Hi all,

Has anyone tuned out a nasty intake backfire. I have a 08 96" softie with RB R 2:1 exhaust AC and SE 204 cams. It has 64,000 Kls, good compression and runs quite well apart from the intake backfire on hot starting. It doesn't do it on cold starts.

When I had the thundermax and AT on I reduced the timing on the 250rpm and 500rpm maps, the TTS doesn't seem to allow retarding the lower rpm ranges.

If anyone else has improved this problem I would appreciate any input.

Thanks in advance,

Bluey

Hi Hilly,

It does it just as it fires, i think. It blows oil mist out the bottom of the Hyper charger over the cam cover.

Some suggest lifter bleed down causes it. I was considering putting S & S limited travel spacers in to see if that improved or eliminated the problem.

Thanks,

Bluey

Hi Hilly,

It doesn't sound like dry lifter rattle so much as like a nasty mass of advanced timing knocks. Thanks for the advice I will try and lower the cranking fuel.

 I have a 6000klm round trip to Phillip Island moto GP coming up and didn't want any problems so far from home.

Thanks again your input, is much appreciated!

Regards,

Bluey

 

sounds like a problem I have suffered from.. from nearly day dot even with stock bike. Sometimes from cold start, but a lot from hot. It is a nasty sound and yes, blows oil back out... easy way round is as soon as you turn the ignition, then hit the start button... starts almost immediately.

 

Thanks Ho, i'll give it a go!

If you send me a copy of your current calibration I can take a look and see if there is something we can adjust to help it. Timing is fixed at "0" when cranking so that's not an issue but there is a transition from start to running. Also check your Closed Trhottle Timing tables to make sure it's not to high there.

Funny you say that Ho! i hit the starter just after the run switch while the pump is making its noise. Seems to start first time every time with that method.

 

I was told by Adelaide Bike Works that it was the clutch in the starter motor... I didn't believe him, but be careful that is not your problem

 

not sure about injectors as you have tried to start without full fuel pressure.... where are you located?

 

Thanks Kiwi and Hilly,

I took your advise and changed cam opening to 2, haven't tried it yet, lated today.

What do you blokes think about the cam close setting? the 204 cams have the same very early intake close as stock cams at 34 degrees. There are 3 settings for closing it was on the latest closing at 3, I changed this to 2 just to try and I am thinking that with such an early close that it maybe should be 1???? Your thoughts would be much appreciated!

 

The reason we called it an estimator was we measure too much varation in the camshafts being installed into the engine. I'm not going to get into where the errors all lied but they are sure differences from what the cam cards say they are as to what really happen in a running engine. USe the opening point from doing the real test and then set the closing by what the estimator tells you to do. We find that works very well when you do not have a dyno. Remeber that you need to set these up PRIOR to doing your final tuning as things will change if you change these settings.