Reversing Engine PTO Direction

[ironbutt]

So...I'd like to be able to reverse a Honda clone's PTO direction by rotating the engine 180 degrees. This would have the cylinder with air filter facing forward rather than backwards.

There are several reasons to do this, one being that my gear box is oriented clockwise rather than counter-clockwise.

The other is the appeal of getting direct air flow for the intake and cooling of the cylinder flowing directly from the front of the bike.

I saw a yootoob video of someone fitting a drive shaft to the flywheel side of a Predator 670cc engine for fitting onto a tractor.

Does the flywheel side of the shaft have the necessary support and configuration to meet the torque requirements of having a clutch or sprocket attached on that side?

Has anyone done this before?

Thanks,

 

[Bbqjoe]

I'll take yes for $1.

 

[mckutzy]

Depending on space available... One could make a modified starter cup/flywheel nut similar to what is being used for seperate hand operated starter units for racing...
In this case, have a long enough piece of keyed shafting drilled and tapped for the crank threads... Have an additional support bearing inboard/outboard of the mounted clutch.

The overall problem I see with this... Is the OEM starter won't be able to be used, needs to be electric start and a modified plate for the blower housing, for lack now of recoil start...

Cool concept for right hand pto clone conversion...

 

[chancer]

Good points Mac.
I wonder if you could re engineer the recoil to go on the other (factory) PTO side?

 

[mckutzy]

Theoretically ya.... I could bump start my bike when I had my manual clutch installed...PTO being standard...... BUT....
You cant just swap the recoil to the other side as it operates in a specific fashion only to that side of the motor.....counterclockwise(when facing shaft).

You would need to have a Recoil from a clockwise rotation motor(as the clones are one way only).....( but this operation would be moot as youll have the right motor to begin with)... and what ever it needs to engage/disengage (starter nut(briggs) or starter cup(honda/clone).
I think that having a modified briggs old school starter cup with a rope....would be fine...

But in the end I think you still better off with an electric start and above...... or make a tight to motor jack shaft setup, on a standard motor......

 

[itsid]

sorry.. why not externally reverse the shaft rotation
and leave the engine itself untouched?

All you'd need is a set of two cog gears one bored for the PTO one for the gearbox IN...
with identical toothcounts you only reverse the rotation.

If you want to reorient the engine to have the cylinder facing forward... then you can just add a jackshaft instead..
1:1 from PTO to JS in and the jackshaft will be your new PTO... turning cw seen from the flywheel side.

frankly.. I don't see why one would want to mess with the enigne instead tbh.

'sid

 

[ironbutt]

sorry.. why not externally reverse the shaft rotation
and leave the engine itself untouched?

All you'd need is a set of two cog gears one bored for the PTO one for the gearbox IN...
with identical toothcounts you only reverse the rotation.

If you want to reorient the engine to have the cylinder facing forward... then you can just add a jackshaft instead..
1:1 from PTO to JS in and the jackshaft will be your new PTO... turning cw seen from the flywheel side.

frankly.. I don't see why one would want to mess with the enigne instead tbh.

'sid

This was actually my original idea. Basically using two parallel jack shafts with gears in inside and sprockets on the left and right for the chains (one from the engine and one to the rear wheel).

But this involves some fabrication and engineering that winds up being more complicated and time consuming that just putting a sprocket on the other side of the drive shaft on the engine.

After seeing the yootoob vid about someone doing that to a 670cc, I was hoping that a simple bolt-on solution might work.

Thanks,

 

[ML-TOYS]

I'll ask. Can we see a pic of said gearbox ?

 

[ironbutt]

It would look something like this but done with jack shafts:

http://www.hobby-machinist.com/threads/pto-reverser-gearbox.8928/

 

[mckutzy]

I did find a "gearbox" that some one made... on the youtube but not a 670...
A 420cc.
https://www.youtube.com/watch?v=Ovy2lXkc_0E

Edit: After doing some more looking.... They call this a front drive stub shaft.....Flywheel stub shaft ect...
This is a factory part for a Kohler comand 22HP and similar motors.... They use these on lawn tractors for pumps and other things....

https://www.youtube.com/watch?v=wE_SJ8VWjFQ

Edit 2: Well... more digging.... they also have a stub shaft for the big twins...A Honda made part.....

http://www.ebay.com/itm/Genuine-Hon...604fc81&pid=100623&rk=3&rkt=5&sd=261252904414