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Discussion Starter · #1 ·
I'm starting to get frustrated. Only sometimes backfires when riding aggresivly chopping off the throttle near redline.
But around town it's fine.

1) I tightened the exhaust bolts.
2) Pair is removed, but no block off plates. Hoses are not crimped but connecting to each other on each side. See previous post(Attn: GSXR-FREAK Pair Removal)
3) Checked all vacuum hoses(to my best knowledge)
4) Dyno chart Air Fuel Ratio seems to be right on with the exception of a higher curve around 11k rpms and up but within specs according to the shop.

Shop says the bike is slowing down faster than the motor????? I think that's bullshit.


Will this upcoming trackdaz tech inspection say my bike is running incorrecly??

My mods are in my signature.

What gives???

[ 03-16-2002, 11:10 AM: Message edited by: rceburner ]
 

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rear sprocket at 47 will give better acc. but this will affect the slowing down also

maybe shop is right
 

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Discussion Starter · #3 ·
Originally posted by jp233:
mine used to only backfire (not really backfire, but "pop") when I let off throttle at high rpm.

just put the block off plates on and that should cure it.

mine never pops anymore since I did that...
<font size="2" face="Verdana, Arial">Yeah, that's the only thing I can think of is installing block off plates. Hopefully it will work. If not, then I guess I'll take it to the shop and have them look at it. I know what you mean about the popping sound. It's like when decelerating(sp) you hear a rumble, rumble, and POP!!!! $30 bucks for the plates is not gonna kill me either
 

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Did you put a new gasket on when you did your pipe? Also, is your pipe a race pipe? If so then you might have a small leak were the head pipe meats the head. This was my problem. It shouldnt be the blockoff plates... My friends 600 didnt do it and he had the tubes running into each other...

My bike did this and I fould out that it was leaking a SMALL amount of cold air into the headers right at the head... I used some 700deg gold gasket maker and some chamber tape. All is good now...


With the full race header, there is a mount that bolts to the head and then the pipe slides onto the mount... That is what was leaking on mine...


John
 

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Discussion Starter · #5 ·
GSXR Freak: I used the same gaskets and yes it's a race exhaust. How would you know a leak coming from there? Could you hear it?

You mentioned 700deg gold gasket maker and some chamber tape. Where would I get these??
 

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mine used to only backfire (not really backfire, but "pop") when I let off throttle at high rpm.

just put the block off plates on and that should cure it.

mine never pops anymore since I did that...
 

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Originally posted by rceburner:
GSXR Freak: I used the same gaskets and yes it's a race exhaust. How would you know a leak coming from there? Could you hear it?

You mentioned 700deg gold gasket maker and some chamber tape. Where would I get these??
<font size="2" face="Verdana, Arial">Well the way i could tell was one, I would hear it, and two it was leaving carbon build up from the POP on the head... On the outside of the head., were it was comming out of the pipe...

If you used the same gasket from the stock header, you might want to get new ones... They are a crush gasket and SOMETIMEs they dont work as good the second time around...

The 700deg gasket maker can be found at Pep Boys or any other auto shop... The chamber tape you should be able to find at a dirtbike shop...

Put the gasket maker in the pipe, and put the chamber tape on the mount... The tape is a pain in the ass you use and it makes the fit REALLY tight on the header to the mounts. But it works great... It doesnt dry out and crack, flake off like everything else I have used...


If you have any questions let me know...

John
 

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im pretty sure all gixers "pop"..mine does and so does every gixer ive ever seen backing off and down shifting for turn 1 at willow springs..
 

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Originally posted by spongebob:
im pretty sure all gixers "pop"..mine does and so does every gixer ive ever seen backing off and down shifting for turn 1 at willow springs..
<font size="2" face="Verdana, Arial">No not all off them do. When mine doesnt have a leak on the header, I get NO pop. my friends 99 750 gets NO pop.

It might just be a problem that the bikes are running so lean. They tend to make more power that way...


John
 

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actually i believe its a rich condition, cause i get a flame too....and i should have said most not all....sorry
 

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Originally posted by spongebob:
actually i believe its a rich condition, cause i get a flame too....and i should have said most not all....sorry
<font size="2" face="Verdana, Arial">Hey no problem on the all thing...


Anyhow. With the backfire, it could be a rich thing too, but most of the time from what I have seen out here, with bikes that dont have a lot of work done to them, they tend to have a few lean spots in the them that will pop... Just about every one I have seen was doing it from lean. Not to say that it might not be rich.

Without seeing the bike it is hard to say. It might be a rich, mixed with a cool air leak causing it...


John
 

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My 96 750 engine pops alot also, thanks for the exhaust sealing tips, I will try them. My cams have more overlap than the stock ones also which I am told can do this.
 

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If you shut off the throttles from high rpm you will momentaraly get a rich mixture into the exhaust headers. If at that point there is a small air leak, fresh air may me drawn into the headers mixing with unburnt fuel and igniting causing the pop.
A number of car company's use a controled version of this to keep the emmision of hydrocarbons down

Cheers sean
 

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its hard to imagine all those race bikes having the same air leak..but i guess anything is possible..
 

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Bob
Agreed its highly unlikly that the race bikes have air leaks its more like they are burning residual hydrocarbons in the headers on overun.

Sean
 

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ahhhhhhhhh, could the same thing happen on a street bike then?? just wondering...
 

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Originally posted by spongebob:
its hard to imagine all those race bikes having the same air leak..but i guess anything is possible..
<font size="2" face="Verdana, Arial">I agree... I would bet they are just running really lean...
lean is power most of the time... and power is good... So if they are lean and sucking a small amount of air (even could be getting enough in from the tail pipe), it could pop...

The other comment about the car companies using cold air to burn extra fuel off in the ex pipes, the bikes do this too... That is the PAIR valve that we all take off to help stop the popping..


John
 

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Ah is that what the PAIR system is, over here(UK)we are not forced to run that.
There are a number of turbo cars that use the system modify it and run a form of antilag.

I still can't see it's a lean mixture causing it. What would cause the pop?

Sean
 

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Originally posted by Sean600:
Ah is that what the PAIR system is, over here(UK)we are not forced to run that.
There are a number of turbo cars that use the system modify it and run a form of antilag.

I still can't see it's a lean mixture causing it. What would cause the pop?

Sean
<font size="2" face="Verdana, Arial">The pop is when enough fresh air is mixed with the gas comming out of the motor (unburnt fuel as well), it makes this gas ignite again... This is the pop. If you run lean, then it takes less fresh air to ignite the gas.
Get it now? I know I was the same way... NO NO it is to rich that is why it pops... lol But the dealer said JUST TRY IT... lol I was like, ok what ever, but your wrong...
Sure enough, they ran a Yosh Box on my bike and set it all at the max, no more pop...


John
 
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