Hi panic,
single lip single row roller: IIRC this is where Norton used a Superblend to prevent edge contact due to crank flex (H-D used a ball bearing).
There's less than 3"1/2 between the crank bearings centers, I can assure you these K/KH/Sporty cranks are not FlexiFlyers!!!
XR750 did go for superblend bearings after 1980, more due to ever higher rpms and brinneling than flexi cranks. They were happy till then with the old KR ball bearings. My roller bearings are the same dimms as the KR ball bearings, drive side 25 x 52 x 15, timing side 25 x 47 x 12. Just went for rollers cause I used the bike on the street, a bit more longevity!!! Also makes for quicker setting of end play and assembly...
Torrington needle bearings: I see the #2 is full-complement, while the smaller ones are cage-separated (1958-* XL used full-complement). Any capacity problems with the lower roller count?
Did not notice any problems with the cage needles. Plenty of oil feed through the cast in oil collectors on the back of the bearing bores. If I remember right, I've done that probably 15 years ago, these where INA needle bearings since I could't get Torringtons at the time. The full complement one is a Torrington.
fitting of a Mikuni adjustable extra main jet: do you mean the power jet, or is there a 2nd main?
There's a fixed main jet inside the bowl at the std location. The OHV was running quite lean even with a 3mm (.120...) diameter main jet... Rather than the hit and miss to increase it bigger, I fitted the Mikuni needle on the outside, makes for quicker setting... It is level with the fixed one in the chamber just below the emulsion tube.
The clear pipe you see on the side of the carb is actually the outside iddle/transition circuit, with transition jet as a 3mm diameter lenght of copper bar with a suitable hole in it and trapped by safety wires!!!
Love the Tillotson wheel
I quite like the whole Tillotson meself!!! Bit of an acquired taste, but once you get the idea, it works and it's got the most wicked response of all Sporty carbs!!!
Patrick