GL1000 main nozzle damage, or........

'step away from that screwdriver.. right now! '

It seems that more and more, as we are doing rebuilds on the GL1000 carburettors, we are coming across damaged main nozzles or emulsion tubes with the delicate 'ears' bent or worse, broken off.

These ears are necessary to maintain the the correct total length of the nozzles. The nozzle is held in place in the carburettor body by the main fuel jet. If the ears are missing the nozzle can drop back into the body with disastrous results for the carburation, since the fuel can now flow unimpeded around the nozzle instead of through the precisely sized nozzle orifice.

They are being damaged by rebuilders, who look into the jet tower and see the slot in the end of the nozzle. They then take a screwdriver and try to unscrew it.

BIG MISTAKE!

The nozzles are a push fit into the carb body, but are most probably gummed up with fuel deposits. The nozzle usually will refuse to turn with the screwdriver and the ears get damaged or broken off.

So how to get them out?

Easy. A big hammer and a drift and just smash them out from inside the piston bore! Don't worry about the precise orifice in the end!

No? You would think so if you saw some of the stuff we have to deal with!

There are a number of ways to get them moving. Boiling the carb body in distilled water is one, or try dripping some acetone down the jet tower.

Access to an ultrasonic cleaner is even better.

When you think that they are ready to move, use a pusher of softish plastic so as not to damage the orifice . If it won't move with a reasonable push, repeat the treatment until it does!

So why is the slot there in the first place?

It's my contention that it is intended as a feed slot for the #35 idle fuel jet. If you look at the outside of the jet tower by the nozzle bore, you will see a brass blanking plug. There is a drilling that goes from the nozzle bore through to the idle jet bore as a fuel feed. I believe that the intention is for the slot to be aligned with that drilling.

The reduced outside diameter of the 'ears' is to allow fuel to flow around them in the case of the slot not being aligned properly, but that makes them weak.

If your nozzles still have the ears intact, take care when removing them so that they stay that way! These parts are obsolete and now almost impossible to find new as OEM. Good undamaged used ones are also scarce.

I know of only one source of aftermarket nozzles. I cannot recommend them as I have yet to check any for accuracy.

Early CB series Hondas had nozzles with a feed hole rather than a slot, which is much stronger and does not temp the screwdriver wielder!