hi can anyone help me i am having problems with my nsr mc18 1988 model,when i turn my ignition on the rc valve servo doesnt make any noise or move, i thought maybe there was problems in the cdi or pgm box's but ther seems to be power getting to the servo cause when you have ignition on the wheel on the servo is hard to turn by finger and thumb but when ignition is off is a lot easier to turn, any help would be appreciated alot
thanks

turn the servo by hand to the hi postion with the key in off position, then turn on the power, it should move back to start up position.
if its already in the start position it will not move again when you turn on.
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feel the wind

thanks for your reply, i will try it first thing in morning, been tryin to sort it for two weeks now, driving me mad

Here's what I would do:

1. Remove the cables from both the servo pulley and the RC Valve pulleys.
   
   
2. Insert pins into the RC Valve pulleys to lock them to the back-plates.
   
   
3. Either:
   
   
   • Start the motor, and rev it lightly. At 2000rpm the servo pulley should move to "Hi". Increase the revs slowly, and at 3000rpm it should move back to "Lo",
     
     
   • or disconnect the T.P.S. and see if the servo pulley moves to "Hi". Re-connect the T.P.S. and the servo should return to "Lo".
     
     If the pulley moves, then the fault's likely to be tight cables or carbon build-up causing the Valve(s) to stick/jam.
   
   
   
4. If the servo operates correctly, extract the RC Valves and thoroughly clean them. Check the cables move freely, and lubricate/replace them as necessary.

If the servo doesn't operate under any of these tests, the the controller is probably dead. RC Valve controllers die far more often than servos do.

You can do a simple test on the servo by removing the pulley and just connecting it to +12V. The spline the pulley sits on should just spin.

There are 2 boxes under the seat on an 88. One says PGM and sits vertically on the side of the subframe and is the CDI, the other sits horizontally and is the RC Valve controller.

RC Valve control circuits fry due to poor maintenance.
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Andy.
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hi andy, i tried all what you said but still no joy, i even borrowed my mates rc valve servo and it didnt work but it works on his bike, i can get my hands on on a servo control unit but its of a cbr250 rr and it looks the same, would it do, any help would be greatly appreciated thanks

The CBR250 box may well look the same but trust me one this one, it's not an RC valve control box.

If you're on about the ones on ebay (items # 270328977900 and 280290440169) they're both clearly visable as KV3 parts and are from an NSR250.

I have no idea what the 2nd box is in auction 270328977900 but the part in auction 280290440169 is an RC valve control box.
As the part numbers are the same (mc16 and mc18 both list 31800-KV3-003 / 013 /023 /033) personally for the sake of £40 I'd buy item 280290440169 and try it. What could possibly go wrong?*

But that said I did plug in an RS PGM, use the biggest jets I've got and took it out in the fast group to check it worked, so what do I know?


*this is what I'd do, it's not advise on what you should do, do not blame me if/when it melts your loom, PGM or just flat does not work.
After all this seller is selling one along with something else for a "CBR250 mc18", it's safe to say he hasn't got a clue what he's got and certainly hasn't tested it or removed it from a working CBR250.
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Maybe he had it in the exhast, like an EXUP valve?
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yeah it would prob work quite well on a cbr250! revvy little buggers

thanks everyone for all your help, i will just have to wait untill the proper box for my bike turns up sometime, pity as i mad to get a spin out on her,
if anyone can think of anything else please let me know, thanks

You could always just lock the valves closed for a decent bottom end but poor top, or lock them open for zero bottom end and a crazy powerband...
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MC21SP Plaything
BMW F800GS Bumblebee
Triumph 9551 Daytona Big boys toy
FJ1100 Sporting relic
GTS1000 oddball

I raced mine with the power valves cable tied open, still didn't come last
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I've ridden a tuned MC18 with wired open RC Valves, and it was a damn sight better than any no-powervalve RD or TZR I've ever ridden! The RC Valves weren't fully open though, probably about 3/4. It only needed a little clutch out of really slow 1st gear corners, but it's not ideal when the system works so well... when it works!

The barrels had been tuned by Eric Gorr.
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Andy.
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hi all, i have been offer a cdi box (brain) of a mc21, will this do my mc18 as it looks the exact same and could this cure my rc valve servo problems

MC18 Mk1 PGM
MC18 Mk2 PGM-II
MC21 PGM-III

Fitting a new PGM (off the correct model) doesn't cure the problem, it only temporarily fixes it! If you don't cure what killed it in the first place, you will just burn another RC Valve controller circuit out.
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Andy.
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any idea's what could burn out the rc vavle controller, the valve's are clean and free and so are the cables