main crank bearing guide pin question

[yama-doo]

ok I know when I use three different engines to try and make one good one there would be some problems but I think I can make it work but I wanted to ask ya'lls opinion about this before I did it.

The Details: all my crank bearings line up on the guide pins in the upper case half except the fat one on the end by the stator/flywheel , I have tried playing with it thinking I must be doing something wrong but it just doesn't line up with the hole in the bearing . I know the picture is not so good but you can see the guide pin hole and right beside it there is a rubbed line where the guide pin lines up about 1.5MM in towards the flywheel:banghead:

Now for ya'lls opinion: I think that is just a guide hole to line the oil hole up. I was thinking of putting the bearing in the mill and cutting that guide "hole" into a oval slot so the guide pin would line up. IS THERE ANY REASON WHY THIS CAN"T BE DONE?

 

[yama-doo]

sorry for got to add picture showing the bearing guide pin hole and where the guide pin is actual rubbing .

 

[SUPERTUNE]

I can't really see the picture very well...
There should be no reason that you couldn't mill the bearing, use a carbide and spin it pretty fast.
Did you compare this bearing to a stock one and determine that this bearing was/is drilled wrong?
The locating pin is only for orientation for the oil drain hole, the pin does not hold the bearing, the crush of the bearing being a few tenths of a thousandths bigger than the case bore when assembled holds the bearing in place.

 

[QuickMick]

whatever you do, mill or grind with a carbide burr be sure not to let any of the grind dust or metal shavings in your bearings where the balls are. Tape everything off really well with plastic bags over your crank. That bearing is hardened steel and good luck. Take your time. You might be able to use a cut off wheel on a dremmel tool.

 

[yama-doo]

supertune ,
thanks for the info . don't have the stock bearing to compare I was thinking it is just for lining up so the oil pilot is in the right place not holding the bearing. sorry about the picture all I had was a camera phone

Quikmick,
ya I would just feel better using the mill to make it as clean as possible and I'd wash it all out metal shaving in any engine part just doesn't go over very well , thanks

 

[SurferSmurf]

just out of curiosity is the hole offset to one side or the other? is the bearing maybe on backwards? or does it go either way?

 

[yama-doo]

no the hole in the bearing is centered the guide pin in the case is off center ,the bearing is on correct even if flipped the hole would still be centered plus I think if flipped it would then block off the oil hole. They where for two different year engines I assume that is one of the minor changes in them and I'm just trying to make what I have work

 

[Moto360]

The bearing should be the same. Even for a couple different years. The 650/701/760 cranks are all the same. They all use the same mag bearing. Can't tell from you pic on witch way the locating pin is, compared to the hole on the bearing.
I would be worried that the crank isn't together right. Or should I say not pressed all together correctly.
Did you take this crank out of the previous cases before you tried to put it in the ones you want to put it in?
I think something is wrong! My opinion.
Also if the PTO bearing on the other end isn't in the right place. That also could affect the crank just a little bit. The big ring around the bearing is what locates the crank in the case.

Moto360

 

[yama-doo]

This is a 1200 crank ,yes it cam out of another engine . The other three guide pins line up fine if the pto bearing on the other end was move the two center pins and the pto pin would not line up and it seems to be press together correctly

 

[yama-doo]

think I am going to go ahead and cut that 1.5mm slot in it today and see what happens , thanks for everyone's input

 

[yama-doo]

I just wanted to update ya'll . I ended up not having a bit that small form my mill after all so I just used a small die-grinder with small round noise bit that I use to port aircraft cylinders with and now the crank fits prefect