Found My Vacuum Leak, Finally

[dan7uk]

I purchased a 99 Interstate about 4 months ago and notice when letting off the throttle bike would not return to idle immediately when shifting.  First adjusted the throttle play, not the problem.  Asked the board here what I might check next and everyone responded that it sounds like a vacuum leak.  Next thing I did was check all the boots and I replaced all manifold O rings, not the problem.  Next thing I did was I desmog the bike hoping I would see where the leak was, didn't see anything that I saw would indicate a problem, strike three.
It was a more of a nuisance problem so for the past four months I lived with it.  Out of desperation I purchased a Digi Sync gauge to check the sync on the carbs.  All the carbs were dead on except #5, almost no reading on gauge no matter how much I adjusted the sync screw.  Bingo problem found.  Used a dental mirror and gave #5 a closed inspection.  Found a small hair line crack in the hose  on the Air Cut Valve.  I replaced the hose and put the gauge back on it #5 was now reading.  
 The Digi Sync save me, it narrowed the problem down to #5 carb and gave me a place to concentrate
on.  I was lost until then.  So don't forget the hose on each carb off the Air Cut Valve, it drove me nuts.
This is not a commercial for Digi Sync any Vacuum gauge could of found it.
Part #24 is the valve & 28 is the hose.
https://www.ronayers.com/oemparts/a/hon/5053ea2ef870021c54be3e8d/carburetor-component-parts

[HayHauler]

Oh, THAT hose.  I am glad you included the ronayers.com diagram with the part numbers.  I have never even looked at those hoses.  I hope that doesn't happen to me.

Glad you found it and got it corrected.

Also, thanks for coming on here and posting your solution as it might help someone else in the future.

Hay
Jimmyt

[Mooskee]

Good thing it was #5. You can get to it and #2. The others are between carbs.

[dan7uk]

Good thing it was #5. You can get to it and #2. The others are between carbs.

Very lucky it was carb #5 easy to get to vac hose and replace, 5 minute job.
Wonder what is involved to get to carb #1, #3, #4, & #6 Air Cut Valve vac hose.  I would say the tank would have to come off along with the air box, not sure what else.

[Mooskee]

Good thing it was #5. You can get to it and #2. The others are between carbs.

Very lucky it was carb #5 easy to get to vac hose and replace, 5 minute job.
Wonder what is involved to get to carb #1, #3, #4, & #6 Air Cut Valve vac hose.  I would say the tank would have to come off along with the air box, not sure what else.

All that, and remove carb bank. Then split carbs. You would at least have to replace the fuel and air rail O-rings because they will have taken a set from my experience. There is one guy on here that swears O-rings never go bad, but that isnot my experience. Basically if you go that far, you might as well refurbish. Otherwise you might be doing all that work again.

[wjamesfl]

I recently rebuilt my carbs and all 6 of those hoses were severely cracked! Something to look out for. Not sure if it was old age or if the previous person that opened these carbs up didn't remove them before spraying carb cleaner.

[98valk]

Good thing it was #5. You can get to it and #2. The others are between carbs.

Very lucky it was carb #5 easy to get to vac hose and replace, 5 minute job.
Wonder what is involved to get to carb #1, #3, #4, & #6 Air Cut Valve vac hose.  I would say the tank would have to come off along with the air box, not sure what else.

All that, and remove carb bank. Then split carbs. You would at least have to replace the fuel and air rail O-rings because they will have taken a set from my experience. There is one guy on here that swears O-rings never go bad, but that isnot my experience. Basically if you go that far, you might as well refurbish. Otherwise you might be doing all that work again.

they go bad due to people using off the shelf fuel additives that eat away at the OEM Buna-N o-rings. that's it. It has nothing to do with AGE and/or 10-15% ETHANOL IN THE FUEL.

[Mooskee]

Good thing it was #5. You can get to it and #2. The others are between carbs.

Very lucky it was carb #5 easy to get to vac hose and replace, 5 minute job.
Wonder what is involved to get to carb #1, #3, #4, & #6 Air Cut Valve vac hose.  I would say the tank would have to come off along with the air box, not sure what else.

All that, and remove carb bank. Then split carbs. You would at least have to replace the fuel and air rail O-rings because they will have taken a set from my experience. There is one guy on here that swears O-rings never go bad, but that is not my experience. Basically if you go that far, you might as well refurbish. Otherwise you might be doing all that work again.

I was looking at a carb set yesterday with this conversation in mind. I think I could change the AVC tubing without breaking apart the carbs. It would not be that easy, but to avoid breaking the set apart, I think it is possible. You would probably have to remove the choke links for a little more room. It would help to have some very thin needle nose or hemostats.

