Pics of fouled plugs????

Raywood

The Pirate
Staff member
Calendar Participant
Troop Supporter
I would probably go back to the sparkplug. Did you pull it and turn the motor over to verify if it's sparking? If not do so.
I would assume that if you had any problems with a lifter, valve or rocker you would HEAR it.
Lets go back to the spark.

:D
 

BadBrad

2005 Pitbull
I would probably go back to the sparkplug. Did you pull it and turn the motor over to verify if it's sparking? If not do so.
I would assume that if you had any problems with a lifter, valve or rocker you would HEAR it.
Lets go back to the spark.

:D
Well, I was able to get the rocker box lid off without removing the tank and the rocker arms looked good. Nothing obvious like a break or loose roller bearings that have broken. I'll get it put back together and look at the plug again. Earlier, I put a voltage meter on the plug wire and got 14V on the cycle, so I feel sure I'm getting fire. I put a plug in the wire and turned the motor over and when I got my hand a little close, it jumped out and bit me. After changing my underwear, I came to the assumption that I was getting a spark to the plug. Something's just not adding up. Should I be able to pull the wire while the bike is running without getting shocked? I cranked the bike and removed the plug wire and the motor did not change in the way it was running, so I know I"m not getting fire and/or gas in that cylinder. :spank:
 

BadBrad

2005 Pitbull
The bike is back together and I re-checked the fire to the plug. I left a plug in the cylinder and used a spare plug and it definitely has fire. Hooked the plug wire back to the plug in the motor, still nothing on that cylinder. So, we have fire, push rods are good, rocker arms are good. If the plug is left out of the motor while running, shouldn't there be gas spewing out? (assuming it's getting any). If it's not, then I'm down to only 2 more checks on my list for reasons why gas would not be going into that cylinder. Also, can I pour a little gas in the plug hole and see if it fires for a couple of seconds or will I be jeopardizing something by doing that?
 

lee

Well-Known Member
Brad - have you actually seen the spark by grounding it to the cylinder and firing? Also, have you done a compression test? Pouring gas into the spark plug hole won't do anything as you won't have compression and liquid gas doesn't really burn.
 

woodbutcher

Mr. Old Fart member #145
Staff member
could an intake leak on the rear cylinder cause the gas not to be drawn into that cylinder???????????
 

BadBrad

2005 Pitbull
Brad - have you actually seen the spark by grounding it to the cylinder and firing? Also, have you done a compression test? Pouring gas into the spark plug hole won't do anything as you won't have compression and liquid gas doesn't really burn.
Yes! I held the plug with a pair of pliers and set it against the jug to ground and sparks are quite visible. Also, while I had the push rods visible, I pulled the plugs, put the bike in 6th gear and rotated the wheel. The rods are moving so I would assume the flat spot on the cam lobe is not really what is wrong here. However, I didn't rotate the wheel when I had the rocker box lid off. This might have confirmed that the valve is being depressed. If need be, I'll take the lid off again and do that. :bang::bang::bang:

Woodbutcher's suggestion sounds more like something feasible.

With the plug out, should gas be coming out of the plug hole? Still trying to determine if gas is entering the cylinder.
 

BadBrad

2005 Pitbull
Brad - have you actually seen the spark by grounding it to the cylinder and firing? Also, have you done a compression test? Pouring gas into the spark plug hole won't do anything as you won't have compression and liquid gas doesn't really burn.
I have not done a compression test. Could low compression cause the cylinder not to fire? I would think it would fire but just may not have the power that it should. There is no fire at all on that cylinder. The exhaust is cold and removing the plug wire while running does not affect anything.
 

DRBarnhart

Insert title here...
could an intake leak on the rear cylinder cause the gas not to be drawn into that cylinder???????????
Absolutely! And a decent sized leak IN the cylinder of any sort (intake, exhaust, or rings) could make that happen. There wouldn't be any suction to draw in the air/fuel mix. The intake manifold is attached to the cylinder tightly, right?

A quick compression test, even if it's just your finger over the spark plug hole, wouldn't be a bad idea at this point. If you do use your finger compare the front and rear cylinders to see if there's a difference.

Dennis
 

BadBrad

2005 Pitbull
Absolutely! And a decent sized leak IN the cylinder of any sort (intake, exhaust, or rings) could make that happen. There wouldn't be any suction to draw in the air/fuel mix. The intake manifold is attached to the cylinder tightly, right?

A quick compression test, even if it's just your finger over the spark plug hole, wouldn't be a bad idea at this point. If you do use your finger compare the front and rear cylinders to see if there's a difference.

Dennis
Dennis is dead on the money. I gave my bike the "finger" test. Lots of compression on the front cylinder. Absolutely none on the rear. Damn near a vaccume! :job: With that mystery being solved, can you give me a few scenarios that would cause this? From your reply, bad rings for sure. I guess that I'm in for a full breakdown of the cylinder, rocker box, head and jug. I have 12 point sockets. Any other special tools needed for this? Just bragging on the sockets Ray. Thanks guys. I may not like the fact that I'm down, but it's great to have you guys on this forum. I feel sure I can do the work. With the forum I may never take that bike back to a stealership. :cheers:
 

DRBarnhart

Insert title here...
...can you give me a few scenarios that would cause this?
This could be anything that "vents" your cylinder to the outside air (or crankcase) like:

1. the compression relief valve stuck open
2. a valve sticking open (or severely burned)
3. rings that are totally blown out
4. a hole/crack in the piston
5. a cracked head
6. a crack in the cylinder wall

Check the easiest thing first (the compression relief valve) and go from there...

