Unchattering the fzr750 and fzr750/1000 Yamaha
Addresses: Chattering under high rpm / hard drag starts.
App: 4BH YZF750, 2GH FZR1000, YZF1000 and similar apps.
Background: The clutch "chatters" under high rpm / high slippage / high power conditions.
The damping springs on the primary gear bottom out and transfer undamped force to the clutch. Stick Slip Stick Slip...... Chatter......
If the chattering is allowed to continue, the clutch hub, "outer" will shatter and the clutch hub, "inner" will become extremely grooved.
WARNING!!!! USE AT OWN RISK!!! REQUIRES MODIFICATION ON PARTS THAT MAY FAIL - POTENTIALLY EXTREMELY DANGEROUS!!!!
Elongate the stock
oil transfer holes outward so that the outer
edge at least reaches the lip radius.
Grind shallow slopped groove to capture oil and channel it in through the backing plate to the inside of the clutch hub, inner.
The groove is about 1-2mm deep at the transfer hole.
Do all 6 transfer holes.
That gets the oil into the clutch.
Add 3 holes, 1 at each of 3 locations as marked in the blue dot on right. Use the same spacing and hole size as existing holes on left. (Note: some hubs have the holes on the peak of the spline and some on the valley of the spline - just duplicate existing style)
These 3 additional holes will allow the oil that's inside the clutch hub to reach the clutch plates and help keep them from oil starving and chattering under hard drag launches.
This mod does NOT work for FZR600!!!
Remember! These are hints only. You are responsible for whatever you do with this information.
If you use this information and it helps your application, please contact Factory Pro with results. Thanks, Marc