Any motorcycle mechanics out there?.

[Johnnie]

Here's my question. I have a '78 GS 750 E that I have been " refurbishing" over the last year or so. Bought it new, never been wrecked / down and has been fairly well taken care of. Well, my chain would go alternately tight-loose when the back wheel was rotated. With 22k sometimes hard miles, I kind of expected to have to replace the OEM chain and sprockets, and I suspected they were the problem.... or at the minimum a stretched chain. But, if you replace the chain your supposed to replace the sprockets too as they all three must like each other.
Anyway, replaced both drive sprockets and the chain as a set. I checked and closely compared old with new. New stuff was *identical* to the old stuff I took off, except the new chain ( which is huge and has a 690 pitch just as the old one , I believe and is not an O-ring chain). All went on w/o issue and not too much cursing. The chain is lined up dead-nuts and with about an inch of play / slack ( manual says 13/16th's to 1 3/16th's inches.) Had her up on the center stand to lube up her new parts (the bike, not the misses BTW ) and the back wheel rotates smooth as glass with the chain not bouncing around at all.
Went for an easy ride around the neighborhood. Noticed a noise I never heard before. You know how some tires -- especially some coarse treaded ones-- will sound on pavement? That is the noise I hear. Not really loud, but definitely audible. Didn't make it ( or at least I didn't *hear* it ) with the old chain and sprockets. I can pull in the clutch, noise gets a little less but is still there. I can weave side to side or corner, and no changes. I'm gonna get it back on the center stand and freewheel the tire , motor running and in gear. I doubt that will shed any light on my noise problem.
But..... You think my drive chain needs a few miles on it to maybe stretch a *little" to get to its sweet spot" ? Or just maybe to,loosen up a bit? Thanks in advance.

 

[No disintegrations]

With the rider weight on the suspension, I like to still have some slack in the chain. If not the system will overload with tension through the suspension travel. Some bikes may give you a spec on the center stand, some may want it done with weight on it.
Does book make mention of this?

 

[Boost231]

I agree with the above. I'm guessing not enough chain slack. I like it on the looser side so it doesn't bind. I race motorcycles. But be careful to loose and it can come off.

What chain did you get? None o ring? Why

Also you dont need to replace sprockets when you change chains as long as they're the same pitch.

Sent from my SM-N930T using Tapatalk

 

[Johnnie]

Thank you for the replies.

The manual specifies bike on the center stand, tranny in neutral. As far as the chain being too tight, after remeasuring, I am right on the slack end of the specific range at an inch and an eighth.

As far as not going with another o-ring chain, I had one helluva time finding a chain with a 690 pitch, yet alone an o-ring one. Suppliers were telling me they could no longer get them, and to go with a 500 something pitch. ( I don't remember exactly the number)' but it would require an additional adapter. I didn't want to complicate matters. I am hoping its maybe just a break in issue.

 

[No disintegrations]

I never heard any abnormal noise with new chain/ sprocket install. (did a few hundred over the years) Just as a reality check you do have some slack with your weight on the seat? Or somehow they gave you mismatched chain or sprockets? Or something is out of place/alignment or too tight or too loose?

 

[Johnnie]

I compared the sprockets new with old and they were identical in size and tooth spacing. Chains were also identical in length / width ( but the old one was a little stretched. I think that explained the alternate looseness/tightness as the rear wheel rotated which is now absent with the new chain and sprockets. ) The wheel rotates smooth as glass , with minimal chain movement when in neutral and rotated by hand . The slack measurement is the same with me on /off the seat. Alignment was checked with a laser and was dead nuts. Gonna put a few more miles on it today and see if anything changes. And thank you much for your input.

 

[No disintegrations]

cool then it should be good after a little run in time.

 

[Johnnie]

ND, took her up to the gas station to put a known quantity of premium in the tank as it has no gauge. This adventure required me to get on a two lane road where traffic goes between 45 and 50 mph. I haven't ridden the danged thing in traffic for almost 20 years and have limited my riding to around the airport where my airplane was and in my neighborhood -- 25 mph tops-- so I was a little nervous to,say the least. . I will tell you why.
I am kind of learning to ride all over again. Plus, I'm not a motorcycle mechanic by any stretch, but I do have a fairly decent manual and some decent tools ( good torque wrench etc ) I have had both wheels off for new tires ( I didn't mount them, the bike shop did) but I put them back on the bike. I also took the bars, the rack and sissy bar, turn signal stalks, rear shocks, blasted them and had them all powder coated black . I had to rebuild both front brake calipers, the rear brake caliper and install a new rear master cylinder ( never changed brake fluid --- aargh !! Learned my lesson on that one!) So, that being said , ( don't laugh) I envisioned *something* falling off --- you know like a wheel ( hahah) or whatever.
So, I took her up to 45 mph, trip was about 3 miles each way. Did a couple of relatively hard pulls each way -- not WOT , just spirited pulls. Came back, cruised around in my hood again, and noise was noticeably less at 25. Chain deflection still the same. We shall see.

 

[No disintegrations]

Now that's a laundry list. Big jobs like that always had me quadruple checking stuff!

 

[daves87gn]

What's it sound like, I kill the engine on my bike a few houses away at night, all you hear is the chain, kinda a buzzing sound it's normal