NC30 Track bike wont rev out cleanly...

[Squiggles]

Hi all, i'm new here and posting with a little problem im having with my track NC30

A bit of background on the bike.... 1989, runs total loss (no charging circuit at all), appears to have had the vacuum mod done (no vacuum line present)... Bike has been a race/track bike for the last 4 years, and has sat for a short period before i recieved it

Now the problem, When i first fire her up the left two cylinders dont always appear to be running, but after a few revs (somewhat hesitant around 5k & 7k rpm) this cleans up to running on all 4. After more warming she'll then redline (although a bit rough & some popping). However, if i go for a rip up the driveway she'll redline then wont and struggles to pass 8k, stop and clutch in we'll see the red, but not underload...

Thoughts? Trackday in 4 days so want to get this sorted asap

[Simon_Ed]

new spark plugs

[Cammo]

What sort of airbox and filter mods has it got?

Remove the carbs and check what jet sizes it uses. Ultimately you won't be able to sort it 100% without knowing this.

[Squiggles]

Checked the sparkplugs yesterday when it was running a bit worse, and regapped them... they werent fouled.

Going to take it out to a big carpark in a couple of hours, then we'll see if shes cleaned up now

[Squiggles]

Went for a good trash, hesistant at first but once warm would take me up to 12k rpm where it popped a bit, am going to have a look at no 3 cyl (rear right) as the plug looked slightly diff yesterday

Edit: Plugs look good, nice light chocolate colour from the right rear, similar but not quite as good for left rear... didnt check the front two this time around

Am going to have a squiz over the wiring around the batt tomorrow, as there is one connection that is a solder job (Neg from batt heading towards the cdi) which ill fix, and give all the battery contacts a clean too

The stater solenoid is still there, and has nothing connected to one of the points, two to the starter button, one to -ve batt , one to nothing (presume this is normally to the reg/rect)

[Squiggles]

Also thinking my battery might not quite be up to it, so have put up another thread in general to see if anyone runs a beefier battery for total loss... otherwise will just use a new standard one. Without load she'll rev to the red, but with me on has a harder time so thinking electrics

[Cammo]

Without load she'll rev to the red, but with me on has a harder time so thinking electrics

Thi sort of problem is usually related to fuelling. Could be induction, jetting or fuel flow.

What sort of induction setup (airbox, filter, etc) does it use and what size jets??

[Squiggles]

Ill try find out jetting etc, will have to compare the airbox to some pics of a standard one though as i can see that its been modified (or at least has been in the past)

[Cammo]

Ill try find out jetting etc, will have to compare the airbox to some pics of a standard one though as i can see that its been modified (or at least has been in the past)

This'll more than likely be responsible for your probs. Check the filter also.

[Squiggles]

Ill try find out jetting etc, will have to compare the airbox to some pics of a standard one though as i can see that its been modified (or at least has been in the past)

This'll more than likely be responsible for your probs. Check the filter also.

Ill take some pictures, interestingly enough, it looks like someone in the past had cut a hole in the top of the airbox, and this has then been covered over since