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Can't wait to solve some of the little issues I have with my 84 Aspencade. Bought it 2 years ago with 18K on it.Its my 4th wing (1979 G/L 1000, 1982 Interstate 1100/ 1982 Silverwing)It now has 20K and I need to solve a low fuel economy problem.

Bike starts and runs fine. No performance issues but won't get over 27 MPG even on freeway trips. Choke isn't used more than 15 seconds at cold start, engine warms up quickly, no brake drag, no black deposits around exhaust pipes. No aftermarket modifications to bike either. What gives? I get 80 miles from the first fuel bar on the gauge then maybe 100-110 miles until the last bar!!!!

I live in Southern California and work for the Navy as fluid Power Engineer.
 
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Hey Stevo :waving: Welcome to the forum and visit often. :clapper:

:leprechaun::18red::leprechaun:
 

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Thanks andI will,

Any Ideas on my low fuel economy issue? I have seen commentary regarding Air Cutoff Valves binmg the culprit but don't know how to locate them...

stevo
 

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Thank you, I appreciate a man of few words...how is this valve supposed to work?
 

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Stevo wrote:
how is this valve supposed to work?
Stevo, The air cut-off valve cuts the (vent) air flow off to the pilot jet circuit on decel or a high vacuum condition...

Basically when you are riding along at part throttle, then drop the throttle (close the throttle suddenly) the engine manifold vacuum goes high, at the same time the carb throttle valve closes so that means the air flow in the carb/intake manifold drops to almost nothing. What happens then is the remaining mixture in the manifold goes very LEAN... What the air-cut-off valve (or valves on early Wings) does is momentarily shuts the air supply off to the pilot jet's air side (blocks off the pilot jet air jet) so the decel manifold mixture goes somewhat rich, that rich mixture is there to reduce the popping out of the exhaust system on decel or high vacuum over-run conditions. There are about 3 ways the air cut-off system can fail.

(1)- the cut-off valve diaphragm starts leaking.. That causes a lean condition on decel or erratic operation of thecut-off valve..

(2)-the air cut-off valve diaphragm gets old & hardens up. That can cause all kinds of problems as it now won't react to the vacuum signal correctly & can cause either low air flow to the pilot jet circuit & therefore a rich carb mixture (poor mileage, fouled spark plugs, probably won't need the enrichener valve for more than a few seconds at start up),, or a lazy valve so you don't get proper decal air cut-off.

(3) a plugged air inlet to the idle air cut-off system. That will give a rich carb mixture (poor mileage, fouled spark plugs, probably won't need the enrichener valve for more than a few seconds at start up).. No air to the pilot jets really richens the low speed mixture & gives terrible fuel economy, rich blubbering at low throttle settings, bad exhaust smell at idle, etc.

That valve can be checked with a vacuum gauge on the signal vacuum line. I don't have the vacuum numbers handy for valve operation parameters but believe it's somewhere in the 16"hg range. (the numbers are in the manual). The problem is; those cut-off valves can hold vacuum OK & even seem to work but if the diaphragm is old & hard it won't operate at the correct vacuum line signal. On an old Wing it's best to just replace the cut-off valve's diaphragm & spring (not much money from someplace like Bike Bandit).

If your engine idles OK & doesn't pop in the exhaust when decelling your cut-off valve is probably at least working. You just don't know if at the corrrect vacuum signal.

Your mileage drop could be to many things from a plugged air filter, to carb problems (those carb floats are real critical to height for economy), to a plugged idle air cut-off air supply, to misadjusted pilot jet needles, to someone before you re-working the carbs for smoother performance, to a weak ignition, to many other possible causes. About all you can do is go through everything one at a time & verify all is OK..

Twisty
 

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OK Twisty lets make this easy-Just tell me what you DON'T know and I'll know whatI can't ask for help on! I would just settle for what you have forgotten about multi-carb theory...

I'm new here so i'm not familiar with Bike Bandit. Is that a site? And I should aso get a new air filter while i'm at it. Is that the kind of stuff he sells?

Can I get to the air valve and to the spring and diaphram without pulling the network?

History on the problem is the bike would't idle without the choke, was popping on decel and stumbling on accel after a long layoff while I had surgery. I pulled the carb network cleaned them out and sealled the plunger diaphram perimeters (diaphrams were still soft and plyable)elliminating air leaks. Chaged fuel filter and bike returned to normal operation but continued to give poor mileage. Been riding it for a year like that with no complaints. First bar on fuel gage gives 80 miles then the drop from there is exponential. I realize the tank is funnel shaped but with one bar under 1/2 tank, the trip meter now reads 121 miles! What a pig...

stevo
 

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Stevo wrote:
I'm new here so i'm not familiar with Bike Bandit. Is that a site? And I should aso get a new air filter while i'm at it. Is that the kind of stuff he sells?

