plugs... swap them over and see if it follwos the plug. If so, easy fix. If not, then carbs

if you need a deep socket the size is 13mm, i found this out when i bought my nc30, the plugs are tiny, i got one from halfords for about £4-5 but make sure it is deep as they do, they do not however do a proper spark plug socket that small. The only downside to using one of these is they do not have the rubber section inside so you will need long nose pliers or something to get hold of the plugs once loose.

I use the HT leads back into the recess to grab the plugs out...

that'll do the job

If it is not the plugs, do all the leads click onto the plugs ok. Mine used to run on 3, the cause being one of the tiny springs in the cap that grab onto the plug being missing. A tiny amount of vibration would cause the lead to disconect slightly from the plug so it would run on 3 and be difficult to start. It can be hard to spot so check em. Took me ages to find the prob.

joshmolloy wrote:When carb cleaner is sprayed into the most suspect cylinder revs rise. Sprayed into the others it has little effect. Cleaning the carbs thoroughly hasn't helped.

Still waiting for new coils but after that I have no idea?!

You have fuel or compression issues not spark, if the revs rise when you add a fuel (in this case carby cleaner) you are getting plenty of spark.


Float levels OK?

Does fuel run out of the carby drains if you crack them open?

What are your idle mixture screws set at?


regards
jon

Right I'm going to check carb settings before valve clearances then. What could cause a compression issue? Plenty of fuel in bowls when I took them apart dunno about float level though. I have an autodata book thing but not a haynes manual. Anyway I'll check jet sizes and settings as much as the book can tell me. Where can I buy jets? I don't think they numbers on them when I had the carbs apart though.

First things first though, new plugs.

CMSMJ1 wrote:It is always dodgy plugs.....

ha ha, the more relies i read of yours, the more i think you have an unhelathy obsession (or perhaps NGK sponsored!!)
although you are probably right!!

SligeA¡ch wrote:

CMSMJ1 wrote:It is always dodgy plugs.....

ha ha, the more relies i read of yours, the more i think you have an unhelathy obsession (or perhaps NGK sponsored!!)
although you are probably right!!

I tell you..it is true!

My race bike was a bastard.. it would pickup on carb cleaner being sprayed in but not fire... I changed the plugs and wahey..it now starts on the button better than my no9 does!

Sorry if you're a PB forumer and are reading this for the second time but I thought I'd keep this thread updated:

"Seemed to be running a little better, still dodgy on one cylinder though, but a bit more responsive bottom end. So took it for a ride. At high revs there was a knocking noise, like a really harsh sound, so came back and stopped. Were just talking for a bit with it at tickover, and then the noise became full time, on every fire of one of the cylinders. Definitely sounds like the front left. Haven't had it stripped down yet but it's awful."

Does this sound familiar to anyone?