Stumped. .... cylinder not "firing"

[DaveWJunior]

I have a '98 standard with 17K that I've owned since new.  The only non-cosmetic mod is a 6into6 exhaust.  As I was cleaning the pipes, I noticed fuel on the inside of one of the pipe ends (cyl. #3).  When I pulled the plug (1 year on the plugs) it was wet, but with a good spark while running.  When I start the bike, I'm able to touch the exhaust pipe at the head for over a minute before it gets too warm (as opposed to about 10 seconds on all the others).  I drained the bowl on the carb (plenty of clean gas ran out),pulled the top off the carb (good rubber) and sprayed some cleaner around and worked the choke, but still no luck.  Any ideas?  I only put about 150 miles on it last year, but always run Seafoam or Sta-Bil in the gas.  The gas in there now is fresh.

[Ricky-D]

First thing to do is perform a compression test on the motor, paying particular attention to that cylinder.

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[Spirited-6]

Welcome Dave. Where have you been since 1998 ?

[98valk]

I have a '98 standard with 17K that I've owned since new.  The only non-cosmetic mod is a 6into6 exhaust.  As I was cleaning the pipes, I noticed fuel on the inside of one of the pipe ends (cyl. #3).  When I pulled the plug (1 year on the plugs) it was wet, but with a good spark while running.  When I start the bike, I'm able to touch the exhaust pipe at the head for over a minute before it gets too warm (as opposed to about 10 seconds on all the others).  I drained the bowl on the carb (plenty of clean gas ran out),pulled the top off the carb (good rubber) and sprayed some cleaner around and worked the choke, but still no luck.  Any ideas?  I only put about 150 miles on it last year, but always run Seafoam or Sta-Bil in the gas.  The gas in there now is fresh.

plug itself could be bad, had that on a truck once, swap plugs to check. bad wire to plug connection?
change your intake manifold o-rings. I had the same problem around the same miles.
use viton ones from http://redeye.ecrater.com/   although not shown on site right now, might be out of stock, contact them.
could also be bad petcock diaphragm, causing lean condition. Is this one of the forward cylinders?

[DaveWJunior]

Thanks for the welcome!  Actually, I've been a VRCC member for over 10 years.  My member number is somewhere around 4500 but I can't seem to find it anywhere.  I think my handle was "Tower" or something like that.  I was a member and active in the New England chapter for a few years, but have since moved to Maryland where there doesn't seem to be as many active members.  I haven't been putting many miles on the Valk lately (but would NEVER DREAM of getting rid of it) because the garage is full of other toys.  I did just over one tank of gas all last year.  I was thinking that maybe the carb is just gummed up, but the cylinder seems to be getting fuel.  

I'll go do a quick compression check and see what I find.

[DaveWJunior]

Ok, checked the compression, I'm within a few psi on the entire right bank.  Swapped out the plugs with no luck.  It's getting spark.  When I run the engine with #3 out, I get a spark jump of over 1/2" from to the case.  The plug is wet when it comes out and I'm getting gas residue on the inside of the pipe end so I'm assuming it's getting enough gas.  I suppose my next step is to take it to the Honda stealership and have them look it over.  I've never really been much of a carb mechanic, so I'm a little nervous about pulling it apart.

[Chrisj CMA]

OK, in terms of basic needs......that cylinder needs compression (has that) fire (has that) fuel (has that) and air.........so one would have to think......maybe a rat made a nest in the airbox and its clogging the intake tube?  Stranger things have happened.  Id pull the tank and check out the airbox at least before taking to the stealer.....

[sandy]

Maybe it has too much fuel to fire. The air/fuel ratio should be about 17:1 but a little rich will fire but leave black plugs. If there's too much fuel and not enough air, it won't burn. It could be a sticking float in that carb.

[DaveWJunior]

Ok, I've got the "system" soaking in B12 just in case something got varnished up.  I'll head out and pull the tank.  It's about time for a new air filter anyway.  I'll let you know what I find.  I think that maybe the "too much fuel" guess may be right.  I'm getting more fuel on the inside of the exhaust system than I thought I'd get.  Also, getting a little "backfire pop" from that exhaust pipe when I release the throttle.

