loose crank bearings

[WILL_S]

I'm building a stroked CT
Rebuilt the crank and used c3 graded bearings,nsk japan bearings.When the cases are buttoned up the bearing has a small amount of movement in the case races.You can rotate easily the bearing in the race and see a small amount of back and forth up and down .The end float is tight.tried another set of cases and it is the same.All my old stock cranks don't have this movement with old bearings.when i used non C3 bearings they were tight.Is this normal for C3 bearings or even rebuilt cranks?
Thanks

 

[sean01]

not good..
must be either wrong bearings or the ID of the c3's aren't the same...

your looking for trouble if you run it like tht..
massive vibrations, engine will knock, you'll more than likely get piston and barrel wear

 

[WILL_S]

bummer
thought the jap stuff would of been good
I've got these china ctk branded bearings which off the crank seem a bit tighter in the cases.
Never heard off them, any good?

 

[coolmodee01]

no you will find the nsk brgs will have been manufactured to a tighter tolerance than your chinese cases are
i dont know why you are useing c3 bearings. A pit bike/CT engine will not create enough heat for the metal to expand enough to make seizure an issue at all in a standard clearance bearing

you can and should use loctite 609 or 641 retaining compound it stops a bearing from spinning in your cases if it fails. means your cases dont wear when the bearing spins up when it seizes. ( i assume something like this happened to the last lot otherwise you would not need to change em) i do this with my wheel bearings and i dont have flogged out hubs at all

 

[WILL_S]

Thanks for the input
These are jap cases
They were replaced because the crank got a full rebuild
C3 was specified
This motor will be used in a 6000km endurance ride
Mostly held wot for up to maybe 20 hrs a day
I would like it to last the 6000

 

[coolmodee01]

i reckon 6000k's in the saddle on a postie will be a tuff slog

i'm not sure where the cases for a postie is made but i'd assume not japan but probably not china either

I'd be pretty confident in the NSK bearings they are the best they use the highest grade steel of any other bearing on the market. i've put em to the test

again loctite will secure the the few thou clearance difference

whats the enduro your doing???

 

[WILL_S]

coast to coast
byron bay nsw to steep point WA

 

[coolmodee01]

nice will be one hell of a trip

take a spare donk with ya

 

[timeeh]

You better be documenting the trip.. Sounds like one hell of a ride, in aid of anything?

 

[Hillz]

C3's are used all the time in CT110's & all Motorcross bikes

 

[coolmodee01]

your right hillz but there not needed
if you motor is running over 80 degree then you've got issues much worse than bearing failure

 

[WILL_S]

You better be documenting the trip.. Sounds like one hell of a ride, in aid of anything?

In aid of madness
also trying to beat the original record of 12 days

Will be documented

here's a quick 1000km test in under 24 hours



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[timeeh]

Looks awesome mate, can't wait to see how it all goes. God Speed LOL

 

[sean01]

a good twin oil cooler setup will help engine temps...

but yeah id just stick with the stock bearings, dont see too many posties stuck on the side of the road and they run near all day with fook all maintenance and ridden like they been stolen...

 

[DHZ_XR8cing]

I recon the reliability of a stock postie would be real hard to match from a worked engine

 

[WILL_S]

a good twin oil cooler setup will help engine temps...

but yeah id just stick with the stock bearings, dont see too many posties stuck on the side of the road and they run near all day with fook all maintenance and ridden like they been stolen...

on to it

you see there are few other posties going and unoffically it's a race.so i am going to run 126cc.got to go better than 105cc
My postie bored to 110 took a piece out of the piston after 50000km,20000 on the piston,after that ride in the vid above.No fault of the postie,it blew all the oil out the breather from the constant hi revs.funny thing is it still ran and would get up to 85kph.