vinkate

High i just bought a 98 superhawl with 25k is it normal for it to occasionally make a hard ka-***** noise. Its unnerving and you can feel the thud if through the tank. It doesn't rattle or make any other noise just a few times a ride it will do it.

Wicky

Hi or are you high

Carb Fart stutter that resonates up through the airbox and tank is perfectly normal generally at lower revs pootling about- though the metallic element you mention doesn't seem right.

Check chain tension is to spec as per manual, cush drive rubbers and add while you're at it the usual suspect OEM CCTs!

vinkate

I think your right my bribery said same thing. It does it between 0-3k rpm and sunds like the air box is tapping the tank. Ka-*****. How do i stop this? Not high LOL

rz_racer_69

Lol, what is a bribery doing giving tuning advise? Are you typing this on a mobile device with autocorrect on?

If the Hawk is stock, you likely have a lean condition from the factory. There are lots of writeups here about slight carb mods to fix it. One thing you can do in the meantime while cruising along, to stop it, is pull out the choke (enrichener) **** a bit. This will fatten up your mixture a bit and let it cruise at slow RPM smoothly. This works on mine, which runs lean when it's really cold and the motor hasn't had time to warm up. When it's warmer out, and I have really heated up the motor, it seems to run 0-3000 smoothly without any choke.

Wicky

Change down a gear and don't labour the engine at low revs in too high a gear - up the idle a notch or two i.e go faster or get a moped to dawdle about

Again check the condition of all your transmission components - Chain & sprockets, Cush drive, tension and alignment for smooth & efficient running - not that it will stop the carbs farting but will improve matters throughout all speeds .

vinkate

Yea posting with my phone sorry. When i bought it the rpm were idling at 2k so makes sense when i idled it down to 800 that it started doing it. Thx for your help saved me a bad nights sleep

7moore7

Probably only does it only under 3K rpm as well, eh? These large carbs slides sometimes slam open pretty quickly. A good carb sync and if you have time/patience going through 8541Hawk's carb setup will reduce this.

Nothing to worry about, though! Happy riding, and like mentioned, may want to look into changing CCT's before you have real metal clunking damage sound.

7moore7

Damn there's like five responses before mine. Idle should be set to around 1200, FYI.

eram

Could be a misfire too; mine does that when it needs a good carb cleaning and it's too cold out

thetophatflash

Check for rear tank grommets. If they are missing it will make a clunk.

rz_racer_69

Back to the looseness question, my tank is not loose at all, doesn't bang or clunk while setting the front wheel down, after it's been... um... up. Also doesn't make any rattley(?) noises crossing railroad tracks, with the front end... um... up. I should probably refrain from doing that so much...

vinkate

OK ill set it at 1200rpm and IM already waiting on the ccts its winter here so IM already half torn into it. You guys rock at advice

aja

My 98 is the same. I can get it to steadily do it around 3200. I get a metal to metal sound also, and I may be wrong but this is what o think it is:

One of the carbs doesnt act as it should for a split second, causing a cylinder to not fire right away, creating slack then immediate tension on the cam chain. At least that's what I picture in my head when it happens.

There's an easy fix though, no tools needed. All you do is with your right hand on the throttle, give it a little twist and voila, its gone.

vinkate

Does it feel like a thump on your gas tank when it does it too?

7moore7

Yes. My very first post on this forum had this very concern. I believe that it is a backfire through the carb which slams your carb slide open. Sounds very metallic, but it's pretty common, and doesn't really hurt anything. Like I was saying, a proper tune will fix it, but you're not doing any major damage.

sailorjerry

Ok, well I'm having this same issue as well with my bike and i have a thread started on it but i guess my search worked a little better this time around then it did in the past, lol. My issue is clearly coming from the front cylinder, its a very hard hit, with the metal to metal clunk sound. RPM's drop when it does it, and every now and again the bike will stall. I was thinking a lot about it today and started to think that it could be a misfire and putting slack into the cam chain as the cylinder slows down, causing it to either smack the valve cover or the case. I have done a tune up and that didnt fix the issue, and am riding to a friends house this weekend to get a proper carb syncing done. My question is, does this sound probable? Has anyone ever heard/felt this due to a miss fire? It is random at idle and does it hot or cold, more so when cold. But as stated above, if I free rev the engine when ECT is under 150deg it will do it constantly. Im at a loss besides syncing the carbs. I am an automotive mechanic so I do have most of the tools and knowledge to fix it my self, but I'm trying to get as many opinions as possible so I dont F**K something up big time riding it. ( my noise and clunk is not a carb fart, I do get them and they sound way different) Thanks in advance.