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dead # 3 cylinder

Posted: Tue Dec 29, 2015 9:57 pm
by badshow
hey guys I am new to this,

over the winter of last year I was given an 82 gold wing 1100 interstate from a relative.. sat outside for 2 years un covered in all types of weather. did some restoring on it over the winter and I have been riding it all summer long its been a blast but I seem to think I have a dead cylinder.

I have rebuilt the carbs, compression is good, and I have spark.

when I pull the boot to spark plug/cylinder 3 it does not change idle or affect how the engine is running but when I pull 1,2, or 4 it does change how engine is running..

so question is. is this a primary cylinder that will not affect when boot is pulled off
(only reason I say that is because when you sync the carbs you use #3 as a primary to work off of.

and if it is suppose to fire or change the way that the engine is running what should I look at?

I just today replaced the boots with ngk, new ngk plug, I do get spark to plug , compression is equivalent with all other cylinder, and its a rebuilt carb not even 4 months ago and its been doing this the entire time, I'm pretty confident its not the carb.

I have read some things on the fuel valve (flapper type diaphragm) could this be my problem>? or perhaps the well hole?..

I do have a slow engine oil leak at the output shaft seal , could that cause it? I'm trying to refrain from pulling the engine because once I do its full restoration :) ..... :(

answers or hints please and thanks?

Re: dead # 3 cylinder

Posted: Tue Dec 29, 2015 10:20 pm
by wingman12
Good evening badshow and welcone to the best GW site out there. Many, many knowledgeable and friendly wingers here. I am no expert but from what you are telling us is: you have spark on #3 but no performance difference. It can't be the coils because then you would have two cylinders not firing. I would suspect there is a fuel supply issue to number 3 cylinder. Pull plug on 3 and see if wet with fuel or dry. I will wager dry. :D :D

Re: dead # 3 cylinder

Posted: Tue Dec 29, 2015 11:09 pm
by Aussie81Interstate
I think from your description - it could be either a bad plug lead (but you have spark) - or a bad fuel supply - can you confirm fuel delivery to carb #3 by undoing the drain plug and see if anything comes out - other than that I would pull the carbs and bench test them for fuel flow, and clean jets and passages again, and reset float height. Pulling #3 lead off should make a difference to the motor when running. Also make sure the vacuum slide is operating smoothly.

What is it like going up any sort of hill - does it backfire or sputter or struggle?

Re: dead # 3 cylinder

Posted: Wed Dec 30, 2015 5:48 am
by Maz
Hi badshow and welcome.
If I'm reading your post correctly, the bike rides fine but, at idle, removing that plug cap makes no difference. Personally I would suggest good ol' blocked idle circuit in #3 carb. As anyone on here will tell you, the idle passages are minute and can clog up very easily. Even though the carbs have been cleaned, it's not unusual to still have a blocked idle circuit. Then again..........I may be wrong!

Re: dead # 3 cylinder

Posted: Wed Dec 30, 2015 8:03 am
by ekvh
Easy stuff first, swap 1-3 spark plugs to see if it follows the plug. Several reports of new NGK fails right from the box. Could also revisit your connections at the caps and check ohms of resistors to ensure you're getting enough spark.

No sense pulling carbs until you're sure.

Re: dead # 3 cylinder

Posted: Wed Dec 30, 2015 8:37 am
by dingdong
To answer your main question. Yes there should be a change when "all" plugs are pulled. I too suspect that the idle circuits are at fault. No reason to worry about pulling the engine, just the carbs more than likely. Compression: Good. Spark: Yes. Only one thing left: Fuel. Rebuilt carbs? Did you do this yourself or did someone else rebuild for you? One other possibility: Are you sure the idle mixture screws are set properly? (by the book and not by ear)

Re: dead # 3 cylinder

Posted: Wed Dec 30, 2015 10:09 am
by badshow
thanks for the help so fast guys!

