New Exhaust and Backfires - SV650.org

15-10-04, 02:12 PM

Have got a K3 and have recently put a 3/4 Gforce exhaust on to replace the standard can. While the sound is now much more like it

I get quite a lot of backfiring when I roll off the throttle. This is all well and good for "shooting" old dears with, but is it damaging my engine?

Even if it isnt, Id like to stop it, or at least reduce it. How can I go about this? Any ideas anyone? Would rather not go down the £300 Power Commander route if poss for the obvious reasons!

15-10-04, 02:27 PM

Check that you have no leaks in the exhaust. I had this problem when the exhaust was broken on my GPZ (espcially in the cold). Air entering the exhaust expands rapidly causing the bang. (At least that's what I remember). I was warned that it *can* (ie not will) cause heating to the cylinder head - but maybe that's just becuase that's where one of my main leaks was...

Stu

15-10-04, 02:29 PM

It's caused by air getting sucked in through small leaks in the pipe work and then fired back out. It's very hard to sort but you could try some exhaust putty or something. I've learned to live with mine.

As for PC, I don't think it will cure backfiring but might make your bike run better with the new 3/4.

15-10-04, 02:31 PM

Bloody hell Baz, did we hit submit at the same time?

Stu

15-10-04, 02:32 PM

Cheers guys. I know the clamps I used were a touch too big. Ive got some smaller ones now and will try them to get a tighter seal. Failing that, where can I get exhaust putty from? Somewhere like Halfords sell it?

If that doesnt work, any other things to try?

15-10-04, 02:36 PM

Halfords should sell it. 'Fire Gum'. But be warned it can be messy as hell, and if you have to lay it on a bit thick it will crack... Used it (lots and lots of it) to keep sealing the exhaust on the GPZ. Sealing? Sorry rebuilding...

Stu

15-10-04, 06:20 PM

For what its worth ( and I am no expert)

Did you re map the ECU when you fitted the system ?

Without the Power Commander and full dynotune, there is a Suzuki tool that remaps the ECU at 3 sites. I was informed of this when my can/ K&N was fitted. Not as precise and exact as a P.Com. & dynotune with over 100 map sites but still required when "rebreathing" the engine by way of new exhausts etc.

My mechanic road tested the bike and one of the things he looked for was popping and backfiring.

northwind · 15-10-04, 07:38 PM

Don't get the exhaust repair stuff, too thick- halfords do a silicone liquid gasket that's designed for exactly this sort of application, works a charm.

Hang on, if it's a 3/4 system, did it replace the rear downpipe? CXould be you just need new gaskets at the "breaks"...

16-10-04, 01:20 AM

Backfiring while rolling off throttle often means that the fuel mixture is too lean. With fuel injection, you would have to re map or use a power commander to sort this out. If the lean situation is excessive, it could cause engine damage in form of a burnt exhaust valve I believe. Best to check with a mechanic.

vtour

16-10-04, 07:33 AM

Mark,

I used bathroom silicon sealant / mastic on mine and it works fine. If you have got some kicking around just use that. Only need a smear round the joints.

15-10-04, 02:12 PM	#1
M65 Guest Posts: n/a	New Exhaust and Backfires Have got a K3 and have recently put a 3/4 Gforce exhaust on to replace the standard can. While the sound is now much more like it I get quite a lot of backfiring when I roll off the throttle. This is all well and good for "shooting" old dears with, but is it damaging my engine? Even if it isnt, Id like to stop it, or at least reduce it. How can I go about this? Any ideas anyone? Would rather not go down the £300 Power Commander route if poss for the obvious reasons!

15-10-04, 07:38 PM	#8
northwind Moderator Mega Poster Join Date: Jan 2004 Location: In the garage where I belong Posts: 17,083	Don't get the exhaust repair stuff, too thick- halfords do a silicone liquid gasket that's designed for exactly this sort of application, works a charm. Hang on, if it's a 3/4 system, did it replace the rear downpipe? CXould be you just need new gaskets at the "breaks"... __________________ "We are the angry mob, we read the papers every day We like what we like, we hate what we hate But we're oh so easily swayed"

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15-10-04, 02:27 PM	#2
MavUK Guest Posts: n/a	Check that you have no leaks in the exhaust. I had this problem when the exhaust was broken on my GPZ (espcially in the cold). Air entering the exhaust expands rapidly causing the bang. (At least that's what I remember). I was warned that it can (ie not will) cause heating to the cylinder head - but maybe that's just becuase that's where one of my main leaks was... Stu

15-10-04, 02:29 PM	#3
Dirty Baz Guest Posts: n/a	It's caused by air getting sucked in through small leaks in the pipe work and then fired back out. It's very hard to sort but you could try some exhaust putty or something. I've learned to live with mine. As for PC, I don't think it will cure backfiring but might make your bike run better with the new 3/4.

15-10-04, 02:31 PM	#4
MavUK Guest Posts: n/a	Bloody hell Baz, did we hit submit at the same time? Stu

15-10-04, 02:32 PM	#5
M65 Guest Posts: n/a	Cheers guys. I know the clamps I used were a touch too big. Ive got some smaller ones now and will try them to get a tighter seal. Failing that, where can I get exhaust putty from? Somewhere like Halfords sell it? If that doesnt work, any other things to try?

15-10-04, 02:36 PM	#6
MavUK Guest Posts: n/a	Halfords should sell it. 'Fire Gum'. But be warned it can be messy as hell, and if you have to lay it on a bit thick it will crack... Used it (lots and lots of it) to keep sealing the exhaust on the GPZ. Sealing? Sorry rebuilding... Stu

15-10-04, 06:20 PM	#7
Shooter Guest Posts: n/a	For what its worth ( and I am no expert) Did you re map the ECU when you fitted the system ? Without the Power Commander and full dynotune, there is a Suzuki tool that remaps the ECU at 3 sites. I was informed of this when my can/ K&N was fitted. Not as precise and exact as a P.Com. & dynotune with over 100 map sites but still required when "rebreathing" the engine by way of new exhausts etc. My mechanic road tested the bike and one of the things he looked for was popping and backfiring.

16-10-04, 01:20 AM	#9
vtour Guest Posts: n/a	Backfiring while rolling off throttle often means that the fuel mixture is too lean. With fuel injection, you would have to re map or use a power commander to sort this out. If the lean situation is excessive, it could cause engine damage in form of a burnt exhaust valve I believe. Best to check with a mechanic. vtour

16-10-04, 07:33 AM	#10
Scoobs Guest Posts: n/a	Mark, I used bathroom silicon sealant / mastic on mine and it works fine. If you have got some kicking around just use that. Only need a smear round the joints.