Bearings...

[BikerDog]

OKay lets talk bearing. Which bearings should be changed on the motor, as well as the bike , how to change them and what kind of bearings would be optimal. any thought or opinions?

 

[Fly1]

ALL but the lower rod bearing.The two crank bearings & two clutch bearings all Number 6202 bearings.
Local bearing supplys have them. Now I changed the upper piston pin bearing because these guys
told me too. It is cheap & if you bring it to the bearing store they most likely have it also. If not
they can be had on line, I think Juice motorbikes have them.
Hope this helped Fly

 

[BikerDog]

for sure man the bearing are the key ingredients to prolonging life especially since im rotating the jug thanks a bunch mate

 

[Fly1]

I know people rotate the jug for ease of mounting pipe. But something you might think about
in doing so. It can make your engine run hotter. That is the reason motor cycle engine exhaust
is in front for air flow cooling.
Fly

 

[MrHungwell94]

I know this thread is a few months old but I figured it was an appropriate place to post rather than starting a new thread.. I am planning to replace my bearings and I know that for the clutch you need sealed bearings and the crank case needs open bearings for lubrication... Now what I'm wondering is which type I should order specifically I would like to know-

For the clutch: do people prefer the 2rs ( two rubber seals) or the ZZ (metal casing) bearings and why?

For the crank: I have heard people say just get the 2rs and pop the rubber out of them; now do you take the rubber out of both sides or just one side on each ( leaving the open sides facing each other) and if you do only take one side off each - has anyone tried the "Z" type bearing (metal sealed on one side only)?

I know the metal sealed bearings only block large debris but not smaller stuff like water sand etc but it seems like it would not matter inside the crank case. They also don't hold grease as well as the 2rs bearings which I could definitely see as a reason to use the 2rs over the ZZ for the clutch, but since the crank one will be oil lubricated it wouldn't matter if I used the Z type bearing correct? I believe the Z and ZZ type bearings have less friction than the 2rs bearings, but I'm not 100% sure on this...

 

[HeadSmess]

as always, just grab the 6202, from the local supplier, yep, the c2 standard abec 5 type...

oh, i can pop seals....

its only a bearing...

c2 tolerance? abec 5...i know what im talking about and the guy at the shop knows it too!

now... go into the shop, and get what you really need, a c3 tolerance, for main crank bearings. good luck finding them. dont worry about abecs for now, though if you can find and afford abec 11... save them for a better engine perhaps


its advisable, before going all silly and replaing bearings and thinking that any old bearing with the same numbers will do, to do some research.

learn what those numbers really mean.... for instance, one kind of bearing suits cold conditions and one suits high temperatures... some are designed for steel housings and shafts, some are toleranced for alloy housings... as irrelevant as it sounds. some are only good for low speeds and minimal duty cycle. some will take high rpm at full load all day every day...

the shop only stocks what is common, easily obtained, and will realise a profit.

thats all im saying. theres more to bearings that meets the eye and the hearsay on a forum board is not the place to get educated about them!


while sealed bearings with one popped out do work(for the crank), the seals place far more load on the engine than normal crankshaft seals. they are designed to retain the lube for their useful lifetime, whilst preventing ANYTHING from getting in, and the added friction is tolerated. they arent really ideal but i do use them myself. they suck up power. best to use plains with seperate seals.


i know. oem bearings cost so much! and they look the same! but there are differences, sadly

and you have to wash ALL the grease out of them first.

btw...never had any issues with stock bearings in china engines.... so why bother at all?

 

[butre]

I've only ever grenaded rod bearings, the crank bearings are fine. the mildest engines to come out of my shop hit 8000 rpm and I've done several with 5 digit max engine speeds and have found that in all cases the crank bearings are completely fine.

 

[MrHungwell94]

I was told it would reduce vibration but it seems like a bit of a task

 

[butre]

nope. if you want to reduce vibrations, get a bottom end with a better balanced crank. I prefer to use the half breed bottom ends with ZAE-50 connecting rods, but if I can't get a hold of one I'll happily settle for an FM80 rod. Z-L rods will rattle your teeth out at high rpm

half breed bottom ends have the best factory crankcase compression and best balance but often have tiny ports