ok so to answers everyones question to the best of my ability. I am not hundred percent sure that the idle mixture screws are set properly, I will look into that, and advice or hint on where to start with them? but I could guarantee that they are all set pretty dam close to each other. I did rebuild the carburetor myself , I have done plenty of work on other bikes and I am a tool maker, I am pretty mechanically inclined. but I could have messed something up...( although I did one carb at a time all in same order )

I have swapped plugs around to see if its the actual plugs and it still the same scenario, ive pulled the carbs about 4 times this year its pretty easy once u got it down:)

and doing so pulling the carbs and cleaning them each time it could be possible that their are passage ways got clogged that aren't replaceable, because the kit I got was from Honda very expensive and it replaced it all jets,springs,seats, ect.... there was a lot of crap and leaves in the carbs and I made sure to clean with carb cleaner and seafoam and too look for a good flow and blasted all out with air now could I have pushed more crap in? probably...

I am going to within the next 2 days pull the drain plug and see if I get fuel coming out.. I think I have done this but I wanna be sure I will try it...and Aussie81interstate, you said vacuum slide operating smoothly? what would be a bad case on that slide? (i have never actually ran into a bad slide, 8 years exp).. also their was a backfire earlier this year but it was fixed with carb rebuilt and set float heights, going uphill it does struggle or sputter it may backfire but not enough that i would notice on a regular.

thanks for all the help guys i will try what you all said and look into it


have any of your hear about the air intake diaphragm causing this problem, that's just about the only thing i did not replace and i did take a brief look at it and it was shot to hell, didn't look to healthy, whats thoughts on that? and how about the well for plug> could that need to be cleaned out?

Re: dead # 3 cylinder

Posted: Wed Dec 30, 2015 5:39 pm
by Aussie81Interstate
Each cylinder head has passages to let out any water or fluid that falls into the spark plug well area. If these become blocked it would more likely cause a spark plug to misfire or short to the cylinder head area instead of the bore. You should be able to just run compressed air through to clear them out - or in extreme circumstances of buildup- poke a small wire through them then make sure you have a clear passage.

If it struggles going uphill then I reckon it is definitely not firing or getting any fuel.

PS- I'm reasonably mechanically minded - and regards rebuilding carbs - I did mine 4 or 5 times on an old 1975 CB750FO, and it was the last time I cleaned/rebuilt them (all with original jets - but put in new O rings), that they finally decided to start operating correctly. Float height was a critical part of that process - as it would run great for about 5 minutes - then the differences in float height would see it start running on three cylinders as one carb level was too low and it started starving for fuel.

All the air passages must be spotless, and jets clear before these will run sweetly. The slides must be smooth and do not need any lubrication to operate.

Good luck - cheers :)

Re: dead # 3 cylinder

Posted: Thu Dec 31, 2015 10:13 am
by dingdong
Off the top of my head, I'm not sure what you mean by fuel valve diaphragm flapper style. Where is this located? There is an accelerator pump diaphragm and an air cutoff valve diaphragm. Accelerator pump diaphragm will cause hesitation on accel. Air cutoff diaphragm will cause back firing on decel. Neither should cause your problem with #3 as you describe.

Look over at Randakks site and read all concerning gl1100 carbs.

Happy New Year

Re: dead # 3 cylinder

Posted: Thu Dec 31, 2015 4:03 pm
by indianakid

to set the record straight................

a failed air cut off valve diaphragm will cause your problem. a stuck valve with a good diaphragm will cause the problem described by dingdong.


If the air cut out valve has stuck in the normal / lean position (spring held position) and the diaphragm is in good condition then it would cause backfiring due to the lean condition. When working normally the spring holds the valve in the lean position (two air bleed jets supplying air) when the throttle is snapped closed manifold vacuum goes up to 20+ inches pulling the diaphragm valve to close off one of the air bleed jets causing the idle mixture to enrichen eliminating backfire.

If the air cut out diaphragm has failed it will cause a very over rich condition. This is because it will port manifold vacuum to the idle air bleed circuit. And since manifold vacuum is much higher than venturi vacuum it will draw fuel and air from the idle jets and air bleeds at a much greater amount delivering it directly into the manifold down stream of the throttle plate.