Topic: Weird Points Plate Issue

[jaytee-nz]

I was fine tuning the timing on my 72 CB500 with my timing light and as I tightened up the last of the three screws that hold the plate on, the bike started to stumble and the idle nearly died. I backed off the screw and the idle returned to normal !
Tried this process about 6 times and the same thing occurred.
The plate is properly positioned in the case recess and is not warped. Tightening the screw can only move the plate a tiny fraction as it's already touching the recess area. Everything else looks normal.
Anyone come across this issue before ?

[Duanob]

Pinched wire under the plate?

[scottly]

Yes, I have. You need to check the timing with the three screws just snugged down. Then, if adjustment is needed, shut the engine off, adjust the points plate where you think it needs to be, snug the screws, start the engine, and check again. Repeat as needed. Once you are satisfied, give the screws a final tighten.

[jaytee-nz]

Thanks Scottly.
I guess the points "foot" is not sitting square on the shaft due to the screws being too loose (or is moving around) and tightening the screws is changing the foot position. Off to the garage !

[Duanob]

Is it a new points plate? I've heard of issues with some aftermarket brands.

[jaytee-nz]

No, it's the original Hitachi plate so no issues there.
I took Scottly's advice and it all seems good now.