5/8" Front sprocket spacer

[liloaty]

Ray, I fully understand WHAT can happen if the shaft bearing fails, but do you have any proof to support that it happens regularly on a relatively stock motor? I mean if you look at the numbers, you are moving the sprocket out 5/8", thats not putting that much more load on the shaft bearing.

I'm willing to pony up the extra money if there is some proof to support that the shaft cant take it...

 

[kichigai]

Rapidray, I appreicate your tech knowledge and comments! I was hoping someone would jump in and provide some pro/cons.

I made up my decission not to get the support kit based on a conversation with the tech from PMFR who told me that for a stock motor I shouldnt need it.
He did though highly recommend it if I was to do any racing with my bike!

Like Liloaty, I dont mind spending the extra costs if it truely is needed, and would be interested to hear of anyone that have experienced shaft bearing problems due to using a offset sprocket. Thanks! :-D

 

[lecroy]

Kichigai, for all that we are doing to build dragbikes & custom streetbikes, that PMFR offset kit is NOT expensive! I have 2 of them & the workmanship in them is a DEAL at $395.00! All you guys that want to move your countershaft sprockets out withOUT supporting the sprocket are just asking for trouble! I don't care how long you have been riding that way or whatever your story is. The reason for the support is to prevent bearing failure due to overloading the bearing! Once you lose an output shaft bearing and all that metel goes THROUGH your oil pump you will listen the next time. Ray.

What he said! Damaged cases.....

 

[liloaty]

What he said! Damaged cases.....

Details on this? Your bike? How much power were you pushing?

 

[lecroy]

Details on this? Your bike? How much power were you pushing?

This particular bearing (output shaft, sprocket side) failed on my first 83 GS1100 I'm thinking after it was maybe a year or two old was all. Maybe I had a pipe on it, but nothing radical back then. I think they were rated for 108HP. I was pretty hard on the bike though. No problem with it sucking the fagments into the pump. The engine locked tight and the bike slid to a stop. The main problem with a ball type bearing like this is that it can not take a lot of load at zero speed. I started to replace this bearing on a regular basis.

I doubt many people use the stock bearings and shafts in their race bikes.

I agree with Ray and Kris on this one, wider tires and moving the sprocket out will just compound the problem. Then again, if your just after the look and don't beat the crap out of it, should be fine.

 

[liloaty]

Whew thats some really bad luck! Did you have a widened tire on it? How much in damage did that end up costing you?

 

[lecroy]

Not so much bad luck. I was just more ignorant back then.

I'm guessing I still had the factory tire on it, or I used to run Dunlop K491s or some thing like that back then. Stock size tires for sure.

Back then I could buy a brand new set of cases for $500 from the dealer. Now they cost damm near that used, when you can find a good set. I think I just bought the cases, new bearings, gaskets, a tire and a days worth of work. Bike stayed upright.

 

[Kris V]

Wait until it does it at over 100mph:shock: then it get`s fun

 

[liloaty]

Whew that's crazy. I wonder how often that really happens. I ran some numbers and moving the sprocket really doesn't increase the bearings load much at all...

 

[Kris V]

Did you factor in a wider contact patch from the tire? How about the different rim and possibly a heavier tire?

 

[lecroy]

Whew that's crazy. I wonder how often that really happens. I ran some numbers and moving the sprocket really doesn't increase the bearings load much at all...

I don't know how often, but just wanted to write in that I had personally had it happen with a stock setup.

When looking at a problem like this, you need to expand your view. Don't just look at one aspect. So, while I agree that moving a sproket out a small amount is not going to add to the problem all that much in itself. But, you need to ask why move it out in the first place... Ah, wider tire. Did your calcs include taking the tire that came on that bike in 1983 and comparing it with a modern wider tire? I would be willing to bet I could get a lot more traction with a newer tire. And with more traction, the load that bearing can see will be worse.

If you ever pull apart an 80s Kaw and look at the tranny, then you know how much less material is in the GS. Not just the gears, but the bearings on the Kaws look a lot stronger than the GS. You can buy a better bearings and it sure couldn't hurt. I think the last set I bought were under $100.

As Ray suggests, the cost of the support and welding the braces for it is not a whole lot when you consider what could happen. Like Kris wrote, it is your bike and your choice. I think they both gave you some good advice.

When will Ray ever get a website????

Good luck with your project.

