My 500 4 is poorly

[paulbaker1954]

Help....

I have been trying to chase down a problem with my bike that started with cylinder 1 sounding like a tractor.

I have checked the exhaust and no loose baffles to be heard.

Next step was to check the plugs and oddly number 1 looks ok but the others all look a bit rich. This a bit odd as carbs have been fully rebuilt with ultrasonic cleaning and all new jets etc so not convinced I have a carb issue.

Next I checked the compression and am only getting 135 psi on all pots. Again a bit odd as she has had new pistons and rings but maybe my bore measurements were off!! On putting some oil down the bores compression climbed to 175 so that would seem to confirm a piston/ring problem. But again why would this cause this noise only from cylinder 1

I think I have come to the conclusion that I need to at least pull the head and block and check all over again.

But before I reach for the toolbox I would appreciate and ideas anyone else has having listened to the sound

As I said in the first sentence the issue is the rough sound from cylinder 1

I have posted here on YOU TUBE.
http://www.youtube.com/watch?v=R-Xa4GgAUno

http://www.youtube.com/watch?v=WscXzWjlIQU

The first vid you can hear the rough sound and in the second I disconnected spark plug 1 so you can hear the difference.

[Seabeowner]

Paul, Difficult to hear where the noise is coming from, but a clicking sound is often an exhaust leak at the head.
As all your compression figures are similar for all cylinders, I don't think that's the problem.

[paulbaker1954]

Paul, Difficult to hear where the noise is coming from, but a clicking sound is often an exhaust leak at the head.
As all your compression figures are similar for all cylinders, I don't think that's the problem.

Definitely not a leak from head or exhaust manifold

It almost sounds as if there is no baffle in no  1 pipe and if you hold your hand over end of pipe you can feel its a completely different pressure pulse

[royhall]

What's it running like Paul. That's the sound you get when a cylinder isn't running or only partially running.

[paulbaker1954]

What's it running like Paul. That's the sound you get when a cylinder isn't running or only partially running.

Seems to run fine and plug 1 a nice tan colour

Wondering if this could be a broken valve spring

[royhall]

Doubt it or your compressions would be out. Does the sound stay the same when you rev the engine.

[paulbaker1954]

Doubt it or your compressions would be out. Does the sound stay the same when you rev the engine.

Stays similar but not as pronounced

[jon stead]

Could be a sticking valve. Does it make this noise with the ignition off and you kick it over?

What have you done to the engine or changed, since it was last running without that noise?

[paulbaker1954]

Could be a sticking valve. Does it make this noise with the ignition off and you kick it over?

What have you done to the engine or changed, since it was last running without that noise?

You can’t hear any noise kicking over or turning over on starter as I said only hear it when ticking over

I have done no engine work apart from a service and oil change and it has been in garage all winter and not used

[Trigger]

You will have to go the elimination process. Remove the spark plug cap on number 1 while ticking over and listen to the rocker cover. I would then remove number one pipe and fit a old down pipe to see if it is the exhaust.
The second vid only lasts 1 second so, I cant see or hear anything.

[paulbaker1954]

You will have to go the elimination process. Remove the spark plug cap on number 1 while ticking over and listen to the rocker cover. I would then remove number one pipe and fit a old down pipe to see if it is the exhaust.
The second vid only lasts 1 second so, I cant see or hear anything.

Thanks Trig by the way I am considering whether a rebore is needed with only135 psi  on all cylinders, what do you think

I am a bit surprised at the levels given i pit new std pistons and rings in only 2k miles ago and swear blind that I measured the bores as in original limit of 56mm but hey ho maybe my measuring was diff.

[deltarider]

Maybe your compression test wasn't accurate. I myself never managed to do it correctly.

[royhall]

If they are all the same pressures I wouldn't worry, your gauge may be wrong. Can you check on another bike and see if that's low as well.

The "duff duff duff" noise really does sound like the cylinder is only partially running, maybe a blocked pilot jet that would go away as the revs rise so appears to be running okay. The fact that the plug is a different colour to the others would suggest carb issues. The plugs tend to blacken up if you check them after the engines been ticking over for a while, and that one hasn't blackened.

Since it's an outside carb it's probably reachable without removing them, I would check the pilot jet is clean first as it's easy to do and costs nothing.

[Colonial-Clive (yindi)]

You say you've refurbed carbs, have you had them synced, my bike sounds like a tractor at the moment and the only thing I haven't don't is carb sync.

[Trigger]

You old boys worry too much  . 135 psi on a dry test is fine for a non rebored engine. I would not even bother if I was getting that result, the engine has only just run in and hasn't had time to really coke up to seal.
The futting noise sound like a exhaust problem, that is where I would start. Block the end of number one pipe with a rag on your had and see what the change is.