arizona. Full Yoshi slip on and open proflow intake

Needle on the 4th spot
Mains at 175/180
Pilots 25

It rings great! You would probably be same on pilots, needle POS.
But with a sealed airbox.... Probably 155-160 just my opinion.
Did you try taking off the lid (more air) and see how it ran?

Also when it's idling, spray starter fluid all around the carbs. Make sure it's not sucking air where it shouldn't be
Sprayed starter fluid...no vac leaks.

Finally got around to working on it again. Bought used OEM Mikuni carbs and rebuilt them. Stock 22.5 pilots, 146L 148R dino jet mains, dino needles set on 3rd clip from bottom, mixture screws 2 turns out on both and she runs great. Need clutch kit tho cause 1st n 2nd are strong but last 3 are weak
138576
 
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