25 Teeth Engine Sprocket - Might be Factory

Transmission, clutch, chains and belts
Forum rules
Please do not start new topics here, but here: New Panhead and Flathead topics
Post Reply
old1955
Posts: 196
Joined: Sat Feb 10, 2007 12:41 am
Bikes: 55FLE, 65FL
Location: Northern Rivers NSW, Australia

25 Teeth Engine Sprocket - Might be Factory

#1

Post by old1955 » Sat Oct 08, 2011 7:58 am

G'day,

Has anyone run across one of these, 25 Tooth engine sprocket? Caught me out!
Went to change the primary chain, and nothing fitted back on, chain too short, had to go
down to a smaller sprocket, now waiting for the new chain to stretch to get the 25 back in.

I'm running a 23 for a fill in, whow! it's so low.
If you look closely at the shot you just see a little of the old 55A part number.
And the weld. Nice job.

My parts book only lists a 24 tooth as the biggest you can get.

Pete
You do not have the required permissions to view the files attached to this post.



58flh
Posts: 3338
Joined: Sat Jun 26, 2010 1:54 pm
Bikes: 1958flh 1969sporty,had a knuckle but sold back to original owner
Location: NEW JERSEY

Re: 25 Teeth Engine Sprocket - Might be Factory

#2

Post by 58flh » Sat Oct 08, 2011 1:27 pm

old1955 wrote:G'day,

Has anyone run across one of these, 25 Tooth engine sprocket? Caught me out!
Went to change the primary chain, and nothing fitted back on, chain too short, had to go
down to a smaller sprocket, now waiting for the new chain to stretch to get the 25 back in.

I'm running a 23 for a fill in, whow! it's so low.
If you look closely at the shot you just see a little of the old 55A part number.
And the weld. Nice job.

My parts book only lists a 24 tooth as the biggest you can get.

Pete
Maybe its just the angle & flash, but that motor sprocket looks like some of the hights on the teeth seem real short compared to others! Could be my PC---anyway check it out, dont mean to raise any alarms!(good-Luck)58flh :!:

Cotten
Posts: 6791
Joined: Mon Aug 26, 2002 9:09 am
Location: Central Illinois

Re: 25 Teeth Engine Sprocket - Might be Factory

#3

Post by Cotten » Sat Oct 08, 2011 7:18 pm

Pete!

The '41-'54 "Spare Parts" lists a 40212-30 25T motor sprocket as (Special).

Note that it also includes 17, 18, 19, 20, and 21 tooth variations!
I have only encountered small sprockets upon VLs, but I am sure there is a time and a place for them on a Pan. You never know when you may want to tow a barge.

....Cotten

Bosheff
Posts: 1206
Joined: Fri Jul 03, 2009 8:23 pm
Bikes: 65 FLH 82 FLH
Location: Michigan

Re: 25 Teeth Engine Sprocket - Might be Factory

#4

Post by Bosheff » Sun Oct 09, 2011 1:53 am

Goin up on the tranny sprocket will make up for goin down on the motor sprocket, but I don't think you can go big enough on the trans to make up for droppin 2 on the engine if you started with a 25 on the motor. I've seen 26T tranny sprockets but I don't think you can run a 26 with a ratchet lid, but it should clear a jock top. If yer gonna wait for the primary chain to "stretch" so yer 25T motor sprocket will fit, yer chain is gonna worn out again, I would think....bosheff

steve_wood
Posts: 947
Joined: Tue Jan 08, 2008 12:32 am
Bikes: 56 FLH, 2007 FLHRCI
Location: Belleville, Ontario, Canada

Re: 25 Teeth Engine Sprocket - Might be Factory

#5

Post by steve_wood » Sun Oct 09, 2011 2:59 am

Pete,

Could you go with a 24 tooth? Yes, that would mean lower top end but more torque.... might not be so bad.