Dennis
 

BadBrad

2005 Pitbull
This could be anything that "vents" your cylinder to the outside air (or crankcase) like:

1. the compression relief valve stuck open
2. a valve sticking open (or severely burned)
3. rings that are totally blown out
4. a hole/crack in the piston
5. a cracked head
6. a crack in the cylinder wall

Check the easiest thing first (the compression relief valve) and go from there...

Dennis

I did a search on this and don't really see anything on the forum or in manual on removal or troubleshooting for the compression relief valve. I had a good look at it when I had the Rocker box lid off today. Still, not sure if checking it out is electrical or mechanical or both. :confused: Is there a "how to" or is it a simple procedure once you know how? I just went out and checked the Compression relief valve to see if it was operational. It appears to be working. It sucks in for about 1 second the moment you push the start button and then pops back up after that second. Does this rule out that valve? Could the valve not be releasing all the way back up? Should I be able to feel pressure coming from the top of the rocker box at this valve while the motor is running if this is the cause for loss of compression? Just a few questions to ponder on.
 
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DRBarnhart

Insert title here...
I just went out and checked the Compression relief valve to see if it was operational. It appears to be working. It sucks in for about 1 second the moment you push the start button and then pops back up after that second. Does this rule out that valve?
That pretty much says it's working.
Could the valve not be releasing all the way back up?
Even if it wasn't popping all the way up the cylinder should have enough compression to fire, after all, even when the valve is fully open the engine fires.
Should I be able to feel pressure coming from the top of the rocker box at this valve while the motor is running if this is the cause for loss of compression?
I suppose that would be possible if the valve had a major leak in it.
Just a few questions to ponder on.
You got that right!

So here's another thought... With the spark plug out, blow air into the hole (a compressor would be good) and see if you can hear it in the carb or the pipes or anywhere else for that matter!

Dennis
 

BadBrad

2005 Pitbull
Dennis, thanks for your help dude. I'll do the "blow test" tomorrow. Running out of time tonight. Been a long day but I'm sure glad to narrow down the problem with that Dog. I suppose that regardless of where air may be leaking to, I still have a tear down in the near future. I'll probably get started tomorrow after work. I still have a few months of summer left down here in the tropics of Lowsyana. Thanks again for all your help today. And to the rest of the pound that chipped in, I really do appreciate it. I'll update when I find the root cause.
 

Raywood

The Pirate
Staff member
Calendar Participant
Troop Supporter
I'm still of the mind that if you have a broken ring or any other broken part you would hear it.
As for not having any pressure in the rear cylinder....... Well guess that could be a overly adjusted push rod that is keeping the valves open on the compression cycle and that will burn valves.

A compression release leak would be minute but the cylinder should still fire properly.

Will be all ears to hear what you find out when you pull the top end off.

:cheers:
 

woodbutcher

Mr. Old Fart member #145
Staff member
just a few things running through my little spinning head.

back cylinder is not firing
plug is hot and firing
plug does not have gas on it
compression relief sounds like it's working but would fire even if it were completely open
just had work done on front cylinder and probably had the intake manifold off
??? intake manifold didn't seat properly on the rear head when re-installed??? not allowing vacuum to suck in fuel mixture.
definitely need to do the compression check but also need to listen around the intake and not just the throat of the carb.

good luck, badbrad

not trying to step on anybody's toes here, just my logical side trying to get some exercise, and maybe open another line of thought before he tears it down. AIN'T THAT RIGHT, RAY???????? :2thumbs::2thumbs::2thumbs:
 

Raywood

The Pirate
Staff member
Calendar Participant
Troop Supporter
not trying to step on anybody's toes here, just my logical side trying to get some exercise, and maybe open another line of thought before he tears it down. AIN'T THAT RIGHT, RAY???????? :2thumbs::2thumbs::2thumbs:
You got that right. Expensive adventure for me for sure but probably necessary after seeing the rear valve guide. :D
 

DRBarnhart

Insert title here...
...just had work done on front cylinder and probably had the intake manifold off
??? intake manifold didn't seat properly on the rear head when re-installed??? not allowing vacuum to suck in fuel mixture.
I was thinking that originally but when he said there was absolutely no compression it seemed to somewhat rule that out. After all, even if there were an intake leak there should still be compression once the intake valve closes and the piston heads in the opposite direction.
definitely need to do the compression check but also need to listen around the intake and not just the throat of the carb.
I agree 110% that's why a said "carb AND pipes". Guess I should have said "exhaust" pipes just to be sure I was making myself clear. Thanks WB! :up:
not trying to step on anybody's toes here, just my logical side trying to get some exercise, and maybe open another line of thought before he tears it down.
I don't know if you're referring to me but if you are don't sweat it, I'm here to help and learn just like everyone else! :2thumbs:

As far as I'm concerned if there's anyone that has any ideas that'll troubleshoot and fix Brad's ride cheaper and easier than any of my suggestions please don't hold back!!! The more ideas that get thrown around the greater the chance that one of them will be just what the doctor ordered! (And the more we'll all learn!) :cheers:

Dennis
 

lee

Well-Known Member
Brad - make sure when you blow compressed air into the cylinder that you have TDC on the compression stroke. Otherwise valves will be open and your mini leakdown test won't tell you much.
 
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