Connection of the Float Chamber Venting Lines to the Rotax Airbox

The vent lines connect to nipples on the carb bowl. There is no clamp, just push on. The carb vent should “see” the same atmosphere that is present at the air inlet if the carburetor, that is why they are plumbed into the air box. You can get 1/8 id Tygon tubing from Amazon. Try to keep both lines equally length and no longer than necessary. 

Hi Michael,

You will have to purchase more tubing. Make sure it is of the correct ID (from aged memory 3mm ID).

I used Tygon however any good quality fuel tubing will do eg Viton.

If you purchase the correct ID the hose will not need clamping at either end, just push on for the full length of the barb/nipple.

Be sure to leave sufficient extra tubing to accomodate movement.

Depending on application, some support may be needed - use zip/cable ties. Be carful not to tighten so much that hose is collapsed/shut off.

Equal length lines are desirable, not essential, as this is a pressure equalisation system that will work effectively, no matter the differences in length over the relativly short distance between carb & air box.

Soap is not a good substance to be using around the carburettor system - there is potential for contamination.

If you must use a lubricant, to assist with fitting - use, a smear of lithium grease,  silicon liquid or grease.😈

Thanks Walt and Sean,

The Rotax Illustrated Parts Manual shows the tubing as 4 x 7.  They do not mention the material.  I ordered some "yellow" fuel tubing from Amazon.  The heading says "tygon" but the specs say "PVC".  I also ordered some 4 x 7 rubber fuel hose (would need to change that out every 5 years).

Mike

"yellow" fuel tubing from Amazon".

Whatever you get will need to retain most of its "rubberyness" for he whole  of its service life.

This is so that it does not  go hard/stiff and brittle, like PVC. When the tube goes hard it looses it ability to cope with movement & vibration.

Its important that the tube be tight enough on the barb/nipple. The beauty of Tygon & Viton is its elasticity which will give it a great grip on the nipple and both will retain their rubberyness well past any 5 year replacement.

😈

Thanks, Sean...good points.  I did get the rubber hose, but it will need to be replaced every 5 years.  Are Tygon and Viton "permanent" materials?