Carb Stand

[ryonker]

Ok, I know this is a bit overkill, but it works. I am working on my carbs to see where they leak. And as you know, carbs are kind of awkward to hold steady to work on. Even you clamp them in a vice, it's hard to look at all sides and really check it over.

I have an engine stand that wasn't being used. So I just put all the connectors at the top, and they slide perfectly into the back of the carbs so you can see them well and level them. I put some electrical tape over the ends of the engine stand bars so as not to mar the carbs.

 

[gbw]

Very interesting. The carbs are difficult to hold and work on...such an awkward shape on the bench. I never thought about working up a jig to hold them, but I like what you did there. Did you find your leak?

Thanks for posting. Very interesting.

 

[ryonker]

Very interesting. The carbs are difficult to hold and work on...such an awkward shape on the bench. I never thought about working up a jig to hold them, but I like what you did there. Did you find your leak?

Thanks for posting. Very interesting.

So far, nothing is leaking. I am ok with that, but it has been leaking after the bike sat for 20 or so minutes. I tried to best simulate the fuel line like it was coming down off of the tank. The line is filled with just enough fuel to fill the carbs and then some left in the line, like when I shut off the petcock.

I was pretty certain it was the float needles and seats, but now I am not sure.

Yeah, the stand works great (if you already have one). You can flip them upside down and work on them that way too. They are very secure, but slide easily on and off the chrome mounting bars on the engine stand.

Rick

 

[gbw]

When the carbs are leaking, is it on the center stand or side stand? Maybe you need to angle them a little to simulate the bike being on its side stand???

Of course they probably won't leak again until you put them back on the bike!!

 

[ryonker]

When the carbs are leaking, is it on the center stand or side stand? Maybe you need to angle them a little to simulate the bike being on its side stand???

Of course they probably won't leak again until you put them back on the bike!!

I did actually angle it a little to the left. I will add more angle and see what happens. You are right, it wont leak until it's back on the bike!

Here is another photo from the back side showing how it mounts on the stand.

​

 

[67fire]

That is a great idea! I take it that you use some kind of rubber hose over the bolts/whatever you use in the intakes?

Eric

 

[ryonker]

That is a great idea! I take it that you use some kind of rubber hose over the bolts/whatever you use in the intakes?

Eric

There is a chrome bar with a hole in it for a bolt to go through when mounting your engine.

I tried a rubber hose over that, but the fit is to tight to go into the carbs. So I just wrapped them really well with electricians tape. It slides into the carbs nice and easy.

I have tilted and shaken the carbs and I can't get the darn things to leak. I even filled the hose with more gas to put some extra pressure on the needles.

I was going to put in new float needles & seats but now I wonder if I should just install them as is and try again? With my luck they will leak a day or so later after they are installed. Maybe I did something after taking them apart and checking the bowls and floats?

 

[byrdman76]

I assume your still running the vacuum operated petcock? Check to see if the vacuum line running down to the carbs has fuel in it. It may be a leak in the petcock diaphram that is allowing gas to get into the intake and carbs, or the loose line running to carb #3 and creating a leak.

I chased a rich running #3 carb for a few days before finding that one. It would only flow additional fuel past the diaphram when the bike was running at about 4500-5500 rpm. Idle and WOT was fine. No flow at idle and WOT was just covering it up.

Great carb bench BTW!

 

[TheCafeKid]

I assume your still running the vacuum operated petcock? Check to see if the vacuum line running down to the carbs has fuel in it. It may be a leak in the petcock diaphram that is allowing gas to get into the intake and carbs, or the loose line running to carb #3 and creating a leak.

I chased a rich running #3 carb for a few days before finding that one. It would only flow additional fuel past the diaphram when the bike was running at about 4500-5500 rpm. Idle and WOT was fine. No flow at idle and WOT was just covering it up.

Great carb bench BTW!

+1...I had already assumed you would have checked your petcock in your other thread...maybe i shouldnt have.. Have you checked your petcock is functioning properly????


