Fistfullofthrotl718

This is going to be tough to explain. If you ease on the throttle there is no problem. And doesn't seem to do it if you get on it hard while in gear. Even from a dead stop at idle. But, if in neutral, and I blip the throttle to a quarter, the motor clunks and rpm's don't climb. I obviously never held the throttle open to see if it would climb. And it seems to do it fairly consistently. Roll it only fairly slow and you would never know. Don't know if this might be a common issue with to rich jetting or something? Maybe boarder line vapor lock? I have no idea. Any ideas would be great. I can take video over the weekend and youtube em or something if need be. I need a starting point. I never heard a motor do this before. Other then this hiccup, the bike seems to run awesome. However, it is my first and I have nothing to compare it to.

NHSH

Not sure what you mean, also as you don't have much to compare to, I would say it sounds pretty normal to me and does not sound like an issue with the bike itself, if you riding at almost idle and try to accelerate with full throttle you may refer the clunking noise from the pistons under heavy acceleration from low RPM, these motors don't like to be below 3,000 RPM while in motion
See if you get it at higher RPM's in full throttle.

Fistfullofthrotl718

Its not a continuous clunking. It is one heavy one. I hear the difference from what your describing. In neutral, and throttle stomped, its one heavy clunk. As rpm's just begin to climb, and the issue happens, they immediately stop climbing. For comparisons sake it almost sounds and reacts as if the piston tapped a valve. Of course it didn't but in my minds eye that's what I thought happened the first time I heard it. Until it continued to idle and run fine. I knew this was going to be hard to explain.

NightHawk1911

Any Mods? If your carbs are not adjusted correctly you will end up having a misfire which will sound and feel like a clunk. Believe me I thought I had a shift fork come loose once it hit so bad. That was before I rejetted the carbs.

NHSH

+1 Good point, that can be what you have described on the second post, if you have a stock bike, the Carb's maybe out of sync'.

sailorjerry

+2

It sounds like either a carb fart or a misfire to me. Either one can happen during a neutral rev up, but a miss fire tends to be more of a clunk that you can hear and feel where as a carb fart is more sound oriented.

CruxGNZ

Was just about to say the same thing CARB FART. I have the same issue. On my bike, it does it when you crack the throttle just a little bit with the clutch disengaged. Still does it after syncing the carbs, but not as much as before.

One time, the bikes engine almost shut off after the carb fart (before carb sync). I haven't got around to adjusting the carbs yet, because I'm looking at installing a custom exhaust soon.

Fistfullofthrotl718

No mods that I know of. The PO said the bike was jetted and synced when he got it. He rode for 6 months. He got into cafe racers and favored riding that one more (I know right? what a weirdo! ha, j/k) so the hawk sat for a while. He did take it out every now and again until I bought it. Oh, and he said it was jetted for warm weather which it is now. But I'm not so sure it is. I could be wrong but it smells like fuel heavy on start up. Once its warm it doesnt smell as bad and is pretty crisp on throttle response. idk. I cant really do a search to investigate because i have no idea whats going on. I'll start with the carb fart/misfire thing and see where that takes me i guess. I will post a vid in a day or two. maybe hearing it first hand can get me more of a definitive answer. Ill research the carb issue on here. thank you gents.

NightHawk1911

The thing with the carburetors is that they have different areas of tuning. At Idle you are using your fuel screws, pilot jet and float height (which is left alone on our bikes). When you start riding you enter your needle size (length) and your main jets with a combination of fuel screws and pilot jet. Once you go WOT you are using you Main jets and fuel screws and if you needles are out of wack them as well. So really you need to narrow down exactly when it happens (rpms, and engine temperature) and go from there.

There is some really good information on here about tuning the carbs and from what it sounds like is the problem you are having. It would probably be a good idea to take the carbs out and inspect them to see if they were actually rejetted or adjusted. If you go with a jetkit I would go with FactoryPro. But thats just my personal opinion. Ive never dealt with Dynojet.

Dac1278

I just bought a 1998 super hawk and when showing it to the father in law I cracked the throttle and heard this very same noise. At first I thought great a bought a lemon, I got screwed by a DB. I hope this is all that is, I haven't even registered it yet.

HawkRider98

Synch 'em. I do mine every couple months. You'll be surprised how much smooother it fires.

Fistfullofthrotl718

Conclusion. For any experiencing a problem like this. I have read and read about little hiccups but rarely do I ever read what was tried or cured the problem. So....Bike was re-jetted and jetting brought back to stock (mostly) from dynojet setup. I was able to witness the clunk happen while I had my airbox off. It was coming from the carb. It was spitting back fuel. After doing away with the dynojet setup, bike has very much improved with smoothness. I still have to fine tune but the clunk has ALMOST disappeared. It still does it but only once in a blue moon. As before the changes it did it pretty constantly. Hope this helps someone.

cybercarl