Home of  my Yamaha RD400  Drag racer.



Ora et Labora


Stuffing your crank.
Now I am not saying you should stuff your crank. There is some debate about it these days.
I'm just showing you how you can do it.
You can plug the balance holes with Ali plugs. This will reduce the crankcase volume by at least 41cc.

We are using Mikuni TM38's and because they are way too big to fit the standard RD inlet rubbers we had to male up some new inlet manifolds.

We are going to use an MRE lockup clutch on this motor so there are a few mod's that need to be done.
A lockup clutch uses arms, that are thrown out by centrifugal force, to put extra weight on the clutch pressure plate. It puts heaps more pressure on the plate than the springs could ever do. That way you never have any clutch slip as your get more power from your motor.
The first one is that the clutch cover has to be widened to allow the lockup plate to be fitted.
We did this by putting the clutch cover in a mill and using a fly cutter to open up the cover.

Then we took a large lump of ali and turned up a flange that we then pressed into the clutch cover.
Then it just need a plate to be bolted on to the front and there you have your new lockup clutch installed.

Sorry that I don't have all the dimensions to put on this drawing. I will find them later.