Cleaning the RC Valves is only half of the story, correct adjustment and well conditioned cables makes up the other half. ANY resistance against the servo operation can be enough to kill the PGM, so even slightly sticky cables, or just one of the four cables being too tight, can cause failure. However, since working to this mantra, we've not had a failed PGM ourselves for well over a decade, which can't just be down to coincidence in my personal opinion.

Reg/rec's are a strange one. We rarely hear about problems with them these days, but were, as you say, an issue back in the day for some reason. Indeed, I had one fail myself, although I believe that was linked more to a damaged stator than individual component failure.

It's impossible to say what setting your MC21s require, without seeing/running them. Every motor is different. We've seen delimited but otherwise "mostly stock" NSRs that have taken both richer, and leaner, main jets.
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Andy.
NSR-WORLD.COM

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