Will I need to rejet my carbs ?

I have just fitted a set of Scorpion pipes to my cruiser. Scorpion claim there is no need to rejet as ALL exhaust systems made by them are set up correctly ( which I accept ).However, although the pipes sound good, they sound much better with the baffles removed, and as I intend to run the bike without the baffles, will I need to re jet ?

I have contacted Scorpion on this and they say it will be ok, but I don't want a blown engine if they are wrong. Any ideas ?

Hey Twisted, i couldn't e-mail you, so, I have a Hyosung GV650. Its very sexy, based on a Suzuki SV 650 unit, and the pipes are dealer only.

it will not cause you to blow the engine but might affect your performance due to the additional air flow with baffles removed. give it a try and see what the performance is like compared to them installed... easiest is to find some open out of the way place with little traffic... try rolling on the throttle from 20 mph at a given point (street sign, telephone pole, tree, etc. something you can gauge by)... up to another given point where you hit 60, or 70, or 80 (pick your own poison based on the surrounding environment) ... anyway, note your speed at bottom and top comparing to fixed objects... go remove your baffles and repeat... is it about the same??? faster??? slower???

that way you can gauge if you need to rejet ... but it shouldn't do any harm to your engine just by removing the baffles (other than irrating people around you by running the louder pipes)...

I used to do that all the time but found there was very little to any performance difference between with or without baffles... just seemed faster since it was louder... and I never had to touch jetting of the carbs...

try it without rejetting for a while and see for your self,, you cant blow an engine by not rejetting

It shouldn't cause any problems, but to take full advantage of the pipes you should take the bike to a dyno centre, and they will analyse the fuelling. Once this is done they can tell you if it needs re-jetting, and will be able to do what needs doing.

naw ur fine


...this i do know

First, don't let anyone tell you that you can't hurt your engine by not re-jetting. But that doesn't mean that you will need to either. Run the bike several miles at highway/cruising speed and without letting the engine idle any more than necessary pull into some place convenient and remove a spark plug from both cylinders. If the plugs are light to chocolate brown, then everything is fine. If they are light gray to white, then it is running too lean and will need to be jetted. If they are black, which I doubt, it's running too rich. Running excessively lean CAN damage your engine.

I am intrigued. I wasn't aware that Scorpion made pipes for cruisers - there aren't any on their website.

What bike have you got?

OK - according to the Hyosung website, they are supplying Scorpion pipes with GV-650's from new. Therefore, it should run absolutely fine - if you keep the baffles in!

It will probably need a slight up-jet if you take the baffles out, though.

basically the bike will run leaner due to greater airflow. will it go bang (depends on how hard you drive, how warm it is, and how good your rads are. 4 stroke exhausts don't really improve a great deal, generally about 5% if your lucky. it might give you an extra 2-3 possibly even 5 bhp. with the baffles removed your probably doing more harm than good to performance but I have the impression you don't care and its more to do with sound. personally i would lower the pin one point and if the bike runs like a pig move it back to the original. ie I would rich the bike up and play safe and then move back until your happy. thats my 2 pence worth