If you determined your vacuum leak was caused by a leaking ACV tube it might be worth it. Not easy but much less expensive and extensive than taking everything apart.

[Mooskee]

"they go bad due to people using off the shelf fuel additives that eat away at the OEM Buna-N o-rings. that's it. It has nothing to do with AGE and/or 10-15% ETHANOL IN THE FUEL."

98Valk, I totally agree with you, contrary to what you probably think. In fact I respect your engineering knowledge and experience. I have actually read almost all of your posts. I worked as a technician for 46 years in the Navy and Nuclear Power. I have worked closely with many engineers, and respect the craft.

That said I have a lot of hands on experience on equipment. The point you make about the O-rings being damaged by using inappropriate additives is a good point. I agree.

I also get carb sets that are in various stages of failure. I am not sure just how many 25 year old Valkyries have never had any fuel additives in the tank. Very often when people report their machine not running correctly, they receive advice to put in additives. Some of those additives will clear up circuits that are not too clogged. Perhaps at a price of an eventual carb rebuild. Or maybe you get away with it and get years more service out of them.

I get a lot of carbs that have been sitting for extended periods with ethanol fuel in them. New riders inherit their dad's or grandfather's bikes, or buy a Valkyrie that has been sitting due to the owner not being able to use it and selling it after some time. The carbs are all gummed up and often leaking on the fuel rail; especially at the fuel tees. Perhaps because of movement of the tees with the fuel lines connected. I don't see it as often on the front fuel rail tubes.

I do not think the ethanol attacks the O-rings. Ethanol does have a big effect on the functionality of the carbs if left sitting in there too long without running the engine.

What I see is the fuel turning thick, then leaving a yellow green deposit in the carb bowls and slow circuits. It can look like dust, or lacquer, and can get so bad it is difficult to remove even using an ultrasonic cleaner. There is often what I call a "fungus" because it is a greenish fuzzy deposit in and on the bowl components. It builds up and clogs the circuits; especially the slow circuits.

I have even seen some cases where the goo had the main needles stuck such that the crossover arm cannot operate the butterflies.  I have 100's of pictures of all these conditions because I take pictures for my customers during the rebuild process.

In summary I agree that it is additives that attack and destroy O-rings. I agree that the O-rings can withstand ethanol fuel. I submit that ethanol fuel left sitting in the carbs for long periods will cause blockage of the slow circuits and if gone long enough will even clog main jets and freeze the main needles in the seats.

I use Marine Stabil in my fuel when sitting up for any length of time. My trike has to have high octane fuel because of the compression ratio. That fuel is generally ethanol free.

I welcome your feedback and input on what if any additives are recommended for use.

I also would appreciate your input on what to use to lubricate new O-rings when installing them. The  Honda manual just says "oil".

Respectfully
Dave

[Jess from VA]

Mooskee, I have some 35 carburetors at my house, including two Valkyries.  I am incompetent as a carb repairman (but have used a gifted motorcycle mechanic and a lawnmower shop from time to time).

I burn no ethanol gas in any of them.  

My county and others close-by do not allow the sale of non-ethanol gas, so about quarterly I drive 100 mile round trip to get about 40 gallons of it to bring home to use in my machines.  I have always dosed this gas with the proper amount of Marine grade Stabil (1/2 oz per 5 gallons), but also have added a "slosh" of both Seafoam and Berryman's B12 to each 5 gallon can.  Of course I've done this to make the fuel last.  And it generally gets used up in 3-5 months, then replaced, but it's been my understanding that it should be good for 1-2 years.  It sits out in a shed in high heat all summer, winters are mild.

The area I can get the nonethanol is where I always ride (out in beautiful horse country, not in urban traffic where I live), so I usually fill the bike I'm riding before the 50 mile trip home.  But some rides are shorter and then I top up from my storage gas at home.

I've been doing this for years, and never had any problem with either of my '99 Interstates, or any of my other equipment from using this treated gas (as far as I know).

But after reading this thread and your posts, I'm wondering if you think the Seafoam and B-12 is a bad idea?  Overkill?  



 

[Mooskee]

Mooskee, I have some 35 carburetors at my house, including two Valkyries.  I am incompetent as a carb repairman (but have used a gifted motorcycle mechanic and a lawnmower shop from time to time).

I burn no ethanol gas in any of them.  

My county and others close-by do not allow the sale of non-ethanol gas, so about quarterly I drive 100 mile round trip to get about 40 gallons of it to bring home to use in my machines.  I have always dosed this gas with the proper amount of Marine grade Stabil (1/2 oz per 5 gallons), but also have added a "slosh" of both Seafoam and Berryman's B12 to each 5 gallon can.  Of course I've done this to make the fuel last.  And it generally gets used up in 3-5 months, then replaced, but it's been my understanding that it should be good for 1-2 years.  Of course it sits out in a shed in high heat all summer, winters are mild.

