PVL ignition help needed!

[nuttyman]

I had to replace the CDI on my ignition (94 RM250) system recently. The stock module was about $100 less thasn a complete PVL system, so I went with the PVL. Problem is, the documentation that came with the PVL does not say where to set the rotor-how many deg. BTDC to set it. I get 120 psi with exhaust valve open & ~ 135 psi with it closed. I run 91 octane pump gas but also have 110 octane race gas readily available. I made a degree wheel with and have set the rotor to ~ 25 deg. BTDC. Please, anyone with any experience with these ignitions help me! Where do I set the rotor, and the stator? I appreciate any help given.

nutty

 

[01RM125]

We use the PVL system in my son's KTM65. Most PVL kits are similar? On the KTM kit, the new flywheel/rotor is NOT keyed. You need to put a dial-gauge in the spark plug hole to find exactly TDC.
Now say you want to time for 0 TDC. Install flywheel so that 0 degree index on flywheel (the new PVL one) is exactly even with 0 degrees on the new stator (while dial gauge is reading perfect TDC).
You want x degrees before TDC. A normal question, but NOT a normal answer here. I guess because they figure we now have a dial gauge involved, the suggested timings are given in mm. I think they are saying to roll back on the crank so that the dial gauge drops x mm, then install the new flywheel so it's alignment marks match the stator. PVL seems to give its timings in mm BTC. NOT degrees BTC.
See:
http://www.pro-flo.com/images/PVL Instructions (Back).JPG
We got our PVL from pro-flo, and they seem to be very knowledgeable. Their website has as much about these ignitions as I have found.
For a 250cc the installation instructions say: Analog systems 1.8-2.2mm; Digital systems 0.8-1.0 mm.

 

[MikeS]

I use alot of PVL stuff. Call them for a spec if unsure it will be in mm. As explained above the spec lets say 1.1mm means you rotate the engine backwards from TDC and measure that the piston moved 1.1mm down the bore.

You can use the engines stroke and the diameter of the rotor ( to get degrees) with some math to convert the 1.1 to degrees. For example 60mm stroke engine would move the flywheel 6 degrees for every 1 mm of stroke

 

[nuttyman]

Thanks for the replies. I am clear on all aspects of the timing now but unclear on 1 point. The installation instructions say to set the stator in the middle of its available adjustment. It seems weird to just pick an arbitrary mark on the stator as opposed to a known por to align the rotor mark with. Does this make sense or am I missing something?

nutty

 

[MikeS]

You can set the Stator half way in adjustment range. Bring piston to timing dimension then pop rotor on with the marks lined up as best as possible. When you tighten the nut on the rotor the rotor may move on the crank. You always recheck the timing at this point you now can adjust stator to get it spot on.

PVL doesnot use a keyway. The keyway is for mass production alignment and has no other purpose (it does seem easier at times :) )