gt750 and o-ring chain

[Eddie]

well about 2-years ago maybe 3 I had to replace the swing arm bushings so I opted to replace the chain at the same time, the guy at the bike store told me the o-ring was the way to go and I asked him if it would fit and he looked it up and said yes,,,i remember it being said they wouldn't fit? but I decided to try it, and it was damn close but did not rub on anything so I thought wow I got lucky or people don't know what they are talking about ,,,,long story short I got an oil leak from the the sprocket side, somewhere not sure where so I took the case off and hell!!!!the damn chain wore down the aluminum behind the sprocket!!!!! ,,,as best as I can tell this is not my oil leak ,,,seems oil is leaking from behind the sprocket but not the case ,, or maybe gear shifter not sure I need to clean things better just saying it did not wear the aluminum down to where theres a hole just freakin wore it down perfect for the chain to fit ,,so anybody had this happen? or am I'm the only dumb ass that has encountered this ?? its weird because I checked and double checked it and it never hit or rubbed on anything ????, maybe this happened from giving my wife rides? extra weight ? she has been on a diet ,,no but seriously should I leave the chain? I'm assuming it wont get worse and its been about 3 years now so I would think I'm good? and now my motor is perfectly ground for an o-ring chain ,,also I have replaced the seal or whatever it was(don't remember ,getting old) behind the sprocket before because it leaked and it stopped for a little while and now its doing it again,,???? any thoughts thanks! or it could also be the gear indicator leaking ? I remember I replaced something on that side that I knew for sure was leaking and it stopped for a few years and just started again ,,,,damn I cant remember a couple of years go by and in my brain its like 20 years have gone by crap.......

[Warehouse1001]

Eddie,
I'm going to be very interested in the reply(s) to your "O" ring chain issue as I'm restoring an L model and just assumed an "O" ring chain would be fine with plenty of clearance. Kind of surprised it appeared ok and then rubbed anyway. Strange.....Chuck

[tz375]

With an OEM front sprocket an O ring chain will rub the sprocket oil seal holder which is steel. One of my GT750s was fine with an O ring chain but if had a slightly offset sprocket. The next one I built with a flat front sprocket rubs. In that case, a couple of lock washers were enough to shim it out but you need to see if the rear sprocket also needs to be shimmed out to keep the sprockets in line.

I'm not sure what part of the crankcase is being worn away. Could you post a picture please.

[jabcb]

Chain widths vary a bit depending on the brand, product & type of o-ring. I looked a few years ago & found a width range of 2+ mm.
May have changed but the DID VX x-ring chain was one of the narrowest.

[rngdng]

I have an RK o-ring chain on my 750. I don't think I had to space it out...



Lane

[Eddie]

I might be able to post some pics tomorrow , not sure though I had surgery and been kinda bed ridden but I will have to go pull the side cover off again and take some pics , I had put it all back because I figured I'd leave it . Thanks for the replies and what I don't understand is that it was fine and had no clearance issues when I assembled it , then about a year or two later the engine case is worn I don't think it has worn any metal behind the sprocket but I could be wrong I had put it all back together since I knew I was having surgery . I will post pics and more info as soon as I can thanks !

[Eddie]

Also it did seem to wear the steel plate down behind the sprocket but not directly behind it but the bottom mounting screws to the plate if I remember correctly , I found this problem a while back and forgot to ask what was up with it until the other day so once I have it apart and know for sure what's worn I'll post some pics ...

[yeadon_m]

I tried an O-ring chain on a 750B but gave up in the end. Spacing out the front sprocket with a couple of lock washers cleared the motor but then the left side of the chain clipped the front of the chainguard and/or sprocket cover.
I know some get away with it! must be small variations in manufacturing in the bikes.
I use DID 530NZ (heavy duty) chains and found the 'stretch' rate is acceptable for road use. The GT750A I have does work that chain pretty heavily and I fairly often need to tighten it up a flat on the adjusters, but the same chain ignores the lesser power of a 550 and 380.
Cheers,
Mike

[Eddie]

Is there 2 different size o-rings that go behind the steel plate that's behind the front sprocket ? They list two different part numbers and the o-ring I got seems to be to small or it's because it's new and the old one is stretched , I can't remember if I had replaced it back then ? Going to take some pics

[Eddie]

I got the smaller o-ring on , not sure if it was the right one because at bike bandit they have 2, different ones listed , also I got some pics of the plate behind the sprocket , I ended up grinding some metal off the plate where the chain was rubbing and yes it looks pretty bad even had to grind the screw heads , I know I feel like I just did some crappy job but it was already worn from the chain I just did it a little more to make sure it wasn't hitting , feel like a just jerry rigged the hell out of it but the damn thing was already worn so it's staying like that for now , as Lon as I have this damn chain on , also what is the torques spec for the sprocket nut ? 36 or 100 ft lbs ? Keep finding those numbers on line ...well I kee trying to upload a photo from my phone but it won't let me ? I'll try latter

[yeadon_m]

I did mine up to 80 lb ft.
Cheers,
Mike

[Eddie]

thanks ! I did mine to 70 ft pounds,, I guess that's enough,,every time I try to post a pic it says the file is to big , and I have no idea how to resize it or whatever needs to be done but ill keep trying.. also if anybody buys parts from bike bandit you can go on their site and look at the transmission,,,,number 29 has two part numbers and they are 29-1 , 09280-63001,,,,and 29-2, 09280-64001 I had the one ending in 63001 and it was smaller than the one I took off so I'm wondering if these o-ring sizes changed through the years??? I have not ridden the bike so I don't know if it still leaks but this o-ring was definitely smaller than the original,,,unless the original is just really stretched out any thoughts? does anybody know if the sizes changed? nevermind after a long search apparently they did have 2 different sizes , damn I used the smaller one and mine needs the big one ,,hope it doesn't leak crap

[pjmcburney]

For info...


A H2 front sprocket has enough of an offset to allow an o-ring chain plenty of clearance from the seal retainer/crankcase on a GT750.

Particularly fastidious H2 sprocket users on GTs have also been known to space the rear sprocket to match the H2 sprocket offset, but there's so little in (about 2mm) it that it's probably not necessary

[Eddie]

Thank you guys for the help!,, the chain fits now , but I'm just wondering if I used the right o-ring behind the sprocket,,,,i ordered both O-rings now just incase this one does fail ill replace it with the big one, I cant believe theres no information on which years used which o-ring , the one I took off is bigger than the one I put on but not sure if its because it was stretched out or if it was the bigger one? my bike is a 74gt750 and I cant find info on which o-ring it calls for but I had the smaller one so I put that on,,,,i haven't ridden it enough to tell if it leaks yet or not...

[tz375]

For info...

A H2 front sprocket has enough of an offset to allow an o-ring chain plenty of clearance from the seal retainer/crankcase on a GT750.

Particularly fastidious H2 sprocket users on GTs have also been known to space the rear sprocket to match the H2 sprocket offset, but there's so little in (about 2mm) it that it's probably not necessary

And I had forgotten that I used an H2 sprocket on one bike and the O ring chain was fine. I replaced it with a non O ring for racing and fitted the O ring chain to the Dunstall with OEM type sprocket and immediately had a rub. Two lock washers were enough to space that out.