Topic: 77F Engine in a K1?

[igraul]

Hey guys, I've been thinking about picking up an extra cheap 750 engine to rebuild; my K1 runs mostly fine, but I figure it's a good way to learn the engine inside and out. I live in Portland, so I can ride when it's sunny and build when the weather turns sour.

Anyway, there's an engine out of a 77F on Craigslist right now for $100 bucks, and I was wondering if that would be a straightforward swap once I finished the rebuild, or if I should wait until I can find an engine closer to 71.

I appreciate your opinion.

Ike

[mcpuffett]

Hi a 77F engine will drop straight in your frame  , cheers Mick.

[JP]

You will need to swap the sprocket from the k1 engine to the F engine though. It will be a different pitch. Swap them out so that it will match up with your chain and rear sprocket.

[eurban]

The 77 and 78 F engines are probably a bit more expensive to rebuild than other 750 engines.  Pistons and rings are unique to the that engine (perhaps the rings are the same as the 77/78ks?) and are difficult to find and more expensive.  The 77/78F engines (larger intake valves) also tend to wear out their valve guides quickly.  New guides would be recommended.  The engine will probably work best with the later pumper carbs and the proper rubber intakes as the intake flanges on the head are larger than the K bikes.  The transmission is also geared more shortly.  This is not to say that the engine couldn't be rebuilt and happily used, particularly for a the nice  buy in price of $100.  Just thought pointing out some of the added challenges might be helpful . . .