Motorcycle Gearheads Needed!

502 Views 14 Replies 10 Participants Last post by spinwax, Oct 25, 2005

InfraRedSVT

Discussion Starter · Oct 22, 2005

Ok, so I am considering getting an exhaust for my bike and everything I have heard says you should rejet the carb whenever you increase exhaust flow because the engine runs lean. My question is, do you HAVE to do this, or is it just to get the maximum power out of the mod. Does not rejetting hurt the engine at all? I would like to not have to do this, at least not right away. The power isn't the big issue right now, its more so the sound I am trying to improve.
Oh, and I am currently looking at either a Vance and Hines or Jardine exhaust (my bike is a Buell, they are the two that make ones for my bike, so these are really my only options.) Any suggestions on the two?

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s2d2

· #2 · Oct 22, 2005

depends on the bike and the exhaust. consult a buell website and see what others have experienced. on the BMW F650 (my bike) you generally don't need to rejet

CentralCaliSVT

· #3 · Oct 22, 2005

Yes, you will need to re-jet it. No if ands or buts. It is necessary.

InfraRedSVT

Discussion Starter · #4 · Oct 22, 2005

Ok, but will not rejetting HURT the engine?

s2d2

· #5 · Oct 22, 2005

seriously, CHECK WITH SOMEONE WHO HAS A BIKE JUST LIKE YOURS AND AN EXHAUST JUST LIKE YOURS

the worst that could happen is that you go the wrong way and get too much fuel in, you run rich and have carbon buildup. could foul a plug and yr engine just won't run to it's fullest. WORST thing. if you run lean then you just run lean, and prolly wouldn't get the most power out of it.

FlaFocus

· #6 · Oct 22, 2005

Jet kit for slip-on not needed.
Jet kit for full system is needed.

spots25

· #7 · Oct 22, 2005

if you run lean then you just run lean, and prolly wouldn't get the most power out of it.

actually, if you run lean, you can burn holes in your pistons, a LOT worse than running rich. At any rate, I would never even consider modifiying the intake/exhaust of a bike without re-jetting. Find a Buell forum, and see what jet size you need

oh, unless of course your Buell is FI, in which case you might need nothing, or you might need to find a tuner/programmer

P-51

· #8 · Oct 22, 2005

Definitely best to either check with somebody who has the exact same bike and exhaust, or go ahead and bring it to a shop to check.

FWIW, I have a 1996 DT200, which is the last 2 stroke enduro. It came with a 1/2" restrictor welded into the head pipe. I removed that, it's now 2" straight through, and didn't rejet. But, it's said that it was designed for this. The Yamaha put that thing in there with a wink-wink-nudge-nudge.

ZX3ST

· #9 · Oct 22, 2005

YES you do need to rejet. I've got a yamaha YZFR6 with a vance&hines slipon. Even on the cruiser bikes like harleys you gotta rejet, but sportbikes in particular. They ususally run hot-momma engines and anything not right will tear them up. Running lean at 15000rpm is not good.

aaron_zx3

· #10 · Oct 23, 2005

I thought it also depends on how new your bike is. I know a lot of the newer sport bikes (honda specifically) are electronic fuel injection, so you don't have to rejet if you have that. But I'm sure the Buells are carbed so you'll probably have to do what everyone else is saying here.

Auto-X-ZTS

· #11 · Oct 23, 2005

I have a 2000 M2 with a WileyCo pipe...you NEED to rejet the carb. Period.

spinwax

· #12 · Oct 23, 2005

What Buell do you have? Doesnt really matter, just wondering. Newer Buells are F/I btw.

We have many people that do not re-jet, but it is not the safe way to go. Jets are cheap anyways. The bike will tend to run lean if you dont. Anytime you open up the exhaust on a bike they run a little lean. Great for power, but bad for burnt pistons.

Good luck.

InfraRedSVT

Discussion Starter · #13 · Oct 24, 2005

It's a Blast (yea yea, but it's my first bike) so it has a carb. A lot of Blast owners say that you can get away with not rejetting but that you do lose the performance benefits. I just have never worked with a carb before and don't wont to mess the bike up. Oh, and do you think the dealer would rejet for me? How much you think it would cost?

spots25

· #14 · Oct 24, 2005

It's a Blast (yea yea, but it's my first bike) so it has a carb. A lot of Blast owners say that you can get away with not rejetting but that you do lose the performance benefits. I just have never worked with a carb before and don't wont to mess the bike up. Oh, and do you think the dealer would rejet for me? How much you think it would cost?

carb work is suprisingly easy. I'd never worked on a carborator before, but I just rebuilt my 10th carb the other day. Its so easy. The jets just screw out. Buy the jet kit, pop the carb off, and take the carb apart. Its a single cyliner, so you won't have to worry about balancing multiple carbs, the only thing youll want to do is adjust the mixture screw.

spinwax

· #15 · Oct 25, 2005

It's a Blast (yea yea, but it's my first bike) so it has a carb. A lot of Blast owners say that you can get away with not rejetting but that you do lose the performance benefits. I just have never worked with a carb before and don't wont to mess the bike up. Oh, and do you think the dealer would rejet for me? How much you think it would cost?

Nothing wrong with a blast. My buddy at work had one that he used off road..LOL. He also hit an amazing 87mph with his wife driving. WTF?

Like suggested above, jets are pretty easy to change. There are tons of books out there to help you along. Any good Harley/Buell dealer should know the right size jets to go with an opened up pipe.

Good luck.

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