- Mar 22, 2021
After re examination of the photos its deffiently 22710 on the base of the barrels ...so appreciate your help... I just found out present owner took ownership of this bike in April this year ?@kernel65 is correct with the part about the 650 needing the "bulge" cases. The 99 crank fits in the standard cases, but the 650ss is a stroked 99, so needs a bit of clearance inside the case for the stock rods and have cut-out skirted pistons. I think it's been said you can grind down the outside shoulder on the rod bolts and grind out the inside of the cases to get a 650 to fit, but sounds sketchy to me! That could be total BS though.
There is some lore around the last of the 88ss bikes running the bulge cases, as Norton was out of the non-bulge cases. Don't know about the stories, but '62/63 was far from the end of the 88ss production run.
Just checked my 650 barrels and all of them (3) have 22710 as the barrel casting number. My 600 is screwed up in a crate, so I didn't get into that. The 88ss barrels were (I think) a different casting that had a fin shape that matched the downdraught head. I don't have one of those, so no point in digging into the barrel boxes for a std 88 casting number. The pics show a fin shape that matches the dd head.
If I'm jumping to conclusions based on the numbers (if correct and genuine numbers) and available pics, I'd reckon the motor was assembled with 99 crank and 650ss barrels. If so, with that downdraught head, some nice pistons, and with an ss cam, it could be a real nice bike. Not as torquey as the 650ss, but still fun and fast enough to kill you.
I'm with @kernel65 again, and be real tempted. We don't get as many pre-Commandos over here though, so pickin's are slimmer.
Now its up for sale ....hmmm