Mercury KF7 Super 10 Bearing Question – UPDATED!!

[chinewalker]

I am rebuilding a KF7 out of a parts motor and some odds and ends. Ordered up new bearings for the crankshaft upper & lower, plus the wrist pins. This motor uses the pressed in needle bearing, Torrington B-912X. I was told that the X was meant for the oil hole that lines up with the hole in the con rod and that the B-912 should work in its place. I pressed the new bearing into the rod and it seized up. The wrist pin would not fit, either. Is this a case of cheapie Chinese junk, or is there more to the difference in bearings than the oil hole? The bearing I received was a Koyo brand. Does anyone have a source for the Torrington B-912X?

[fastjohn]

You have a PM

[foot_doctor]

Not a case of Japanese junk. The X following the number on Torrington’s early bearings denoted what later became G prefix units. They are precision ground drawn cup units. Order KOYO GB-912 AND DON’T BE SURPRISED BY THE PRICE. The price could be up to 10 times the price of the B versions. The ones that require it, will be labeled OH signifying Oil Hole. Example would be GB-98-OH. The GB prefix units are several thousandths smaller in diameter than the B prefix versions. R.T.

[chinewalker]

Thanks R.T. That’s what I suspected, as I had someone bring me a Quicksilver unit years back that they couldn’t get to go together. That’s when I learned about the B vs. GB prefixes. This behaved the exact same way. I wasn’t aware that the X suffix and G prefix essentially meant the same thing. Thanks!
– Scott

[dave-bernard]

OH YEA!!!!! so little difference but large results.

[chinewalker]

Thank you for the help guys! I Found a pair of them on eBay for about half of the price I was quoted! Hopefully they’ll be here by the weekend so I can get this thing together!

[20mercman]

Love the KE7 & KF7 motors! There are a lot less KF’s than either of the previous or later motors. Glad to see you put one together Scott!

Steve

[chinewalker]

Steve,
This is what I started with… A little banged up, but after combining it with some leftovers of a motor I parted out awhile back, I’ve got enough to put one together.

[20mercman]

Beautiful Scott!
I am now doing the finish work on the lower cowl for our lastest KG-7 project. Same lower cowl as your KF-7 there. You don’t happen to have an extra lower cowl for a KE-7 laying around do you????? 😉 After I found one for my 1st KE-7, I picked up another one at Tomahawk! This hobby is like a circle! 😀

Steve

[dave-bernard]

I have 2 cowls 1 metal 1 fiberglass. 1 914 310 7086.

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