backfiring

[banjaxxed]

And i think we have a culprit. after changing over my airbox to an early version Evo unit, i had okay running if somewhat woolly & down on power for a while with a rene #2 chip & Rene pipes.

The Rene airbox was out of comission for a while as the previous owner neglected to mention that the filter should have had a wire mesh on the inside to stop the top of the filter being sucked down into the velocity stacks causing a large hole & burnt filter goo everywhere -I have this posted somewhere with amusing photos.

Got the time to switch back to my stock bodywork(silver), soldered some led signals which had been broken in a prang back together & attempted to replace a clutch slave seal, but failed in this, no biggie I'm sure someone has been through this before!

Back to the airbox change & general rece of the intake area, I hadn't changed anything after fitting the evo unit & the rene airbox had produced clean, smooth results previously.

There was some slight fraying around the hose going into the evo pressure reg, but I cut the affected piece off & taped around the hose at the end to stop wear from the baseplate wearing against the top. I will make another mod of the plate to accomodate this properly when I next pull it apart. all the other airbox hoses were routed correctly & looked fine.

There is no obvious physical cause as many others have experienced, like missing lambda sendor plugs or leaking pipework around clamps & such, so I can only guess that the tech who recently serviced the valve train messed around with one of the following or it just needs to be reset after the switch back:-

1. Evo fuel pressure - 43 PSI (using guage & engine off - 1st fuel prime ~3seconds), maybe 1 or 2 PSI+ as this bike has an open system which should probably be a little more fuelhappy for optimum
2. TPS = 0 when diag wires connected - adjust if needed
3. Throttle synch/bleed screw setting - start 2 turns out for both, bring in rear to ~1 1/4 turns out (or centre line on guage), match front off this to centre line, should be another 1/4-1/2 turn out again as normal.
4. Wires under pressure reg are not grounding

i guess every filter will have it's own exact characteristic, i did'nt think the outcome would be so dramatic that I would get the dreaded ka-boom around 4, 500 rpm on the throttle, that's right on, not off, you can almost feel the fuel build-up, when it hits 6000+ it tears right off though!!!!

i want to get this right before doing anything like putting a powercommander on it, best results are gotten from a good baseline i would have thought?

Here's some pics of my cack-handedness(had too redrain the slave cyclinder after forgetting to put back on the half-moon shaped spacer under it $%^&£"), a man too mean to buy 2 new copper o-rings & possibly the dirtiest rag ever posted.

Two questions I ask thee: -
Anything i might have missed for sorting the backfire?
How do you break apart the slave to replace the seal, I even put it in a bench vice & gave it a few digs with a plastic mallet, not a budge!

[Bikoman]

Here are some thoughts:

Prob 1 - Backfire
It sounds as though your throttle bodies need to be properly re-synched and your trim pots need to be adjusted (yours should be enabled with a rene chip).

Prob 2 - Slave
To take apart, pull your clutch lever and the slave piston will pop out in your hand.

John

[twowheels78]

Prob 1 - Backfire
It sounds as though your throttle bodies need to be properly re-synched and your trim pots need to be adjusted (yours should be enabled with a rene chip).

I'd check the TPS first... I installed a set of Evo 54mm throttle bodies and afterwards had a similar problem... once I reset the TPS to 0 it was much better a further throttle body sync helped fix the last vestiges of the problem.

As for the clutch slave just buy an Evo slave... it's got triple seals and is guaranteed not to leak plus the lower lever effort make it well worth it.

Good luck!

[banjaxxed]

thank you - didn't think we had the trim pots enabled on the chip - i'll re-read the proceedure on Ken's most excellent site. i have print outs somewhere too.

I had the slave off, but you're saying that the piston will come out of the engine block when I depress the clutch lever, even when the entire unit is drained?

I have a piccie - I think you can see this is the point when I realised I had forgot to place back in the spacing ring under the slave!.The entire slave is in one piece in the parts diagram it is shown as a separate unit, not sure how depressing the lever can help 'break it down' to components

part diagram
http://www.af1racing.com/store/Scrip...idproduct=2382

[Bikoman]

The red arrow points to the piston, since it is already sticking out, just pull it out with your fingers, the seal is in the bore.

John

[banjaxxed]

ahhh, I was expecting it to come apart like in the exploded diagram.

it makes sense to me now, thanks for that John, your paintshop skills are pretty good too!.

yeah i did a search for these things, after you've been using the forum for the first 2 or 3 yrs you tend to unlearn some things heh, it's like being a noob all over again . that & I'm now up to 51,500km on it, so i have an excuse too, honest!

Twowheels, good advice, I was going to start with the fuel pressure, then the TPS, finally the body synch, I haven't needed to adjust the idle screws yet, if it ain't broke

Al

[Wot_bike_isit]

Backfires? So some unburnt fuel is escaping the cylinder and going off in the exhaust with the throttle on. Is it just one can/cylinder or both? If it is one I would say check your spark plugs and the coils. If it is both perhaps your pres.reg. is shot. I'm no expert but those are my thoughts.

[Exdukenut]

You might want to just check your exhaust header probe ports, that they are in fact tight, as well. Just a thought. Some people have had there's pop out.

[banjaxxed]

Yeah, they are actually in there really tight! I guess all the muck has them selaed very well. There is a fair bit of dark smoke as well, and the pop (more pop then backfire really) has been there ages ago when i first set up the system.

I just thought I would be able to replace the airbox & set off, silly me

I bet an hour or 2 will have it sorted the way it's supposed to be, the fly in the ointment is that my workshop is 100mls away from where i actually live & theres a france/ireland rugby match on saturday, my skills are needed in slatterys around the corner from landsdowne rd