 

[lecroy]

LOL, he was ahead of me.....

 

[kichigai]

The big thing about the sprocket spacing is tire clearance. I have had chains that were not totally aligned and they worked fine. The tire and the frame are crucial for spacing. Kosman use to make an outboard bearing assy and they were and still are the best I have seen but good luck trying to find one. I think Schnitz makes one or carries one. Gixxer rims are pretty wide and the 90 model is around 5 to 5.5 in where your 80 GS is 3.75"

Here is the link to the PMFR outboard support kit in case anyone needed it!
http://www.pmfronline.com/out_board_bearing_support.htm

 

[Guest]

Guess I've been lucky. Bike has 103,500 now. Course I've never done a burn out in my life and probably never will. Do I get on my bike hard when its already rolling, absolutely.

From lifting the two I would say my 160 RF900 wheel and radial tire is substantially lighter than stock set-up (hollow aluminum vs cast). 530 chain is lighter than stock and rolls with a lot less drag.

I don't have an old sproket handy but Katman's site says stock sprocket spacer that is bolted to the stock sprocket is 10mm wide. 3/8 offset is 9.52mm.

Could a ham fisted drag racer F#@k up my set up with a 8500 rpm launch, I bet they could.
That why I avoid those antics

 

[lecroy]

Could a ham fisted drag racer F#@k up my set up with a 8500 rpm launch, I bet they could. That why I avoid those antics

I have never heard of that term before....

Adj. 1. ham-fisted - lacking physical movement skills, especially with the hands; "a bumbling mechanic"; "a bungling performance"; "ham-handed governmental interference"; "could scarcely empty a scuttle of ashes, so handless was the poor creature"- Mary H. Vorse
lacking dexterity or grace : heavy-handed

Too funny. Again, I agree with you. Don't beat on it and it should be fine. Not sure how many of you remember this, but the 83 had some problems when it first came out. Bad front discs was one problem. I personally had this and so did a friend. Newer discs where true.
It also seems like Suzuki made some changes to the 83 cases and beefed up this area after the first release. Seems like I remember getting the new set and thinking, ah, I was not the only one with problems in this area. But it's been 20 years.

I remember after I had owned the ESD for a few years I rode it to a bike show. I met a guy who had rode one in too and he told me that I was the first white person he ever saw with one. LOL. I had good taste! The stories my bikes could tell.....

 

[tone]

just as a balance to some of the above posts ....... from my experiance its a fairly common thing for gs etc front sprockets to work loose i guess this is mainly down to previous owners as ive never had it happen to one ive fitted ...... yet [-o<

A katana i helped build 9 years ago has been running a 157 rwbhp gsxr engine on an 12
mm home made ofset sprocket since day one & the total damage so far is lots of rear tyres, chains & sprockets, but i will admit the output shaft oil seal is just starting to leak

from that my opinion is that a small ofset only puts a small strain on the gearbox (i cant bring myself to call it a tranny as that means something entirely different over here :-D) I'd say an incorrectly ajusted chain will put more strain on a gearbox than a small ofset but for bigger ofsets & more power a propper outrigger with bearing is a good idea & its no real hassle as you would probably be into frame mods by then anyway

 

[lecroy]

Just to be clear, the key with any ball bearing like this is to not load it at stall. As long as things are spinning, you can give it heck. We used to race a lot on the streets when I was younger and doubt the bike had actually seen a real drag strip at this point. But low tire pressures, yes. I never over tighten a chain on a street bike but it's a good point. It's not an apples to apples compare, but my GSXR is about that same HP and has a lot wider tire than the GS. Looks like what people are trying to make the GS look like. I have never had any problems with this bike but it has never had any hard launches on it.

For the ham fisted......

I'm not sure if you would need to mod the frame for the lower end outboard. I have not used one of these on a Suzuki. On the Kaws they just bolt into the stock holes. I'm not sure at what point you need to tie the crank and the output shaft together on a GS. We broke a motor in half a couple of years ago and believe that this was the cause.

I electric start my race bike so there is no good way to tie them together. So I modifed the inside plate to add a third tie down point. Then milled out the entire crank bearing support. Not the greatest setup but seems to be holding so far.

 

[Kris V]

Nice lookin hair dryer ya got there\\/

 

[kichigai]

Check out this interesting write up on offset sprockets! :-D

http://www.gsx1100.com/site4/tips/offset_sprocket.php