High performance pipes

[Silvermachine81]

This is one of the most interesting threads ive read in quite a while.
I also had almost the same experience with my 1100 (RS38's, 348 webcams, Mild Porting, Wiseco 1134 10.5-1, Star Racing pipe).
Nothing fixed it on the dyno and the (not very good) tuner was completely bemused.....
98 rwhp and a hole the size of the Grand Canyon.............

[Craig]

So......what did you end up doing?

Craig

[Silvermachine81]

Got angry, pulled the motor apart, looked over everything, gave up, sat it in shed (4 years ago!!) and occasionally I look on here for theories as to what could be wrong.
Have had a few ideas to try and will attempt to put it back together one day soon.
I might order those carb parts as suggested above as this time I want it to go together right!
As a side note I too thought all was perfect on my bike when it was together but after over-analyzing the engine during the past few years ive realized much more goes into these things than we sometimes think and one thing slightly out can cause a huge chain reaction, making something appear to be at fault that wasnt ;-)

[Craig]

Well, we haven't given up yet. We are trying a few things with the cam timing. I will post my results as they come in. I have too much invested to let it sit in the shed!

[Silvermachine81]

I have too much invested to let it sit in the shed!

So do I, But I dont have anymore to invest :-(

[gsgeezer]

you need to rejet

[oldschoolGS]

The VERY first thing I do when installing flatslides on any bike I build for someone is to back the accellerator pump ALL the way OFF! Trust me, do this & THEN start tuning! With the mods you have I would start with the 130 main if you aren't high altitude. Then go from there. Also, an A/F meter makes it SOOOOO much easier & faster to figure out. Good luck, Ray.

taking the acc pump out of the picture for tuning purposes is excellent advice. That would have saved me a few headaches the first time I ran my Bandit on the dyno.

an A/F reading is absolutely necessary and will make the tuning process much easier.

Good Luck, Ed

[Silvermachine81]

I also think your problem is jetting as ive never seen anyone have a problem with the V&H exhaust. When I had problems I actually thought of ordering a V&H myself!

Tuners always seem to blame the pipe but that V&H pipe is in use on thousands of modified GS's all around the world and always seems to perform well.

Cam timing wont solve your problem, I've been down that track too so you really need to pay close attention to everything youve done and triple check it, then wind the accelerator pumps adjustment screws RIGHT OFF and work on your midrange.

Also check your compression as that could be part of the issue.

You never know quite what could be causing this so be meticulous.