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Some time ago, I posted a question about my 84 Aspy that it would tend to backfire when I decelerated. It happened almost everytime when I was gearing down for a stop. Nothing when I was riding. Most of the suggestions had to do with the exhaust pipe gaskets. No, that wasn't my problem. Then, I learned that it could be possible that I needed to sync my carbs. I finally broke down todayand got a carb tuner made by Pro Motion: http://www.motionpro.com/motorcycle/tools/syncpro%3Csup%3Eandtrade;%3C-sup%3E/

It took me 15 minutes to put it together and learn how to use it, 25 minutes to remove the lower farings and 5 minutes to actually tune the carbs. And yes, they were what I would consider "way off". It took me another 20 minutes to get everything screwed back together and I was off for a test ride.

I was blown away. 98% of the backfire was gone! My total cost for the tuner was about $103.00 from a Kawauski dealer. My Honda dealer didn't have one, of course. Now that I know what I'm doing, it shouldn't take over 15 minutes, start to finish. I'll be checking on this on a regular basis. Anyway, I just though some of you with older machines would be interested.
 

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There is also an air return valve(if memory serves) located on the underside of the plenum, that enrichens the carb mixtures upon decelleration and puts an overly rich mixture into the exhaust pipes to prevent detonation or backfiring. If this valve fails, there will be backfiring. It is vacume controlled.
 

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Ken is right, the valve is one of the more common causes of backfire on decel. We call it the anti-backfire valve. The GL1200 carbs really need balancing every 5-6000 miles.
 

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There are 2 diaphram devices located under the carbs on a 1200. One is the air cut-off, most common cause for the back fire on "deceleration". The other is the anti-after burn. The air cut-off you can find just about everywhere. The anti-after burn, not. Honda doesn't even show a part number for it. Has anyone ever come up with a replacement for one?
 

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Keystone742 wrote:
There are 2 diaphram devices located under the carbs on a 1200. One is the air cut-off, most common cause for the back fire on "deceleration". The other is the anti-after burn. The air cut-off you can find just about everywhere. The anti-after burn, not. Honda doesn't even show a part number for it. Has anyone ever come up with a replacement for one?
Oh goodie. Something else to deal with.

OK, can it be tested and/or repaired? If so, how? If not, can replacements be purchased?
 

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Yes there is a vacuum test and it's outlined in the manuals. Can't remember exactly how, but you put so much pressure in and then switch and take so much pressure out. Do you have a manual? You can downloadone here from the site.
 

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Keystone742 wrote:
Yes there is a vacuum test and it's outlined in the manuals. Can't remember exactly how, but you put so much pressure in and then switch and take so much pressure out. Do you have a manual? You can downloadone here from the site.
Yeah, I have one. I'll have to do some reading on it. Thanks.
 

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W5BLT,

Nothing really to add to this, but I couldn't resist making a comment about the callsign! :cheeky1:

Paul

KB9VWJ
 

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GSarducci wrote:
W5BLT,

Nothing really to add to this, but I couldn't resist making a comment about the callsign! :cheeky1:

Paul

KB9VWJ
Paul,

My call sign formerly belonged to my father. I acquited it when the vanity calls came out. It's circa 1932. Pretty old.

Bob
 

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Bob,

Wow! Very neat! I immediately thought of the fun you could have with things like Field Day with that call!

Paul
 

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My 1980 Gl 1100 also has a bcakfiring problems and I was going to sync the carbs Was it an easy project any tips on doing this job ? Do you like the carb sync tools you got from Motion Pro ? Iam also going to replace the AIr cut off valves . I am currently in a cast ( broken Ankle ) so this job will have to wait for a while .

Oh yeah N1LAL here
 

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Kinker wrote:
My 1980 Gl 1100 also has a bcakfiring problems and I was going to sync the carbs Was it an easy project any tips on doing this job ? Do you like the carb sync tools you got from Motion Pro ? Iam also going to replace the AIr cut off valves . I am currently in a cast ( broken Ankle ) so this job will have to wait for a while .

Oh yeah N1LAL here
Yes, it was very easy. The hardest part is removing the faring parts. Once done, the kit includes the adapters you need to hook up to the carbs. My Haynes book showed exactly where to hook it up. The meter is very streight forward. Now that I know what I'm doing, I'm sure that I could do the sync in 15-20 minutes, start to finish. I think that it's one of the most beneficial things that I've done to my Wing since I've gotten it.

