Honda NC30 misfiring

**crazy man** · 23rd July 2011, 13:17

just build a new race bike and it misfires at around 6-7000 rpm onwards just changed the plugs and leads ..same thing .. l find if you take the air filter out the bike it improves it buy 50% but starts to die like its running out of fuel after you get into 5 gear.. anyone got any ideas ....cheers

**crazy man** · 23rd July 2011, 13:42

just build a new race bike and it misfires at around 6-7000 rpm onwards just changed the plugs and leads ..same thing .. l find if you take the air filter out the bike it improves it buy 50% but starts to die like its running out of fuel after you get into 5 gear.. anyone got any ideas ....cheers

**Shaun** · 23rd July 2011, 13:43

Originally Posted by crazy man

just build a new race bike and it misfires at around 6-7000 rpm onwards just changed the plugs and leads ..same thing .. l find if you take the air filter out the bike it improves it buy 50% but starts to die like its running out of fuel after you get into 5 gear.. anyone got any ideas ....cheers

Are they carbed model bikes?

From what you have said it is fuel related. It sounds like it is running WAY to rich in one zone, and lean in another. The air filter removel response would keeps me focused on fuel area for now

**crazy man** · 23rd July 2011, 13:48

Originally Posted by Shaun

Are they carbed model bikes?

From what you have said it is fuel related. It sounds like it is running WAY to rich in one zone, and lean in another. The air filter removel response would keeps me focused on fuel area for now

yes it is carbed what your saying does sound right think the carbs have been played around with just a bit somone may of done somthing very silly.. ta

**Shaun** · 23rd July 2011, 13:51

Originally Posted by crazy man

yes it is carbed what your saying does sound right think the carbs have been played around with just a bit somone may of done somthing very silly.. ta

If you can ride it again? Go out and when it slows up 7K or where ever ( Starving) PULL choke on, Im guessing it will pick up again, so RICH on NEEDLE and LEAN on MAIN

**lostinflyz** · 23rd July 2011, 14:09

have you got the air filter and airbox lid and snorkel on it still???? if you've taken it off, put it back on.......

**crazy man** · 23rd July 2011, 14:38

Originally Posted by lostinflyz

have you got the air filter and airbox lid and snorkel on it still???? if you've taken it off, put it back on.......

the only thing l had of was the snorkel should try it with it on but run so bad l would of thought the diffents with it on would not be much . l agree you would would thing with the airbow and filter on it should work fine as l found out 99% of road bike like

**lostinflyz** · 23rd July 2011, 15:44

airbox is the common one. if your running the stock box there better with the snorkel.

outside the carbs (needles, jets, float height), check/change coils, check plugs (im assuming there new), check fuel tap rubber diaphram, check carby boots.

has it ever run right?

**crazy man** · 23rd July 2011, 16:00

Originally Posted by lostinflyz

airbox is the common one. if your running the stock box there better with the snorkel.

outside the carbs (needles, jets, float height), check/change coils, check plugs (im assuming there new), check fuel tap rubber diaphram, check carby boots.

has it ever run right?

only bought the motor. l see the carbs have had the few mods done like drill out slides to 2.5 mm bigger jets 120. maybe the needles need a play with

**Wannabiker** · 23rd July 2011, 16:16

First, check the diaphrams and covers have been fitted correctly. They have a tab on them which goes a certain way (one of the 4 cover screws has a small passage next to it, and the cover has a corresponding passage. It is not uncommon for the covers to be fitted without these passages aligned. There will be little or no vacuum to lift the diaphram in that carby. (and dont forget to put the big spring back in too.!!)

The NC30 is quite fiddly when altering the airbox / filter / trumpets.

I will have a look in the garage...I think I have a jet kit you can have ( My NC30 is long gone...)

**crazy man** · 23rd July 2011, 18:09

Originally Posted by Wannabiker

First, check the diaphrams and covers have been fitted correctly. They have a tab on them which goes a certain way (one of the 4 cover screws has a small passage next to it, and the cover has a corresponding passage. It is not uncommon for the covers to be fitted without these passages aligned. There will be little or no vacuum to lift the diaphram in that carby. (and dont forget to put the big spring back in too.!!)

The NC30 is quite fiddly when altering the airbox / filter / trumpets.

I will have a look in the garage...I think I have a jet kit you can have ( My NC30 is long gone...)

maybe just maybe its the coils giving up ?

**ducatilover** · 23rd July 2011, 18:16

I'd go with your slides lifting poorly or jetting. I've got some jets in the garage, I'll check to see if I have some a few sizes bigger or smaller.

You're in Palmy? I may be able to pop around and have a looksie

**racefactory** · 23rd July 2011, 18:19

Dude- you took the speedo out didn't you?

Every person racing an NC30 stumbles into this bitch. When you take the speedo out it will miss badly from 6k. The bike has a safety feature built into the CDI to stop the spark to 2 no plugs if the speedo is not detected.

Easiest way is to just put the speedo back in! Or you can cut the little circuit board out of the speedometer, plug it back into the loom and wrap it in a plastic bag to make it water-proof if you are removing the clocks. You can also get an M-Max etc box that you plug into where the clocks would be or use an after-market ignition box like the ignitech. Finally there is the 'resistor mod' you can do.

**ducatilover** · 23rd July 2011, 18:24

Originally Posted by racefactory

Dude- You took the speedo out didn't you?

Every person racing an NC30 stumbles into this. When you take the speedo out it will miss badly from 6k. The bike has a safety feature built into the CDI to stop the spark to 2 no plugs if the speedo is not detected.

Let me guess, little circuit board that sends a signal to the CDI that sits behind the speedo face? Just like the problem I ran into with the 600....

Obviously didn't read your whole post