750cc Guys....Decel backfires

[MotorBikeMike]

Hey there,


Just wondering if the 750's are known for those little "backfires" on decal while blip throttle down shifting down to a complete stop. Maybe not so much backfires, (bad choice of word perhaps), but more like girgles/backfires. Hard to explain. Anyways, mine does it and just wanted to be sure that's normal. I suspect I may be running a little rich. But I guess its better than running too lean. Other then the little backfires on decal, the bike runs tip top. Also have the Delkevic slip on installed. She's loud, but want it louder...lol


My Kat is a 2002 fyi

[dano68]

Hey there,


Just wondering if the 750's are known for those little "backfires" on decal while blip throttle down shifting down to a complete stop. Maybe not so much backfires, (bad choice of word perhaps), but more like girgles/backfires. Hard to explain. Anyways, mine does it and just wanted to be sure that's normal. I suspect I may be running a little rich. But I guess its better than running too lean. Other then the little backfires on decal, the bike runs tip top. Also have the Delkevic slip on installed. She's loud, but want it louder...lol


My Kat is a 2002 fyi

I have the exact set up, 2002 750 with the Delkevic slip on, with silencer removed.

My bike does the same thing, if I am not mistaken it is "afterfire", just cruising and down shifting not so much, but doing a little "agresive" yes.

[92xjunker]

AFTERFIRE on decel is a lean condition, turn the A/F screws out to 2.5 turns from seated.

[MotorBikeMike]

I have the exact set up, 2002 750 with the Delkevic slip on, with silencer removed.

My bike does the same thing, if I am not mistaken it is "afterfire", just cruising and down shifting not so much, but doing a little "agresive" yes.

Good to know...thanks. Like yours, it only happens when I am being aggressive with her. Riding normally, it doesn't do it when I decel.


How do you remove the silencer? I would love to hear what it sounds like without it in.

AFTERFIRE on decel is a lean condition, turn the A/F screws out to 2.5 turns from seated.

Is it the single screw that you can see through the fairing?

[92xjunker]

No, they are on the bottom of the carb. After market cans/ exhaust will lean the fuel mixture out. You compensate by adding a touch more fuel (A/F screws).

[MotorBikeMike]

Okay...thanks man. I was hoping not to take the fairings off....*sigh*

[dano68]

Good to know...thanks. Like yours, it only happens when I am being aggressive with her. Riding normally, it doesn't do it when I decel.
How do you remove the silencer? I would love to hear what it sounds like without it in.
Is it the single screw that you can see through the fairing?

At the outlet of the exhaust on the bottom there is a (can not remember if it is a hex head or Phillips screw) 1 only, remove and pull silencer out. That easy

There is difference not huge but noticeable.

Just checked 4mm Allen key will take it out

[MotorBikeMike]

SWEET!!!!!!!!!! Thanks Dano

[MotorBikeMike]

At the outlet of the exhaust on the bottom there is a (can not remember if it is a hex head or Phillips screw) 1 only, remove and pull silencer out. That easy

There is difference not huge but noticeable.

Just checked 4mm Allen key will take it out

Took it out last night......LUV IT!!!!! Throwing that silencer right in the garbage....lol

[dano68]

Took it out last night......LUV IT!!!!! Throwing that silencer right in the garbage....lol

Did not throw mine out, I have it in a bin with spare parts for the Kat

[4wred]

Backfire on decel was your original complaint,normally caused by a lean condition.Removing the silencer will make it more lean?? Gonna have to turn out the mixture screws a little

[MotorBikeMike]

Is there a way to know if the engine is too lean or too rich? Usually with cars ECU's its easy to figure out. But how do you do it with a bike with carbs? I'd rather not mess with the mixture unless I know whats running at before making adjustments.

[92xjunker]

Stock A/F settings are all over the place, 2.5 turns out is the recommended setting. Anybody who asks for this kind of help, sets the A/F screws to 2.5 turns out.

[shpielers]

Is there a way to know if the engine is too lean or too rich? Usually with cars ECU's its easy to figure out. But how do you do it with a bike with carbs? I'd rather not mess with the mixture unless I know whats running at before making adjustments.

Dyno the bike, or install an oxygen sensor in the mid pipe and ride around with it hooked up to a data logger, or go by spark plug color.
There's also something called an idle drop. Look it up in the wiki. That'll dial the bike in at idle at least. If you stripped the can, might want to consider a jet kit so you can easily richen up the mid and top end a bit too.

[clevelandmanwhore]

I'm running with essentially an open Yoshi can. I removed the resonator and most of the packing and stored them both in the closet of my girlfriend's apartment. The bike does make some minor popping every now and then (not all the time, just on decel after hard riding every so often if its below 60 degrees outside) but I love the sound. Been running this way for 500 or so miles now with no ill effects.