Identifying seal 81 750

[Crankthatback]

Good afternoon.

I am currently cleaning, replacing seals and gaskets on my 81 750 carburetors.

They are very clean though a bit of work is being done here and there. (bowls were ran out then drained before parked)
The bike has been sitting for around 10 years and so my gaskets and seals are to dry to be reused.

The seal I am trying to replace are located between the bowl gasket and the main carb body.

I have looked at a few part diagrams but not able to identify this seal.

Any help will be appreciated!

 

[Big T]

Pilot jet plug
Need it to idle

 

[Nessism]

Short cuts, are LONG cuts. Follow the tutorial, and do EVERYTHING called out, or you will (likely) have to redo it.

https://gsarchive.bwringer.com/mtsac/~cliff/storage/gs/Mikuni_BS-CV_Carburetor_Rebuild_Tutorial.pdf

https://www.thegsresources.com/_for...vices/1703182-mikuni-bs-cv-and-vm-o-ring-kits

https://www.ebay.com/itm/175906655700

 

[dgates1]

May be referring to that flat rubber ring that goes under the float bowl gasket...?

 

[Crankthatback]

Pilot jet plug
Need it to idle

I have a new set of plugs.
What is needed is the seal that the arrow is pointing too.
the gasket sits directly over it.
I think 20 years ago when I last rebuilt them I had the same question.
thank you for the response though and I am glad you are still here!

 

[Crankthatback]

May be referring to that flat rubber ring that goes under the float bowl gasket...?

That would be the one. : )

 

[KiwiAlfa156]

I've never seen a seal in that position. There is a metal blanking plug which appears to be related to the machining process during manufacture. The float bowl gasket seals this area (which the fuel pick up/air bleed for the choke circuit). I think a PO may have tried to 'improve' sealing... The nitrile plug visible in the pic blocks off the pilot jet which is fed through the main jet. Without them the bike will idle, and run fine up until about 1/4 throttle after which it will run super rich and fall on its face, as the unplugged pilot jet access hole effectively becomes the (massively oversized) main jet. Don't ask me how I know this.

 

[KiwiAlfa156]

Nothing on the parts diagram either.

 

[Nessism]

Some carbs have those seals, and others don't. I've never seen them offered for sale before.

 

[Crankthatback]

All 4 have them and I vaguely remember asking this question many years back the first time I took them apart.
My memory is not so good. ; )
I cannot think of a reason I would have put them there otherwise.

Now the carbs have been apart a few times from my original rebuild, but the seals were not replaced after the first rebuild.
It has been many years!

I half think I was told to use the same seal that something else on the carburetors used.

I had one of Roberts kits that I had bought or possibly given to me from Ken over in Maryland. The gentleman that raced sidecars.

He upgraded his carbs instead of using the originals and that seal was not in the set.
At least that is what I think?

I may try ordering the #57 seal in the diagram and see if that is it if knowone reading this has a answer.

To tell the truth It likley is not nessary as it looks more like a flow restriction more then anything else.

The bike always ran so well though and I would like to ensure it continues to do so.

THANK YOU!

 

[dgates1]

#57 is a lock washer for the float bowl screw. The carbs on my GS850GL have the same rubber "spacer" in there. I just reused the old ones.

I believe it is just to take up space and hold the float bowl gasket flatter when you tighten it down. Or maybe to keep the metal plug from vibrating out. The metal plug must sit lower in some models. Doesn't really seal anything and you could just use any piece of rubber that would fit there. Perhaps cut from some rubber sheet.

 

[rphillips]

Probably just the birthdays, but for some reason I'm thinking I remember some carbs had just a flat rubber solid disc and others had a little rubber gasket that looked like a flattened out "O" ring.

 

[gustovh]

I have the rubber washers in all the cv carbs on my Suzukis. They have been there from the start. Have used appropriate sized O rings as replacements, with success.

V

 

[Crankthatback]

Probably just the birthdays, but for some reason I'm thinking I remember some carbs had just a flat rubber solid disc and others had a little rubber gasket that looked like a flattened out "O" ring.

May not have started out flat , ) truth told they look alot like the drain bolt seals I took off but may be because they are so flat, with a hole in the middle.

 

[Crankthatback]

I've never seen a seal in that position. There is a metal blanking plug which appears to be related to the machining process during manufacture. The float bowl gasket seals this area (which the fuel pick up/air bleed for the choke circuit). I think a PO may have tried to 'improve' sealing... The nitrile plug visible in the pic blocks off the pilot jet which is fed through the main jet. Without them the bike will idle, and run fine up until about 1/4 throttle after which it will run super rich and fall on its face, as the unplugged pilot jet access hole effectively becomes the (massively oversized) main jet. Don't ask me how I know this.

I do have a couple sets of carbs that I have never taken apart rather curious if they have them.
One from another 16 valve 750 and I think the other set is from a 16 valve 1100.

The bike never had a manual choke from time I bought it, and I never had a problem starting it after my first rebuild.
I am curious if it was meant to have a manual choke or not and if the seal was put there as a assist?

The carburetors have a indent there as if it is meant to be there.

 

[Crankthatback]

#57 is a lock washer for the float bowl screw. The carbs on my GS850GL have the same rubber "spacer" in there. I just reused the old ones.

I believe it is just to take up space and hold the float bowl gasket flatter when you tighten it down. Or maybe to keep the metal plug from vibrating out. The metal plug must sit lower in some models. Doesn't really seal anything and you could just use any piece of rubber that would fit there. Perhaps cut from some rubber sheet.

Glad I did not jump the gun and buy that.
Hopefully I would have noticed while looking at corresponding part # in diagram but chances are I would not have.
So you likley saved me a few bucks.

 

[Crankthatback]

Some carbs have those seals, and others don't. I've never seen them offered for sale before.

Thank you. Another person/handle remembered from my original introduction into the world of GS.

 

[Crankthatback]

I have the rubber washers in all the cv carbs on my Suzukis. They have been there from the start. Have used appropriate sized O rings as replacements, with success.

V

I may go the o-ring route.
Vitriol o-rings? For fuel resistance.

 

[KiwiAlfa156]

Just because I've never seen one doesn't mean it's not meant to be there. Its interesting as it sits underneath and is covered by the gasket (carbs inverted for reassembly) so what does it seal? I've never had a problem with leakage or starting. As far as I know the choke plungers are the same and the only difference is the method of actuation, either by lever or cable to a remote lever (bar mounted) or in the case of the 550/1000/1100 Kats a side-cover knob. A Mikuni mystery.

 

[Nessism]

Just because I've never seen one doesn't mean it's not meant to be there. Its interesting as it sits underneath and is covered by the gasket (carbs inverted for reassembly) so what does it seal? I've never had a problem with leakage or starting. As far as I know the choke plungers are the same and the only difference is the method of actuation, either by lever or cable to a remote lever (bar mounted) or in the case of the 550/1000/1100 Kats a side-cover knob. A Mikuni mystery.

Those plugs are press fit into the body, but sometimes they fall out. When faced with a hopeless carb body that can't be repaired, I hack saw the body apart and extract the plug, because sooner or later someone here will need one (or maybe me). The donut seal must be Suzuki's (or Mikuni's) acknowledgement that this can happen. Or, leakage can occur.