Ferrous_Head wrote:I've had a good look at my -57 parts book can see where there are different part numbers used on the KH and XL. I did notice that the KH and XL have different rear rods. Don't know why.
There is a different number(s) for the pinion bearing sets between the KH and XL. Possibly the shoulder on the XL shaft necessitates a shorter pinion bearing ? There is also a different pinion shaft nut. So, I just need to determine if it has KH or XL pinion shaft on it. I'll have a look in the morning.
I'm presently in the process of converting my KHK to the Sportster PTO and pinion shafts, so some technical overlap with your project.
Regarding your query about the difference in rear rods between KH and XL (both are -52 casting numbers), I believe it is due to the longer stroke KH rear rod being clearanced/machined differently on the big end to provide clearance with the male rod at BDC. With the shorter stroke XL the extra clearance in the rod big end was not required so they left the rod sturdier with more material on the big end. The front rod remained the same for both KH and XL since it had nothing to do with BDC clearance.
Regarding differences in the KH and XL flywheel, as noted by others, the left KH flywheel has a shoulder (~0.060” proud) at the PTO shaft bore. The Timken bearing seats against this shoulder when the engine sprocket nut pulls the entire assembly together. This of course is also the Achilles heel of the shoulderless KH PTO shaft, i.e., the shaft is tightened into the flywheel taper, but when the engine sprocket nut is torqued to pull the entire assembly together, it pulls directly on the PTO shaft in the flywheel taper. Which end of the shaft do you think wins this tug-of-war for real estate, the daintier nut inside the flywheel or the bulkier ¾-16 sprocket nut?
Anyway, eliminating this tug-of-war was likely the reason the shouldered PTO shaft (item 13 in image below) was introduced for 1957. To install the shouldered PTO shaft in a KH flywheel requires that the shoulder on the flywheel be narrowed/removed to provide clearance between the flywheel and shoulder when the shaft is fully tightened into the flywheel. When this was done on my project it resulted in the flywheels shifting right in the KH cases ~ 0.125” because the PTO shoulder presents a new obstacle ~0.125” further to the left of the flywheel which in turn results in the Timken bearing seating on the new obstacle (previously seated on the 0.060” flywheel shoulder). Some creative whittling, shimming and a new custom seal retainer by my engine builder alleviated this misalignment issue. In your XL case the Timken bearing is located ~ 0.125” further to the left so you will not have this issue to deal with and everything should align perfectly. This leftward shift of the Timken was likely due to the combination of the shouldered PTO shaft and the bore growing from 2.75" in the KH to 3.0" in the XL, and the desire of the design team to leave the more complex pinion/cam chest side of things alone and instead alter only the PTO side of the world.
- Shouldered XL PTO Shaft.jpg (13.31 KiB) Viewed 10166 times
Wish I could provide some insight on the -54 and -57 pinion shafts but have none. The shaft from my KHK flywheels and a new S&S -57 pinion were measured as carefully as possible and no difference could be found. Seems either the -54 and -57 pinion shafts are the same, or possibly the shafts I am measuring are not -54 and -57 parts. So if somebody knows the difference please enlighten all of us. I have queried other builders on the subject pinion shafts and nobody is aware of any differences and they routinely put the -57 pinion in KH engines with no issues.