Sigma slipper clutch for Yamaha FZR400
Prevent those dangerous over-revving situations that lead to expensive head and/or crankshaft damage and increase stability into corners.
One of the quickest ways to kill an FZR400 is to over-rev the machine.
Due to the oil pressure release valve only being a couple of psi higher than is needed to get the oil into the crank at the redline and subsequently lubricate the inner main bearings it is very easy to damage those bearings.
Even if you drill out the oilways which are restricted on the standard bike aggravating this issue it is still a fine balance between power and wear / damage.
Most of us remain vigilant not to over-rev the engines on the way up the rev range when the revs are rising relatively slowly and we are looking for the change light, but when changing down we are normally looking at or for the apex and concentrating on our braking. Also the rev limiter in the ECU clearly only works on the power and not in an engine-braking situation.
As such it is most likely to over-rev the engine during a down-change leading up to a corner and this reverse load situation is in fact more dangerous for the head than on the way up the revs.
If you're running tight piston-valve clearance for max power then the margin of error becomes ever more critical.
This is where a slipper clutch can be a massive saving preventing unnecessary DNF's and expensive, time consuming repairs.
Finally of course fitting a slipper clutch can improve your stability entering a corner by reducing the chances of rear wheel hop.
It must be noted however that some changes to suspension settings are likely to be needed as you may well be reducing the uncontrolled engine braking into a corner so a stiffer setting on the front and most likely a slight increase in rear compression damping due to the reduced chain tension fluctuations.
Comes with installation instruction CD