Help MC19 Spark unit

When my '88 MC19 gets to around 12,500 rpm I start to hear what sounds very much like detonation. Timing and valve clearances look good, so I'm thinking maybe the spark unit. I can't track down one for an MC19 (30410-KY1-003) but there is one for an '89 (30410-KY1-701) not too far away from me. Can I use the spark unit from a '89 on an '88?

 

Sure, if pinouts match, it should be Ok.

Need to verify AFR, very well could be case of dirty clogged carbs getting lean at high-RPMs

 

Carbs were cleaned and rebuilt in 2021. I went ahead and bought the '89 spark unit. If that doesn't fix the problem I'll go through the carbs again.

 

Here's the spark unit that came with my bike. Looks like someone's been in there at some point. New unit seems to be OK but I haven't had a chance to do a proper test ride yet.

 

I knew that was too good to be true.

Bike starts and runs with the new spark unit but as soon as it gets to 5K is starts to misfire and doesn't want to rev.

Back to the drawing board

 

Plugs, leads and coils are all new.

Old spark unit runs great until it gets to about 12.5K and then it gets "fizzy". New spark unit goes flat at 5k.

Ali Express anyone?

 

Ordered one from Ali Express, so fingers crossed.

I'll pop the original back in for the time being, 12K is enough to get me to Radwood next weekend.