Honda-SOHC

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 

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

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.

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

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

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.

Look up Gerben 1956 on eBay. Excellent kits and good a good price.

Link to his web site

https://www.ebay.co.uk/usr/gerben1956

Julie I was actually after full kit including jets, etc but they don’t seem to be on this site

Did you have the throttles wide open and a warm engine?

Should have said
Throttles and choke open on cold engine, would a warm engine make that much difference