carbs balancing

[bullitt]

hi guys
sorry for the noob question
would a novice like myself to these engines be able to balance the carbs
on my nc21
i have access to a set of mercury balancers
is 1 carb set to work off of and what size fuel line do i need
cheers

[Neosophist]

Easy to do, but it's a fiddly job. Take you time and shuoldn't be any issue.

You need vaccum take-off adapters, the NC2x doesn't have spigots for you to attach the vaccum hose, it has threaded holes blanked off with a screw and a washer on each cylinder.

Morgan Carbtune sell the adapters if you don't have them.

http://www.carbtune.com/



These are what are needed, Morgan sell brass and plastic, I have brass for heavy-duty but the plastic ones are fine and cheaper. The also sell the vaccum hose to use too.. i believe it's 5mm ID. (Perhaps 4.0mm)

Guide to balance.

On each of the cylinders locate and remove the screw and washer and screw in the take-off adapter.

The NC2x engines have 4, one for each cylinder.

If you sit on the bikes seat.

Fr/Rr = Front / Rear
R/L = Right / Left

Rr-L: #1
Fr-L: #2
Rr-R: #3
Fr-R: #4

The screws and washers for cylinders 1,2,3 and in the V at an angle underneath there rubber that holds the carbs to the engine, look with a torch and you'll find them.

The screw for cyl #4 (Fr-R) is on the outside of the cylinder and partially hidden behind the thermostat housing and can be fiddly to remove. It's also a Looong screw!

With the screws and washers removed fit the take-off adapters and pipes to your gauges.

There are 3 screws in the V on the underside of the carbs (the fiddly part is adjusting them... morgan sell an angled driver that makes it easy or if you have small heatproof hands you can use a 7mm socket.. or make your own device to turn the screws.

warm the engine up until the needles 1/4 way on the scale and start to balance by turning the screws.. increase your idle to around 1800 beforehand.

You cannot adjust carb 2, this is the front left and serves as the master.. you adjust all 3 other carbs to match it's vaccum reading.

Bear in mind turning one screw will have an effect on the other carbs the more your turn it so you might need to go aroudn in a cirlce a few times to get the balance done but it's not too difficult.

If the fan does come on its too hot.. turn it off and leave it for an hour to cool down and start again.

[djcouch]

I might be being completely thick (excuse me if i am) doesn't the vacuum line for the fuel tap come off one of the connections that the carb balancing fittings need to be screwed into ??

If so, do you use a temp fuel supply that is doesn't require the vacuum line or do you tee in somewhere so that you take into account the fuel tap line as well.

[uber pikey]

Spot on, you need an alternative fuel supply.

[Neosophist]

I might be being completely thick (excuse me if i am) doesn't the vacuum line for the fuel tap come off one of the connections that the carb balancing fittings need to be screwed into ??

If so, do you use a temp fuel supply that is doesn't require the vacuum line or do you tee in somewhere so that you take into account the fuel tap line as well.

NO

Not on the NC21 / NC24

These use a seperate take-off for the vaccumn tap, on the side of cyliner 1, it has 4 extra take-off points for balancing the carbs.

The NC30 and NC35 use cylinder 3's balancing take-off to supply the vaccumn tap so you need to disconnect the vaccum pipe on these bikes (I usually suck on it to open the tap and then fold it over and clip it together to stop the vaccum going away.