Now, it runs much better, better mileage and smoother running.
 

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I only have the fairing top with the windshield no lower parts at all it only takes about 5 minutes to take off
 

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Kinker wrote:
I only have the fairing top with the windshield no lower parts at all it only takes about 5 minutes to take off
Then you're looking at about 20 minutes the first time you do it after you learn how to connect up the meter.
 

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WeLLLLLLL

I have fought with this for a long time. I had according to the honda dealer a bad cold purge suctionvalve. Honda has discontinued this item! It apparently doesn't "hurt" anything with the way the bike runs, but......after having the purr of the goldwing motor it suck's to have this remain a constant ANNOYANCE!I eventually went on ebay and found a set of used carbs(240.00, wouldn't sell the cold purge valve seperately ,new part (if avail.) would have been 160.00) and had the cold purge suction valve swapped out. It runs great but still have some mild backfire if lettinf the engine slow the bike to a near stop.

My question is? is there a way to bypass all this pollution control stuff like we did on our 1700cc yamaha silverado(cured it's problem)? Any one with some ideas or expierence with this?

I did have the carbs reset.

amungus
 

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Bump!

because I would like to hear from one of guru's on this. I've never heard of a bypass fix, but it would be nice, and I'm certain that if there was one, someone would have mentioned it before. However...?:baffled:
 

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This is a quote from the FAQ on the Sabre Cycle web site.

Over time, air cutoff valves will harden up, perforate and/or disintegrate leaving your bike in a permanently lean, low RPM range (0-2200). When this occurs, your bike will progressively require excessive choking on warm-up and will miss during idling, miss and backfire when throttling up or down, and/or hesitate and backfire when trying to accelerate quickly. This condition will eventually cause "afterburn" generated by a lean fuel mixture when closing the throttle. An alternative to purchasing the costly OE assembly is our inexpensive air cutoff valve kit and, at the same time, replace your inexpensive carburetor manifold o-rings to insure against any additional vacuum loss.

In addition, they had this as well:

[align=center]AIR CUTOFF VALVES [/align]
THE AIR CUT-OFF VALVE IS AN EXTREMELY IMPORTANT PART OF THE FUEL/AIR INTAKE SYSTEM THAT IS FREQUENTLY MISSED EVEN BY COMPETENT MECHANICS, MOST OF WHOM ARE NOT EVEN AWARE OF ITS EXISTENCE OR HOW IT FUNCTIONS.

EVERY GL1000 HAS ONE LOCATED IN THE AIR INTAKE TUBE BETWEEN THE AIR CLEANER BOX AND THE MANIFOLD. EVERY GL1100 HAS FOUR LOCATED IN THE TOP AIR INTAKE PASSAGE OF EACH CARBURETOR. AND, EVERY GL1200 HAS ONE LOCATED IN THE PLENUM BOX BELOW THE AIR CLEANER BOX, SIMILAR TO THE GL1000.

THESE VALVES ARE "AIR BLOCKERS", ALONG WITH THE CARBURETOR MANIFOLD O-RINGS, SERVING TO RESTRICT AIR FLOW AND INCREASE THE FUEL/AIR MIXTURE RATIO WHEN THE CARB SLIDES ARE IN THE LOWER RPM RANGE DOWN TO CLOSED. WITH HEALTHY VALVES, THE MACHINE WILL START AND IDLE SMOOTHLY WITH VIRTUALLY NO CHOKING AND ACCELERATE RAPIDLY WITH NO STUMBLE OR HESITATION.

MOST PEOPLE WILL START FOOLING WITH THE AIR SCREWS TO TRY TO OVERCOME STARTING THAT REQUIRES HEAVY AND PROLONGED CHOKING TO KEEP THE BIKE RUNNING, STALLING AND HESITATION EVEN WHEN "WARMED UP", AND BACKFIRING WHEN THE THROTTLE IS SHUT OFF WHILE CRUISING. THESE ADJUSTMENTS ONLY MAKE IT WORSE, ALONG WITH KILLING THE GAS MILEAGE.

