Typical Crankshaft Step-up for 3/4" Horizontal Shaft

[minibiker8357]

Hi all,

I'm retrofitting a piece of equipment to my utility engine for my mini bike and I've noticed that I have three different types of crankshafts on my three engines. The part I'm concerned with is the increased diameter step up that occurs on the crankshaft right before the 4 bolt mating surface on the engine. I want to slide a piece that has a shaft that rides on the crank and then has a plate that bolts up to the motor. The problem is, the crankshaft has a slight step up at the very end of the crankshaft near the motor. This doesn't allow the shaft to slide on all the way (because the step-up stops it), and the plate doens't make full contact with the bolt pattern flange and leaves a gap. I was wondering if you guys could take a look at your motors and see what type of step up is typical here and how long that distance is. My predator motor has only a 1/16" long step up, my honda has no step up, and my briggs has a 1/8" long step up which leaves a large gap. Any input would be greatly appreciated.

Thanks,
M

 

[Bill Ellerby]

Post photos so we can better assist you with your question. Especially of the piece of equipment you are attempting to attach to the motor.

 

[bigrob]

How about an aluminum plate 1/8 thick with the apropriate holes drilled in it

 

[sludgeboy]

Can you make the hole bigger on the plate to go over the step up? Is it a 3/4" crankshaft that increase to a 1"? With the engine running, would it be wise to grind down the crank a bit to allow the plate to bolt to the engine. Just throwing things out there. Or make/use a spacer like bigrob said.

 

[minibiker8357]

It's not so much that I'm looking for a solution, I'm just curious what step ups are typical with most of these standard horizontal shaft utility engines. I'm guessing that the distance between the end of this step up to the four bolt pattern must be controlled so that when someone wants to use a motor for a mini bike, the centrifugal clutch lines up with the standard motor mount holes. If this distance was not the same and I had a 1/8" step up, It would mean that my centrifugal clutch would not line up and I would have to shift the motor over to the right...

 

[The Restore Kid]

I don't know why they do that.. I have a Tecumseh Powersport that has a pretty long step on it too.. Gokart engine ever since the day it was made..

They use tham on all kinds of stuff.. water pumps or hydraulic pumps, generators..

If the step is too long to use, and you can't just ad a spacer between the motor and tav, like was suggested earlier.. You can fire the motor up, the turn the crank down to 3/4 with a file..