The Sportster and Buell Motorcycle Forum GL Sportster  

Go Back   The Sportster and Buell Motorcycle Forum > SPORTSTER MOTORCYCLE ZONE > Sportster Motorcycle Era Specific and Model Specific > Ironhead Sportster Motorcycle Talk (1957-1985)
XLF Gallery XLF Classifieds XLF Blogs XLF Shout XLF Arcade XLF Disclaimer/Privacy Statement/Terms Of Use

Ironhead Sportster Motorcycle Talk (1957-1985) For all those that wanna talk about Ironhead Sportster Motorcycles

Members Birthdays
Progressive Suspension
Superbrace
Motor Stage
RYCA Motors

DK Customs
Reply
 
Share Thread Tools Display Modes
  #1  
Old 4th April 2010
bobber58 bobber58 is offline
Senior Chief Know It All 3rd Class
 
Join Date: Dec 2009
Posts: 1,792
Sportster/Buell Model: XLH bobber
Sportster/Buell Year: 1964
Sportster/Buell Model #2: XLH
Sportster/Buell Year #2: 1969
Other Motorcycle Model: Kawasaki ZX6E
Other Motorcycle Year: 1994
Reputation: 5759
bobber58 is just really nicebobber58 is just really nicebobber58 is just really nicebobber58 is just really nicebobber58 is just really nicebobber58 is just really nicebobber58 is just really nicebobber58 is just really nicebobber58 is just really nicebobber58 is just really nicebobber58 is just really nice
Default connecting rod length

Well, I listened to a friend and assumed all lower end parts in an ironhead are pretty much interchangeable, but I guess I was wrong. I get a good deal on a set of rods at a swap meet. They were listed as for 1981-85 sportster. Well, my indy told me they won't work in my 64, that they are slightly longer than my older rods. Does anyone have the specs on these rods and the older rods? How much longer are these rods? Also, does a two hole pin or a three hole pin matter?
Reply With Quote
  #2  
Old 4th April 2010
Hopper's Avatar
Hopper Hopper is offline
Senior Master Custom Bike Builder
 
Join Date: Dec 2007
Location: Australia
Posts: 8,557
Sportster/Buell Model: XLCH 1000
Sportster/Buell Year: 1977
Sportster/Buell Model #2: 75 motor in Norton frame.
Other Motorcycle Model: 42WLA 45, Harton, Narley
Other Motorcycle Year: 1942
Reputation: 61736
Hopper is a splendid one to beholdHopper is a splendid one to beholdHopper is a splendid one to beholdHopper is a splendid one to beholdHopper is a splendid one to beholdHopper is a splendid one to beholdHopper is a splendid one to beholdHopper is a splendid one to beholdHopper is a splendid one to beholdHopper is a splendid one to beholdHopper is a splendid one to behold
Default

Rods are the same part number from 57 to 78 but I dunno about 81.
Hard to imagine a change of rod length from 78 to 81 when there was no other changes to the engine that would require it.
But you never know.
Maybe someone with a later parts book can check it out.
__________________
In theory there is no difference between theory and practice. In practice there is.
Reply With Quote
  #3  
Old 4th April 2010
billy bob's Avatar
billy bob billy bob is offline
Senior Chief Master Mechanic
 
Join Date: Jul 2009
Posts: 894
Other Motorcycle Model: Custom Rigid XL
Other Motorcycle Year: 2007
Reputation: 7974
billy bob is just really nicebilly bob is just really nicebilly bob is just really nicebilly bob is just really nicebilly bob is just really nicebilly bob is just really nicebilly bob is just really nicebilly bob is just really nicebilly bob is just really nicebilly bob is just really nicebilly bob is just really nice
Default

Info I found : 57-early 81, oem#24275-57 --- late 81-85, oem#24275-80A
*Rod length is the same= 7.440"

** The only mention of rod length difference, was when the EVO XL was introduced.
Rod length was reduced by 1/2"

Crankpin is shown as oem #23960-54, 3-hole, Sportsters and K models, 54-early 81
Reply With Quote
  #4  
Old 4th April 2010
IronMick's Avatar
IronMick IronMick is offline
Rider Of The Iron Steed
 
