Posts
15
Joined
7/16/2013
Location
CA
Edited Date/Time
7/18/2013 2:13pm
i have 2 1982 yz 125s and for some reason both of the bikes have worn down cases where the bearing rubbed on them. the cases are destroyed and they are both destroyed on the same side (clutch side) i do not know why this happend but i think we are going to try and fix it by making a plug on a laith and bore out the case so the plug fits the same size as the case. is this a good way to fix something like that or should i try welding it
proper i.d. interference fit of the original, best ones I received had
brass inserts in it. You could do a plug like you say or machine it to
say 1mm of desired i.d., install it and finish machine the i.d.
I believe its a better way to go over welding........
and you said the same thing that my dad was saying
have a steel insert into the case but only the aluminum. Some bikes quite common,
like a Suzuki Lt 500 (Quadzilla)-lots of vibes on fairly small main bearings.
Sounds like your in good hands with your your Father involved!
you said brass worked the best for you but would it work good if i used steel or aluminum (i dont know about aluminum because i dont want the same thing happening)
and do you mean bore the case as big as you can safely make it and then basically make it like a cast iron cylinder but put the bearing inside
and what kinds of bikes has this happened to you with?
I've been working on these bikes for a long time so i want it done good
The Shop
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displacement bikes but it gets fairly expensive in the diameter you would need.
I would not make it too large, I see no reason to make it more than about 3mm
thick per side and steel is fine-should be more durable.
Older Rm 125's & 100's had the lh main bearing loose its fit quite
often, have had transmission bearings re-fitted as well. Just my opinion but it
seems pretty common for people to drive the old main bearings out with cold
cases, this can easily lose the fit quickly-especially if someone drives one IN
cold and gets it crooked at the start........bad news.
You may check the dimensions on your bearing, the simplest way would be if a
standard bearing had the same id & thickness but a couple mm larger o.d. :-)
the 1 thing we need that we are getting within this month i think is a laith.
what do you recommend as the best
if you can slide the transmission bearing in and out of the case should you fix that to
the transmission ones I've had repaired were major failures....like loss of oil & not
knowing until toooo late.
Paw Paw
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