WORSE YET, EXTENDED RUNNING WITH DYSFUNCTIONAL AIR CUTOFF VALVES CAN CAUSE SEVERE ENGINE DAMAGE OR FAILURE. WHEN THE VALVES ARE DYSFUNCTIONAL, THE ENGINE PULLS IN JUST ABOUT TOTAL AIR IN THE LOW RPM RANGE THROUGH THE CARBS AND ON TO THE COMBUSTION CHAMBER. THE FUEL/AIR RATIO IS EXTREMELY POOR WITH PRE-IGNITION LONG BEFORE THE NORMAL 38-40 DEGREE FIRING POINT. AN ENORMOUS AMOUNT OF HEAT IS GENERATED WITH NO POWER, WHICH IS TRAPPED A LONGER PERIOD OF TIME IN THE CYLINDER BEFORE THE EXHAUST VALVE OPENS. THIS HEAT GOES MOSTLY UP THROUGH THE CYLINDER HEAD GRADUALLY INCINERATING THE HEAD GASKETS AND ALLOWING ENGINE COOLANT (ANTI-FREEZE) TO SEEP INTO THE ENGINE.
YOU CAN EASILY SPOT WHEN YOU ARE IN TROUBLE BY A PUFF OF BLUISH-WHITE OR WHITE SMOKE ON FIRST STARTING THE ENGINE. DON'T LEAVE IT ALONE. CHANGE THE HEAD GASKETS IMMEDIATELY OR YOU COULD TAKE OUT YOUR BOTTOM END BEARINGS AND RUIN THE ENGINE.

ALSO, FOR THOSE OF YOU INSTALLING NEW EXHAUST SYSTEMS, FAULTY VALVES WILL DISCOLOR YOUR HEADPIPES, EITHER BLUE (LEAN STATE), OR GOLD (RICH STATE) . YOU CAN DE-STAIN YOUR PIPES USING "BLUEAWAY" OR "BLUE-OFF" BUT BE CAREFUL NOT TO RUB THE CHROME. JUST DAB GENTLY. THESE COMPOUNDS ARE USUALLY PURCHASED AT A HARLEY DEALER OR HARLEY ORIENTED AFTERMARKET SHOP.
HONDA GENUINE PIPES, LIKE MANY YAMAHA PIPES, HAVE A DOUBLE WALL FOR A PORTION OF THE HEADPIPE WHICH MASKS THIS DISCOLORATION BUT ALSO MASKS A BAD STATE OF TUNE. SO, IF YOUR PIPES ARE ORIGINAL AND STILL IN GOOD SHAPE, DON'T THINK THAT YOU ARE OK. IF THE BIKE HAS ANY OR ALL OF THE DYSFUNCTIONAL AIR CUT-OFF VALVE RUNNING AND PERFORMANCE CHARACTERISTICS, YOU'RE IN TROUBLE.

IF YOUR `75 - `87 GOLDWING IS NOT GETTING 50 TO 58 MILES PER GALLON (20 - 23 KM/ LITER), YOU HAVE ONE OF THE MOST OBVIOUS SIGNS OF TROUBLE. IT IS LIKELY YOUR AIR SCREWS HAVE BEEN BACKED OUT TO TRY OVERCOME THE EFFECTS OF THE POOR RUNNING, STUMBLING AND STARTING WITH STALLING AND QUITTING.
RESYNCHRONIZE ALL FOUR CARBS TO THE NUMBER 3 CARB VACUUM LEVEL USING MERCURY CARB STICKS OR VACUUM DIAL GAUGES. STAY WITH STRICT USE OF THE SETTING LEVELS IN EITHER THE HONDA, CLYMER OR HAYNES MANUALS. DO NOT ATTEMPT TO TUNE ANY OTHER WAY. GUESSING WILL NOT WORK AND CAN CAUSE DAMAGE!!!



This sounds reasonable to me. Any input from the GURU's? What's the difficulity of replacing this valve?
 

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This is a different item, the air cutoff valve(s) are different than the cold air suction purge valve! The cold air suction valve is located on the bottom of the carbs along with the reed valves and the unit is removable as a single section. you have to remove some body parts to remove it. the item that is refered to can be bought aftermarket(JC Whitney) has them. you have to get into the carbs to fix them and be able to resync them.

amungus
 
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