Baisley Roller Rockers

I had these roller rocker arms made by Baisley in a 1.685 ratio to bump another twin cam from .577 lift to .600.  Nominally, they will bump the lift with Zipper's Redshift XR575 cams to .600 also.  The Baisley rocker arms are a very nice quality.  I wanted to see the impact of  the roller rockers on the performance of the XR1200.  A comparison of before and after dyno data is at the end of this page.

A Look at Roller Rockers

The stock rocker arms are still in the rocker box.  The roller tip on the Baisley arms rides on top of the valve stem and takes care of geometry issues with higher lift cams and large valve travel. 
Here is a quick look at the tip of the rocker arms. 
These pictures really don't do them justice, especially because they had already been in and out of another engine a couple of times...

Roller Rocker Tip vs OEM Rocker Arm Tip

Installation is relatively easy, and I won't go through the top end disassembly since I have done that on other pages, but once the fuel tank and rocker boxes are removed, here is how the rocker arms go in....

Installing the Rocker Arms

The rocker arms are held in the rocker cover base with a pin.  This pin is located and retained by one of the four main mounting bolts.  Once removed from the top of the engine, the pin can be pushed out with a punch.  (A large round, soft metal, flat ended punch is ideal for this purpose.)  The pins will come out easily.  A few light taps with a hammer will get it started, and then it can be pulled out and reinserted by hand.  Be careful to keep the punch centered on the pin and not marr or deform the soft bushings in the rocker base.

Rocker Arm Removal

Once the pin is pushed out, the old rocker arm is simply lifted out, and the new one dropped in place.  The Baisley arms are stamped for front and rear, intake and exhaust, to make it easy to see where they go.  A bit of assembly lube on the rocker bushings will ease installation and help with the initial starting of the engine.

Arm Removed

Once the new rocker arms are in place, the rocker cover base is reinstalled on the engine.  Again, I put a bit of assembly lube on the ends of the pushrods and the valve stems and rollers.  During disassembly the engine is rotated to position the lifters at their lowest points, but with the top end disassembled the lifters will expand.  The rockers are tightened down incrementally, in a X pattern to re-compress the lifters.

Rocker Box In Place

Voila!  The bases with new roller rockers are installed.  Here is a look at how the roller rocker arm tip rides on the valve stem tip.  I am installing these ams more to experiment with increased valve lift than for their benefit as roller arms, but the rollers help improve the angle of the rocker arm tip with the valve stem when using high lift cams.

Rocker Arm Tip

With the roller rockers installed, the rest of the top of the engine is buttoned up.  A dab of blue loctite on all of bolts is good insurance when finalizing assembly.
Once the engine was back together, I fired it up and let the Thundermax do its thing re-setting the IAC stops.  Right off the bat one could tell that there is a difference at idle.  If one does not automap the IAC, idle will "hunt" and not be steady as the engine warms up.  With the IAC settings tuned, the bike seemed to have a deeper, healthier, idle tone.  Did this improve performance - only the dyno will tell...

Dyno Testing

The end result, after hours on the dyno and a lot of back and forth adjustment of AFR and timing, was that pushing the valve lift to nominally .600 with the roller rockers did not improve performance and actually hurt performance slightly on this build.  There was no advantage in pushing the XR575 cams to .600 lift in this 1200 engine build in the XR1200.  Here is a look at dyno runs with stock rocker arms and with the rollers pushing the XR575 cams.
The Dyno run in Blue shows the engine "before" with the XR575 cams and the stock rocker arms.  The run in Red shows the engine pushed to nominally .600 valve lift using the Baisley roller rockers.

Comparison Between Stock Rocker Arms and Higher Ratio Roller Rocker Arms


In the end, this was an interesting thing to check - but increasing the lift of the XR575 cams in this 1200 engine build in the XR, did not improve performance. I had to do a bit of tuning to get the engine performance back to what it was with stock rocker arms, and no amount of adjusting AFR or timing could produce an improvement over the performance with the stock arms. In fact, the increased lift of the roller rockers yielded a slight decrease in performance.
So, the Baisley Roller Rockers look great.  They are a precision item.  They actually ran as quiet in this engine as the stock arms.  But - there was no reason to install them in this build, since pushing the lift in this 1200 build did nothing to improve performance.

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