Are RC01 and RC42 engines interchangeable?

[rasta]

Hi there,
it looks, that my rc01 engine is dying. It takes oil and make an ugly smoke. Compression is almost 10 bar (140-145 psi) in all cylinders. The smoke appears when engine is cold or during acceleration.
 The valve seals have been replaced - did not help. Then, we changed cylinder head - did not help. Do You have any ideas, what may be the reason?

My second question is - is it difficult, to replace the rc01 (1981) engine with rc42 (1992-2002)?

Mike

[TOOLS1]

Welcome to the forum. What color is the smoke? If it is black it would be a rich condition with the carbs. As, for the swap, I don't know, but I'm sure someone will chime in.
TOOLS

[Re-run]

As tools said, it depends on the color of smoke. You generally have 3 colors.
White = water, usually in the form of condensation that gets trapped in the oil or in the pipes.
Black = too much fuel, the A/F ratio is too rich.
Blue = oil burning

Now, you changed the seals but if the guide is work and valve stem is worn, the seal may not be enough to hold back the oil.
You changed the head, do you mean a whole new head? Any work on that head or just a different head?
now, on the sohc engine, there are oil passage o-rings, if they are bad, oil can go by. Same might be happening here.
Otherwise, rings are usually the issue.

What is odd is that you say the compression is good.

How much oil is used? How hard do you ride? In these old engines, riding hard consumes oil.


As for the engine swap, the dimensions of an 81 dohc are probably not that much larger than the later 750 but the geometric shape will be different as in different angles. The mounts will also be different.

I am sure you could shoehorn the engine in but you would need to custom weld mounts. From there, you would need the exhaust for the newer engine. And you would need to correct the chain alignment.