Half moons leaking.

[Duece]

The front left and front right half moons are leaking slightly. its a slow steady drip that forms at the bottom of the end cap (cover that screws on). Would I be able to smear some rtv on the side around the half moon to stop that or do I need to replace the whole gasket.

If I need the gasket can someone recommend a place to get an OEM gasket with the half moons built in? I looked but all I can seem to find are ones without the half moons for my specific model. 1978 GS750E

Thank you!

 

[tkent02]

The half moons are separate from the gasket, and you can glue them in to the head.
They tend to leak when the old rubber gets hard.

 

[Nessism]

Remove the valve cover. Remove valve cover gasket and half moons. Clean the surfaces of any old gasket and sealer. Most of the time the half moons can be reused. Clean them really well using a degreaser like brake cleaner or carb cleaner. Focus on the curved section. Using some Ultra Black RTV, or Three Bond 1194 gasket sealer, lightly coat the curved portion of the half moon and reinstall them back into the head. Lay the gasket back down, install the cover and tighten the screws thus setting the half moon back into the head.

Do not apply sealer on the flat portion of the half-moons or they will stick to the valve cover gasket. Do not apply sealer to the gasket either or you won't be able to save it for your next valve clearance check.

And speaking of checking the valve clearances, I trust you have performed (or will) this critical bit of maintenance. DO NOT ignore critical maintenance like this otherwise your engine will die a horrible, and avoidable, death. Adjusting the valves is one of the easier maintenance tasks, and is 100% mandatory if you want the engine to live.

For original Suzuki parts consider your local dealer or one of many on-line dealer part sources like Part Shark. There is no such thing as a gasket with the half moons built in for your bike so don't even look.

Good luck

 

[Duece]

Thank you for the responses. I like to take care of my motors and was planning to do the valve adjustments. I saw for a different year the half moon did come built in but now I know my year doesn't. Do you know where I could buy new moons?

Thanks again guys!

 

[850 Combat]

Z1 Enterprizes has Vesra ones pretty inexpensively. OEM ones are available at all the usual places. I like to put anti sieze on my gasket to head joint, as the alure of gasket scraping has dimished over the years. I have had good luck with the Vesra half moons do far.

 

[chuck hahn]

Good time to do a valve adjustment check while its all opened up.

 

[MAJikMARCer]

RE: Seating the half moons

RE: Seating the half moons

Using some Ultra Black RTV, or Three Bond 1194 gasket sealer, lightly coat the curved portion of the half moon and reinstall them back into the head.

I wasn't able to find the Ultra Black, but they had Blue. Is that fine or should I return it and keep looking for the Ultra Black?

 

[Nessism]

I wasn't able to find the Ultra Black, but they had Blue. Is that fine or should I return it and keep looking for the Ultra Black?

Should be fine but you may want to check the Permatex website to see if there are any differences other than color.

 

[MAJikMARCer]

Should be fine but you may want to check the Permatex website to see if there are any differences other than color.

Well by the website it looks like they are about the same. The black is OEM rated, "For dealership warranty requirements" but they have the same heat rating. Looks like I should be fine for the little bit I'll be using.

 

[Griffin]

This stuff is the shiznett:

http://www.permatex.com/products/au...ng_Formula_Gasket_Dressing_Flange_Sealant.htm

I use it on my valve cover gaskets and half moons (actually all gaskets on a GS engine), and when I go to remove the valve cover to check valves later, the sealant is still soft, tacky, and sealing. You can just peel the gasket off the cover using your thumb and index finger.

Indy car and drag racing teams have been using it for years (before Permatex was licensed to sell it here). I was turned on to it in a slightly different compoiund in the military, where it was used in jet engine assembly, among other things.

Just the thinnest coating you can make with your finger is all you need. I've had one tube of it for several years, it has been enough for about 10 or so valve checks, several stator changes, a few clutch covers, etc... and there's still some left in the tube.

Great stuff.

 

[1_v8_merc]

Black is the **** you really want.
It's more rigid and holds against gasoline.

Red works well too, just a tad more stretchy.

Both should be high temp, one might be a little more than the other.

 

[Steel Toed Tank]

Just used the black for the first time day before yesterday doing my valve job.
it holds those little half moons in there without any leaks at all.
Just had a b**ch of a time welding over the old petcock holes from the POs non OEM petcock on the bottom of my tank.
Weld, leak, weld, leak, weld, leak.
It was paper thin, but once I got a new thicker flat surface on it, I drilled the holes, bolted it up, added gas and it dripped everywhere.
So I loosened off the bolts and spread ultra black all over them and tightened em back up.
Now I have vacuum operated OEM petcock and no leaks or drips from my tank.
And I applied it WHILE fuel was dripping from the petcock, and it worked perfect.

Also, my female roommate giggles every time I say 'petcock'


Tank

 

[rustybronco]

Just had a b**ch of a time welding over the old petcock holes from the POs non OEM petcock on the bottom of my tank.
Weld, leak, weld, leak, weld, leak.
It was paper thin <snip>

Boy, do I know what you are talking about as I went through the same thing with my 78's tank.
If you ever have to do it again, try hard soldering in a couple of plugs instead of welding everything up.

http://i32.photobucket.com/albums/d44/rustybronco/PICT3497.jpg

 

[Steel Toed Tank]

My tank is pretty much pooched. It's on it's last season.
Somewhere in its history a PO had removed the oem petcock and bondo'd or epoxied over the place it was (may have welded something under the bondo, it was not shaped right once I started digging through the bondo) and they moved the petcock to the other side of the tank. When they moved it they drilled 3 round holes, and installed an always petcock that actually needed 2 holes and an oval.
Instead of cutting an oval in the tank, they cut down and plugged off the reserve line. So I had no reserve. I think they moved the petcock under the sending unit so they could get into the tank to push the bolts out from the inside, as there was now no way get nuts welded to the inside.
I first welded 2 nuts to a pre-cut and drilled piece of steel, and I was just going to weld the plate onto the tank like the factory originally did. But while grinding into the bondo I found the tank badly misshapen and there wouldn't have been a flat enough spot for petcock installation.
So I welded over the non oem petcock holes and then welded over the holes made by the tank melting away as soon as heat got near it. after several hours and rewelding and regrinding I finally had all the leaks stopped. I had gasket washers to go under the bolt heads, but because I had to install them with the nuts on the outside of the tank, the washers didn't stop the gas from running down the threads and through the nuts, and dripping everywhere.

So to not hijack this thread too much more, I used some black RTV on the threads and tightened my nuts and the dripping stopped. Same RTV I used on my halfmoons that are oil tight!


Tank

 

[MAJikMARCer]

I've been researching further about the differences between Ultra Black and Ultra Blue...this is the best answer I've found so far:

"The blue Permatex is formulated to cure even in the presents of oil, whereas most other silicone sealers are not."

I feel pretty comfortable using the blue if that's the primary difference. I plan to clean up all the surfaces really well since it looks like the last time the valve cover was removed the PO used a LOT of Ultra Black...so much it's all over the outside.

Now if those parts would hurry up and get here.

 

[Badooka]

This is all I ever use- the high temp is 700 degrees. Used it on every motor I ever built and it NEVER failed.

http://www.permatex.com/products/au...mum_temperature_rtv_silicone_gasket_maker.htm