Back Pressure

[Steve Hamm]

I have been putting some miles on the new to me ride , 2009 , RSTD, it had 3200km on it when I got it . I put a different pair of mufflers on that have had several big holes punched in the ends , so it is rather loud . Every one says it sounds more like a hot rod than a bike , they all seem to like it as well . There is quite a pop most every time I shift from first to second , and does back fire quite often . My question is , does this hurt the motor ?? There have been no other changes . Oh ya , I do not ride fast , but I do like to kick it in the a?? a lot , I hit the ref limiter a lot .

How any of you have tried this with the factory mufflers ?? I really like the sound , just do not want it to cost me a motor .

[vzuden]

Sounds like you have a rich fuel mixture. I would sync the carbs first.

[slowrollwv]

The pipes drilled out should not hurt the motor. Most of the people switch there pipes. The backfire could be from not plugging the AIS.

[Great White]

With holes punched in the mufflers you've changed the dynamics of the exhaust system and thus, the carburetion. An engine is a system. It all works in concert together.

 

What you have done is reduced restriction in the exhaust. This usually leads to a lean condition.

 

I recommend you pull your spark plugs and see what they look like.

 

If rich, they will be black and sooty looking. If lean they will be whitish looking. Just about right will have a light tan look.

 

You can adjust the carbs to match the new dynamics of your system, which should eliminate the "pops". Probably messing with the idle screws will help the pops if your sparks support a lean or rich condition as popping on decell is usually a closed (or parts closed) throttle condition and then; not on the main jets or needles.

 

If the plugs look good, the mixture is still good and the engine isn't going to be hurt by the popping. In this case, its likely (as mentioned) a lean condition in the exhaust caused but the ais system introducing too much oxygen and causing lean pop....

Edited August 20, 2015 by Great White