Missfire/exhaust bang on wot

[Dannel94]

Hi, just bought my first sidewinder today.
Noticed that when i give it some gas (80-100% throttle) it will make a loud pop from the exhaust. Only once. If i let throttle go and give it some gas again it will pop again.

Also smelled some burned oil/plastic from it once.

Im leaving it to the dealer to install a CAI in a few days and will have them take a look but is it safe to ride until that? It has Maptun stage 1.

 

[sideshowBob]

I wouldn't run it a high throttle settings until you get it sorted out.

 

[KnappAttack]

Shouldn't be popping. I'm wondering if its the boost cut or just too lean, maybe hitting the rev limiter too.

I'd be calling the tuner to ask why, and you may want to rethink the CAI as it may get leaner and worsen. Something is defiantly not right when popping and need to know the answer. They can spit the valve shims out pretty easily when popping on these 998's.

I also wonder if someone has spun the engine backwards as the cam sprockets can and do skip and throw the valve timing out of whack if doing so under certain conditions when tensioner is about ready to ratchet to the next tooth on the internal tensioner ratchet mechanism.

 

[Turboflash]

I'd say at the very least, it's way too lean. Something is not right. I'd be calling the tune company to start the process of sorting it out. Do not ride it. Bad things can happen.

 

[Dannel94]

It was tuned from the previous owner. Bought it from a Yamaha dealership, guess they will have to look at it.. Should be ok to ride as long as I stay away from WOT tho, right?

 

[Turboflash]

IMO, NO! Do not run/ride until the issue gets sorted out.
You don't have a big vacuum leak (ie a hose off or broke or have a hole in it) do you?

 

[Turboflash]

IMO, what's going on is not normal. It's a $5500-$6000 engine! Do you really want to run it while this is going on? It's not normal, it's not right, and there's something going on that could be, or is destructive to the engine. Don't not run it until whatever is going on gets corrected.

 

[Dannel94]

Dealership said it was fine to ride but not too hard until they looked at it. I reset my "max rpm" and went for a ride, got a bang and looked at it and it was at 9480rpm so im hitting the rev limiter.

 

[KnappAttack]

Don't use the max RPM for clutching, the max recall is quite worthless for that. What is the RPM when your on a wide open pull on the tach looking at it. Should be around 9000 or so.

When is the bang/popping happening? Part throttle? Rolling into it easily? Give some more detailed information here or we cant help you, and typically the dealers are no up on performance stuff and quite honestly idiots. Them telling you to ride it leads me to believe their idiots. Bad things happen quick on tuned sleds if things are not right.

 

[Dannel94]

Don't use the max RPM for clutching, the max recall is quite worthless for that. What is the RPM when your on a wide open pull on the tach looking at it. Should be around 9000 or so.

When is the bang/popping happening? Part throttle? Rolling into it easily? Give some more detailed information here or we cant help you, and typically the dealers are no up on performance stuff and quite honestly idiots. Them telling you to ride it leads me to believe their idiots. Bad things happen quick on tuned sleds if things are not right.

They are a specialized Yamaha dealership with their own workshop so i think they know what they are doing.
I checked a clip from today and noticed that it pops when i let off the throttle, i thought it was on acceleration before but now im not so sure.
I uploaded it to Youtube so you can watch if you want to. Gopro dont quite catch how loud the pop is.

 

[Turboflash]

They are a specialized Yamaha dealership with their own workshop so i think they know what they are doing.
I checked a clip from today and noticed that it pops when i let off the throttle, i thought it was on acceleration before but now im not so sure.
I uploaded it to Youtube so you can watch if you want to. Gopro dont quite catch how loud the pop is.

You know, they're not gonna fix your engine for free when it get wrecked. They will gladly fix it, at your expense! Like I said, what's going on is NOT NORMAL. Run it at your own risk! Backfiring on decel is not right.
You're right. the GoPro video doesn't do well to let us hear what's going on.
Go ahead and add clutch weight to bring RPM down to 8900 and see what happens.

 

[earthling]

As tempting as it is to ride right now I would pull a plug and have a look. If its either rich or lean it should be obvious. Either way, if you are going to run a tune, especially at that RPM, you want it to be working perfectly. The risk of costly engine damage is pretty high if its popping.