Good sealant for carb float bowls?

[KEITH KRAUSE]

I've about had it with leaking bowl gaskets on my '79 GS1000 (VM26mm). The carb body gasket surfaces look good, clean, no corrosion. I always use new genuine Suzuki gaskets. I also use stainless steel hex bolts instead of the original Phillips screws.
As has been the case the last couple of times servicing the carbs, the gaskets leak. I keep snugging down the hex bolts, hoping the leaks will stop. I finally made things worse when I discovered one bolt started spinning as I tried to snug it up again. The bolt is fine but the carb body must have cracked even though I don't see a crack on the outside. I can imagine this could be close to happening with other bolts. I hope I have a good number 1 carb body or I'll be asking for help with that too.
So this time I think I'll have to use some sealant to assist the new gaskets. The sealant will have to be applied as a fairly thin bead so excess sealant doesn't squeeze into the bowls and cause other problems.
My concern is that it will take several minutes to carefully apply (with a toothpick?) the sealant to both sides of the gasket. In applying the sealant so thinly, I'm concerned the sealant will start to dry before I can tighten each bowl.
Is there a sealant anyone uses that's 100% gas resistant and dries slow?
I apologize if this should've been posted in the carb section but I want to get as much help as I can. I don't like the idea of using sealant to help the gaskets seal but I don't see any other choice. Thanks for any help.

 

[Nessism]

No sealant on float bowl gaskets. If the carbs won't seal with normal torque on the screws something is wrong. Fuel level too high? Did you check with the clear tube method? Replace the float valves with original Mikuni parts (Dennis Kirk sells them for fair prices?) The gaskets Z1 sells are thick and pretty soft. My cat chewed up a set much to my chagrin. I doubt they would last as long as the OEM Suzuki parts but they are soft and thick, so they conform and seal well.

 

[GregT]

FWIW the purple Loctite instant gasket is fuel resistant - incl Methanol.

But I'd pick that you've got slightly warped gasket faces on the carb bodies. I have had to recover a couple of unobtainable bodies by lapping them on the usual flat surface.
Where there's a raised ridge around the edge, I have in a couple of cases removed this to get the working surface flat.

Clean what you have and offer the bowls up without gaskets. If they'll rock rather than sit flat, you know what you've got.
And sorry to say it - but where I have encountered it, socket head screws have been used rather than the phillips OE type. Overtightening does it.

 

[KEITH KRAUSE]

No sealant on float bowl gaskets. If the carbs won't seal with normal torque on the screws something is wrong. Fuel level too high? Did you check with the clear tube method? Replace the float valves with original Mikuni parts (Dennis Kirk sells them for fair prices?) The gaskets Z1 sells are thick and pretty soft. My cat chewed up a set much to my chagrin. I doubt they would last as long as the OEM Suzuki parts but they are soft and thick, so they conform and seal well.

Thanks, Ed. No fuel level issues. I did check, a few times. I always use the over-priced genuine float valves too and never mix valves and seats.
I'll try the Z1 gaskets. I've always wondered how old the gaskets are that I've bought. Generally they feel very hard. I never had leaking until the last 4-6 years and 2 sets of new gaskets. I think it's interesting that the carb body has that thin raised lip to help the gasket seal, but the bowl is just flat. I appreciate the help.

 

[KEITH KRAUSE]

FWIW the purple Loctite instant gasket is fuel resistant - incl Methanol.

But I'd pick that you've got slightly warped gasket faces on the carb bodies. I have had to recover a couple of unobtainable bodies by lapping them on the usual flat surface.
Where there's a raised ridge around the edge, I have in a couple of cases removed this to get the working surface flat.

Clean what you have and offer the bowls up without gaskets. If they'll rock rather than sit flat, you know what you've got.
And sorry to say it - but where I have encountered it, socket head screws have been used rather than the phillips OE type. Overtightening does it.

Thanks. I don't want to try removing the raised ridge on the bodies. I think any warping would be the bowl surfaces. I never considered the bowls could warp. I'll try to see if the bowls are flat. I'll check out the purple Loc-Tite too. I appreciate the help.

