engine type

- crank, rod, pin, piston ... scooped oil feed, rods were 140mm, crank pin 29mm, pistons with a lower crown for clearance

- i think there were some cosmetic differences wrt headlight and rear brake pedal too
 
- youre not likely to have a 533 motor in the states unless it has been specially imported, these were mostly sold in europe...have 533 cast into the conrods
- at least model codes 3L1, 4G7, 5E6 ...?
 
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Thanks. What I'am doing is a big bore on a 72-70 this is what I call this bike someone before me wanted this bike to look like a 70 with the paint looks good .What I want to do is replace crank with a 81 welded pins in crank, shell cam 447 on cam, new timing chain and 36mm round slide mikuni,with a spring kit on the valves,larger jugs and the 20mm piston pins.any suggestions would be helpful.thanks
 
This is the info I have on engine types:

There were 3 types of engines.

256 series.........XS1 to TX650 (1970 to 1973)
17 tooth gear on crank, 34 tooth gear on camshaft
Conn rod 136 mm centre to centre
gudgeon pin 22 mm

447 series.........TX650A to 1983 ( 1974 to 1983 in North America)
18 tooth gear on crank, 36 tooth gear on camshaft
Conn rod 130 mm centre to centre
gudgeon pin 20 mm, but is 6 mm lower on piston

533 series..........1974 to1981 in UK and Europe
Conn rod 140 mm centre to centre
gudgeon pin 20 mm, but is 10 mm higher on piston than 447
 
Pretty sure that no matter what motor you have, the internals will fit, just need to use them all, well most! :cheers:
 
Thanks retiredgentleman that's what I was looking for,thanks to inxs and yamahaman for your help all I can learn to finish this project,I have 2 more to start a restore to 75 and a 81 bobber,I will post some pictures when I figure out how to
 
- you have to be careful with 533 classification as many models sold in europe did not have 533 cranks
 
I believe Yamaman is correct -- if you replace your 256 motor's entire crank assembly, including pistons, and the cam, with 447 ones, you should be okay.

If you have access to the rest of the '81's internals, you might want to use its transmission as well. That way, if you think you might want to use MikesXS OD 5th gear, you can.
 
Hello All,

If you replaced the stock 256 rod/pistons with 447 rods/pistons, would that be a workable arrangement? The reason I would desire to go this way is that I have a 1969 XS1 that I built in 1970 as a flattrack racer with a Trackmaster frame, Branch Flowametrics head, Tom Sifton Cam and the crank wheels have been balanced and the taper on the crank has been re-machined for to fit a crank fired magneto. My goal in addition to freshening up the internals is to go to the full 750cc allowed by the class. The 447 components seem to be more available.

Thank you in advance for your input.

Dave
 
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