SF engine rebuild with an SF2 crankcase

Cyriel

Cyriel

Full member
I want to rebuild an early 750 SF engine with a later type SF2 crankcase. Can i put al the early SF parts in the new SF2 crankcase, or are there any differences?

Why?
I`am stuck with an engine which i believe has a top and bottom crankcase from 2 engines. Changing gears gives problems and all the engine covers do not fit properly.

Thanks in advance.
 
No doubt Piet will read the textbook on this but from my experience you can definitely do it, the only difference being the way the LH crankshaft main bearing was located for the ball or roller type bearing. Definitely the cases have to be matched from new as they are line bored as a set and you can't swap halves between sets.
 
Yep, depending on how early, the LH crank main is different.  I don't see any issues using the early ball bearing in a roller bearing case, simply omit the half-ring that engages the ball bearing and use the thicker half-ring for the roller bearing.  Or simply swap out for the roller.  RH layshaft bearing can differ too, early engines used a ball bearing with locating ring, the groove for this ring was omitted on later cases.  Again, either make do or swap out for the later type bearing.  Gearbox shaft end-float should be checked and adjusted accordingly, otherwise the 'box will be just as crap as it was before.

piet
 
just get on with it, install the crank first to check on the primary side outer main bearing, some cases take both types, but you will certainly want the later type of bearing in any case, then the gearbox, then the top, checking everything as you go (normal practice) you will soon know if something is not right, There will be no problems with the top end, but as in all cases, (no pun intended) if you decide to fit a new cam chain (good idea) you will almost inevitably have length and joining difficulties.
CLEM
 
"you will almost inevitably have length and joining difficulties"
Why so? The only time I experienced that was with a recent motor job. Nothing had been planed and with new gaskets an Iwis wouldn't close, so I got a Regina (DID as I stand corrected) from Piet, almost impossible to measure any difference. The Iwis is now on a motor that has had its head planed and it fitted fine.
 
Tippie said:
"you will almost inevitably have length and joining difficulties"
Why so? The only time I experienced that was with a recent motor job. Nothing had been planed and with new gaskets an Iwis wouldn't close, so I got a Regina from Piet, almost impossible to measure any difference. The Iwis is now on a motor that has had its head planed and it fitted fine.
Click to expand...

It was a DID, not a Regina, Lee.

No issues with the DID duplex on the 750's, best fitting chains I've worked with.

piet
 
You must log in or register to reply here.
Back
Top