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General Category >> Rubber Side Down! >> Drag pipes and re-jetting
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Message started by Ryan Craft on 08/20/15 at 00:41:32

Title: Drag pipes and re-jetting
Post by Ryan Craft on 08/20/15 at 00:41:32

Hey there! I'm building a bonner set-up after laying down my 1998 savage ls 650! My main question and concern is that I'm changing out the exhaust. I'm cutting the original exhaust and putting the drag/straight pipe on. However I know I need to re-jet the carb. But I need help figuring out what to do to re-jet the carb. Any help helps!

Title: Re: Drag pipes and re-jetting
Post by strang on 08/20/15 at 03:24:00

The consensus is that drag pipes are very difficult to tune and always give poor performance on the Savage. There's a dyno testing video that has been posted before that tells the drag pipe tuning tale but I can't find it now....

However I dig the look as well, so if you don't care about performance, go for it, at a guess a couple of sizes on your pilot and main jets will get you close.

Title: Re: Drag pipes and re-jetting
Post by Dave on 08/20/15 at 03:37:46

A straight drag pipe allows pressure waves to cycle up and down the exhaust pipe. The waves really mess with the way the engine runs. There really needs to be a baffle system that prevents the waves from getting back to the cylinder. It doesn't need back pressure....it needs something that breaks up the pressure pulse/wave.

Engines with open exhaust might run great at full throttle and high rpm, but they often don't run well at partial throttle....which is where you spend most of your time on a street ridden bike.

https://www.youtube.com/watch?v=KjKUKhHQLHg

Title: Re: Drag pipes and re-jetting
Post by digitaltrucker on 08/20/15 at 03:42:47

I can relate my experience with a Raask 60mm pipe. I'm only using the main outer baffle.

Raask recommends going up two jet sizes when installing the pipe. I installed a Dial-A-Jet. DAJ recommends going DOWN two jet sizes when installing their unit (to force the engine to run lean, y'see).

Bottom line; no rejetting, bike runs sweet, and a dyno said it was putting out just a hair shy of 30 horses. The only other modification I made was the complete removal of the white spacer and popping out the brass plug on the carb and richening up the idle. It doesn't backfire anymore now either and goes like stink. Accelerates fast, plenty left at 75 mph and the engine doesn't act like it's going to have a stroke at expressway speeds.

Title: Re: Drag pipes and re-jetting
Post by Yoshi on 08/20/15 at 03:44:01

Pm me for a Mac exhaust, loud and has baffle so good for jetting...
you wont enjoy an opened drag pipe

https://youtu.be/ct0gefwRxAY

Title: Re: Drag pipes and re-jetting
Post by JutMan on 08/20/15 at 07:16:38

I went with the Dyna, baffles still in it. I cannot be happier.

I did have someone make a custom piece between the header and the muffler out of stainless. They also took the bracket off the stock or moved the Dyna one then put it on the Dyna for a nice fit. They charged me $120 to do the work which was really reasonable.

Title: Re: Drag pipes and re-jetting
Post by justin_o_guy2 on 08/20/15 at 07:45:02

Straight pipe, straight shooting.
You'll hate it, and everyone around you will too.
Dyna, cheap, good looking, EASY to tune the carb to it.