#3 Cylinder Issues - General Operating Question

[Lotsokids]

When I bought my bike a little over 2 years ago, I rode it home and found the #3 coil wire broken. I repaired it, and eventually upgraded to Coil Over Plugs (COPs). It's continually had strange "popping" sounds from #3. I have a true 4-into-4 exhaust now, so I can hear and feel what that particular cylinder is doing. Riding at slow speeds it sounds rough. When I pour on the gas, it clears up and stretches my arms. I'm a somewhat big guy - 235 pounds, and can run the 1/4 mile at 11.65 ET with everything mostly stock and modified exhaust.

When I put my hand at #3's exhaust exit, it doesn't seem to have the positive flow like the others. It does a "pop - pop - pop." Not like the others.

I don't know how long the previous owner rode the bike without #3 firing. Could this have messed up the valves on that cylinder a little? :confused2:

 

[RempageR1]

Did you check the carbs? Are all jets clean and are the diaphragmsall still in tact?

I`d start there if I were you and not worry too much about the engine itself at this time.

 

[Traumahawk]

First of all, there is a method of cleaning, called a shotgun. It cleans out the idle circuits. The idle circuits on a Vmax operate from 0-4000 rpm, and from 0-1/8th.....maybe 1/4 throttle.

The idle circuits are VERY small, and easily clogged up with sediment, or ethanol in the gas. The idle circuits can even be clogged up in as little as 30 days from the bike sitting. (Ive heard that gas nowdays only has a shelf life of 90 days or less.)

When you do the shotgun, that will give you the chance to look at the diaphragms, and see how everything is.

Ive also had better luck with taking out PAJ#2 to get a full blast of air.

http://vmax.lvlhead.com/tips/shotgun.htm

 

[Traumahawk]

Oh.......usually a "pop" is a lean condition (caused by a carb circuit being plugged....or partially plugged.)

So start there......and report back what you find.

 

[Lotsokids]

I've done the shotgun procedure a while back, but no improvement.
I might need to do it again.

It's quite a coincidence that I'm having these problems with the same cylinder that has not fired in an unknown amount of days / months / years.

 

[Traumahawk]

I've done the shotgun procedure a while back, but no improvement.
I might need to do it again.

It's quite a coincidence that I'm having these problems with the same cylinder that has not fired in an unknown amount of days / months / years.

Did you take out PAJ#2? I had a clog that happened a couple of years ago after changing jets. I did 2 or 3 shotguns, and still couldnt get rid of it. i took PAJ#2 out, so that way i could get a FULL blast of air into the idle circuits, and got it out the first try.

LVL head recommends using an air compressor that has like 100-110 lbs of pressure with it. Even though that PAJ#2 is a 170, thats still a small area trying to get all of that pressure thru. With the jet out, then you can get the full nozzle into the carb, then you can get the full blast of air.

 

[fbnewell]

If you think you did a good job at cleaning the carbs and it's still running rough at idle / slow speed, I'd consider synching the carbs. Shotguned mine 3 or 4 times, still a low speed miss. Bought a CarbTune Pro 4, hooked it up, and the synch was so far off that one of the cylinders wouldn't even indicate on the gauge. Almost 4 turns to balance #1 & #2, over 2-1/2 turns to balance 3 & 4, and over one turn to balance left and right. Like a brand new bike after that! Like you, it seemed to run really well at higher rpm and on VBoost. I was afraid I had a valve train problem. Just my 2 cents worth, and worth every penny!

 

[caseyjones955]

If you think you did a good job at cleaning the carbs and it's still running rough at idle / slow speed, I'd consider synching the carbs. Shotguned mine 3 or 4 times, still a low speed miss. Bought a CarbTune Pro 4, hooked it up, and the synch was so far off that one of the cylinders wouldn't even indicate on the gauge. Almost 4 turns to balance #1 & #2, over 2-1/2 turns to balance 3 & 4, and over one turn to balance left and right. Like a brand new bike after that! Like you, it seemed to run really well at higher rpm and on VBoost. I was afraid I had a valve train problem. Just my 2 cents worth, and worth every penny!

Aside from Erics excellent advice, every Vmax owner should have a Carbtune. I can feel it when they are even a little out of whack, after a shotgun or even just as routine maintenance I synch em' up a couple times a season.

