Topic: 350Four engine tune up to 400Four

[andyman]

Hey guys!
I want to tune up a 350Four engine with cylinder and head from the 400Four engine. I know that there are the 50mm bigbore pistons for the 350 to get 393ccm but i think to do this with 400 parts is the better way because the 400 has a little bit bigger valves.

So what is to be done? Spinning on to put the 400 cylinder into the 350 crankcase, is there anything else to consider?

Greets and thanks for answers!

Andy

[carnivorous chicken]

Why not the whole engine, and get an extra gear out of the process? 400F engines bolt right into 350F frames, with a few small mods to make everything work.

[turboguzzi]

when you previously posted about this, i recall someone saying stud spacing is different... check you old thread....

[carnivorous chicken]

when you previously posted about this, i recall someone saying stud spacing is different... check you old thread....

For mounting the engine? It's identical.

You've got to switch over to 400f pegs, brake lever and shifter linkage and use a 550F kicker if you are using 400F exhaust. And I made an alteration to the rear brake lever mount, but I think that is about it.

[ttr400]

The front 2 cyl studs will need to be changed to the length of the 400 studs (350 are longer), but with an M8 thread both ends.

Also you will have to open up the crankcase to allow for the larger diameter of the 400 sleeves.

Kevin

[carnivorous chicken]

Duh, engine studs. I don't know, I've never swapped a top end like that, just the whole engine.

What about boring what you have?