1989 NC30 track bike few issues

[Haydn]

Thanks a lot for the help. The black exhaust could well just be from idle so ill take your advise and go 118/120. Hopefully get all this back together in the next week. (As long as i can get a B needle).

Has anyone had one of the cylinder coolant drain bolts shear on them? Mine went like chocolate today, it went tight on the way out so I used loads of spray and slowly worked it back in but eventually it snapped on me. Hopefully it won't leak but as its a steel m6 bolt and ally cast then even dobbing a weld over it is out of the question. No access at all for easy outs. Sounds terrible but maybe a smear of high temp silicone or liquid metal might do the trick. It's obviously pretty tight in there now.

[Haydn]

Finished rebuilding the carbs today, and found even more things that were wrong. When i checked the pilot screws a few weeks back they were 3.5 turns out and today whilst replacing the o rings i discover each pilot screw had two O rings. So when the screw was fully down it would have already been further out than it should be then another 3.5 turns. Poor thing.

Hopefully this combined with all the other stuff explains the rich running at idle :-)

[TommyTheGun]

I have been reading your thread as i think im having a similar problem as you. My exhaust has been sooting up and when i go do high revs it blows it out over the number plate and back of he bike i expect it soots up on idle. Also when starting the bike the choke floods it and it starts no problem with no choke.
I am running 118f 120r, with pilot screws out 2.25. I took my carbs off to have a look tonight and took the pilot air screws out, and didnt find any orings in any of them just a spring and tiny washer. I am wondering if this could be the cause.
Any luck with yours?

[TommyTheGun]

Forgot to say the sliders are drilled out to 2.25 also.

[Haydn]

Hi,

I'm yet to find out as the carbs are still off. Currently doing vlalve clearances.

It seems with your setup the bike should be running ok part from missing the o rings, you really need to get them installed. Did you check that the emulsion tubes and needles were in the correct carbs?

Mine was all over the place tbh, so it was probably a combination of things, that's hoping it runs right.

[TommyTheGun]

Checked again and have found an oring in the bottom of one but it was nackered and broke into pieces. One of the pilot screws is also missing the washer that goes on the end of the spring. Its hard to see down those holes. Might be orings stuck in the bottom of the others probably nackered too.

[Haydn]

Yeah they are really difficult to see. By shining a torch down at the right angle you can just see. Once you have the washer and o ring out of one you then know how the other should look when you shine the torch down. If you have a compressor blast air into the small hole near the butterfly, it will blow the o ring and washer out of the screw end. Make sure you don't loose them! I also used a bit of lock wire but tbh without the airline I would of struggled.

[Haydn]

Ive worked on the bike all weekend, did the valve clearances, got the carbs back on, fluids in and Started it up today for the first time since all the work has been complete. Although I've not ridden it or put it under load, it's running so much better. Idles perfect, it used to run ridiculously rich at idle and one blip of the throttle would see the garage wall covered in shit. Blipping the throttle now, it seems much more responsive, and no bogging down at 9000rpm. No fuel leaks, no oil leaks and no water leaks. So thanks to all the people that have helped and given advice. The valve clearance and carb guide were invaluable.

It's nearly ready to be back on track now, just needs a screen and some tank grip pads.

Put some of the body work back on made a coolant overflow bottle.

Very happy with it, it's been worth it.