I bought an MC16 a little while ago to use as a circuit practice bike for my younger brother. It was set up as a race bike and has a couple of obvious mods; race body and seat, all excess wiring removed , oil pump blocked off to run on pre-mix and rgv250 forks and rear wheel.

I overhauled everything i could; fuel cock, carbs, forks, stripped brakes and changed pads oil etc. New plugs were installed (NGK B9ECS) and standard unleaded fuel with CASTROL TT oil at 30:1. The carb settings seem pretty close to standard and the airbox is std except the filter has been removed and so I added some fuel proof mesh foam covering the inlets.

On the table in the garage it started up by hand with the kickstart and ran very nicely; engine was snappy and seemed fine; when we got it on the circuit it warmed up and ran for half a lap with brother onboard before he came in and said was running irregularly. I took it out and sure enuf it chugged and then snapped into life before dying again. It didnt seem to be dropping to one cylinder, it seemed to be cutting out. Loath to put any more time into it as we had 3 bikes there for 3 brothers and wanted to use track time efficiently we shared 2 between 3 and left the NSR till later..sadly.

I am assuming it is electrical at this point. Looked around for loose connections etc, carbs still look fine, today put the multimeter on the plugcaps and coils and they are reading same (dont know actual parameters but readings identical).
Anyone have any way to bench test the MC16 PGM unit or the two big (!) CDI units or am I looking in the wrong area?

I build and modify bikes for fun but electrics is my weak point and would appreciate any guidance.

thanks all,

Sean

In my experience this sounds like the CDI and was is exactly how mine first started behaving. Mine would always play up on one cylinder swapping the CDI's over moved the fault to the other cylinder and make the tacho/rev counter go nuts. I guess it could also be a fuel blockage but seems unlikely.
I did manage to repair mine but wouldn't recommend it unless you have alot of time to dig the potting out. I believe they are still available new however, I sourced a new one in the uk anyway but got the old one fixed whilst waiting.

Sparky currently has a similar? problem with an MC21. See this thread.
It looks like it may have ended up just being the battery?
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[color=#808080][size=9]Yes,.. I too know how to waste Time and Money,...

did you wiggle your wires when doing checks on the coils? That shows if you have a bad connection. You need to check your coils are the right resistance.

How old is your fuel too? The NSRs don't like old fuel, and foul plugs quite easily. You would have to check the lietrature but the correct plug should be a BR9-ECM, unless you have done mods to it?

nxrsr20 wrote:
You would have to check the lietrature but the correct plug should be a BR9-ECM, unless you have done mods to it?

B9ECS is the correct plug for the MC16.
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Andy.
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Thanks for all the replies.
Just to eliminate a few things; fuel was new and so was the oil(?). Battery was also new but spent a month or so fixing it. I am sure I charged it before we went on the run as I did with all 3 batteries for all 3 bikes but the seed of doubt is sown there...
I am pretty sure all electrical connectors are fine and carbies also ok.

No one has mentioned if there is an electronic bench test you can do to both the CDI units and the PGM.