 

[salty_monk]

I’ve never had an issue with a bowl seal, even re-using gaskets. Something is definitely wrong... good luck with it

 

[rphillips]

Me too, I've been watching this thread & thinking, I've been lucky, never remember a problem getting a bowl gasket to seal & reused the gaskets lots of times. Are you having problems with more than one carb?

 

[Gorminrider]

*Permatex makes a wide variety of 'sealants" that work around fuel...but this might be a place a CORK gasket would work...they conform well to warpage but need care torquing down and I seldom use them...a thicker paper might work but these won't "conform" to a big warp.
Is there meat to re-tap a larger bowl screw? or even a small bolt passed through with nut (albeit funky).
That said, I haven't seen trouble at the bowl gaskets either. Seems to be rare.

...on the level, fuel level doesn't overtop them excepting the tilt of the carbs, ie:sidestand or tilt per suspension and/or airbox.., so yes they need to seal but pressure is very low.

*the "permashield " looks interesting...but read all the blurbs for each.
https://www.permatex.com/product-category/gasketing/gasket-sealants/

 

[KEITH KRAUSE]

*Permatex makes a wide variety of 'sealants" that work around fuel...but this might be a place a CORK gasket would work...they conform well to warpage but need care torquing down and I seldom use them...a thicker paper might work but these won't "conform" to a big warp.
Is there meat to re-tap a larger bowl screw? or even a small bolt passed through with nut (albeit funky).
That said, I haven't seen trouble at the bowl gaskets either. Seems to be rare.

...on the level, fuel level doesn't overtop them excepting the tilt of the carbs, ie:sidestand or tilt per suspension and/or airbox.., so yes they need to seal but pressure is very low.

*the "permashield " looks interesting...but read all the blurbs for each.
https://www.permatex.com/product-category/gasketing/gasket-sealants/

Thanks for the reply. I'm looking at the Permatex P/N 85420. Gas resistant, used specifically for use with fuels, fills minor gaps, can be used to form a gasket that's easily removed and stays permanently flexible.
I'm considering ordering the Z1 gaskets that Ed says are softer. After checking them out for myself, I'll decide if I want to apply a thin coat of the Permatex.
As for the hex bolt that won't tighten, I don't believe it's stripped. It snugged up as expected the last time I tightened it. Then when I went to snug it up this time I could feel immediately it was loose. So I believe it's loose because the carb body has cracked around the bolt hole and it happened between tightening? I kept noticing a bit of fuel collecting on the bottom of the bowls and I would turn the bolts maybe 1/16th turn now and then. Obviously I finally over did one.

 

[KEITH KRAUSE]

Me too, I've been watching this thread & thinking, I've been lucky, never remember a problem getting a bowl gasket to seal & reused the gaskets lots of times. Are you having problems with more than one carb?

Thanks for the reply.
Yes, all four carbs are leaking, various amounts. Not a serious drip anywhere but when you inspect with a flashlight you can see all four carbs are "shiny and damp" where the bowls meet the bodies. Then the fuel slowly collects on the drain bolts or other low spot. Each time I tightened the bolts about 1/16th turn at the most, it seemed to help but within a week or so the carb leaks would come back as before. This all started about 5-6 years ago and involves 2 different services where I cleaned the carbs and replaced some o-rings and float valves. I haven't done anything different so I blamed it on maybe the genuine Suzuki gaskets being "old" and a little harder than they should be? I don't know. Driving me nuts. I've owned the bike since it was new so I know the carbs history. No previous problems the first 35 years or so. I've always used stainless hex bolts for the bowls.

 

[Agemax]

I have never seen or heard of a carb body crack due to overtightening of the bowl screws. The thread will strip long before the body cracks.

 

[Guest]

I'm not sure whats going on here as far as the leakage but Seal-All is gas/oil resistant and I have used in fuel situations before, good luck

 

[Gorminrider]

Highly suspect when all four are leaking.To me, It points to fuel level. Your replacements of the float needles+seats is suspect...I'm not familiar with the VM carbs but I'd be looking very hard there. repeating myself but I'm pretty sure the level should not be above the gaskets when the carbs are level.

