Since there is a lot of discussion of the mysterious front cylinder dying lately on the mc16 can anyone give me a clue as to why my bike fires up okay on both cylinders but no sooner as it gets warm then it will only fire on the rear cylinder.

Plug good
Coil swapped and worked but by this time the engine had cooled again.
Carb not touched since bought of ebay 3 months ago but fuel is getting through as the plug was wet when I was inspecting it.

i thought of fitting a bentley radiator to keep the bike cool?

Any advice would be appreciated

here too dude. starts up both firing but when it heats up stops firing for good, didnt let it cool down and try again. the only way to get it working is to change new plugs! $$$
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feel the wind

by which time the bike as cooled. i change my plug on the front but sort of sat their deliberating somewhat whilst doing it and by the time i'd checked over several other things it started first kick on both cylinders.

normally it would kick in occasionally when riding back home but the last trial run it stopped firing on that cylinder altogether. when i got home and left it for a while it started again.

read the new thread as a guy with an mc21 has had similar problems and identified a dodgy coil, which is what i am going to try as having a spare coil if i'm wrong isn't such a bad thing to have.

have you solved your problem with the new plud or did it persist? how many miles out of a plug then?

thanks

around 500km from a plug. i have changed lots of pugs already after my rebuild. will see what happens after i get it back from the paint shop and put on b9es plugs see if it makes a difference. just to ask does **** plug look black an greasy? my does. but my never starts again after it stopped unless i change a new plug. $$$
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feel the wind

Hi have you tried cleaning the pulsers

pulsers?? please veryfie what they are, never been told what they are but i am ready to go for anything.
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feel the wind

there are two pulsers that are round the magneto behind the left hand engine cover

the problem may be to see if the carbies are feeding the engine with too much of a rich mixture... thus resulting in greasy sparkies...that wont fire...
other than that, maybe check the cooling system isnt defect cos pistons will seize.... braking issues can occur too...

THANKS ALL FOR THE HELP AND THIS GIVES ME SOMETHING CONCRETE TO GO ON.

I'll start with the easiest obviously and work my way through especially since the weather is pup now.

i'll take some pics of the harder stuff and post to those that are having problems.

Just got my bike back fromt the paint shop, it now has b9es (rear) and b8es (front). has a look at the front after using it for 20 km and it looks ok at the electrodes with a brown coating which can be rubed off with no problem. but the other parts of the plug are bloack which needs brake cleaners. its the first time i have ever used plugs without R's will see how it goes.
will also have a look at the carbs because it feels different in the power output, it does this after a little while after a tune, so i am guessing settings are out of place for the needles.
i also have a question (Needle No.1 2QY No.2 2QZ) what does 2QY and 2QZ mean?
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feel the wind

The 2QY and 2QZ are the part sizes, obvious you say, but if i'm correct the Y and Z mean the Diameter of the straight portion of the needle before it then tappers to the point. Y being slightly richer and Z being slightly leaner. do you know what the standard needle size is?

on a closed to quater throttle (and probably all the way to full) this will determine the minute change in fuel distributed into the fuel air mixture and probably lead to a size change in tapper i.e. allowing more or less fuel from close to full open throttle as well.

if there is a number after it, this determines the needle clip position e.g. height. i don't think the 2 signifies the standard needle clip position but i could be wrong.

When its only firing on the rear does the front have spark.. Could be a coil
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1996 MC28 SE
NSR250R2R

the rear went dead just after 30 km of the new plug(b9es), put the old br9ecs and started working, will check the whole electric systems soon or something... and they forgot to put the front tank rubbers after the paint job. the front is working fine with the b8es, nice brown coats on the electrodes. might just put one in the rear when it dies again.
any idea where to check for the crap miledge?
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feel the wind

i checked the coil for resistance with a multimeter (ohms tests) and all seems good except for some minor adjustments to the coil lead to plug then i got a reading again. thought this might have been the problem and still could be. i checked the measurements with the other coil and it was very similar.

i looked at most of the connectors and all seems good. I cleaned a couple of greenish connectors too and now am going to check all connectors (well most)

i checked the pulse generators, but apart from a little greasy all seemed okay, there was a difference in gauge, i.e. 0.40 thou rear cylinder clearance and 0.50 thou front clearance. i degreased the lot and took it for a spin.

I didn't dare ride as fare this time as i didn't want to ride it on one cylinder all the way home again. this time it went off the front but came back on for much longer and seemed to idle better. i get the feeling i've probably got a poor earth somewhere as it feels like a minor electrical short which i think is in the wiring loom under the tank as it all seems a little untidy and when i got the bike and had a look around it etc i might have dislodged an old coupling or something.

so i'll do the resistance checks on the wires linked and connected to the front ignition and pulse generators and then go out for a run to see if i've cured it.

AT LEAST I'M SPENDING SOME QUALITY TIME WITH HER THIS YEAR BEFORE THRASHING IT NEXT YEAR.

I'VE ALSO GOT VERY GOOD AT GETTING THE BODYWORK AND TANK OFF.

P.S having wanted fuel line couplings for a while but being to tight to pay £20.00, i've found a mx dealer who sells them for £7.99 for 6mm and 8mm pipe if anyone is interested. i've ordered two myself and will let you know what they are like.