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Discussion Starter #1
Hi all i'm new to buying pipes and cruisers and pretty much everything motorcycle. I bought Cobra pipes from the dealership where i bought the bike from with the jet kit they installed and i just picked it back up today. It sounds great. Except there is more popping than i care for at low speeds and when shifting. And when letting the engine break. This erks me i thought the jet kit was suppose to do away with the popping?

It sounds really good when cruising interstate or highway, (although i did notice a bit more vibration in the handlebars over 70mph), but the popping sound can't be right. Is there a break in period? Should i contact the dealer yet again and ask about this? Thanks for any help guys.
 

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Actually the Mikuni Tuning manual says that some crackling and popping is to be expected from a properly tuned bike with an open exhaust. What you can do to help with this is adjust the PMS screw out about 1/4-1/2 turn and or remove the AIS if you haven't already. The PMS adjust will help with the sudden leaning when you chop throttle and the AIS will help by cutting off a supply of fresh oxygenated air in the pipes.
 

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don't know what either of those things are haha. This noise is so annoying it's almost embarrassing. What causes backfiring/popping? I don't want to let the engine break when i'm coming down from high speeds cuz it'll pop like crazy, and when shifting up it pops almost every time i shift. calling dealership tomorrow....
 

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The AIS (Air Induction System) adds air to your exhaust manifold. The 1/4 in diameter tubes that run to your manifolds along Left side of motor, as you sit on it. They are used to clean up emissions in your stock pipes, especially if you have catalytic converters. Did you get slipons or a full from the head cobra system? Do you do any of your work yourself? You probably won't find a dealership that will take AIS off. PMS (Primary Mixture Screws) screws adjust the fuel mixture as it steps off the primary jets. They are usually capped from the factory, but may have been uncapped by the dealership when jetting kit was added. All the info is on this link under Performance.

http://www.sloneservices.com/SilverBack/VStar1100-FAQ.htm
 

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Sorry didn't answer the whole question the popping backfiring is caused by a combination of factors. 1) The sudden leaning when you shut off the gas and the engine is still turning higher revs than idle or forcing higher revs than the engine has fuel for (engine braking). 2) The introduction of fresh air into the exhaust, either through the AIS or an exhaust leak.

Opening the PMS softens this abrupt fuel transition and the removal of the AIS (only if you have no catalytic converters) will remove this air in an otherwise (no exhaust leaks) well running bike. Some will say one or the other works fine. I have found the combination of both these actions works best.
 
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