Yes, that "still turns" screw is a sinking feeling...I'm afeared when the original screws are replaced with SS or something"better"...the threads don't seem exactly the same whatever they are supposed to be..perhaps a new SS replacement "cuts" or forces the old alloy thread to slightly different dimensions and weakens them.
A very bad fix is to find an imperial size that almost matches until you can fix it properly.(a newpart really but I have to mention JBWeld if you can thicken up the surface across the break and use a longer screw and possibly nut too through the hole

(I forgot "Seal-All"! I still carry a tube whenever going far but haven't used it in anger for many years does work for rusty tank pinholes but is also an excellent glue.)

 

[KEITH KRAUSE]

I appreciate the replies. All 4 float needle valves were replaced less than 1,500 miles ago. I always buy the over-priced genuine Suzuki valves and seats. Fuel level isn't the problem.
I have a #1 carb body that just needs basic servicing. It looks like I'll try the "thicker/softer" Z1 bowl gaskets. I haven't made up my mind about applying a thin coat of sealant to each side of the gaskets. If I do, it will be the Permatex 85420.
I really do appreciate the advice/help.

 

[roeme]

VM fuel bowl/body gasket surfaces are not completely smooth. They have a small groove on the body, and a small ridge on the bowl which should line up - at least on the VM22SS. I assume it's the same on the 26mm.

I've had limited success with rubber gaskets ? for me they're mostly one-time use ?, and stick with paper-style since. Either self-cut or some randos off ebay, worked fine so far.

I don't think using sealant will help and rather make things worse, or at least a mess for the next guy digging into the carbs.

 

[Carter Turk]

Would it be worth trying to double up the gaskets for trial n error purposes?

 

[Nessism]

If you want to go down the rabbit hole regarding checking fuel level read this post from over on KZ Rider...https://www.kzrider.com/forum/forum...ative-to-a-clear-tube-when-setting-fuel-level

 

[KEITH KRAUSE]

I appreciate the reply, but doubling up the gaskets wouldn't work. While it's possible it could effect the leaking one way or another, it would lower the bowl. That would change the relationship between the jets and fuel level. I may be wrong, but with more fuel available in the bowl, I believe it could change how the jets draw fuel and compromise the air/fuel ratio? At the very least the over-flow tube built into the bowl would be lower and fuel would overflow too easily.

 

[KEITH KRAUSE]

Ed, thanks for sharing that info.
As far as fuel level and my carbs leaking, fuel level isn't the problem. The gaskets, if doing their job, would seal against leaks regardless if the fuel level was at what I would consider an extreme, say, 1/8th inch too high. At 1/8th inch too high, the bike would run so rich it would be un-rideable. My bike runs well, which tells me the fuel levels are at least reasonably accurate.
I won't get into my reasons, but I've always had a habit of turning off my Pingel valve about 15-20 seconds before actually turning the motor off. I place the bike on the center stand, turn off the valve and let it idle those 15-20 seconds and turn the motor off. As far as the usual several days between rides, the bike sits there, level, with lower-than-normal fuel levels.

 

[Gorminrider]

not TRYING to be an Ahole, but per"

I've always had a habit of turning off my Pingel valve about 15-20 seconds before actually turning the motor off

"but if you want to lower the level further, maybe run the bike until it really dies, including using the choke.

I looked up your fuel level and I gather it's within 3-5mm of the "mating surface of the float bowl, with the engine idling ..." so I can see why the gaskets are a concern where there's a rich level... 5 mm above "the mating surface" seems quite a lot
"...the height is measured 20mm from the rear of the bowl" suggests a tilt taken into account but maybe it's the position of the jets that's the crux, or simply the mechanical properties of the flexible pipe in the gauge.

BUT all that aside, when I look at the pictures in several shop manuals, they always seem to show this...whatever the "allowable" limits(CV carbs..)


Obviously the picture they chose to display as an example shows the fuel is well below the seam. The picture in your manual,that I have anyways, I can't see. It's not argument, it's an idea. Your bike might run a little leaner than the "highest allowable level" or you won't notice. I don't know. But it certainly could fix an unfixable gasket problem.