Rubber replacement with silicone hoses

[WWhunter]

I removed the engine on my S7 the other day due to a persistant ignition issue that I can't figure out. I am guessing it is the ignition or stator wiring at the rear of the engine. Not sure if I want to send the entire engine off to Hal to diagnos, or attempt doing it myself. Unfortunately the northern MN temps have been quite fridgid this past month and I have no heat in my hangar. I do have a torpedo heater, but it is noisy and smelly. Heck, spent a day in -20 temps getting the engine off and nearly froze!!

Since I have the motor removed, I may as well replace all the coolant hoses. I think Hal (Zipper fame) uses the blue silicone type hose on engines he works on. I had thought that I read a post on here that gave all the sizes of the hoses. I figure it is metric, but you can usually get english standard size close enough to work. I left everything in the hangar and with 3-4 feet of snow out there and it dark, I don't feel like driving over to mic it out.

Anyone know the various sizes of hose?

Thanks!!

[Dave S]

WW,

The hose which goes to the cylinder heads is 17mm.


The hose which goes to the radiator, as supplied by Kitfox (unless there has been a recent part number change) is 1"; but, I am sure there is a metric equivalent labeled by Rotax.

[jrevens]

I used high-quality reinforced silicone hose, 5/8”, and it seems to work well. You may find that 17 mm silicone is very hard to find, as I did. 1” is no problem. The slightly smaller size (0.625 vs 0.669) seems to work just fine, and the total cross sectional area of 4 hoses is still well above that of the single 1”. I previously posted info about that, including some suppliers on my thread “John’s build”.

[WWhunter]

Thanks John!! I tried searching for the thread but couldn't find it. That is the info I was looking for. Still haven't gotten over to my hangar, it has been snowing again and we have probably gotten 4' plus of that white crap this winter.

[WWhunter]

I used high-quality reinforced silicone hose, 5/8”, and it seems to work well. You may find that 17 mm silicone is very hard to find...

Thanks John!! I tried searching for the thread but couldn't find it. That is the info I was looking for. Still haven't gotten over to my hangar, it has been snowing again and we have probably gotten 4' plus of that white crap this winter.

I do have another question. In my research it is stated that one must use a different type of clamp verse the 'worm gear' type. The new Rotax one look like the type you squeeze with a plier (sping clamp) to install. The otherone I noticed is the 'Ear clamp' style. The silicne hose manufacturers recommened ones are either the constant tension or the T-clamp type that doesn't have the grooves like a worm gear type. Are you guys having good luck with the spring clamp type or best to use the tension ones?

[jrevens]

I used the “spring” type that came on the engine. They have a smooth inner surface that doesn’t hurt the silicone or whatever type hose you use, & they provide “constant tension” also. They worked perfectly with my silicone hose.

[WWhunter]

Local NAPA has it in stock!! Awesome! $5.00/foot. little cheaper online, but with shipping it actually costs more. I wanted the red colored to match the plane, but not many options out there.