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Discussion Starter · #1 ·
ok so there is a trillion lean and rich questions but i dont know how to word this to find out.. so please help.
bought 01 raptor 660r completely factory. bike was running rich would smoke black when revving. installed pro design air filter adapter uni filter and a slip on exhaust for now. and i figured doing these would lean it out so before i jetted i raised the needle 2 clips and now it runs like absolute butt no power at all so i lowered the needles back to stock but i know there is no numbers anyone can supply but i live in utah right about 4000-4500 feet elevation for these mods will i need to raise the main
can someone give me a general start jet size 660 at 4200-4500 feet elevation "utah" slip on exhaust "going to buy header pipe next month so want to jet for that so i dont have to rejet then" and uni air filter box lid on at this point
 

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I am unique
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Welcome to the forum.................
Now, this is my opinion, if you can see that the bike is smoking black, you cant be driving it and testing for jetting by just reving it is useless.......:)
 

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It's smoking black because you're throwing unburnt fuel out of the tail pipe by revving it up and down in neutral. If you want to test your jetting you need to do so with the engine under a load, either on the dyno or out in the world.

Mains don't get raised or lowered, simply replaced. Raising the needle 2 clips would have definitely made your midrange too rich, further contributing to the smoking.

So you want to know what to use for a full system with a pro design/uni filter with the lid on, to match the header you'll be getting soon, at an elevation of 4k-4500 feet.

The rule of thumb on a mikuni carb is one main size for every 2k feet or so. If the pipe company recommends 160/165 you should start out with 150/155.
 

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Discussion Starter · #4 ·
thanks for an answer lol i have been looking for a starting number for a week no one was willing to give me an idea. and i know they have to be changed the way i worded it just didnt sound right. and i called the yamaha dealership and they said that i need to bring the old jets in so they can match them up but that sounds stupid to me since i know there mikuni bsr33's so couldnt they just get the jets for that carb? and i was recommended to come here because willykiller is quote " a raptor god" lol
 

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If I remember correctly they use the small round mains, but your dealer, knowing little about the actual mechanical bits of these atvs, needs a part in hand so someone from the service department can tell him what it is, or so he can use the number off it to match it up on his computer.

It was smoking because you had the needle on the richest clip, but when you said "revving" I took it as sitting in place, and I think willy did as well.
 

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Master of the Electron
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150L/155R because you are at 4500 feet which makes the bike run richer... at 1 step (5 count) per 2000 ft, the recommended 160L/165R drops to 150L/155R.

I think they were assuming you already have your lid off - 160L/165R with aftermarket needles at middle clip and 25 pilots is the common recommendation when lid is off with aftermarket exhaust at sea level.
 

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Discussion Starter · #10 ·
Wrap this around your head riding today with lid of and exhaust with the factory jetting its running rich like the plug is black as could be and I put a new plug in twice to check color what do ya think ?
 

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Master of the Electron
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Well, if your exhaust is still that restrictive, it's certainly possible that the intake/airbox changes didn't lean it up enough to compensate for your elevation.
 

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Discussion Starter · #12 ·
So maybe pull the quiet core spark arrestor out and put in just the spark arrest less restrictive and lran it might lean it up thanks man I'm pretty new to this world and just need a little guidance another question the factory header pipe is hollow so is the aftermarket pipe why does it make such a difference in other words why not just buy a slip on
 

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Master of the Electron
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One, the aftermarket pipes are usually larger diameter and two, the pipes and muffler are tuned as a unit to minimize resistance to flow... the more flow, the more air/fuel you can get into and exhaust product out of the cylinder - MORE POWER!
 
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