 

[[email protected]]

Compression test would be a quick way to clear or confirm your worries

Sent from my SM-G930V using Tapatalk

 

[Jan Bee]

When I bought my bike a little over 2 years ago, I rode it home and found the #3 coil wire broken. I repaired it, and eventually upgraded to Coil Over Plugs (COPs). It's continually had strange "popping" sounds from #3. I have a true 4-into-4 exhaust now, so I can hear and feel what that particular cylinder is doing. Riding at slow speeds it sounds rough. When I pour on the gas, it clears up and stretches my arms. I'm a somewhat big guy - 235 pounds, and can run the 1/4 mile at 11.65 ET with everything mostly stock and modified exhaust.

When I put my hand at #3's exhaust exit, it doesn't seem to have the positive flow like the others. It does a "pop - pop - pop." Not like the others.

I don't know how long the previous owner rode the bike without #3 firing. Could this have messed up the valves on that cylinder a little? :confused2:

I asked my brother jon if he thought it could be the COPs and he said it could be one of 3 things. Gas ,fire or compression. If you have completed the shotgun and a carb sync check the ohms in the cops to see if it is any different from the others. He also has not heard of one going bad yet. If it is a COP he will be happy to replace at his expense. Next would be a compression test of all cylinders to see if #3 if lower than the others.
One member he sold COPs to pushed the connector onto the stock coil connector and it pushed the stock blade out of the harness. i would check the connections in the harnesses also. Please send me a message if it is a COP gone bad (as that happens in the US all the time) and he will send you a replacement. JB.

 

[Bill Seward]

Can't get any more reasonable than that. I bought one coil stick extra to keep as a spare. I think I paid about $4.00 on EBay. I keep it up under the seat near the voltage regulator "just in case" one of the 4 COPS fails while riding. Honestly, I don't think that's gonna happen, though.

 

[Lotsokids]

UPDATE: JUST STANDARD MAINTENANCE!

I decided to sync my carbs today. Found #3 way off (lean I think) and #4's vacuum cap was very dry-rotted and probably leaking.

After syncing the carbs and installing all new vacuum caps, it idles very smoothly without popping.
Also, yesterday I added 1/2 can of SeaFoam to a 1/2 tank of fuel.

 

[Jan Bee]

UPDATE: JUST STANDARD MAINTENANCE!

I decided to sync my carbs today. Found #3 way off (lean I think) and #4's vacuum cap was very dry-rotted and probably leaking.

After syncing the carbs and installing all new vacuum caps, it idles very smoothly without popping.
Also, yesterday I added 1/2 can of SeaFoam to a 1/2 tank of fuel.

1/3 of a can to a full tank.

 

[Traumahawk]

UPDATE: JUST STANDARD MAINTENANCE!

I decided to sync my carbs today. Found #3 way off (lean I think) and #4's vacuum cap was very dry-rotted and probably leaking.

After syncing the carbs and installing all new vacuum caps, it idles very smoothly without popping.
Also, yesterday I added 1/2 can of SeaFoam to a 1/2 tank of fuel.

Glad that it was something simple.

 

[Jan Bee]

+1

 

[MaxMidnight]

Glad that it was something simple.

It usually is but there must be something in the human psyche the makes us want to look for something complicated rather than checking the basics first.

A good lesson for all of us.

 

[Traumahawk]

It usually is but there must be something in the human psyche the makes us want to look for something complicated rather than checking the basics first.

A good lesson for all of us.

VERY TRUE my friend.

I am a huge fan of occams razor.

With all other things being equal. the SIMPLEST answer is usually the most correct one.

 

[Jan Bee]

https://www.youtube.com/watch?v=G-tCIRJH9p0

 

[Lotsokids]

* Disregard previous update. The problem is back. *

I had an appointment yesterday after work 2 hours away in Budapest. When I started my bike, I could tell I lost power in #3 again. I felt the exhaust (reminder: I have true 4-into-4) and #3 was dead. When I rode it to work, it was fine. But after sitting for 8 hours, #3 died. Not sure how that's connected.

During the first mile ride, during acceleration, it was backfiring occasionally very loudly from #3, then cleared up.
I rode it for the next 5 hours with no problems at all and awesome performance. It ran perfectly

Could I have a piece of trash in my float bowl? I've drained it a couple times. Next step I suppose is removing the bowl and cleaning / inspecting. The problem is that I live in Hungary and I cannot get a bowl gasket in less than about 30 days. I've done this task before and the gasket tears every time.

Thoughts?

 

[adambweird]

Well, in lieu of removing the bowl you could open the drain screw for the hose that sticks out, keep a mason jar under it and cycle the key as needed to get gas pumping out... or pull the carbs off, set em on a stand next to the bike with the drain plug removed from the bowl and a jar under it and attach a fuel line extension and cycle the key as needed to get gas flowing. May or may not work, but its something to try if youve got no luck with bowl gaskets.