Honda-SOHC

SOHC.co.uk Forums => CB500/550 => Topic started by: paulbaker1954 on April 28, 2018, 05:24:05 PM

Title: My 500 4 is poorly
Post by: paulbaker1954 on April 28, 2018, 05:24:05 PM
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=R-Xa4GgAUno)

http://www.youtube.com/watch?v=WscXzWjlIQU (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.
Title: Re: My 500 4 is poorly
Post by: Seabeowner on April 28, 2018, 05:36:58 PM
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.
Title: Re: My 500 4 is poorly
Post by: paulbaker1954 on April 28, 2018, 06:09:28 PM
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
Title: Re: My 500 4 is poorly
Post by: royhall on April 28, 2018, 06:19:21 PM
What's it running like Paul. That's the sound you get when a cylinder isn't running or only partially running.
Title: Re: My 500 4 is poorly
Post by: paulbaker1954 on April 28, 2018, 06:22:55 PM
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
Title: Re: My 500 4 is poorly
Post by: royhall on April 28, 2018, 06:25:09 PM
Doubt it or your compressions would be out. Does the sound stay the same when you rev the engine.
Title: Re: My 500 4 is poorly
Post by: paulbaker1954 on April 28, 2018, 07:42:10 PM
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
Title: Re: My 500 4 is poorly
Post by: jon stead on April 28, 2018, 09:09:05 PM
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?
Title: Re: My 500 4 is poorly
Post by: paulbaker1954 on April 28, 2018, 11:39:04 PM
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
Title: Re: My 500 4 is poorly
Post by: Trigger on April 29, 2018, 08:17:51 AM
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.
Title: Re: My 500 4 is poorly
Post by: paulbaker1954 on April 29, 2018, 09:19:48 AM
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.
Title: Re: My 500 4 is poorly
Post by: deltarider on April 29, 2018, 09:31:36 AM
Maybe your compression test wasn't accurate. I myself never managed to do it correctly.
Title: Re: My 500 4 is poorly
Post by: royhall on April 29, 2018, 10:11:11 AM
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.
Title: Re: My 500 4 is poorly
Post by: Colonial-Clive (yindi) on April 29, 2018, 10:54:04 AM
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.
Title: Re: My 500 4 is poorly
Post by: Trigger on April 29, 2018, 11:09:22 AM
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.
Title: Re: My 500 4 is poorly
Post by: K2-K6 on April 29, 2018, 01:00:40 PM
I'd agree with Trigger, it doesn't at first impression appear to be running any problem with the engine.

It just looks / sounds like you've lost part of a baffle. As above I'd try to investigate that first and certainly not pull the motor apart at this stage.

Would you be able to get a camera down the pipe or try it with another pipe to get a better appraisal?

As a slightly off beat method could you swap the 2 and 3  pipes or another combination,  even if you have to stick them on at odd angles, to see if the pipe sounds the same on another cylinder.
Title: Re: My 500 4 is poorly
Post by: K2-K6 on April 29, 2018, 10:27:09 PM
http://forums.sohc4.net/index.php?topic=131905.0

It's obviously a 750 pipe,  but gives more insight of what is happening inside these exhausts.

Title: Re: My 500 4 is poorly
Post by: Trigger on April 29, 2018, 10:42:55 PM
Took me yonks to find this again >> https://www.youtube.com/watch?v=G2W68pThPCc
Title: Re: My 500 4 is poorly
Post by: paulbaker1954 on April 30, 2018, 08:24:03 AM
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.

Hi Trig
I have opted to do a top end rebuild anyway (just love the fun !!) just to check there is nothing horrendous happening internally and I want to clean and rebuils carbs again anyway.

I will then get the bores measured again just as a sanity check and if they are still in original spec(ie under 56.1) I will leave the existing pistons and rings since they are pretty new (2k miles) anyway. That sais what I don't get is why the Honda repair manual quotes 170 psi and says that anything below 140 indicates bad bores/rings/valve seats etc.. Honda says nothing about testing wet or dry in their repair manual.

As for the damned exhaust I swapped 1 and 2 over (I had to laugh at the exhaust angles !!!) before I started stripping but was really hard to tell if I still had the phutting on n0 1 as I was getting a lot of phutting from around the exhaust ports. I think it was hard to get a good seal on the copper gaskets with the weird exhaust angles.

Title: Re: My 500 4 is poorly
Post by: Trigger on April 30, 2018, 08:53:36 AM
If you were getting smoke and too much pressure from the breather that goes to the atmosphere and it is 140 or below on a wet test, then it is time for a rebore.
Another good way to test psi is, start with number one. Plug the tester in and start it up, you should see the psi go up as you rev the bike. But, I would be more than happy with 135 across all four.
What was the piston skirt to bore clearance ?
Don't believe everything you read  ;)

 
Title: Re: My 500 4 is poorly
Post by: paulbaker1954 on April 30, 2018, 11:39:08 AM
Took me yonks to find this again >> https://www.youtube.com/watch?v=G2W68pThPCc

Interesting I have opened a ticket with CMSNL along the line of this pipe is only just 2 years old any only 2K miles of dry use and a baffle failure !!!

See what I get back !!
Title: Re: My 500 4 is poorly
Post by: paulbaker1954 on April 30, 2018, 11:48:00 AM
If you were getting smoke and too much pressure from the breather that goes to the atmosphere and it is 140 or below on a wet test, then it is time for a rebore.
Another good way to test psi is, start with number one. Plug the tester in and start it up, you should see the psi go up as you rev the bike. But, I would be more than happy with 135 across all four.
What was the piston skirt to bore clearance ?
Don't believe everything you read  ;)

Cant remember what the clearance was as I measured the bores and they seemed on spec at 56 and as they were new NOS standard pistons assumed all OK. I did check the ring gaps before I installed them and they came up again in spec for an unbored unit.


One further point on the damned exhaust issue I forgot to mention is that I forgot to post my plug pics. Plugs were pulled after a good run around ie not long idling.

Order is back to front in the image ie 4-3-2-1 and there is a lot of variation which is why I wanted to do a carb rebuild again but I wondered if the very lean look of plug 1 (ie the one on the right of pic)has anything to do with my problems

Title: Re: My 500 4 is poorly
Post by: hairygit on April 30, 2018, 11:51:30 AM
A very weak mixture can cause a few problems, and detonation (Think Nurse Julie's 400/4!)
Title: Re: My 500 4 is poorly
Post by: paulbaker1954 on April 30, 2018, 03:39:20 PM
Took me yonks to find this again >> https://www.youtube.com/watch?v=G2W68pThPCc

Interesting I have opened a ticket with CMSNL along the line of this pipe is only just 2 years old any only 2K miles of dry use and a baffle failure !!!

See what I get back !!

Should have added that there are no rattles or odd noises when I bang or shake the pipe
Title: Re: My 500 4 is poorly
Post by: paulbaker1954 on May 01, 2018, 02:24:04 PM
Now here's a great result ---- thumbs up tp CMSNL !!!!!!!!!!!



Subject: Re: Problem with Exhaust
From: Gert Pruisscher
Date: May 1, 2018 12:19:46 
Dear Mr Baker,

Thank you for your order and sorry for the inconvenience.

We never had this issue before, and I agree it's not something you can expect after 2000 miles.

I will send you a UPS shipping label, so you can return this exhaust. We will examine it and send you a new replacement exhaust.


Please give me your address where UPS can pick up the exhaust.



Kind regards,


Gert 
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