GRM 250cc Motor Timing

[Al Peffley]

I am having trouble getting the aluminum rope plate off of the rotor top to reset the timing at .035 BTDC. What am I not doing right?

[Guest]

As I remember, isn't the flywheel wheel attached to the magnet by the 3 screws. I don't remember, but the center nut may be also over the flywheel. It would be easier to remove the center nut and pull the flywheel and magnet assembly. Even if the center nut doesn't trap the flywheel, it will be easier to separate the assembly on the bench, if that is what you want to do.
It has been awhile with my 500cc GRM, but I never separate the assembly (flywheel & magnet), I would remove the center nut, pull the assembly, re-time the engine, seat the flywheel assembly, and tighten the center nut. Then recheck the timing.

[Al Peffley]

Thanks for the response. I had the crankshaft rebuilt by Pete and when I took the crankshaft out I left the rotor attached to the flywheel (aka rope plate). I took this photo while the motor was apart. I am trying to understand if those two cap screws in the photo on the bottom of the rotor are part of a two-piece rotor sub-assembly, or are they also threaded into the rope plate bottom? I can find a scribe mark on the rotor top edge without taking the plate (flywheel) off of the rotor, but I can't see a scribe mark on the stator ring with the flywheel and rotor mounted onto the crank to make sure the stator ring's cap screw positions are correct. It seems like a simple key locator on the crankshaft end would be a better design...am I missing something here?

[Al Peffley]

Success! I finally was able to remove the rope plate from the rotor with a small plastic dead blow mallet (and a lot of patience while tapping on it hard) tonight. Since the rope plate is attached to the rotor with three hardened 6mm cap screws, I don't understand the need for such a tight machined-surfaces fit between the plate botton inset and the upper rotor surfaces. The plate was stuck on the top of the rotor by a small amount of hardened grease with metal powder grit in it and some Loktite overflow from installing the cap screws with thread lock (I don't Loktite these cap screws and I always torque them down with double washers.)

I will clean and polish the mating surfaces to eliminate the rope plate dismounting problem after I time the motor tomorrow. Thanks to all who helped me solve this ignition system maintenance and timing problem.

Cheers!