Left Side Crankcase Knock

[Turtleface]

did you check for loose springs in the back of the clutch hub while it was apart?? just a thought before you go after the starter clutch

You mean the piece numbered 1? How do I go about checking those springs? It doesn't seem like it'll come out of the engine through the clutch cover opening, but I didn't really mess around with it terribly much. I pulled out everything up to the inner basket piece, #5.

[Turtleface]

You mean the piece numbered 1? How do I go about checking those springs? It doesn't seem like it'll come out of the engine through the clutch cover opening, but I didn't really mess around with it terribly much. I pulled out everything up to the inner basket piece, #5.

Figured out how to remove the hub. Four of the six springs in the clutch hub are quite loose. Two of them aren't as loose, but still loose. Two of them are painted yellow, if that helps identify them. Interior of clutch area has sediment in the bottom of it. Grey in color, very very fine particles. No large pieces of anything looking like metal. Perhaps it's clutch material?

[rapidray]

Yes on the clutch material & yes on the APE hub nut. I am guessing you may want to send the clutch hub out & have it rebuilt into a heavy duty one since 66% of the springs are loose. If I can help you out give me a call at 714-356-7845. I am up for another half hour or so & will answer questions to help. Ray.

[mushman]

I've got the same (similar) problem only mine started knocking when I'm underway. I checked for and tightened a loose chain and that did remedy it initially, but then the noise returned. Countershaft sprocket is fine, clutch basket looks fine and doesn't feel loose. I had to button it back up before I could completely pull it because I had to move my entire household and shop. Major pain. I guess now I'm gonna pull the motor and eventually split the cases to have a look inside the tranny. Hopefully in the process I'll find it before I have the top end off, (clutch removal and alternator covers first). Maybe it'll be the starter clutch but as I said, I only get the knocking noise when I'm accelerating so I'm not holding my breath on that diagnosis.

[Turtleface]

Yes on the clutch material & yes on the APE hub nut. I am guessing you may want to send the clutch hub out & have it rebuilt into a heavy duty one since 66% of the springs are loose. If I can help you out give me a call at 714-356-7845. I am up for another half hour or so & will answer questions to help. Ray.

Indeed, I'm definitely sending it off to have it rebuilt. Think it'd be worthwhile to go with a billet basket? I'm planning on building a larger (1300cc-ish) motor in the distant future, and I'd like to make things as strong as reasonably possible, and am willing to spend the cash. Falicon? APE? Who's got the strongest rebuild?

[Spyderman]

Indeed, I'm definitely sending it off to have it rebuilt. Think it'd be worthwhile to go with a billet basket? I'm planning on building a larger (1300cc-ish) motor in the distant future, and I'd like to make things as strong as reasonably possible, and am willing to spend the cash. Falicon? APE? Who's got the strongest rebuild?

so it would seem you have found the problem
if i were you i would wait until you get the clutch back in before pulling the starter clutch apart.
chances are that it's fine and is more of a hassle to take apart than the clutch (at least in my view it is) anyway keep us informed on the progress of it all

[Turtleface]

Cleaning up the parts today, noticed a few odd things.



Here's the back of the clutch hub. Three of the springs look to be a smaller diameter than the others, and the larger diameter springs are shimmed with a small washer. All of the larger diameter springs were loose enough to rattle if I shake the hub, as is one of the smaller diameter springs. The other two springs do not move back and forth, but can be easily spun with light finger pressure.



Inside look ok?



Inner hub, overhead view.



Inner hub, teeth. I'm not a fan of the notches that seem to be forming in the teeth, but I'm not familiar with motorcycle clutches, either.



Close up of teeth.

[rapidray]

The outer hub looks GREAT other than the loose springs. I would send it to John Pearson at Pearson Racing & have him rebuild it. I have seen the stock hubs in Pro Stock motors before so I don't think a 200 HP street motor would be an issue. A billet hub WOULD be the strongest but if you are going to go that route, with a 1300 cc or more engine, I would go straight cut gears too. I have seen worse looking inner hubs than that one & still used them but a new 1150 inner hub has a steel insert where the splines are & is around 75 bucks. Give me a call & I will read you a list of the parts you will need to build a big motor correctly & make it live. Ray.

[OzJavelin]

Sorry for high-jacking this thread, but I can't seem to post new ones? I've just purchased on EPay (sight unseen) a '79 GS750 "project bike" (unfortunately more project than bike).

It starts runs and rides OK, but when it warms up it seems to have what APPEARS to be a rod knock noise at idle? From what I've read on here this is almost impossible due to the roller-bearing setup in the bottom end? Supposedly the usual culprits are the starter clutch and the clutch itself?

The weird behaviors of this noise are that I can make it almost disappear if I lean the bike over to the right; when it's on the sidestand (leaning left) idling the noise is most apparent. I'm wondering if it's the weird cam-endplay issue? I can't hear it when riding but as you slow up you can hear it when you pull the clutch in and when you got to take off its obvious again (riding without helmet in my field) Any ideas where to start - i.e. don't want to pull down block/bottom-end?

Oh .. other thing was when I FIRST started it, it backfired a few times while running so I suspect the plugs/leads are on their last legs too ..

[rustybronco]

You can post new threads in the "new" subdivided technical section.

http://www.thegsresources.com/_forum/forumdisplay.php?f=129

the only thing I'd like to say without being able to hear the noise, is get it running correctly then diagnose the noise.

[OzJavelin]

You can post new threads in the "new" subdivided technical section.

http://www.thegsresources.com/_forum/forumdisplay.php?f=129

the only thing I'd like to say without being able to hear the noise, is get it running correctly then diagnose the noise.

Thanks for that.
BTW: It seems to run fine now .. that backfire was only after first startup ..

[etype]

so what did you find ? if you posted i missed it i have the same problem started during a ride .you can not hear the knock when cold .

[Turtleface]

so what did you find ? if you posted i missed it i have the same problem started during a ride .you can not hear the knock when cold .

That's a good question. I still have yet to get my clutch hub back, but when it comes it and I get it reinstalled, I'll let everyone know.

[nevillebrown]

The noise is possibly coming from the starter clutch bolts ready to give up the ghost.Pull cover off and check.

[Turtleface]

Alright, it's been a while since I've had the bike running. Finally got the carbs set up well enough to get it to idle steadily. And, the noise is still present.

I'm going to go through everything I touched, and double check things. Everything seems to be working well enough, but you never know. I guess the next suspect would be the starter clutch hub? I understand I'll need a special puller of some sort, and that these things can be an incredible pain to take off. What's the best way to go about removal? Which parts will I need to order, assuming I don't break anything essential while dismantling?

At least I know my clutch isn't going to be a problem in the future.