Suzuki RM125 1977 cases

narrowfarm
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narrowfarm
Hello, I noticed on my 1977 air cooled engine that my crankshaft has a little movement up and down and side to side when I grab the Flywheel. My engine has new seals and bearings and has running time of about two hours and still runs but I am very concerned..
I once heard that the engine case on the left side that hold the left main bearing in place can wear out.
Does anyone know of an oversize bearing that I can get ??? and than I have to get my case machined out. Or should I just try to get another USED left side case and go that route? Thanks
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WRH
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WRH 11/28/2016 5:25am
11/28/2016 5:25am
There is an oversized bearing that requires case boring. It was actually used in another Suzuki engine of the era. I am at a loss to the part number but was commonly stocked in our parts dept.at Garland Suzuki in the day. It should be as simple as getting the dimensions of your current bearing and then get one with a larger O.D. The Suzuki part numbers actually contain the bearing number for a starting point.
narrowfarm
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narrowfarm 11/28/2016 11:08am
11/28/2016 11:08am
Thanks WRH ! any idea though could the bearing have come from a street bike or would it have been a dirt bike of that era??? I think I will go the way of getting a larger bearing and getting the case machined.
WRH
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WRH 11/28/2016 11:23am
11/28/2016 11:23am
I actually believe it was a middle crank bearing from a GT 750. Or a T500. I can make one phone call to see if there are still paper notes on it. Long shot but I will check.
fookyoo
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fookyoo 11/28/2016 11:46am
11/28/2016 11:46am
I bet the play is on the crank journal( bearing id on crankshaft) not in case
Suzuki , machined the crank journals
for a slip fit!
If you have a factory suzuki manual, you
will notice the crank assembly, removals
require only a case splitter, and soft hammer , to install
Many of mine , took very little effort to
install all the crankshafts, from 125-500

The Shop

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WRH
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WRH 11/28/2016 12:06pm
11/28/2016 12:06pm
Koyo roller bearing. DQ 2555.. 25x55x15. It has a hole in the outer race for a pin . This kept it from spinning in the cases in its original application I suspect. The LH cases did wear out occasionally. Sometimes you could touch the outer race O.D. with a welder to help take up the slop. Or simply red loctite a feeler gauge into the case with the bearing to tighten up the clearance.
MaxPower
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MaxPower 11/28/2016 1:26pm
11/28/2016 1:26pm
I might do another set of cases. And red loc tight the bearing for good luck. Ive heard of guys using shim stock which would work. I would think,its a psin in the butt getting everying in nicely. Instead of boreing the case to accept a larger size main, is it possible to machine a groove in the outer race and case and knock a pin in there of some sort to keep it from spinning? I remember as a kid someone telling me to use a punch and go around tbe case smacking punch marks in to create a raised surface. All that did was eff up my cases. You are not alone. This was a eeakness of old Suzukis. Spun main bearings and defective stators were the norm
project racer 11/28/2016 4:43pm
11/28/2016 4:43pm
Loctite also makes a stud and bearing mount formula. Hope you all are heating the cases during bearing removal. Driving them out cold takes an ever so slight of case material with them each time.

Cases, hubs, etc., will quickly lose their ability to hold a bearing by beating new ones in and out. Only takes a couple or so times for things to get sloppy, especially if things are not driven in square.

A cocked hardened bearing driven in cold will eat the soft bearing areas quickly.

Freeze the bearings and heat the cases during install.
narrowfarm
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narrowfarm 11/29/2016 7:36am
11/29/2016 7:36am
Any Idea if I try LOCTITE 660 would possibly work??? Just reading about loctite
fookyoo
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fookyoo 11/29/2016 9:34am
11/29/2016 9:34am
Are you sure the bearing od has spun, or
has clearance in the case set?
How about after the engine is warm?
narrowfarm
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narrowfarm 11/29/2016 10:06am
11/29/2016 10:06am
I plan on tearing my engine down to see what is going on. I was riding my bike for about 25 minutes at a track and all of a sudden it felt like the engine was going to seize up so I slowed down and in about 20 seconds ran good again. My jetting in the carb is close. I pulled the plug and it looked good. Just happened to noticed a very slight play in the crank at the flywheel when the engine is cold. I am just assuming the bearing may be loose in the case.
fookyoo
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fookyoo 11/29/2016 11:36am
11/29/2016 11:36am
If the bearing stay's in the case when separating, and it does not take a lot of
effort to pull ignition case off of right
side (down) it would be crank journal
play you are feeling
WRH
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WRH 11/29/2016 6:49pm
11/29/2016 6:49pm
Could be both as old as it is. Just saying.
narrowfarm
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narrowfarm 11/30/2016 4:30am
11/30/2016 4:30am
Everything looked good with the crankshaft when I installed new bearings and seals. The bike started easy after a rebuild. I put about 2 easy hours on the bike riding at a track. Every now and than running her like it is suppose to be run. Than for about 20 seconds I thought my engine was about to seize when I was riding it. I slowed down and than it ran fine again . I stopped and I checked the spark plug for being Lean but plug looked good. I ran it again for another 15 minutes on the track and it ran good.
At night in my garage, I than notice the slight flywheel movement when I grab it by hand, engine was off and cold. The Flywheel was tight on the crankshaft.
If its a crank journal, What can be done about a crank journal problem?? If its a spun bearing, I am sure the case bearing holder will show wear marks.
fookyoo
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fookyoo 11/30/2016 7:14am
11/30/2016 7:14am
When was the last time you cleaned your
petcock fuel filter? or remove it and use
an inline, or nothing
It does not take much to plug or slow fuel
down on the old Suzuki petcocks
As stated above, Suzuki cranks do not
have a press fit like Yamaha , when you
install your crankshaft into new bearings

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