M6 hose nipple for intake manifold

Hi Carlos,

I also use the "method 4". The M6 is a metric thread, you can use every hose nipple with european M6. (are you sure there is a M6 thread? for checking use a another M6 srcew) I use standard nipples (brass niples from amazon - the longer the nipples the better). My M6 nipples fits very well if the thread ist really M6 - easy to install by hand. I installed the nipples permantently and closed them with a silicone cap. So i can remove the cap and i am ready for measurement. Best result you get if the compensation tube is closed while you adjust the carburators. The ROTAX technic with Clamp or pliers at the rubber hose to close the compensation tube dont work well so i installed permanently a little fuel valve into te compensation tube. Shorten the alluminium tube a little bit that at one end you can insert the little valve between the rubber hose. So you can open or close the compensation tube whenever you want.

For syncronisation, close the compensation tube, remove the silicone caps and connect it with your measurement. Thats it. After syncronisation reopen the valve of the compensation tube, remove the tubes of the measurement device and dont forget the caps at the nipples. The syncronisation is done in this way in a short time and you can check the syncronisation easily every 100h.

Greetings

To clamp off the balance tube hose;

I use a small Vice Grip, with long narrow jaws. The jaws have split rubber hose pushed onto them, to prevent damage to the compensation tube hose.

The Vice Grip clamping pressure can be adjusted to get sufficient pressure to close off the rubber tube.

Note: Only one side of the compensation tube has sufficient hose length for clamping.

I would advise against installing a permanent valve, in the compensation tube, as this may effect, to some degree, the free flow of air pressure between the carburettors.

I use the small (M6) carburettor flange holes, for my motorcycle, twin vacuum gauge carburettor balance but made up my own nipples from hardware supplies.

😈

The Rotax number is 940558 a M6 hose nipple.  It is used in the type 582 cylinder head for the coolant vent tube.

Cheers

Hi Carlos and Sean,

shorten the aluminium tube at this side where the longer rubber hose is. So use a longer rubber hose and split it for insert the fuel valve. Its a small ball valve for fuel, thats important. By having a look through the open ball valve (if uninstalled) you can see there is a smooth passage without resistance like a free tube. So its important to find the right ball vent with the similar inner diameter like the aluminium tube is. If the carburators syncronisised there is only a pulsation in the compensation tube not really a flow. If there is a relevant flow then the carburators are not good syncron. 

There is a system on the marked where the intakes have much bigger compensation tube. They promised 75% performance at the engine if one carburator failed. I dont know if this work but at his circumstances maybe there must be a relevant flow in the compensation tube and at functional carburators the enginge runs a littel bit smoother. I saw this on the marked but never used.

Why this efford with a valve? My rubber hoses are fuel hoses, very strong and a little bit stiff (Rotax origin) so you need extreme force to squeeze it.That really hurts my heart.

Greetings

Each to his own HKK.

My Vice Grip clamp works. Is quick and easy to install/remove. Adds no additional cost (I have the Vice Grip in my tool kit) or complexity (additional joins & moving parts). All that is required is that the balance tube connecting hose, be longer on one side than the other, so that the Vice Grip has space to clamp, without doing any damage to aluminium balance tube or hose.

I do a carburettor balance check, followed by a propeller balance, every 100 hrs,  - about once a year. 😈