Btw...how much would you charge to make me one of those bad boys?? Id like to have one...they look damn handy for sure!

 

[ryonker]

+1...I had already assumed you would have checked your petcock in your other thread...maybe i shouldnt have.. Have you checked your petcock is functioning properly????


Btw...how much would you charge to make me one of those bad boys?? Id like to have one...they look damn handy for sure!

I should have mentioned the petcock. I have a brand new pingel. It is working great.

The engine stand is about $70 from Northern Tool. You can get one just like it for a bit cheaper from Harbor Freight.

 

[TheCafeKid]

I should have mentioned the petcock. I have a brand new pingel. It is working great.

The engine stand is about $70 from Northern Tool. You can get one just like it for a bit cheaper from Harbor Freight.

You DO know that you CANNOT leave that Pingel ON when the bike isnt running right???:-k

 

[ryonker]

You DO know that you CANNOT leave that Pingel ON when the bike isnt running right???:-k

Yep. Good question though. I am fanatical about shutting it off. I have another aftermarket Petcock on my 79 as well so I do it now instinctively.

It's not for everyone. I talked a friend into getting non-vacuum petcock and he forgets to shut his off all the time. Can you say, "time for another oil change".

Rick

 

[TheCafeKid]

Yep. Good question though. I am fanatical about shutting it off. I have another aftermarket Petcock on my 79 as well so I do it now instinctively.

It's not for everyone. I talked a friend into getting non-vacuum petcock and he forgets to shut his off all the time. Can you say, "time for another oil change".

Rick

So then im confused...If you're shutting off the petcock, how are the carbs still leaking gas??? Or are they leaking while its running?

 

[ryonker]

So then im confused...If you're shutting off the petcock, how are the carbs still leaking gas??? Or are they leaking while its running?

Sorry Josh. I had two different issues and somehow I blurred them.

Issue #1 Initially I had some minor dripping, really just a coating, of fuel about twenty minutes or so after shutting off the bike. I thought this might be the float needles & seats. You could feel the gas in the bottom of the bowls and small amounts would drip down onto the engine.

Issue #2 Today I put my carbs back on after I tested for leaks on that stand set up you saw. When I started the bike, it shot small spurts of gas out of carb #3's overflow tube...while it was running.

I am not sure if these two issues are related. The only thing I wonder about is that I think the carb overflow tubes were accidentally scrunched behind the airbox and pinched somewhat by an over tight zip tie holding them together. So I am theorizing that I had no overflow out the tubes before because the tube for Carb #3 was pinched off...possible causing the carbs to weep/seep a little gas out later since there would have been excess gas in the carbs at the time I shut them off.

Sorry if this is confusing....I am still flustered by this whole Favre thing that happened today.

Rick

 

[byrdman76]

Is the bowl bleed screw allowing fuel to pass? Check the screw tip and seat for pitting, distortion, or trash. Also remove the bowl on carb three and fill it with gas (below the over flow tube) to see if it leaks. If it does the bleed screw is leaking and fuel is coming out of the overflow/bowl drain tube.

 

[mart850]

Hi, May be worth a look. I had a gs750 years ago that was running rich on #3 for no apparent reason and weeping fuel from under it when parked.
Turned out to be a porous casting between the inlet tract of #3 carb and the main fuel feed to #4 carb that runs directly underneath it. The hole was tiny to begin with acting as an extra jet but as the fuel flowed through it it made the hole bigger so the symptoms got worse.When stopped of course the fuel after the tap continued to leak slowly out of it. Once I'd found it after much head scratching and the air box removal I patched over it with araldite but that affected the air flow into the carb so I ended up getting another set. Problem solved.

 

[almarconi]

Good idea..I have an old engine stand that's not being used.

 

[mills]

Check for cracked overflow tubes in the bowl of leaking carb. Take bowl off and fill with fuel then watch for a drip. Common failure.