eBay undersize main bearings?

[Rauno Vekkila]

Hi,

Has anyone ever tried to fix the engine with those bearings (manufactured in China I presume) ?

https://www.ebay.com/itm/155118439754
I have too much oil clearance in the first main bearing even with the thickest factory bearing (0.05mm/0.0019") and only option is to grind that surface undersize or buy a new crank.

 

[RempageR1]

I also have too much clearance, but been riding it for 10 years like that..... You could up the oil pressure with the HD oil pump from Sean, much safer I`d say.

This might also be a good read, it`s what I did almost 11 years ago.

https://www.vmaxforum.net/threads/how-to-select-main-bearing-and-connecting-rod-shell-sizes.21235/

 

[MaxMidnight]

Perhaps I'm being more thick than usual but I'm not sure what it is they are selling. They say '+25' but don say what unit that is. Number in stock, thou, mm?
Also Yamaha part numbers they list are those of the OE shells. As each size is matched to to the journal to give the correct oil clearance they are not interchangeable i.e. there is no 'universal' shell.
They don't say what the 36.75mm relates to, crank journal o.d or shell i.d?
Even if they were oversize there is no guarantee that they would give the correct clearance for your journals.

Too many unknowns for my liking.

An alternative to a replacement crank would be to get the crank journal built up by having it plasma sprayed then grind it back to the OE size.

 

[Rauno Vekkila]

Perhaps I'm being more thick than usual but I'm not sure what it is they are selling. They say '+25' but don say what unit that is. Number in stock, thou, mm?
Also Yamaha part numbers they list are those of the OE shells. As each size is matched to to the journal to give the correct oil clearance they are not interchangeable i.e. there is no 'universal' shell.
They don't say what the 36.75mm relates to, crank journal o.d or shell i.d?
Even if they were oversize there is no guarantee that they would give the correct clearance for your journals.

Too many unknowns for my liking.

An alternative to a replacement crank would be to get the crank journal built up by having it plasma sprayed then grind it back to the OE size.

Hi,

I think diameter 36.75mm(+25) means that you’ll have to grind every crank journal app. 0.25mm under and check clearances after that. The journals are polished after the clearance is close enough factory specifications.

Product quality is my main concern here

 

[Rauno Vekkila]

I also have too much clearance, but been riding it for 10 years like that..... You could up the oil pressure with the HD oil pump from Sean, much safer I`d say.

This might also be a good read, it`s what I did almost 11 years ago.

https://www.vmaxforum.net/threads/how-to-select-main-bearing-and-connecting-rod-shell-sizes.21235/

Hi, thanks for the info. I’m worried about my 0.05mm ’cos the are also some scratches on the surface which I don’t like. I’ll have to think about this. New crank would be the best option but (good) used parts are hard to find in Finland