rejet?

[03svrider]

i just picked up a factory repair manual, a sargent recovered seat, and a mac 2 into 1 exhaust on ebay. the exhaust and the seat were steals but the manual set me back a little. i'm a sucker for the actual thing. the clymer model i have says if you are doing an aftermarket exhaust you really don't need to rejet but then again it's an old clymer. should i rejet the carbs? i can talk to the mechanic who did the carb rebuild and he could let me know if he jetted it lean. i hope not. obviously since i had someone rebuild the carbs you know i'm a bit intimidated by carb work. the guy who did the work is a master mechanic on the old bikes. he holds records in drag racing his old kawi so i figured he's do a great job. he did because the bike runs like top!

[Steve]

First of all...what bike. A MAC 2-into-1 is a clue, but we need more details, please.

Second, "running like a top" is not always good. Most tops I have seen in operation would just sit in one place and spin. :shock:

Finally, to answer your question, yes, you will probably have to re-jet.
How much would depend on what baffles (if any) are in the pipe.


.

[mark]

What kind of bike to you have?

Is your bike totally stock now? Stock airbox?
Each pipe is different...........when I recieved mine it said "no-rejetting required". That was correct, but I did need to re-adjust the needles and mixture screws in order to get the thing to run right.

Its not that hard to get it right in terms of what you actually do, but it will take time and patience.....any maybe jets too.

[nabrams]

If that stock exhaust is good (no holes) then do yourself a favor and LEAVE IT ON.
I have two identical bikes (in terms of engines). One with with non-stock exhaust and one with stock exhaust. The non-stock would NOT run as well across the RPM range as a whole, no matter how much I played with needle heights, mixture screws or even different jets. Yes, you might get a particular RPM range to run better with non-stock, but you inevitably end up with a deficiency in some other part of the power band.

[03svrider]

it's an 81 gs450l. stock airbox. that sucks to hear it won't run well across the range with an aftermarket exhaust. i thought it would sound pretty cool though. i'm not relishing the fact i'll probably have to take the carbs on and off to experiment with what settings will work best.

[03svrider]

i was hoping somebody had done the same thing and knew exactly what settings work the best so i could just do it once. nothing is ever easy. if i just put the system on and see how it runs will it damage the bike just shooting up and down the street to test it out?

[mark]

i was hoping somebody had done the same thing and knew exactly what settings work the best so i could just do it once. nothing is ever easy. if i just put the system on and see how it runs will it damage the bike just shooting up and down the street to test it out?

Nope, you won't hurt the bike testing it out. Running too lean over time may do damage but running it up and down the road a bit won't hurt anything.

[nabrams]

Look guys, there's a reason for everything. Why do you think stock/OEM exhaust systems (even in only mediocre condition) for ANY bike go for so much $$$ on eBay compared to the aftermarket stuff? Yep, you got it - because that's what works right for your particular model. Many folks have tried the aftermarket exhaust systems because they were after lower weight and/or a cooler look/sound, only to switch back to stock in the end.
Same holds true (even more true) for those "cool" pod filters - they just never end up working as well as the stock airbox.