Hi everyone I am new hear, Not new to bikes been riding for 30 years. I just brought my first 400xs and have a question about the exhaust, have a set of fish tails to put on it but need to know if the lack of back pressure will mess up the carbs??
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staight pipe on 78 400xs?
- Thread starter ssmartin
- Start date
Yes, you will need to re-jet the carbs with a high flow exhaust. The bike will probably run too lean (hot) and pop/backfire. I bought new jets from MixesXS.com for my '78. The jets are cheap enough to buy a range of sizes to experiment. Other people will suggest using a "colortune" to get everything just right.
vfost
XS400 Addict
Before going through the trouble of rejetting i would just start it up with the fishtails on first to see how loud it is. As daddio said these bikes are VERY loud and you may decide that you dont want to do that. Just my two cents worth though
I have washer in the pipes right now from my ultra classic, the pipes came from this bike and I ran them open with the washer to create the back pressure. Is it the flow that I need to worry about with the carb or the back pressure for the motor?
lhaolpa
XS400 Junkie
Universal cycle shops used to have"snuff-or -not" baffles for open pipes.They were essentially washers with springs and a handle,so that you drill a hole,the springs suspend the "washer"and kept the baffle open or closed,thus the name.I haven't seen them in quite a while,but haven't been looking either. lha
i gotta re-jet mine, im runnin pods and stock exhaust to and adapter to a 2inch tip. slash cut. stops right past my feet. 
cant wait to hear it.
cant wait to hear it.
