[BigNorm]

What would the displacement be of a stock 103 with a S&S stroker crank? My guess is a 113. Is case boring necessary to fit a larger cylinder or for clearance for a larger crank? This is for my general knowledge. Thanks as always for your help. :smile:

 

[JacktheBagger]

Without boring , the 103 is a 4.375" stroke

a 4.500" stroke is a 106

a 4.625" stroke is a 109

boring to 4.00"

stock stroke is a 109

4.500" stroke is a 113

4.625 stroke is a 117

increasing one or the other .125" yields around 3 c.i.


JtB

 

[BigNorm]

Thanks. I just saw I wrote case borking. lol. Is the case boring needed to clear the new stroke?

 

[Hillsidecycle.com]

With a 4.375" crank,(103") it is very common to bore the cases to
accept a 4 1/8" cylinder allowing 117" total swept volume to be established.
Longer stroke engines require the C/L of the wrist pin bore to move up into the ring pack, 1/2 the length of the total stroke increase, and can pose a problem as far as a piston being available.
Iron XL's with 4 5/8" stroke actually have an aluminum botton that rides in the end of the wrist pin, to support the oil control ring, as the wrist pin bore is well into the oil ring groove.
Not the greatest way to fly.
Wood's site shows a street-driven touring 4 3/8" X 4 1/8", 117" at 141/144 that we built yeeears ago.
Scott

 

[BigNorm]

Since I have my current build figured finally I'm researching for when I have to rebuild. Hopefully not soon. It seems that the crank is the weak link so when rebuild time comes at 200k (lol) I can do a total rebuild. It looks like S&S is the way to go with a crank. I'll probably go with a 4.625 crank and have it welded for extra security. I like that you can just bolt on an extra 14 cubes but how much is too much before you compromise the crank shaft? I'm looking for usable torque not drag racing rpms. I appreciate everyone's help and advice here. I'm learning and I'm having fun with it.

 

[SMOKENJOE]

If it was me i would sell the engine in the bike and put a S&S 124 in it just my thoughts

 

[BigNorm]

Thanks Joe. That may be the direction I head in eventually. Right now I'm learning and seeing what works and what doesn't. I love to ride but I also like to know how the nuts and bolts go together. The whole process fascinates me. I haven't built a motorcycle engine yet but I have done a few V8s in my time. I can't wait to get my hands in there. Thanks again.

 

[SMOKENJOE]

Good for you it is not as easy as you would think if you build one from the bottom up. It takes a full shop of equiptment like balancing the fly wheels one screw up there and the build goes up in smoke. I have been working on bikes from the 60s Indians/Harleys no Jap bikes and one thing I always had done by others was the fly wheels I never got the hang of static balancing or dynamic balancing I only do my own work now because I have nothing to do with my time. Good Luck

 

[BigNorm]

I just like to do my own work because I like knowing what I put in there and it's therapy for me. Although all the obsessing I do prior to a build probably offsets the therapeutic value. :grin:

 

[Hillsidecycle.com]

S&S cranks are the industry standard, and yes, your OE crank would need to be attended to prior to the advent of a 4 1/8" cylinder kit.
We pin/weld those here.
Scott

 

[BigNorm]

Without boring , the 103 is a 4.375" stroke

a 4.500" stroke is a 106

a 4.625" stroke is a 109

boring to 4.00"

stock stroke is a 109

4.500" stroke is a 113

4.625 stroke is a 117

increasing one or the other .125" yields around 3 c.i.


JtB

HarleyJack could you post me some numbers for the 4 1/8 cylinders and pistons. I swear I look at these numbers you posted about every other day. Thank you for your time.

 

[JacktheBagger]

4.125 bore x 4.375 ( stock ) stroke is 117

4.125 bore x 4.500 stroke is 120

4.125 bore x 4.625 stroke is 124

 

[BadBagger08]

Since I have my current build figured finally I'm researching for when I have to rebuild. Hopefully not soon. It seems that the crank is the weak link so when rebuild time comes at 200k (lol) I can do a total rebuild. It looks like S&S is the way to go with a crank. I'll probably go with a 4.625 crank and have it welded for extra security.

Let ya know when ya weld a S&S Crank you will be voiding the warranty
attached is a S&S crank that could not be warrantied because of welding.
Granted most will never break the spindle off like I did, but I didn't think it would happen to me ether.

P3R FlyWheels Crank that replaced broken S&S crank. Ya it's Purdy, Purdy Expensive

 

[Hillsidecycle.com]

Any crank can become fubared when/if subjected to extreme useage.
We've seen all buggered at one time or another, Jims, S/E, OE HD, and early S&S.
The late S&S cranks are very robust, due to their manufacturing methodology.
I'll add that more 1/4 mile and Bonneville records have been etablished with the use of S&S cranks, than all others combined, X 10.
Scott

 

[rg113]

Badbagger, did Ironhorse (Cox) do the install on that S&S?

 

[BigNorm]

Thanks for the info. What are they using to get the 143?

 

[BigNorm]

How'd you break the spindle? There has to be a story there. Most of mine start like, "Hey y'all watch this!" :grin: it sucks that it broke and they won't warrantee it.

 

[JacktheBagger]

143 is 4.425 bore and 4.625 stroke

if I knew it wud last I wud get it over the 124

 

[Hillsidecycle.com]

Thanks for the info. What are they using to get the 143?

You cannot build a 143" in an OE HD set of cases.
Raised deck cases to allow a piston/piston at BDC, different bolt pattern, etc,etc.
Fininshing another one currently.
J&E is manufacturing a domed piston for this one to up the power, with the use of a different cam.
Scott