[Bunnycop]

i just put my bike all back together (750 brute) after installing a HMF utility exhaust, Dyna CDI, snorkel kit, and jet kit( 150's front and 155's rear, air screws 2.5 turns out) and all it wants to do is spit and sputter under throttle. it idles good but thats about it. any ideas? im at about 1200' in PA...thanks

 

[Bunnycop]

thanks, ill rip it all back apart and try the 140 and 144's.. i also put on an twinair filter

 

[Bunnycop]

i had the twinair on when i tested it ,,, i have the air screw at 2 1/2 turns out

 

[Bigmike750]

Do you have your snorkel setup on the bike now? If so 150/155 main's will be waaaaay too rich!

 

[Bunnycop]

yes, everything is on the bike. should i try 140 and 144's?

 

[mudlift]

<div class='quotetop'></div>

Originally posted by Bigmike750
Do you have your snorkel setup on the bike now? If so 150/155 main's will be waaaaay too rich![/b]

That's what I used to think. My buddy just got his back from the shop & it runs like a champ. Here's what he's got....150 front, 155 rear, 4th notch on needle, 3 1/2 turns out. Yes, he has snorkles, HMF & module. I have the same mods. with 130 front, 136 rear, 3rd notch & 2 turns out. I guess every bike is different. Sometimes it can be a pain to tune these things.

 

[Bigmike750]

I agree with you Mudlift,every bike is different in how it respond's to jetting.I ran my 05' with an HMF slip on,Dynatek ingnition and a dynojet jet kit. As per the dynojet instructions I used the 150/155 mains and at our elevation it was too rich in the mid and upper rpms.This was without a snorkel.

 

[Bunnycop]

i finally got it tuned in i hope. i used a 140 front and 144 rear with 2 1/2 turns out... clip on 4th grove with two shims... we are going riding tommorow so i will let you know

 

[B Man]

you will definatley have to play and tune your bike wit those snorkles. Mine was still rich with 140/145's.
My next bike will have dual snorkles so maybe it will not affect it or add some air flow only time will tell. And i will have my next one dyno tuned with the snorkles so it will be spot on.

 

[Bunnycop]

ok, just got back from a ride and its still sputtering at full throttle with the 140/144's in the carbs...should i go leaner? 138/142 air screw is 2 1/2 turns out..helppppppp

 

[Bigmike750]

Is it ONLY doing it at full throttle? In other word's it's running good at ALL other throttle position's? Is it poping out the carb's at all? or just the exaust? How bad does it sputter? Just a little or does it sound really bad? Lemme know.

 

[Bunnycop]

about 3/4 to full it just like cuts out and sputters...... im pulling what hair i have left out

 

[Bunnycop]

PS, i have lots of cold beer in the fridge Mike,,,hint hint

 

[Bigmike750]

LOL! 10-4 on the cold beer Tom!

That's the number 1 thing on our list of "trail supplies" when we ride. Ok, here's a crash course on carb jetting. Your idle mixture screw control's your idle mixture (Duh :roll: ) Your pilot jet is responsible for for your fuel mixture from just off idle to about 1/3 throttle then your needle takes over and controls it from about 1/3 up to about 1/2 to 2/3. After 2/3 throttle it's all the main jet. Since your main jet control's your fuel mixture from 3/4 to full throttle and that's where your having the problem then your main's still gotta be too big. I'm runnin a 140/146 main on mine and I don't have it snorkle'd and mine runs great! I'd drop down to the 138/142 combo and see how it work's. P.S. before you pull the carb's again (I'm sure your getting tired of that by now) try pulling your snorkel off or proping your airbox lid open a little (1/4 or 1/2 inch is all it will take)and take it for a spin. Doing that will add air to it and it will probably help with the full throttle poping. Lemme know what you come up with.

 

[Bunnycop]

tonight i ripped all the dam plastic back off and pulled the carbs off to rejet again. i went from the 140/144 set up to 136/140.... i let it warm up, ran it down the road at 70mph and it sputtered in a different way at full throttle. i pulled back in the garage after all the neighbors lights came on to see what the hell just ripped up the road at 70 mph.... and i pulled a plug and no its running lean(white plug). so i put in 138/142 and i will see how this works tommorow after work. i am running 100LL so ill drain it and put in some 94 sunoco tommorow to see if this has any affect...

 

[Bigmike750]

Did you try the airbox thing like I said? Also some of the high octane fuel's wont color the plugs right away cause it burn's so clean,it take's a little time.

 

[Bunnycop]

yep. it cleared it up some, thats why i went down 2 sizes thinking it was way to rich still, and now its lean,,i hope the 138/142 work,,its driving me nuts

 

[Bigmike750]

If opening the airbox lid helped it then I'd think it's still gotta be too rich no matter what the plug's look like.How far did you open the lid? BTW I forgot about you saying brfore that you had TWO shim's under your needle's, I think I'd take one out. Good luck buddy! Let us know how you make out.

 

[Bunnycop]

actually the shims are on top of the c clip. i guess its to adjust the spring seat, thats what the instructions said to do from the jet kit.

 

[Bigmike750]

Oh, ok, yea there are two shims that go on top but I though you also meant that you put two additional shim's under the needle too.