Thursday, January 19, 2012

Motorcycle question about pipes?

i have a honda shadow spirit 750. I bought it with vance and hines straight pipes on it. I was told that something had to be done to it after the pipes were put on it or it could burn up the motor if the fuel was too rich running through? Any help? it has a choke on it if that helps to know and it runs good but it sounds like its missing but its due to the pipes... any advice? and how do i know if it was done, something to the carburetor ? its suppose to be something like calibrated.Motorcycle question about pipes?
pull the spark plugs and take a look at them. If they are white, you are running to lean because of the pipes and need to change the fuel air mix richer. If they are tan, you are fine. If they are black and sooty, you are too rich, and black and tar or oily, you are burning oil.

A fuel injected bike will normally self adjust up to 20% by itself so that you can ride from sea level to the high mountains without having to reset the fuel injection mixture. A carbed bike may need the jets replaced with a major altitude change.

The reason you need to change things is because going to the V%26amp;H or other performance pipe, lowers the back pressure and causes the bike to run lean. At the time you replace the pipes, you should also go to a higher input air intake. Both of these will lean the air fuel mix which will make the bike run hotter, and lose performance and HP. You should have the carbed bike re jetted a little richer, and a fuel injected bike remapped.

hope this helped

ride safe
it is running LEAN from a less restrictive exhaust. this lean condition is making it run HOTTER! the fuel mix needs to be richened up,if its carberated it needs larger main jets and or changing the jet needle position with a shim. if its fuel injected it needs to be remapped.the choke is just for cold starts.Motorcycle question about pipes?
chopperchopster is 100% right. Including, I'm afraid, in his assessment of Tom's answer...



Enriching the mixture is standard practise when installing freer-breathing exhausts and you need to do it now, before you put a hole in one of your pistons.
Chopper is 100% correct.You need to find someone that knows how to do a plug reading to tell you just how lean it's running.Chances are good it can be fixed by moving the metering needle and re adjusting the mixture screws.Motorcycle question about pipes?
Have the carburetor re jetted, ideally on a dyno but in the mean time google others with the same set up and see what # jets they are using. If you don't have carbs, I don't know. Jets are easy to put in in a few minutes if all is exposed. But I'm not familiar with your model. Be sure to keep air cleaner the same type afterwords.
Never bore out a carb just get them re jetted. We use to bore them before smooth bores got cheap enough that people could afford them.
When you have an unrestricted exhaust on a carberated engine, in most cases it will need to be re-jetted to richen up the mixture to keep it from over heating and causing other internal engine damage. on fuel injected engines , normally you only have to remap if you change anything on the intake side. remapping can still be beneficial to performance but is not necessary to prevent engine damage
usually the carbs have to be bored out

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