The area I can get the nonethanol is where I always ride (out in beautiful horse country, not in urban traffic where I live), so I usually fill the bike I'm riding before the 50 mile trip home.  But some rides are shorter and then I top up from my storage gas at home.

I've been doing this for years, and never had any problem with either of my '99 Interstates, or any of my other equipment from using this treated gas (as far as I know).

But after reading this thread and your posts, I'm wondering if you think the Seafoam and B-12 is a bad idea?  Overkill?  

 

Well, I am sorta waiting for 98Valk to come in on the answer. He has done a lot of research on said subject. I think I know what the response will be, but I am not the engineer. We might have just started another "What oil" thread!

[Jess from VA]

Well, I am sorta waiting for 98Valk to come in on the answer.

Well, I'd be glad to hear it from him too.

A "slosh" is not scientific, but I would guestmate about 1/4 to 1/3 cup of each additive per 5gal can. 

I've used B12 in higher doses (once) to clean out a weedwhacker, blower, yada also (with good results).

[Jess from VA]

Thanks Pluggy. 

The Marine Stabil at a half once per 5gal of non ethonal is GOOD.

I've added the Berryman's B12 and Seafoam (at a quarter to third cup each per 5gal can) as added insurance to keep all carbs and fuel systems clean, as well as add longevity/stability to my stored gas.

But these additives may well go above your 99.2% gasoline recommendation (I'm not doing the math).

I'm wondering if I should reduce the B12 and Seafoam per can, or just stop using it all.  Again, I've been doing this for years and have no ill effects that I'm aware of.

All this is because I am a terrible carburetor mechanic.

I take almost no medication at all, and I am very sensitive to it as a result.  I have probably not taken a single aspirin or Tylenol or cold medicine in 15-20 years.  The stuff in my medicine cabinet should probably go in the trash.   

[Pluggy]

Jess, a friend recommended Berryman's.  I bought a bottle but had not used it.  I coated the deck with Sherwin-Williams Acrylic and the brush hardened up solid.  Nothing would clean it, until I tried Berryman's.  Out of the bottle and onto the brush, it softened and removed that material quickly.  Saved a $14 brush.

Some guys will dump a whole bottle of Sea Foam or Berryman's into a small motorcycle tank.  That seems risky.  Consumers don't know at what point a product goes from helpful to harmful.  We should follow the instructions or avoid such products entirely.

[Jess from VA]

Out of the bottle and onto the brush, it softened and removed that material quickly.  Saved a $14 brush.

Ha ha, never used to clean a paint brush. 

I use gasoline, which is a bit brush destructive, but works with all paints.  Cheaper and faster working than paint thinners. 

I have a can with 10-12 brushes in it (large, small and tiny) half full of old gas, which I just leave them in.  When I need one, I select the size, wire brush it clean, dry with a rag, and I'm all set. 

Funny you mention it because I'm about to go out and use one right now for a little touch up work. 

I painted my way through college (industrial) and as the FNG, was often put in charge of cleaning dozens of nasty 4" horsehair brushes with toxic skin burning solvents.   

[Jims99]

While on a chemical kick, what do y'all recommend for an ultrasonic cleaner? I’ve used the hospital grade simple green a few times with good results. I was told it wouldn’t hurt the aluminum. If I’m soaking a set of carbs that are not completely disassembled (still have rubber attached) what do you recommend?

[98valk]

While on a chemical kick, what do y'all recommend for an ultrasonic cleaner? I’ve used the hospital grade simple green a few times with good results. I was told it wouldn’t hurt the aluminum. If I’m soaking a set of carbs that are not completely disassembled (still have rubber attached) what do you recommend?

there was a report/memo over 20 yrs ago that made the rounds throughout the military aviation departments about not using simple green on certain types of aluminum per military dept testing.
your favorite adult search engine should bring that up.

[h13man]

With my low tech mind, 28 yr. old rubber is definitely a major issue and Berryman B12 is highly corrosive but a good cleaner all the same for carbs on the bench. I've been using Supertech additive for 7 yrs. now for winter lay up and a occasional thru the season though my seasons have been short in comparison before 00' thus haven't been using it. ST has strong diesel/petroleum smell and never sluggish running out the winter tank like red Stabil was and always 2 push of the start button start up with the ST. Last year one push and always full on choke. Thru the summer 2 wks. or less, no choke needed. Had to use it yesterday after a 3 wk. sit. I'm in a area where non ethanol is still available most anywhere though I65 stations are a lot of 10% additive. Read the pumps.