For those of you that have fitted the Hy-Vo cranks in order to handle increased loads. I'm well aware that the following is all about the DOHC engine but what I'm showing you contains lessons that can be applied to the SOHC.
Here is my Gear drive conversion for the 900-1100 DOHC engine and has proven to be an effective and viable solution to eliminating the primary chain failure. In addition it has shown a reduction in parasitic losses and oil temps dropped with this conversion fitted. Without question it has proved to be a major advance over anything else in this area.
The story behind this is that we have progressively developed the DOHC engine to a point that we can no longer keep the primary chain in them when road racing. Our engine now exceeds 180 RWHP and operates between 11500 -12000 RPM and during sustained operation the chain would fail and this Gear Drive development solved the problem.
Brent
https://www.facebook.com/100004676028806/videos/551798074986055/
https://www.facebook.com/100004676028806/videos/551773721655157/
Jesus christ the work that has been done to this DOHC... amazing, very nice! It sounds fantastic with the skinny crank.
Though I'm surprised the main hy-vo chain gave such issues. I have a gpz turbo also with identical style primary hy-vo chain and people have been pushing 275hp with those engines with huge torque numpers. Mine's at 190hp at 21psi.
The engines go from 100 to 200 hp from 5500 to 6500 rpm so are getting quite a bit of load also.
No one has ever reported issues with the primary chain as far as I know. But then again those bikes aren't raced for extended periods, only some top speed runs and a lot of drag racing. The output bearing fails sometimes as the engine cases are being pushed apart and the bearing starts to spin in it's seat. More or less the only weakness.
The part about the dampers and chains failing of the SOHC engine got me wondering... how do you notice if the dampers are out?
My sohc turbo bike also is pushing quite a bit of HP and already had 72000km on its bottom end pre-turbo.. and I'm hearing a lot of clacking and rattling down there, especially when clutching.