NC30 running problem

[BenF125]

I've been to Elvington today to watch a mate racing. And got roped in messing about with his bike after it cut out during the last race. He's only just bought the bike and it's was running crap all day. It was obviously only running on 3 cylinders. We tried taking plug caps of 1 at once and discovered that the rear right hand cylinder wasn't running at all. The front cylinders were running but they didn't seem to be running very well. When the plug cap was removed from the rear left cylinder the engine cut out all together so we pressume that was running ok.

My experience is with two stroke singles that give a good blue spark on the plug. All the plugs on this gave a weak orange spark. Is that ok?

Has anybody got any ideas? Any help would be much appreciated. Thanks.

Edit to add; we replaced the plugs and coils and this changed nothing.

[zimm]

cdi ?

nc's can have manky earthing issues

total loss ? knackered battery ?

[BenF125]

cdi ?

nc's can have manky earthing issues

total loss ? knackered battery ?

Yes it's running total loss, but it was still starting on the starter so we decided that it probably wasn't the battery.

By earthing issues do you mean just on the cdi or in general?

[rc30rob]

always start with the basics

make sure the fuel pipe isnt kinked,fuel cap breather is clear and the fuel tap works(make sure the vaccum pipe to the tap is conected and not split(i think it is to no3 carb on the nc ),the valves are adjusted properly,then a compression check,has the bike been stood for a while if so the fuel may have varnished in the carbs,check the earth to the frame etc (but if the starter is spinning her over it should be ok

the cdi wouldnt normaly cut out just one cylinder

valves is alwasy a good starting point as they are always left

hope that helps

[BenF125]

always start with the basics

make sure the fuel pipe isnt kinked,fuel cap breather is clear and the fuel tap works(make sure the vaccum pipe to the tap is conected and not split(i think it is to no3 carb on the nc ),the valves are adjusted properly,then a compression check,has the bike been stood for a while if so the fuel may have varnished in the carbs,check the earth to the frame etc (but if the starter is spinning her over it should be ok

the cdi wouldnt normaly cut out just one cylinder

valves is alwasy a good starting point as they are always left

hope that helps

Thanks its certainly given plenty to think about. Should the weak looking orange sparks the plugs are providing be cause for concern?

[rc30rob]

Thanks its certainly given plenty to think about. Should the weak looking orange sparks the plugs are providing be cause for concern?

yes you want big fat blue ones that make your hair stand on end if you grab the plug(dont do it you will cry)

have you tried new plugs ,they do work hard

[BenF125]

yes you want big fat blue ones that make your hair stand on end if you grab the plug(dont do it you will cry)

have you tried new plugs ,they do work hard

Yes we tried new plugs. As I said we thought the sparks should be vicious but between us we don't have much experience with 4 strokes so weren't sure. They were so bad I held a plug on purpose while we tried to start it, to see if there was anything there, and it just tingled. I've had belts from HT leads before and this wasn't anything like that.

Think it's probably an ignition fault of some sort, rather than the mechanical side, so we'll have to set about it bit by bit. We'll rule out the CDi (for now), as you said, it would probably affect all the cylinders.

Thanks for helping.

[zimm]

there was a thread about nc30 earthing n stuff on 400gb,

here's a link to the translated (was japanese) source article that sparked it, sorry cant help with specifics, i dont actually run an NC, just know a few that do.

http://www.jacksons-lair.co.uk/ground.htm

poor spark is enough of an issue for rick oliver to be making an "extra earthing for NC30's" kit though.

[BenF125]

Thanks.