Mikuni Carburettors Mystery Ports/Hose?

[Hubbskiboy]

Hello all,
I've just joined the 400 grey bike forum, having purchased a 1994 GSX-R 400 GK76A a few weeks ago.

I'm in the process of stripping and cleaning the carbs with an ultrasonic cleaner.
Does anyone have a recommendation for a good solution to use when cleaning tarnished and corroded metal.
Don't want to damage the aluminium, but would be nice to get a good finish.
So far I've tried washing up liquid and Soda Crystals, but they're not even touching some of the corrosion on the choke lever and screws.
I'll buy some of that sea clean 2 this week and give that a go.

The main reason I'm here is because I've notice that there appear to be a mystery port with no hose attached to two adjoining carbs (see attached photos below - I've circled the ports I'm referring to).
The two on the other side also have a port but there is a hose attached.
Can anyone tell me what these two ports are supposed to be connected to?
I suspect that they may be breather hoses, but please confirm?
When I blow through the one hose that is actually present, air comes through the port I've highlighted in the roof of the float bowl (see photo).

Any advise would be appreciated.
Cheers.

https://app.box.com/s/7aqz3dry18nx9bdrjb04929q61scoz11
https://app.box.com/s/395uq6kh4egja1j0mwyo8kkwx8ityesp
https://app.box.com/s/gujxtohefgwy1ggwj19ann7uxvh8b8xw

[moforockband]

That is the port to equalise the air pressure in the float bowl, and is vented to atmosphere via the hose you pointed out.

[Hubbskiboy]

Thanks for the reply.
That is what I suspected the ports are for.
There seems to be quite a few 'breather' hoses on this bike that lead to nowhere!
Always worries me when a hose isn't connected to anything.

[dobbslc]

As for ultrasonic cleaning solution I use stuff supplied by Anything Goes Racing, I can't see it on the website but you could call Jeep and ask him to send you some or he regularly goes to Kempton Park autojumble and you can buy it there.
It won't completely clean rust etc but it will clean inside all the tiny carb drillings.
PS: GSXR carbs are a complete ball ache to get right! Buy the rebuild kit from Lite Tec in Thailand or you will spend the rest of the year pissing about trying to set up the carbs....

[Hubbskiboy]

Good call dobbslc.
I already bought and payed for the 'O' ring rebuild kit about 3 weeks ago.
One of the 1st things I bought.
Problem is that it hasn't arrived yet.
The postage system in Thailand can't be that bad can it?
I've also bought some Apl Chemicals Ultrasonic Engine Cleaning Solution, which is supposed to be good stuff.
I'll let you know what the results are.
I'm planning on getting the carbs vapour blasted at a local place to get a decent finish.

[wullie3xv9]

As for ultrasonic cleaning solution I use stuff supplied by Anything Goes Racing, I can't see it on the website but you could call Jeep and ask him to send you some or he regularly goes to Kempton Park autojumble and you can buy it there.
It won't completely clean rust etc but it will clean inside all the tiny carb drillings.
PS: GSXR carbs are a complete ball ache to get right! Buy the rebuild kit from Lite Tec in Thailand or you will spend the rest of the year pissing about trying to set up the carbs....

Too true, as I found out from bitter experiance. As Mr Green says, get the Lite Tek seal kits from Blair in Thailand. Most definitely value for money &, as they're made from Viton rubber, won't be affected by the Ethonol in unleaded petrol.