missing vacuum plugs....

[bbroj]

twice now, in the past few weeks, I've lost vacuum plugs from the carb ports. I have block off plates, so only 1 of my vacuum ports is used, the other 3 are blocked off. the bike started idling roughly and I found a missing plug from carb #3. No big deal, I replaced it with a plugged piece of hose until I get to the parts store to buy some "real" plugs. Today, the bike was idling roughly again and #1 carb was missing it's plug. Is this common or is it a symptom of a problem? The bike is running well in all other respects and seems fine again after replacing the plugs, any thoughts? Thanks.

[GeeBeav]

I know some of the parts store caps dry rot/deteriorate pretty quickly, the Kawasaki ones are higher quality.

[T Cro ®]

Dat's why I find it easier/better to use a short snippet of hose with a screw threaded into it; hard to find properly sized/fitted plugs that don't rot in quick order.

[snarf]

I'm sure that there is a good chance that the original plugs that you lost were from me.  This is the first I have heard of there being an issue with the fit.  The plugs that I get are fuel, oil, and heat resistant.  I can send ya some more if you would like.
Is it possible to get a misfire large enough to put back pressure into the carbs and actually blow the plugs off?

[bbroj]

Right now, a short piece hose and a screw is exactly what I have in 2 of the 4 ports. 1 is the vac line for the petcock and the last has a thick walled plug (factory?) which seems to be holding ok. Tony, have you experienced loosing them?

Chris, thanks for the offer to send more, but it would probably cost more in postage than it would cost me to get them locally. I'm not worried about the lost plugs, I'm more concerned that it may be a symptom of something else. So far nothing is showing itself and the bike continues to run fine, no backfires etc.

[T Cro ®]

Tony, have you experienced loosing them?

It's not that I've seen them go MIA on my Concours it's that I've seen far too many issues with them overall on automotive, motorcycle, industrial applications. If they are too loose they can get puffed off, if they are too tight they can split, also once aged they are easy to damage when removing but with a small piece of "properly" fitted hose that has been plugged with a screw they are easy to grasp.

[Sparkie]

Would a proper fitting piece of hose connecting two carb vacuum ports together be ok to do? Or would that cause problems with the individual carb vacuum balance. Mark

[T Cro ®]

Would a proper fitting piece of hose connecting two carb vacuum ports together be ok to do? Or would that cause problems with the individual carb vacuum balance. Mark

Do not cross connect vacuum ports as that can create idle related issues.

[Sparkie]

Thanks, that makes sense. Mark

[jworth]

Isn't that, cross connecting carb vacuums, exactly what you do when you sync the carbs?  Also, don't a lot of people tie multiple carbs together just to be sure they get good vacuum to cruise servos?  I think I have 2 tied together for said purpose  No idle problems here.  Interesting.  Has me thinking.  Perhaps it would function like an air leak depending on what each jug was doing relative to the others. 

[bbroj]

The carbs are not tied together during a carb sync, each is connected to it's own independant meter, not tied together. Others have had problems with LOW vacuum by tying ports together, as you said, due to which piston is moving up/down at the time. Tying ports together also actually creates a small vac leak in each carb, or so I've read from trusted sources. I seem to recall someone (SNARF?) having petcock and/or cruise control problems by using a tee between 2 carbs to provide the vac source.

[T Cro ®]

I seem to recall someone (SNARF?) having petcock and/or cruise control problems by using a tee between 2 carbs to provide the vac source.

Yes he did and it drove him absolutely nutz trying to figure out what was wrong with his bike... In the end he found out that he was starving for fuel when running hard as his petcock was closing up due to vac loss between cylinders.

[jworth]

The carbs are not tied together during a carb sync, each is connected to it's own independant meter, not tied together. Others have had problems with LOW vacuum by tying ports together, as you said, due to which piston is moving up/down at the time. Tying ports together also actually creates a small vac leak in each carb, or so I've read from trusted sources. I seem to recall someone (SNARF?) having petcock and/or cruise control problems by using a tee between 2 carbs to provide the vac source.

The only thing I would add is that it depends on the type of gauge one uses when doing the carb synch.  Several methods do in fact tie two carbs together.

[Steve in Sunny Fla]

 If you're using the vacuum caps available at the local parts store, they can split and / or pop off from reversion in the intake - btdt. I found that if you buy the package with the various sized caps, you can fit a set that of the smaller caps, and then fit a set of the larger caps over the small caps. that'll hold up really well. I have done that for a few years with no issues.

  and yeah, you don't want to inter-link the hoses if they're going to the petcock, it kills the signal and the petcock doesn't open reliably. HTH, Steve

[snarf]

Yes he did and it drove him absolutely nutz trying to figure out what was wrong with his bike... In the end he found out that he was starving for fuel when running hard as his petcock was closing up due to vac loss between cylinders.

Yep that was me.  I had never paid any attention to the bike when I got it.  When we rode home from the rally in Tomah, my wife was riding my 02 so we never really rode hard.  After I got it home I still sorta took it easy.  Then one day I decided to flog the cr@p out of it and thats when the hair pulling started.
Under heavy load i was basically canceling out my vac and my petcock would begin to shut. You can pair up two carbs for extra vac.  1-3 or 2-4, but not all of them; bad things start to happen

[T Cro ®]

The only thing I would add is that it depends on the type of gauge one uses when doing the carb synch.  Several methods do in fact tie two carbs together.

What kind is that? I've never seen or heard of such an instrument.

[jworth]

One such method ties both carbs together to two bottles each containing a bit of fluid and those bottles are in turn tied together.  One can tell which carb is pulling more volume by measure which direction the fluid flow, from bottle A to B or vice versa.  For a different method, I made one out of a sort of diaphragm ( condom) held  between two chambers.  I can tell how to adjust the carbs by monitoring which way the "diaphragm" is being pulled.

[snarf]

One such method ties both carbs together to two bottles each containing a bit of fluid and those bottles are in turn tied together.  One can tell which carb is pulling more volume by measure which direction the fluid flow, from bottle A to B or vice versa.  For a different method, I made one out of a sort of diaphragm ( condom) held  between two chambers.  I can tell how to adjust the carbs by monitoring which way the "diaphragm" is being pulled.

Oh man, I remember that thread. That was ingenious and funny all at the same time

[T Cro ®]

One such method ties both carbs together to two bottles each containing a bit of fluid and those bottles are in turn tied together.  One can tell which carb is pulling more volume by measure which direction the fluid flow, from bottle A to B or vice versa.  For a different method, I made one out of a sort of diaphragm ( condom) held  between two chambers.  I can tell how to adjust the carbs by monitoring which way the "diaphragm" is being pulled.

Oh yeah I plum forgot about that type of manometer devise; my brother used to use one like that on his BMW twins. But in reality the carbs are not "freely" connected to each other as the liquid forms a barrier between to two. If not built too big or heavy the liquid manometer is quite an accurate devise.

[Daytona_Mike]

The only thing I would add is that it depends on the type of gauge one uses when doing the carb synch.  Several methods do in fact tie two carbs together.

That just sounds silly. I do not know what model that would be but I can tell you that will not work. Carbs have to be synch separately in relation to each other . If you join them together  then what  you did is not called 'synchronizing carbs'.