Can I get to the air valve and to the spring and diaphragm without pulling the network?

History on the problem is the bike would't idle without the choke, was popping on decel and stumbling on accel after a long layoff while I had surgery. I pulled the carb network cleaned them out and sealled the plunger diaphragm perimeters (diaphrams were still soft and plyable) elliminating air leaks. Chaged fuel filter and bike returned to normal operation but continued to give poor mileage. Been riding it for a year like that with no complaints. First bar on fuel gage gives 80 miles then the drop from there is exponential. I realize the tank is funnel shaped but with one bar under 1/2 tank, the trip meter now reads 121 miles! What a pig...


Stevo, Bike Bandit is a rather well stocked parts supply company that handles many OEM type Honda parts at a reasonable price. I just checked & B/B shows those air cut-off valves as no longer stocked. Bike Bandit click here http://www.bikebandit.com/partsbandit/OEM.asp

I did find the air cut-off valves here though. http://www.cyclewareables.com/pages/air_cutoffValve_replacements/aircutoff.htm


Can I get to the air valve and to the spring and diaphragm without pulling the network?
I haven't ever done an 84 Wing but I seriously doubt you can get access without pulling that whole intake.


First bar on fuel gage gives 80 miles then the drop from there is exponential. I realize the tank is funnel shaped but with one bar under 1/2 tank, the trip meter now reads 121 miles! What a pig...

You really can't go by the fuel gauge bars as they aren't all that linear. 121 miles to a tank full is not good though. I get at least that at 90+ mph.

If you had those carbs apart be sure they are balanced, then verify the pilot jet needle setting using the idle drop method, if you messed with the floats be darn sure the float height is correct as just a little off can play havoc with the carb metering on those Keihins.

Twisty
 

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Hi Stevoand welcome to the forum. You didn´t mention what yourspark plugs look like Are they balck and sooted up? Also, are you sure the choke is shutting off completely? I´ve see a few of these where the choke pivot on the front of thecarbs (where the cable goes on)stays at the part-on position and this won´t be obvious when using the choke lever. That can see the fuelconsumption upby at least a third more. :waving:
 

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Pretty sure the choke is all the way off and yes the plugs look a little black but no fouling in 2K miles.
 

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To use the site you show i need to know the Honda part number for my Valve diaphram, I do not havea manual and the local shop has no idea whatI am talking about...we don't have a local dealer anymore. Now they sell every maner of bike in there and specialize in none! Any chance you might have that info?
 

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Stevo.. You mentioned you sealed the diaphrams... How? I believe that after cleaning and reassembling the carbs, no sealers should be used.. if you blocked the hole in the metering piston diaphram, even just a little, the piston will lag on it's up and down travel and delay leaning the mixture. Just pull the carb tops off and re-clean them completely, including the vacuum feed hole.. The 64 carbs are quite easy to overhaul and adjust.

Inspect the timing belts for the correct position, (cam gears & crank), re-set the pilot screws and re-balance the carbs.. use #4 as the master as it's not adjustable. Replace the plugs. If all the parameters are correct, you can't help but get standard fuel mileage out of a 1200. Let me know if you need any specifics. I am in the process of rebuilding a set of 64 carbs now, and can give you some tips & pics...
 

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Stevo wrote:
I found the same at Bike bandit. Found another site http://www.siriusconinc.com/carb/parts.asp?category=7&supplier=6&id=1

but it doesn't give the valve for the 84 1200 Aspy. there is one valve dia for the 1983 Aspencade then it jumps to the 86. Just my luck...
Stevo, I don't have a parts manual for the 84 1200 Wing, my parts manual is only for the 86-87 1200 Wing. There are some on-line Honda parts manuals (usually on parts sellers web pages).

I found this on that second web site I put in the reply above. It's down the page a ways. ---

CW18-2798KL $34 FITS GL1200 GOLDWING 84; GL1200A ASPENCADE 86-87; GL1200 I INTERSTATE 86-87: REPLACES 16048-MG9-741--

That sort of says the same diaphragm for 84 & 86-87. I really don't know as I haven't ever put a diaphragm in the 84 air cut-off valve. My 86 1200 uses the 16048-MG9-741.

