Triumphrat

powwow1940

need to know if a 63-64 triumph 650 bonniville has the same crankshaft as the one used in the same model in 1969?

Catenaccio

Welcome! I'll send this where you can get some help.

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GrandPaulZ

They are very similar, and can be interchanged, but I believe they have different threads for all of the various fasteners.

Depending on the year, the flywheel may be heavier or lighter (some like them heavy, some prefer them light)

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jimmy bush

As per my "Kim the CD Man" CD, the part number for the crankshsaft without the flywheel is the same for a 63-70 (didn't check anything after 70) so it should work. The numbers for the flywheels are different. They used a lighter flywheel in 68 and the early part of 69 before switchin back to the heavier one for the late 69's so the 69 could have either depending on when it was made. I think the earlier (63) crank assembly had thinner (cross sectional) rods. The ones on a 69 should be stronger.

Mecchanica

They will interchange, but are drilled for different balance, given the rod mass difference. The 69 will have a heavy flywheel, like the early crank, but will have two timing slots cut into the flywheel so that a timing plunger can be used to set the TDC and 38 degree BTDC locations. The early cases won't have the timing plunger hole, so the slots are a moot point.
So, putting an early crank in the late cases negates the timing plunger function and if you fit the rods from one to the other, you will NEED to rebalance.
66-68 used the light flywheels, with the 68 having been fitted with the heavy rods and TWO timing slots, the 66 and 67 with only one slot and the light rods. There is also a weird 68 MK3 fitted to cases with two timing plunger holes...one in the front at 180 degrees away from the standard one under the carbs. Pretty rare, but they're out there.
BTW....Aloha everybody. I'm back, at least for a while and occasionally. Much going on here in my little corner of paradise.

Kim

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