On a dutch motorcycle forum is a guy that has a GS500 engine with worn out counterbalancer bearings. He says this is the 2nd GS500 engine he sees with worn out counterbalancer bearings. There was enough oil in the engine but the problem appeared after a full throttle ride.  

Right now he's doing a needle bearing conversion because the bearings were so worn that the balance shaft was running in the engine casing instead of on the bearings.

I'm a bit concerned by this, as this is the 2nd engine with those problems, and I'm often riding at high speed, 85-90 mph for 2 hours without stopping.  Is there a real possibility that I will have the same problems too, or are there dozens of riders here that ride in the same manner as me?

No, not if you change your oil regularly and don't keep the engine screaming at red line.
The only time I've ever heard of this problem has been on race motors, where they have been built and spend alot of time at max revs.

im sure pablo will see that then.. he runs 9K in the canyons all the time.

Quote from: LarsRight now he's doing a needle bearing conversion because the bearings were so worn that the balance shaft was running in the engine casing instead of on the bearings.

I'd be really interested in any details of the needle bearing mod. I thought about it briefly after I spun my CB bearing in my race bike, but it didn't seem like there is much clearance for a bearing on the one side. It is awhile since I looked at it though.

If he has any photos, or even bearing part numbers, I'd appreciate seeing them:

kcaldwel *at* telusplanet.net

I'll keep an eye on the thread since some questions are unanswered about the needle bearings. a (very good) mechanic has asked questions regarding oil pressure. Since needle bearings are much more open, the oil pressure would probably drop too much.

With needle bearings you can probably get away with capping off the CB oil jets.

The CB oil pathways would probably end up capped whether you liked it or not! There are restrictor jets on the CB oil passages there already, so I doubt if the bearing is the control on the flow to the CB bearings.

11,000 rpm is going to be pretty hard on needle bearings I expect. I was thinking more along the line of balls or rollers originally, but I don't think there is enough space.

Yeah, there isn't unless you can find some with very thin races, or maybe turn down the balancer shaft (which creates a whole new set of worries).

I would either fine a new(er) engine if its a streetbike, or just ditch the CB and have the crank rebalanced if this is a trackday/sunday hooligan.

how would the rollors get oil if you converted the bearings, granted they no longer need the pressure as a cushin, but still need oil.  now, i'm sure i can do it to CB shaft, and maybe even the ends of the crank, still thinking on how i could cut a bearing race in half and have it fit correctly like 2 halves for the middle of the crank figure flat roller bearings can handle heavy loads, and still would spin less rpm then crankshaft, my old Yamaha 175 enduro had roller bearings and only the fuel/oil mist from carb to lube them.  im thinking a grooved bearing race, machined to be split in half and held tight by torquing the cases. if only it were a V, this would be simple.

What happens when you make the oil pressure higher? can it prevent bearing damage at high rpm? Would probably be easier to implement than needle bearings.

No it won't help except maybe to help disapate heat.  In plane bearings, the oil acts like the ball bearings in a regular bearing. Having more of it moving faster might be less effective.

Blue- You want to cut the roller bearing in half?!? why?

With the one piece crank, you can't get rollers onto the inside two bearing surface.

Cutting rollers isn't going to work, and they don't make two peice ones because there is no known way to make it work.

I've only toasted one set of crank bearings, and I think that was my own fault. But the CB seems to be vulnerable for racing. Maybe I'll just chuck it and rebablance the crank. Or buy that SV....

Isn't there a way to modify the oil system to deliver more oil to the CB bearings?

yes (Bigger oil jets)

BUT

You run the risk of lowering pressure to other, more critical areas like the crank or cams.

If my Idea with the spin on adapter incorperating an oilcooler works, i was thinking of the old Honda V4 problems, the early modles use to eat cams (poor oiling) they have a mod that runs sep lines to the cams for better pressure and cooler filtered oil. now,  upping the pressure on the oiling system wouldnt be too hard, but you couldnt do it unless your crackin the cases open.  im still working kinks out on paper.

Bob, was thinking to cut a race in 2 halves matched like bearing shells for center of crank.i dont think the alluminum saddles would hold up to the rollers. but i think the machining would have to be super precise and very expensive.

QuoteMaybe I'll just chuck it and rebablance the crank

But would the reballenced crank be a streetable engine?  has anyone taken down the rotating mass of the CB? and then reballenced? less mass spining, faster up the rpms, but still wont rattle the fillings out. atleast thats the theory

Quote from: JamesGyes (Bigger oil jets)

BUT

You run the risk of lowering pressure to other, more critical areas like the crank or cams.

If there's a way to modify the oil pump or replace it with a more powerful one, this would be solved.

But I don't know if this is an easy fix ?