Winter work on the 650r

I did some work this winter on the 650r so I could prevent a problem that seems to be reoccurring.

My last track day I about dropped a valve again.  I blame this to downshifting into a gear that it was not ready for and over reving the bike in the process. (operator error)  I decided to try and alleviate this problem by using Kibblewhites Heavy Duty valve springs and installing a slipper clutch.

Another problem I was having was with missed shifts.  I decided to install the hybrid shift arm that follows the shifting cam and replacing the spring with a heavy duty unit as well, all from Factory Pro.  If this doesn’t help with the missed shifts my next step will be to microfinish the gears and shafts.

ex650 valve collets and retainers
Notice the valve retainer on the far right has lost its collet. It was busted in two and laying on top of the valve retainer. Notice the valve collet on the valve next to it. That valve almost had the same fate and I feel lucky that this is all that had happened.


APE pro series cam chain tensioner
Rather than rely on the ratcheting mechanism of the stock self adjusting cam chain tensioner, I opted for a mechanical cam chain tensioner from APE. These take a bit more maintenance,but are much more reliable.


650r Yoyodyne slipper clutch
Fancy new slipper clutch from Yoyodyne. I opted to go with the 5% stiffer Barnett clutch springs and EBC friction plates. If this slipper clutch is installed in a 09 or newer. The thicker steel clutch plate will need to be purchased and replace one of the thin steel plates in the pack. I need to get this to the track to see if this setup works or if I need to go back to stock springs. I have read that the EBC frictions grip better than stock.


Koyo temp sensor
Koyo temp sensor before


Koyo temp sensor
Koyo temp sensor after


Top arm and spring are the stock units. The bottom arm and spring are the Factory Pro units.



Riding motorcycles and wrenching since my preteen years, I have moved from motocross to street bikes. Being a teen back in those days it was tough to get me off of the bike. Now days even though I am very busy being a dad I still have my weekends and go to the track to race and on occasion will do a track day or two.

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