HD sportster cranks

[KnightEngines]

Going to be doing a freshen/toughen up on my sporty bottom end shortly so I'm not worried about it whenever I spin it past 7000rpm & so I can screw some more HP out of it reliably.

Bike is a 94, originally 883, converted to 1200 with bored 883 barrels & wiseco pistons, currently making in the region of 110-120hp @ 7000rpm, which I'm told is pretty close to the long term reliable limit on stock 883 crank & rods, which have done 45,000 miles & have not been touched since the motor rolled off the line 30 years ago.

It's the earlier bolt together crank (which apparently is a good thing).
Is it possible to fit a 1.5" crank pin (stock is 1.25") to the existing crank along with 1.5" pin rods?
1.5" pin cranks are available, but require a fair bit of work to fit to earlier solid mount cases.

I'm a pretty decent machinist, machining the flywheels or whatever is required doesn't scare me, but there is a solid lack of info on if it can be done out there in google land.

Looking to have a bottom end capable of surviving 8000-8500rpm, 140+HP & maybe a 25 shot of nitrous.

[wfolarry]

I don't think it's possible to fit a 1.5" pin to stock flywheels
I have the S&s race catalog from 2021 that lists all the parts they had available at the time
If you want a part# I can help you with that
They show complete flywheel assemblies as well as rods, pins etc.

[hoodeng]

As Larry said, a full S&S crank would be the best way to go at the HP you are envisioning.
We have used a S&S race prepped crank for a number of years now in a 145hp sand drag Sportster engine with no issues at all. Previously we had an S&S rod set in stock flywheels that would go out .003" and stay there regularly, it does not sound much but at 7500rpm it was enough to effect the ignition pickup.

[KnightEngines]

As Larry said, a full S&S crank would be the best way to go at the HP you are envisioning.
We have used a S&S race prepped crank for a number of years now in a 145hp sand drag Sportster engine with no issues at all. Previously we had an S&S rod set in stock flywheels that would go out .003" and stay there regularly, it does not sound much but at 7500rpm it was enough to effect the ignition pickup.

Ahh, $$, maybe I just beam polish & shot peen the rods, get you to balance it, be happy with 130 odd HP & keep it under 7500rpm.
It's not like I can use what it's got now 95% of the time anyway, just figured a bit more wouldn't hurt out at Tailem & it's coming apart for a freshen anyway.

[hoodeng]

We tried a couple of crank tidy ups, first one, S&S pin HD rods and Kenworth tight. Second was full S&S rod set, Kenworth tight. Third was S&S wheels, S&S rods, Kenworth tight 350ftlb [this is the one that kept moving. Fourth was send that flywheel set to S&S and get them to do a race prep service to the crank. This was the best outcome.
Don't polish the stock rods, half their strength is in their skin. They were peened in production, crack test if using them.

This is an earlier engine from the same bike that had been assembled with stock wheels and rods, the top end came here to be leant on which we did. Not long into its use it ventilated. We found a fracture in the top of one of the rods. This engine had held together for a number of seasons with no problems until we leant on it.

S&S crank Tony if you are going to put anything like you plan to do in it.