If your bike starts & runs fine that pretty well tells us your carb slides & main jetting is operating pretty good. Malfunctioning slides cause very uneven operation.

Have you checked your pilot jet needle settings? If not, first count the turns to seat the needles (on all 4 carbs) & write that down (so you return to where you are now if needed), then re-set to book specs, then warm engine & hook a precision tac up then do an idle drop pilot needle adjustment. Slightly rich pilot jets make those 1200's run good but can have a big effect on fuel economy.

There was also a service bulletin on those 84 1200 carbs to re-jet the pilot jets & install new slide needles. That was to remove an off idle sag & lean spot. That could also have a big effect on the fuel economy. (just a thought)


Twisty
 

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Renegade/Twisty, You guys are great!

I sealed the outer gland ONLY as they were passing vacuum externally. I used inert rubber grease we Navy types have lying around here...fixed my accel stumble and "sneezing" on decel.

I was unable to locate my air cuttoff valve as shown in Twisty's pic above. Do you have the manual photo for the 84 and perhaps a P/N for the diaphram/spring?

I also learned from another source that you can R&R the valve w/o removing the Carb Network, I think this only is true however with the 1000...

Rode bike to work again today so no carbs in hand...
 

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Stevo wrote:
I sealed the outer gland ONLY as they were passing vacuum externally. I used inert rubber grease we Navy types have lying around here...fixed my accel stumble and "sneezing" on decel.

I was unable to locate my air cuttoff valve as shown in Twisty's pic above. Do you have the manual photo for the 84 and perhaps a P/N for the diaphram/spring?

I also learned from another source that you can R&R the valve w/o removing the Carb Network, I think this only is true however with the 1000...
Stevo, I'm getting a little confused on that cut-off valve. Bike Bandit shows the same part was used on 84-87 1200 so that is one end.. Some web sites only list those cut-off's for 86-87. You are probably going to have to call your local Honda dealer & have them look the cut-off up for you so you know for sure what years fit what.

I did find this on E-Bay--see link-

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&rd=1&item=4524347410&category=35597&sspagename=WD1V

Twisty
 
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twisty wrote:
Stevo, I'm getting a little confused on that cut-off valve.
Im getting a little confused myself. :crying:

:weightlifter::18red::weightlifter:
 

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You can add me to the list of confused people on this air cutoff valve. I now know how it works, but finding the correct valve is the next challenge. I have been waiting 2 weeks for my service manual to arrive. Meanwhile, info found on the internet is all over the place. Some sites skip over '85 Aspencades, others say I need 1 valve per carb. Cyclewearables showes this: CW18-2798KL $34    FITS GL1200 GOLDWING  84;  GL1200A ASPENCADE  86-87;  GL1200 I INTERSTATE  86-87:  REPLACES 16048-MG9-741. No '85s?? Several only show "86-"87s Has anyone replaced the valve on an '85 that can help clear this up?
 

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johnmac wrote:
You can add me to the list of confused people on this air cutoff valve. I now know how it works, but finding the correct valve is the next challenge. I have been waiting 2 weeks for my service manual to arrive. Meanwhile, info found on the internet is all over the place. Some sites skip over '85 Aspencades, others say I need 1 valve per carb. Cyclewearables showes this: CW18-2798KL $34 FITS GL1200 GOLDWING 84; GL1200A ASPENCADE 86-87; GL1200 I INTERSTATE 86-87: REPLACES 16048-MG9-741. No '85s?? Several only show "86-"87s Has anyone replaced the valve on an '85 that can help clear this up?
John, I can't help here very much but can add; Bike Bandit (a motorcycle parts supply company) lists the cut-off valve as the same for 84,85,86,87 (not that it is Gospel). Problem is; they don't sell that part anymore.

My 84-87 1200 service manual doesn't differentiate between the operation or service of the cut-off valve between the 84, 85, 86, or 87. It also shows the same basic picture for all years (again, that can't be used as positive proof they are the same).

I have installed only the 86 1200 valve so I can't really give you a definite there either.

As far as needing 4 valves. The earlier 1000 & 1100 used a separate cut-off valve in each carb so that is probably where that came from.

I would suggest you call your Honda dealer (or better yet make a visit) & have them look up the 84-87 1200valve to see if it is serviced with the same Honda part.

Twisty
 

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Twisty,



When you did your 86 1200 where was the valve located? Could it be seen without removing the carb network? IfI take it to the dealer I'll have to ride it over there.

Stevo
 
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