Cured the S4 backfire.....and the culprit was??????????

[jerryz]

OK problem solved ,,, and the culprit was ??


probably the TPS .. just done another complete valve train service , shims etc , new belts , one was badly frayed , all rockers still perfect ...then noticed that TPS had drifted off very badly ,, although still bolts tight ? did some experimenting and found that you can set TPS so only 1 cylinder fires and vicious backfiring if set out of limits one way or the other ,, set back at 152mv perfect again .

bike is now bouncing off the rev limiter with NO backfires ..

I have also now fitted POD filters over the velocity stacks , no new PC3 maps required sweet but the induction roar is now even more awesome , much better access without the standard airbox.
__________________
MONSTERMAN

[lazylightnin717]

Interesting

My S4 was popping like crazy before I put it away for the winter.

I'm going to start taking a look into once I am moved within the next few weeks.

[jerryz]

Lazy its easy to do with a good digital multimeter ,, but its very very sensitive and as you tighten the retaing screws it can move do need checking and then recheking  and  patience ,cool head, lots of valium ...

[abby normal]

Yup.  I've had this on the S4R and the 851.  In both cases, mine would
Spit through the intakes and stall coming off idle.