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Discussion Starter · #1 ·
If I don't rejet my carbs after installing new exhaust pipes (samson Shogun free flowing exhaust pipes) can I cause engine damage? The
Honda store wants $290.00 to adjust my carb jets. I have a '92 Honda Shadow vt1100.
 

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It will either run poorly, run great, or run great and run lean. The last one will cause damage......eventually.....

You could do a spark plug test if it runs ok, and see how they read at full and half throttle with new plugs each time. If it looks like it is running in the tan range you would be good to go.

Go to the Jetology sticky above it walks you thru re-jetting with pictures - it's not that bad of a job.
 

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Rejetting

If you replace your stock exhaust, you change the quality of the air/gas mixture. In some cases you need to rejet the carburetor, in some cases recarbing is an adequate solution. After replace the exhaust, the easyest way to know what to do is to ride 0.5-1 mile with 3/4 throttle. If it backfires, then you surely need to rejet. After stop the engine, look at the spark plugs. The color of the electrodes will say you what's going on: if it's wet and dark, your mixture is too rich, if it's dry and white/light gray then the mixture contains too few fuel. If you can recarb it, then it's a good solution, if no, you must rejet. If the color of the electrodes is brown/dark brown, then you're on the right way. To play safe, take a gas-analyzer or call for a specialist!
 

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Discussion Starter · #4 ·
re: aftermarket exhaust pipes

Thanks for your response, my bike runs like a bat outa hell, noticeable increase in performance, the only backfire is when I let off the throttle from a medium to high speed, then it sounds like the Fourth of July, my plugs are running in the tan range, thanks again for your help, BULL.
 

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Re: re: aftermarket exhaust pipes

Bull said:
Thanks for your response, my bike runs like a bat outa hell, noticeable increase in performance, the only backfire is when I let off the throttle from a medium to high speed, then it sounds like the Fourth of July, my plugs are running in the tan range, thanks again for your help, BULL.
Simple fix then....back out the idle screw adjustment on each carb about 1/4 turn - the idle circuit is running lean according to your description causing deceleration popping. Not an issue with hurting anything just annoying. Take a look at the Pictures in the Jetology sticky it should show the approximate location of the idle screw adjustment screws.
 

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Jeez, I have Samsons too, have rejetted my Spirit a dozen times already and I am really close...
Most of it is, how does the bike feel? You say yours runs OK.
Check the plugs after a few hundred miles.

I finally ended up with DJ kit, 5th groove, 160 mains, 045 slow jets, using K&N filter and 1-3/4 inch diameter Samson baffles. I might be able to take out the baffles, now that I installed 045 slow jets in place of factory 042, the bike should no longer crack when I decelerate.
The Samsons move a lot of air through them, I would be surprised if you get by without some carb mod.
Good luck.
 

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IN THEORY, either Cobra or Samson should work with same jetting. But try it to see for sure.
Check plugs, etc. before calling it good.
 
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