Making a jack shaft questions

#1
Ok so the paint dried enough to throw the motor into the frame and visualy see how its going to line up with the sprocket. Its going to be too close even when I install the spacer I ordered to lift the engine over the frame rail that prevents the blower housing from moving far enough over currently. I think what I'm going to have to do is put a jack shaft in and turn the wheel around. I think this is how the bike probably was meant to be configured in the first place. Then someone put the foot brake on what appears to have been jack shaft mounts anyway. So I'm thinking I'll take the footbrake out and installing a jackshaft there. But what size holes would need to be there for bearings? Are these brackets thick enough to hold bearings? It looks like the holes would need to be much bigger too. Basically before I go down this time consuming and I'm sure frustrating road, can anyone who has done this before tell me if it looks like it can be done. I'm sure there are issues I have not thought of. Thanks





 

CarPlayLB

Well-Known Member
#2
JT,
with as many engines as you have, why not put a small block in there? I hate to see you muck up that nice bike!

plates are thick/strong enough for a jackshaft. Bearings are 1 3/8 (1.375) outside diameter. Good luck drilling holes that big on each side, perfectly aligned. It can be done, but criminal charges may be pressed! Where's that Bonanza/Powell hacker guy? Dave, you there?
 
#3
JT,
with as many engines as you have, why not put a small block in there? I hate to see you muck up that nice bike!

plates are thick/strong enough for a jackshaft. Bearings are 1 3/8 (1.375) outside diameter. Good luck drilling holes that big on each side, perfectly aligned. It can be done, but criminal charges may be pressed! Where's that Bonanza/Powell hacker guy? Dave, you there?
Wait, one of the first things someone said to me was get rid of that footbrake when I posted this bike. IT was added by someone. I've googled my fingers to bone and never found one with a scrub footbrake. A disk footbrake yes. But that goes on the other side. You can see the mounts under the engine mount plate. I'd be restoring it further I thought. I was keeping the scrub brake there out of sheer laziness. But now it looks like I need a jack shaft there. I've had an H35, an HS40 and 50 and a Power Bee 580 on there and not only did they not line up either (Well the power Bee did) but they looked way to small for the frame. I honestly think this is the way it should be. Also I can install a disk footbrake on it again on the other side.
 
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#8
You don't have to turn the wheel both chains can be on the same side .. And not the machine shop u took your kids sprocket too !!!!
Yeah but for purposes of the brakes i want to.

Haha you remember that machine shop doing that?? Holy crap they ruinned my chance to complete my build off Minion Cycle. I gave them such a scathing write up on Yelp.
 
#13
If the rear wheel isnt adjustable youll have to make the mounts bolt on and slotted like this. And that way you wont have to worry about making the holes even either
 
#14
If the rear wheel isnt adjustable youll have to make the mounts bolt on and slotted like this. And that way you wont have to worry about making the holes even either
Agreed but I think if I'm not mistaken NOt So Minibike is talking about one that moves with the engine on the bikes engine mount? That's what it sounds like...
 

CarPlayLB

Well-Known Member
#16
I don't think there is any offset with the PMR jackshaft.
Jeep is the man! Cut those plates off above the frame and use an adjustable plate! Easier than trying to drill big holes and gives you all the adjustability needed. OldMiniBikes even has a kit that is inexpensive!
 
#17
I don't think there is any offset with the PMR jackshaft.
Jeep is the man! Cut those plates off above the frame and use an adjustable plate! Easier than trying to drill big holes and gives you all the adjustability needed. OldMiniBikes even has a kit that is inexpensive!
Very good idea !!
 
#20
Hey Johny
Dont know if you solved your problem yet , but I have drilled out the bearing hole with a bimetal hole saw on a few projects

The pilot bit in the hole saw is 1/4" , so the easiest thing to do is drill a 1/4" hole in a piece of scrap steel then clamp it to the back side of your jackshaft plate as a drilling guide

A good drill and lots of cutting oil and your good to go
 
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