What motors can go in a 1972 sportster

[paddyberk]

So I am just starting a 1972 sportster rebuild. The motor is fine, minus some stripped bolt holes and the transmission and clutch need a little love. I am debated just replacing the motor and tranny as one unit. Maybe get a nicer motor and avoid some headache. This doesn't keep it all original, but I'm pretty sure it isn't that way already. Anyway, my question. What motors (years and size) can be put into that frame with a medium amount or less of modification. Let me know what you guys think

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[campsurf]

The easiest would be 1971-74.. because of the right side shift and clutch in the same place.. with a little work all engines bolt up the same.. I would suspect 1957- 74 would work too. The clutch is different on the 1957-70. They use the dry clutch.

The 1974 is a great year and quite a few bikes were made. Plus, the top end would be compatible with the later models..

The money you would have to put into another engine, you could sink that money into your engine..

When I got mine... I had to sink $750 into the tranny.. you can get more parts for the 1971 and up bikes than the earlier ones.. especially the electrics and clutch..

Get a Shop Manual and a parts manual if you are going to do the work yourself.. I assume you are.. every classic bike will set you back if you don't do the work yourself..

Jim

[shepdog]

when you change motors you have to watch out for title problems, here in ohio the frame and motor numbers have to match so i would try to keep the correct number motor for your frame, if you dont do this correct it may cost you alot of problems or even your bike if any of the numbers come back as "hot" .so if your numbers match now i would put the effort into your motor you have now.with the factory service and parts manuals it is not that bad to go thru your motor and clutch, and there is alot of help here also!

[seventyiron]

Witch holes are stripped,and whats wrong with the tranny/clutch? all sounds like a easy fix.

[piniongear]

Originally Posted by paddyberk

So I am just starting a 1972 sportster rebuild. The motor is fine, minus some stripped bolt holes and the transmission and clutch need a little love. I am debated just replacing the motor and tranny as one unit. Maybe get a nicer motor and avoid some headache.

This doesn't keep it all original, but I'm pretty sure it isn't that way already.

Anyway, my question. What motors (years and size) can be put into that frame with a medium amount or less of modification.

Let me know what you guys think

I would simply rework what you have.
Believe me when I say there is no ACME Sportster Store that sells rebuilt Sportster engines at reduced prices and full warranty. This kind of place does not exist anywhere except in Dreamworld.

Any engine you buy from someone is almost guaranteed to have issues of one kind or another. It
is a given considering the age of any ironhead engine.
Better to take yours and repair it as needed.
Then you will know what you have, what you chose not to fix, and so forth.
Just my opinion and 2¢ of course. Nothing more.
pg

[Moon Wolf]

Pinion speaks the truth. Unless you have X-ray vision, you never know what you're getting. Last year I took the top end of a great running motor only to discover the bottom end was completely shot, possibly ready to grenade. Weird thing was that the top end was fresh, so someone rebuilt the top end on a worn out motor for god-knows-what reason. It wasn't that much of a cause for despair, though, because whenever I buy a bike or just a motor I expect the worst, and anything better is just a happy accident.

Rebuild the motor you have, especially if the numbers match your frame. The two belong together, and in the end you will know what you have.