Join Date: Dec 2003
Location: London, ON Canada
Posts: 27,231
Sportster/Buell Model: XLH
Sportster/Buell Year: 1978
Reputation: 130508
IronMick has much to be proud ofIronMick has much to be proud ofIronMick has much to be proud ofIronMick has much to be proud ofIronMick has much to be proud ofIronMick has much to be proud ofIronMick has much to be proud ofIronMick has much to be proud ofIronMick has much to be proud ofIronMick has much to be proud ofIronMick has much to be proud of
Default

The newer parts book uses the term "commonized taper" with the -80A. I do not know what this is, but i recall a discussion from some years ago where this is a technical improvement? The part number is otherwise the same so i think more info is needed to make a decision.
Reply With Quote
  #5  
Old 4th April 2010
tracbike's Avatar
tracbike tracbike is offline
Senior Chief Know It All 1st Class
 
Join Date: Jan 2010
Location: Boston
Posts: 1,126
Sportster/Buell Model: Sportster XLH
Sportster/Buell Year: 1974
Sportster/Buell Model #2: Sportster XLH
Sportster/Buell Year #2: 1977
Other Motorcycle Model: Trac Dynamics / Razor,
Reputation: 3498
tracbike is a jewel in the roughtracbike is a jewel in the roughtracbike is a jewel in the roughtracbike is a jewel in the roughtracbike is a jewel in the roughtracbike is a jewel in the roughtracbike is a jewel in the roughtracbike is a jewel in the roughtracbike is a jewel in the roughtracbike is a jewel in the roughtracbike is a jewel in the rough
Default

It is not rod "lenth"but the crank pin....as of 81, flywheel tapers were commonized.
after 3/81 flywheels, crank pin, pinion,and motor sprocket shafts will not fit interchange, except as a complete set
newer crank ppin has a smaller keyway, and only one oil hole instead of three.
there are differences in pinion and motor sprocket also.
Reply With Quote
Know Thy Hog

  #6  
Old 4th April 2010
rivethog's Avatar
rivethog rivethog is offline
Senior Master Bike Builder
 
Join Date: Jan 2010
Location: S.E. LA (Louisiana)
Posts: 2,172
Sportster/Buell Model: XLH
Sportster/Buell Year: '78
Sportster/Buell Model #2: 883 XLH
Sportster/Buell Year #2: 1993
Other Motorcycle Model: 93" Shovel/Pan
Other Motorcycle Year: 1967
rivethog has disabled reputation
Default

The commonized taper is in reference to the tapers on the crankpin, sprocket shaft, and pinion shaft. It doesn't have anything to do with the rods themselves. My parts book shows P/N 24290-57 (connecting rod, rear) and 24294-52 (connecting rod, front, as fitting all the way to 1985. The P/N only changes to a -80 number for a set of rods, since a set includes the crankpin.
As far as a 2 hole vs. a 3 hole crankpin, I've never seen a 2 hole crankpin for Sportsters, anywhere, and I looked for one just recently. Where can I get one?
Reply With Quote
  #7  
Old 4th April 2010
billeuze's Avatar
billeuze billeuze is offline
XL FORUM TEAM MEMBER
 
Join Date: Jul 2008
Location: Coastal BC
Posts: 1,178
Sportster/Buell Model: shovester project
Sportster/Buell Year: 80s
Other Motorcycle Model: Kawasaki kz440
Other Motorcycle Year: 1983
Reputation: 7200
billeuze is just really nicebilleuze is just really nicebilleuze is just really nicebilleuze is just really nicebilleuze is just really nicebilleuze is just really nicebilleuze is just really nicebilleuze is just really nicebilleuze is just really nicebilleuze is just really nicebilleuze is just really nice
Default

yup, later ironhead rods are still 7.440. I measured mine while it was out. I don't know what the different part number is for.

