counter balancer???

[tecatecrazy]

I need a little diagnosis help with my lt250r (86). I was out riding today and the bike was riding great, I mean excellent! Just before I was going to load up my entire quad started vibrating bad (worse than my tecate even). Other than that it ran fine, good throttle response, no unusual noise from the motor and all the motor mounts were still tight. The only thing that I can think of is that the counter balancer must have something wrong with it. I would have thought that if something came loose inside I would have major engine noise or at least detonate or lock up the bottom end, but I didnt have none of that. Would it be possible for the balancer drive gear to jump a tooth? I really dont want to tear apart this engine, It has just been rebuilt and powdercoated gunmetal gray and is soo pretty. Any thoughts? sorry for the long post.---Joe 8)

[J.D.]

Well I'll be the first to admit I don't know a lot about engines, but it does sound like something with the counterbalance. Does it only vibrate when your driving, or idle, or all the time? Any certain RPMs it does it at or all the way through?

[TimSr]

Does the LT250R even use a counterbalancer? I thought that was only a Honda thing, but I really dont know much about the Suzook.
On the Honda the counterbalancer is is geared right into the crank, so when it goes, you would would normally get catastrophic results such as lock up, or extremely noticeable clunks and bangs. What normally happens is the bearings on the counterbancer wear out, and you start getting a low level roaring or whirring noise that gets progressively louder, and you replace it before it ever falls completely apart. Also even when the beairng is worn out, it still performs its function. I doubt its the counterbalancer.
The fact that it happened suddenly would make me suspicious of rod bearings, but Id check the crank bearings first since they are easier to get to, and can be checked by simply removing both sidecovers. Also when the sidecovers are off you can make sure that the flywheel is not loose or wobbling, and also the clutch basket on the other side. If everything is good and tight, then Id be tearing the top end off and check wristpin and rod bearings.

[tecatecrazy]

well I pulled the ignition cover off so that I could see the left side of the counter balancer, kicked it over by hand a coulple times and the balancer didnt budge. It will still move freely by hand and the bearings seemed to be pretty smooth. Obviously there is a serious problem with the gearing on the clutch side. I'll open it up tomorrow and let you know what I find.---Joe 8)