My 929 bangs fromthe exhaust pipe (big boom) when slowing down from high speed. Is it something wrong with exhaust or it could be something else?

 

is it backfiring? Probably needs to be remapped.

 

I wouldn't say remapping right away. Answer this are you burning 87 or 93, you need to burn 93. Also try burning a tank full of racing 101 octane VP its perfectly safe because 929 has a compression ratio of 11:1 which matches 101 perfectly. If that doesn't you might what to take to it a dependable mechani to tell you something different.

 

I'm burning 93 but I've tried 101,also I've been putting some aditive but no difference still the same. I've contacted some mechanics but all of them told me different things. One told me that the exhaust is causing the problem other that is something wrong with fuel injection.

 

did you try "blowing it out" redlining the bike a few times and getting up to speed fast possible about 140 and then see how it runs, if that doesn't work take it to Honda and let em see whats wrong, but they are gonna hit u in the posket pretty hard

 

The bike runs perfectly fine. The acceleration is normal but when slowing down and shifting down then it bangs. The main problem is that here where I live (Montenegro) is no authorizedHonda shop. Redlining? One machanic told me that it can be restarted like this: on neutral,full RPM and swiching the start butonoff and on. Is this really doing something?

 

YES! it's gonna cook the motor, especially if you try that with the engine cold.

It is something to do with fuel mapping / timing. If it's off just a little with retarded timing or too advanced timing, or something related to that, it will cause backfire. Disconnect the battery and reconnect, try it, note any changes if any.

Best of luck to ya.

 

Sorry to go against what everyone else is telling you, but here is the real explanation... THERE IS NOTHING WRONG WITH YOUR BIKE!

The 929 & 954 have a PAIR valve. this part injects air into the headers to burn off excess fuel in your exhaust system, it is part of the emissions controls. That is the popping you hear on deceleration.

You will notice the popping with a slip/bolt on more than with the stock exhaust. You can get a kit to block off the pair valve, but it is not really worth it for any performance improvements. Just live with the noise, and realize that you are driving a honda - there is not much you can do to it to kill it.

Also, don't bother running race gas, or even high octane for that matter. the manual states you shouldn't run anything less than 86 octane. I stick to regular in my 929 and it has always run fine. You run higher octane if you experience pinging/predetonation, and if no predet. is present, then run regular.

I think the honda techs that designed our bike know what they are doing, and if they say regular, than thats good enough for me.

 

I agree with every thing u said but not with this statement: "That is the popping you hear on deceleration." What I hear on deceleration are indeed big detonations. I know that I should hear litle poping but this what I'm hearing is not natural 100%. The best way for you to explain is this,when I ride through the city people are afraid when they hear the bang because the detonation is so hard that it sounds like gun fire :-) So I guess that Honda didn't make something like that to scare people furthermore my friend owns a 954 and his bike is not making detonations like mine.

 

well, that is a big problem...

What have you got for mods?

Definitely sounds like a fueling issue...

your throttle bodies could be way out of synch, dumping way too much fuel into one cylinder, and then exploding in the exhaust.