Direction of Throttle Shaft Seal

[fenbrancis]

Hi all,

Just got some fresh OEM throttle shaft seals in the mail and want to make sure these go in correctly. I think I know but want to double check with the XS gods to ensure proper installation.

Does the open end of the seal face outwards away from the carb?

 

[jetmechmarty]

The open side faces out away from the butterfly.

 

[gggGary]

Yes, because the intake operates at lower than atmospheric pressure. I like to put a bit of grease in the recess during install.

 

[fenbrancis]

I was actually about to ask that, since the carb is basically sucking in air it’s operating at lower than atmospheric pressure, so this facing outward will cause them to expand and seal.

And noted on grease.

 

[jetmechmarty]

Yes, because the intake operates at lower than atmospheric pressure. I like to put a bit of grease in the recess during install.

Yeah. I use Parker O Lube. https://www.aircraftspruce.com/catalog/cspages/parkerolube.php

If you have some, I believe dielectric grease is a good option.

 

[gggGary]

5twins will say red rubber grease, I say some WS2 powder while the seal is dry before install.

 

[Mailman]

I have used dielectric grease , and I’ve also had good results with plumbers silicone grease, available at any hardware store.

 

[5twins]

Yes, I use red rubber grease. First I pack the hole .....

..... then insert the seal .....

..... and then I pack it full too .....

I also use it on the diaphragms. Besides putting it in the seal groove on the carbs, I smear it all over the entire diaphragm .....

Besides sealing them very well into the carb top, it seems to make the diaphragms nice and soft.

 

[fenbrancis]

Thanks for photos and information! I had originally bought some crap seals that were not dealing properly. So I’m giving OEM a try and will grease these up before putting shaft back in.

There isn’t any play in my shaft but have just had a ton of issues with these carbs. Hoping this resolves it all

 

[5twins]

Yes, the throttle shaft seals are an important part of a complete overhaul. If you don't replace them, you haven't done the job 100%. The P.O. of my '83 said he always had carb issues and when I refurbed them, I think I discovered why - he didn't replace the shaft seals nor did he replace the mix screw o-rings. I did all that and the carbs have worked fine for me. I could see he tried to get at the shaft seals because a couple of the butterfly plate screws were buggered up. I guess he just gave up when that happened, lol. Not sure why he didn't do the mix screw o-rings. Probably didn't know they were there. Well, they were, all mashed flat and hard as little rocks, lol.

 

[GLJ]

I use Dow Corning "High Vacuum Grease" because it's specifically made for vacuum sealing applications.