1925 JD Cannonball Bike

[Randy STL]

I am also starting to think of chains, sprockets and gear ratios. Anybody have any experience with this. The bike needs to run comfortably at 55/60 mph but still have decent low end power.

I would appreciate any input on this - even negative because knowing what not to use is as important as what to use.

Jerry

Jerry,

Presently my ‘26 JD has an overall ratio of 4.65:1 and 28” OD tire (I have an odd setup, don’t ask) this 3000/3350 rpms at 55/60 mph, which to me, seems too high for sustained riding for the Cannonball.

I will be experimenting with the 17/18 40/44 sprockets and will report back.

I have already calculated several gear ratios:
Engine Rear Clutch Trans Overall
17 48 43 28 4.34
18 48 43 28 4.10
17 44 43 28 3.97
18 44 43 28 3.75
17 40 43 28 3.61
18 40 43 28 3.41

I also use the Baker Transmission calculator with tire size to calculate motor rpm
http://bakerdrivetrain.com/gear-ratio-calculator

Using the wider VL rim and tires are you going to run the later dished sprocket, or run the flat sprocket and compensate when lacing the wheel? Mark Masa is making some dished rear sprockets if you go that way.

Randy Hassler
#68 2012 Cannonball

[Jerry Wieland]

Randy Thanks for all the gear ratio info. I plan on using the offset dished sprockets. Front wheel is done but the rear is still awaiting spokes. I am hoping that I will not have a clearance problem with modern 4.00 x 18 tiries.

It would probably really help if I had ever ridden one of these bikes much before - only around the shows.

Jerry

[fillibuster]

Jerry,

Presently my ‘26 JD has an overall ratio of 4.65:1 and 28” OD tire (I have an odd setup, don’t ask) this 3000/3350 rpms at 55/60 mph, which to me, seems too high for sustained riding for the Cannonball.

I will be experimenting with the 17/18 40/44 sprockets and will report back.

I have already calculated several gear ratios:
Engine Rear Clutch Trans Overall
17 48 43 28 4.34
18 48 43 28 4.10
17 44 43 28 3.97
18 44 43 28 3.75
17 40 43 28 3.61
18 40 43 28 3.41

I also use the Baker Transmission calculator with tire size to calculate motor rpm
http://bakerdrivetrain.com/gear-ratio-calculator

Using the wider VL rim and tires are you going to run the later dished sprocket, or run the flat sprocket and compensate when lacing the wheel? Mark Masa is making some dished rear sprockets if you go that way.

Randy Hassler
#68 2012 Cannonball

Randy, your 28" od times pi = 87.92" divided by 12 equals 7.326 feet. One mile (5280') divided by 7.326 = 720.72 revolutions of the wheel in a mile. If you are going 60 mph you are going a mile a minute, or 720 rpm at rear wheel. Your overall ratio times 720 equals your motor rpm. 720 x 3.41 = 2457 rpm at 60 mph. At 45 mph your rpm then is 45/60 times 2457 = 1842. ....... If your ratio is 4.34, multiply times 720 to get 3125 rpm, at 60 mph, or if at 70 mph take 70/60 times 3125 (70/60 = 1.1666) = 3645 rpm.

Scary part to me is 20 mph or less (it all approaches zero). 20/60 x 2457 equals 819 rpm. lugging. with your 3.41
20/60 x (the high ratio of 4.34) 3125 rpm = 1041 rpm, a little less thump.
Scary part to me is 20 mph:

[Jerry Wieland]

I am doing most of the work on this bike myself but one of the things I farmed out is the wheel lacing and truing. Here is the original wheel that I robbed the hub from. It was a chromed out hub with a junk chopper 19" wheel laced to it.





Here it is all finished and ready to roll after my friend Larry laced it up to an OEM 18" WL rim.





It was a nice rim and he got the radial run out to less than .025" and the lateral run out to less than .015".

Jerry

[Jerry Wieland]

Tommo How do you deal with the .060" width difference on the right end mainshaft bearing? It might not matter as I have not gotten that far yet but it is something I noticed.

Jerry

[Tommo]

Jerry,
I've attached a couple of photos that should help.
On 1925 boxes sometimes you don't have to do anything but if you have to, grind the necessary off the face of the sleeve gear where I've got the screwdriver tip
You can generally get enough without breaking into the oil holes.
The most important one to check, especially as you have repaired your gearbox, is the sprocket to case clearance.
They run very close and as you generally only put the sprocket on after the rest of the gearbox is assembled it's a pain to find the sprocket fouls the case.
We try not to break into the oil holes and have on rare occassions had to make a slightly longer spacer to get the sprocket clear of the case.
Hope this helps

[rwm]

jerry have you but the front wheel in you fork yet? it looks like you have a 45 brake drum. i always thought that the lip for the dust cover would rub.

[Jerry Wieland]

Rob Yes it is a WL hub. It doesn't rub but it is real close. I had to modify the hub some to get it to fit. I have been working on it and will post some pictures real soon. The problem is going to be the brake anchor arm. I'll probably have to get real creative.

Jerry

[Jerry Wieland]

Tommo Thanks for the pictures and the explanation. I actually was more worried about the other end of the mainshaft and the wider bearing there. I do have an NOS rightside bearing that I could use if need be.

I pre assembled a hi gear and a sealed bearing tonight and it seems if I leave the brass slinger in place I will be within a few thousandths of an inch of the OEM setup. Maybe tomorrow night I can assemble the whole gear in a tranny case and see where it all lines up.

Jerry

[Jerry Wieland]

I am in need of the following 2 pieces for my rocker clutch pedal assembly. It is the rocker stand off and the disc that mounts to it.





Have cash or parts to trade. Jerry

[MMasa]

Michael Breeding makes the disk or at least he used to. Maybe the bracket too.
Mark

[Jerry Wieland]

Thanks Mark - I called Mike an ordered them. Jerry

[Slojo]

Jerry

I am using CP forged pistons. The clearance must be opened up more than the manufacture suggested clearance (I told them IRON air cooled). I will open my clearance up to about .008" this time, from originally .003", then .006". I don't know where to run Lonnie's pistons other than on the loose side of what he suggested to you. I have scorched two sets of pistons already so I am going loose this time.

joe

[Jerry Wieland]

Joe Thanks for the info on the clearances. I did not realize my mailbox was full. I cleaned it out. Lonnie suggested +.006" to +.0065". Jerry

[Jerry Wieland]

Today I received the rocker standoff and the friction disc from Michael Breeding. They are nice but sorry I forgot to photograph it before I riveted it to the strap.

Here it is after riveting.



I also bought the rocker foot 'flipper' from him.





Jerry