the 2 hole crankpin I haven't seen but someone just got one and wondered about why it only had 2 oil holes. Now I vaguely remember hearing something that might explain it. I don't remember the source, but it went something like this:
"the three hole crankpins proved to flow too much oil and the rollers would skate on the oil film rather than rolling and would develop flat spots. So they started making them with fewer holes to allow just the right amount of oil"
Reply With Quote
  #8  
Old 4th April 2010
bobber58 bobber58 is offline
Senior Chief Know It All 3rd Class
 
Join Date: Dec 2009
Posts: 1,792
Sportster/Buell Model: XLH bobber
Sportster/Buell Year: 1964
Sportster/Buell Model #2: XLH
Sportster/Buell Year #2: 1969
Other Motorcycle Model: Kawasaki ZX6E
Other Motorcycle Year: 1994
Reputation: 5759
bobber58 is just really nicebobber58 is just really nicebobber58 is just really nicebobber58 is just really nicebobber58 is just really nicebobber58 is just really nicebobber58 is just really nicebobber58 is just really nicebobber58 is just really nicebobber58 is just really nicebobber58 is just really nice
Default

Ok, so the taper on the crank pin is different. Are the rollers and retainers different? Can I just get a new crank pin that"s the same diameter as the one in my rod set that fits my engine and use the rods and rollers I have now or do I need to change the pin, rollers, and retainer?
Reply With Quote
  #9  
Old 4th April 2010
78ironhed 78ironhed is offline
Biker
 
Join Date: Mar 2010
Posts: 84
Sportster/Buell Model: ironhead sportster
Sportster/Buell Year: 1979
Reputation: 10
78ironhed is an unknown quantity at this point
Default

Heres some info that might help.


how do you calculate the bearing size. Well it ain't rocket science, but like so many other things mechanical it does take at least a half a brain and decent tools. First off, measure the crank pin diameter. In my case the crank pin mics out to 1.2480”. Then measure the inside diameter of the rod races. Use a telescope gage and then measure the length of the telescope gage. In my case the rod races mic out to 1.6265”. Then subtract the pin diameter from the race diameter and you end up with .3785. Now you need to factor in the desired running clearance that is about .001”. So subtract .001” from .3785 and that will leave you with .3775”. Now divide that number by 2 and you will end up with the desired diameter of the rollers. So the desired roller diameter in this case is .1887. A standard roller is .1875” so I need a roller that is .0012” oversize. Got all that?

Connecting rod big end inside diameter 1.6265”
From which subtract the crankpin diameter - 1.2480”
The result = .3785”
Now subtract the desired running clearance -.0010”
The result = .3775”
Divide that by 2 to get desired roller size = .1887”
Subtract standard roller diameter to get oversize -.1875”
Desired oversize = .0012”
Closest available oversize = .0010”

As it happens I have a set of standard size rollers, at least the digital readout vernier caliper would have me believe they are standard size, and they felt a little loose when I test fit them so a .001” oversize should be just about right. So that is what I will order and hopefully they will fit just right. Actually I decided to hedge my bet a little. I also decided to order a set of .0008” oversize rollers, just in case I was off a little.

Finally, these are the rods I've decided to use. I found this set in my dumpster diving a couple of months ago. No nicks or scratches on the bearing surfaces, out of round by less than .001, I think they will be just fine. I had contmplated buying a set of new S&S rods, but $300.00 plus gets to be a chunk of change and this set looks damn good. A word to the wise, there are other " stock" rod sets sold in the various catalogs. Those rods sell for about $100.00 less tha the S&S rods and I think they are made in China. I bought a set once and tried to use them. I could not true the fylywheels with those rods installed, the best I could get them down to was about .006" out of round, that is way to much for a crank assembly. I think the tapers were cut wrong. In fairness, I may have just had a bad set, anyway, I sent them back and will never buy a set of rods that are not genuine HD or S&S.
Reply With Quote
Reply

Bookmarks


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


Custom Search

All times are GMT +1. The time now is 04:59.


Powered by vBulletin® Version 3.8.5
Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
XL Forum - Linson Media LLC