I've bought a beat up '92 MC-21 sp and it had a few issues I found that the gear selector sensor ground away a little by the chain around front sprocket causing the battery to drain all the time. The horn and some of the front end of the wiring harness had been re wired and tampered with, so i've replaced the wire harness and spliced for pmg III. The air valve solenoids don't seem to work (I have yet to get the multi-meter on it) and have been bypassed and are just open from the X connecter to the carby (sounds much better). Sparky's came out black and a little oily and gap is good with good spark (may someone please explain further about colour and how often should i check?)

Engine starts first or second kick idles and warms well, seem to wind like a 4 banger till 7000 revs (in first) feel band try to kick in and continues to wind and 9000 revs (all other gears) feel band attempts to go for 1000 revs and then just winds again!

I have a feeling it's the power valves, the top servo under the tank seen to work properly, under low revs it points down (to "L") and mid and idle it's centered and higher revs it points up (to "H") flicklering sometimes between them. how do I check both valves at the bottom are set in the right place and working properly?

The bike feels and sounds like she just wants to go but something is restricting her and it doesn't feel like a fuel related problem (still could be). The air box and filters are good. The solenoids are bypassed but they are still plugged in and They don't click (well I haven't heard them) but because they are open to the carby it should just suck air through as it needs it! Anyways any help and suggestions are good.

Cheers

Speaking strictly from my little epxerience with a WONDERFUL MC28, cracks in my hoses that connected to the solenoid were preventing the servo from doing what it should have been doing...or at least sending the correct signal me thinks.

First I would suggest checking/replacing the air hoses and getting them hooked up as normal. (Mine were cracked and letting air in).

I think you may find your servo will (should) work more accurately to start adjusting the RC valves as explained here in the tuning section:

http://www.nsr-world.com/tuning/250-tuning/engine/

Dana
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2016 Husqvarna 701SM
2021 Husqvarna FS450 supermoto
2014 Honda CRF250R supermoto
1995 NSR250r MC28

Cheers for the quick reply Dana, I'll get a multimeter onto the solenoids just to see if they hold current and I'll replace all the hoses and setup the rc valves and see how it goes! I'll attempt to buff the carbon out when I've got a bit more time.