Greetings from Oz. Help needed with vibration on CRM250AR 99

[rmm355]

First of all, hello gents. I have referred to this site many times for the CRM250AR 99 and all the information and suggestions have been more than helpful. I have a question for you. As the topic suggests, I have a bad vibration through my bike. I am currently in the process of stripping it down, (I just have the clutch centre nut to remove) before I split the case. I will try my best to describe the issue.
I was out riding the other day and bike was performing perfectly. Then instantly I got a tooth shaking vibration through the whole engine, bike, well everything. The bike at this point idled, reved correctly had all power etc. BUT from idle to approx 3500rpm there was nothing to notice but anything above that whould send a resonance right through the bike. My original thought was countershaft balance and / or crank bearings. As mentioned I am half way through the strip down and the internals seem almost perfect. I have pulled many bikes down before and these are the cleanest internals I have seen. The piston, crank, bore etc are perfect. I admit I have to remove countershaft before I state this is fine but, in the casings, there is no movement or oil leaks from the magneto side seal. I did notice there was some movement between the clutch basket and the primary gear that is riveted to it. I was wondering A: is this normal movement? and B: could this be the source of vibration or would you guys think it is the counter balance shaft. I have read all the "counter balance shaft" topics but wanted confirmation on the clutch basket issue.
Sorry for the long rant but any suggestions would be appreciated.
Ryan.

[knackeredMk1]

It is very likely that either the balancer shaft bearing(s) (and probably the shaft with them) or main bearing(s) have gone, but from what you describe it is not the big or little end.

There should be no noticable movement if you take the clutch basket out and try to move the basket whilst clamping the drive cog in a vice. They should be very firm, though there must be some play under force as there are cush rubbers under the plate that is riveted to the basket.

Finish splitting the cases and you can make a better assessment..........

[fallenmikethebike]

Main bearing, sounds like.
The autolube hasn't been run dry recently has it?
Mike

[rmm355]

Since original posting I have split the casings. It's amazing what some people do when they lack the skills required for a job. When I split the cases I found that the washer from the counter balance shaft was actually fitted the to primary input gearset along with the original, (This has marked the clutch cover housing and caused the counter balance shaft to wander.) and the collar on the gear selector shaft where it conects to the ratchet assembly was missing requiring futher movement of selector shaft to grab gear. Believe it or not I have measured the needle bearing journal and there is only a difference of approx 1/4 thou. There are marks on the load side but I assume this is to be expected due to load itself. I put the shaft between centres and dialed it up. There is no flat spotting on the counter balance shaft so I think I will get away with re-using it. Needle bearing is dead. Well spotted knackered.

Has anyone considered turning this down and rebuilding with "Hard Chrome" (material used on hydraulic cylinders) I haven't check the hardness rating but may be worth a look into as spray metal and mig welding are way too soft as per the post in "Mark 3 balance shaft" topic (I think) and hard chroming requires the finish to be done with cylindrical grinder. I guess you would have to check on a bearing running on this surface also. Anyway just a though!

Mike,
Auto Lube system has not been run dry (since I've owned it anyway). Main bearing seem fine but are getting replaced anyway. Did find a few notchy bearings in the gearcase though.
Thanks for your help guys.

[rmm355]

After checking the complete engine and finding a few smaller issues I am in the process of a full rebuild. I have ordered all parts from Honda. Bearings are all "special" sizes here for us (no bearing company has replacements). I have ordered a new counter balance shaft also as I thought I would just replace it rather than use old one which I still think is ok though. Price from Honda was $98 AUD (pretty good I thought). It was the last one they are carrying in the country but they did say that all parts are still available from Japan. The guy at Honda does look after me with price though as they are a Suzuki and Honda dealer and I also get all my parts for my K4 GSXR1000 from them too.

Just thought I would let you guys know the current price of the counter balance shaft $98 AUD.

Thanks again guys for your opinions.

[Jeram]

thats a good price mate