[1fastbob]

which cylinder are you calling number 3?  If it is the back one on the left side that is number 6 and the diaphram is bad on the fuel tank shutoff causing excessive fuel to be sucked in through the intake manifold vacuum hose and fitting.  If you are correctly identifying number 3 then uhhhh, "Never Mind".

Hope this helps.

Bob

[DaveWJunior]

It's the center cylinder in the left bank.  I only call it #3 because that's what the plug wire says on it.   

Odd though, I've been riding the bike for about a week now (heck, maybe longer)with a dead cylinder and didn't really notice any decrease in HP (granted, I don't ride it that often) on 5 cylinders.  I can't wait for the new pep-factor once it's "firing on all cylinders" (to use a cliche' phrase literally) again.

[98valk]

It's the center cylinder in the left bank.  I only call it #3 because that's what the plug wire says on it.   

Odd though, I've been riding the bike for about a week now (heck, maybe longer)with a dead cylinder and didn't really notice any decrease in HP (granted, I don't ride it that often) on 5 cylinders.  I can't wait for the new pep-factor once it's "firing on all cylinders" (to use a cliche' phrase literally) again.

if it is the manifold o-ring as I have stated this is what is happening; huge vacuum leak so that cylinder is too lean to fire but there is still enough fuel to wet the plug, and so on.
 u can buy an o-ring I think its #123 (a search on this site will confirm what the # is) at most local hardware stores. about $0.60 for one.
or the carb sync vacuum cap on that manifold is leaking causing the same lean condition.

[Warlock]

It's the center cylinder in the left bank.  I only call it #3 because that's what the plug wire says on it.   

Odd though, I've been riding the bike for about a week now (heck, maybe longer)with a dead cylinder and didn't really notice any decrease in HP (granted, I don't ride it that often) on 5 cylinders.  I can't wait for the new pep-factor once it's "firing on all cylinders" (to use a cliche' phrase literally) again.

If it's the middle one on the clutch side that is #4 cylinder and not #3. Has anyone been fooling with the plug wires?
David

[Chrisj CMA]

I noticed that too....sometimes people call left and right as looking at it from the front, or as sitting on it.....but thats a good point if #3 wire is on the clutch side, that thar would be the problem, the plug in the actual #3 cylinder is firing at the wrong time

[1fastbob]

While seated on the bike.  Cylinders right bank from the front to rear # 1, # 3, # 5...left bank # 2, # 4, # 6.  If memory serves me correctly ther eare 3 coils that control 6 cylinders and #1 and #2 fire together #3 and #4 fire together and #5 and #6 fire together. Could be as stated earlier a large vacuum leak, but I would think it would fire under wide open throttle.  It is possible that #3 has a stuck or leaky needle valve that is causing a near hydrolock and / or the carb is overfilling causing excessive fuel in the number 3 cylinder.  This might account for the wet plug. Mine does a similar thing and the cause is a plugged (again) slow jet in the #6 carb. IE: Exhaust on #6 is colder than the rest of the pipes, misses at idle, slobbers (misses) at 2000rpm to 3000rpm, runs fine wide open.  The difference here is that my number 6 plug looks fine. I would be very curious as the the cause when you find it.

Best of luck

Bob

One other thought........I notice you have 6 into 6 exhaust.  Check the effected exhaust pipe for an obstruction such as mouse nest or mud dobbers nest.

[DaveWJunior]

Yeah, you're right.  I meant "RIGHT BANK MIDDLE".  The plug wires are in the right place.  If the B12 soak doesn't cure the problem, I'll start tearing the intake tube off and replace the o-ring.  Exhaust is flowing fine.  Thanks for all of the suggestions.

[salty1]

Was the B12 soak successful or did you have to pull the carbs? I'm presently doing a Chemtool soak and was curious how you let it sit the float bowls?