RUBONE
Moderator
Posts: 4680
Joined: Sat Nov 15, 2008 4:09 am
Bikes: Multiple H-D, Ducati, BMW, Triumph, BSA,...

Re: 25 Teeth Engine Sprocket - Might be Factory

#6

Post by RUBONE » Sun Oct 09, 2011 4:08 am

I don't think that is a factory item. All the compensator type sprockets I am aware of came in 22, 23, and 24 tooth configurations. All the other sizes were solid type only. and all the compensator types I recall were machined in one piece, not with the teeth welded on like yours. And theweld obscures the part number, not factory practice. I have a couple 25 tooth solids around here that I ran on strokers years ago. I'll have to look in the shop tomorrow and also check the books but pretty sure yours is a one-off item. And the sprockets Cotten mentions were all tapered shaft types. The really small ones were never made for splined shafts. With the big center hole the teeth would be floating in the air! The small ones were primarily used for Hill climbers and endurance events. Also on package truck equipped bikes where 19 tooth types were often specified.
Robbie

Cotten
Posts: 6791
Joined: Mon Aug 26, 2002 9:09 am
Location: Central Illinois

Re: 25 Teeth Engine Sprocket - Might be Factory

#7

Post by Cotten » Sun Oct 09, 2011 4:02 pm

Pete!

Now that I can view the pic on my wife's broadband, I see that its weld is substantial!
It would require controlled heat-treating after the weld, or the teeth would be like mud.

If the Factory saw a "special" need for them in the tapered shaft era, there is reason to believe they might in the splined shaft era as well.

....Cotten

Dave_R
Posts: 64
Joined: Thu May 06, 2010 4:19 pm
Bikes: 1953 Panhead
2001 Heritage
Location: Clarkston, Michigan

Re: 25 Teeth Engine Sprocket - Might be Factory

#8

Post by Dave_R » Mon Oct 10, 2011 3:12 am

Pete,
Thanks for this post and Picture!
I've been wanting to modify one of my tapered shaft compensator sprockets up to a 25 tooth, and I was going to do exactly as you have pictured. Glad to see that is is possible!
I ran a solid 25 tooth for a few years, but used to "eat" primary chains (stretched beyond use) after just 1K miles or so.
I went ot a 23 tooth compensator (Biggest I can find for a tapered shaft motor) to keep the chain life, but I would like to run the ratios like I used to.
I also used to add two links to the new primary chains to get them to fit the 25 tooth. (Punch out the pin, and peen in two links).
I know that I could run a belt to get the ratios, but I am cheap and the chains are forgiving on alignment, and I never broke one yet.
- Dave

old1955
Posts: 196
Joined: Sat Feb 10, 2007 12:41 am
Bikes: 55FLE, 65FL
Location: Northern Rivers NSW, Australia

Re: 25 Teeth Engine Sprocket - Might be Factory

#9

Post by old1955 » Tue Oct 11, 2011 12:06 pm

G'day
58FLH, No worries! No shes a good one, just the shot looks strange.

Steve, I may have to go 24T as 23 is driving me nuts. That chain stretched initially but
has pulled up now, I don't think its gonna stretch much more as Bosheff said. I even had to run
my chain tensioner in the low position (65).

Cotten, you're right on the heat treating, and this one is hard, been on there 12 years hardly any wear on it. Good info thanks!
You gotta love that broadband Cotten, go on,.. ditch the dial up. I know you dislike some modern stuff. We all resist it!

Robbie, good info as usual, thanks!

Dave_R, now you got me thinking, I did try a longer chain I think it was 84 link, I know it was a baker drive train chain, but it was too
long and the standard is to short (82 link), so i was stuffed (catch 22 I think), or rock and hard place. Solid sprockets eating chains, shit
I was gonna go with a 24T solid, I have found a good one for $24. I might rethink that.

thanks everyone
Pete

Post Reply

Return to “Transmission, Clutch, Belt & Chains”