Clunk clunk clunk ...transmission?

I have a 93 VFR750. It is fairly new to me. It has a few problems, but the biggest current concern is the clunking from what appears to be the transmission.


Here are the symptoms:

*The bike was very hard to upshift, and would clunk pretty badly in lower to upper gears (1st to 2nd, 2nd to 3rd mostly).

*When the bike is idling in neutral with the clutch out (no hand on the clutch) the bike makes a clunk clunk clunk noise. I can feel it in the bike as well as hear it. If I pull the clutch in the bike quiets down.

*If I have the bike on the centerstand and put it in gear with the rear tire off the ground and let it idle it clunks and pulls the bike around, as in it is very rough. The idle is fine, but something between the engine and the chain.

What I have done:

*I did an oil change. The oil was pretty dirty and I put Amsoil Synthetic Motorcycle Oil 10W-10 in.

*I also replaced the very dark brake oil from the clutch system. There are some gel-like deposits in the bottom of the master cylinder, so I'm guessing a dissasembly / rebuild / good cleaning is going to be in order here. I think there may have been some air in the lines, but it was hard to tell. I think I'm going to bleed the whole system again over the weekend to be sure.

Changes:

*The bike seems to shift much better, especially noticable is first to second. Still have all the clunking stuff.

Any tips on where to start or what to do?

Thanks!

Mark

 

Oh Man that's one of those tricky questions where being there helps big time, that said, seems it is in the shift drum, by pulling on the lever you take the load off the drive train and shift drums. when Moving the shift lever with the clutch pulled, does it snap smoothly into gear? or? does it seem to be notchy? it should be a firm yet smooth tug. then just pops in gear if that makes any sense. you have two things going on at the same time when you shift, and to me just by what you are explaining it is in the shift drum transaction where it slides the gears into position kinda hard to put into words, here's a parts diagram to show you all the parts, also Google for more info on the subject as motorcycle transmission's tricky little buggers. that said it could be in the clutch by it not releasing all the way therefore not taking all the load off the drive gears to keep things working smooth. I say that because of the millage all though that is not a lot, could be a combo of all the above too, but I'd start looking at the clutch first.
Here's a little trick, go out and ride like you would, but instead of using the clutch in the shift process try just a little bit of backing off the throttle and shift, the idea here is to see if that works any better than when you use the clutch, if it doesn't then yea go the clutch route and look into seeing if it disengages all the way, could be in the master cylinder that isn't allowing or the slave too. Hope this helps a bit. I know it's long winded.

 

Great info, thanks. I will give it a try this afternoon.

Mark

 

OK,

It seems "notchy". It is significantly better since I changed the oil and clutch fluid though.

I shifted without using the clutch quite a bit today (fun in the rain I might add). It typically is way smoother shifting without the clutch. There were a few times I couldn't get it to shift, but that may have been me.

I guess I'll start with rebuilding the master and slave cylinders and making sure it is bled properly?

Thanks,

Mark

 

Also food for thought; if the clutch basket grooves are worn and the engine needs a tune up (valve adjust, spark plugs and carb sync), the noise you are hearing might just be some typical sloppy parts. Is it more of a "clacking" noise than a "clunking" noise at idle? Since you pull in the clutch lever and the sound goes away, that would suggest more or less normal wear.

Based on what you found with the clutch fluid, it sounds like maintenance was not high on the previous owners list, which is why a good tune up might help smooth things out. How do the chain and rear sprocket look? Or, if you have replaced them, how did they look when you got the bike?

 

Chain was terrible. Rear sprocket was OK. Rear tire was pretty bad.

I purchased it on 9/23 and put new tires on it on 9/27. After about a week and a half I got this terrible clacking / slapping noise whenever I went off throttle. I checked the chain and it was very loose, so I tightened it, which would fix it for a day or so then it would start again so I brought it down and put new front / rear sprockets and chain on. That was on 10/15.

The oil in it was pretty brown, and it was hard to start. I ran 5oz of SeaFoam through the gas tank last fillup and that seems to have helped the cold starts and idle quite a bit. I also replaced the coolant last weekend when I did the oil change and hydraulic fluid replacement.

Spark plugs and air filter are next on my list. Valve adjustments (it doesn't "chatter") is expensive. I will get the carbs synced when I have the valves done though.

Mark

 

Good to hear, with the right timing and a clean throttle cut with a smooth foot you can actually shift really good with out the clutch. cool, sounds like this is the right direction.

 

I re-bled the clutch system today.

It appeared there was a LOT of air in there still, but it didn't subside at all so I figure some air was getting in at the nipple threads. I just cracked it a little and got some small bubbles out I think. It is really hard to tell though..

I love how the service manual refers you to the Common Service Manual for like everything. In any case, the Common Service Manual states that you should wrap the threads with teflon tape. I didn't feel like pulling the bleeder nipple out, so I just did the best I could.

In any case, something happened because the bike is now super easy to shift. Before it was very hard, as a matter of fact it required so much effort it would hurt my foot if I rode for a while and did a lot of shifting. I still got some clunks, so maybe there is still a bit of air in there. I'll probably bring it down to a shop and have them bleed it for like 20 bucks when I get a chance.

Thanks,

Mark

 

sounds like ure on the right track now

 

Cool, glad to hear it's for the most part fixed ...