The following series of events happened with my pilot can anyone help, After 15 mins of running and then idling at standstill the Engine revs rose to approx 3000 kill switch and ignition were turned off and made no difference, the Engine was only stopped by shutting off the fuel.
I have taken the head off supecting head gasket as the coolant smelled of fuel. Gasket had no obvious signs of leaks. On re-assembly with new gasket the compression was reading low However bore and rings looked OK. Any ideas!!!!
Also does anyone know where to get a workshop manual from

Was the Engine over heating, sounds like the Engine was dieseling, the
air/fuel was being ignited by heat not spark, what is the fuel quality you
are using, you using a low octane like 87 or 89 octane?

Most of the time when this happens its is because of excess carbon build up
on the head and or piston, was there any carbon build up?

You low on coolant, look at the level in the over flow bottle, also look for oil
or black pepper looking specks in the radiator, that is a sign that the head gasket
was leaking at one time or another.

What was the compression?

What is the ring end gap?

This Engine stock?

What is the history how long you owned it?

Thanks for the reply
The fuel is regular UK unleaded which is 95 Octane
The coolant level was OK but it did have like a black scum and smelled like fuel so I assumed the head gasket was the problem so took off the head. The gasket showed signs of someone having bodged it at some time as there was sealant on the gasket. New gasket was put on and rebuilt. Prior to taking the head off the pilot would still start easily and run although power seemed down. After replacing the head gasket the pilot would not idle so I did a compression test which was 50PSI which seems low and suspicious. I have stripped down again to ispect the piston and bore. The Bore looks good measures 80.04mm and is round Piston is stamped J77F3 STD577PS and measure 79.5 at crown Rings and piston also look good.
As far as I am aware the Engine is stock I have owned the pilot for 4 months and it has run ok up to now although has not been run for any great length of time. Ring end gap is .7mm
Thank you for all of your help!!!!!!!!!!!!!!!!!

So if I did the math right you have .021 piston to cylinder clearance?
but this was measuring the piston at the top?

To calculate the piston to cylinder clearance you need to find the largest
outside diameter on the piston, this is usually found at the bottom of the
skirt or piston, this is because there is less heat than at the top of the piston
and less expansion to worry about.

So after the rebuild you still have the problem where the Engine wont shut off?

HI Hoser,
I guess you are helping me out on 2 forums. again sorry for my lack of reply I have been away.
You were right the measurement of the piston was at the top the skirt measurement is 79.86. I have decided to put in a new piston and rings anyway as it is stripped so I am waiting for the delivery. I will let you know how it runs and pressure tests when the bits arrive. I Did spot doming of the cylinder head mating surface though and have flatted it. Do you know where I can get a workshop manual. ??

Precisely measure your bore again the stock Pilot bore is 80mm

Why in the world would you buy a shitty wiseco piston when you can still get a piston form Honda?

Any Honda shop should be able to order you a service manual, there is a online version
of the manual but I don't have the link.

Hi The bore is definately 80.04 and shows no signs of ovaling.
I have ordered a new piston and rings from Honda but I guess from your comment that the piston that it has been running is a Wiseco.
Thanks again for the advice

Sorry I miss read your comments and thought you ordered a wiseco, you want the
HONDA not the wiseco, if you ordered a Honda piston you did right!

On the stock bore Honda offers 3 different sizes for the stock bore only, they have
a "A" "B" and "C" size if you look in the manual and measure your cylinder you can
figure out what one will fit the best .0031 is the required piston to cylinder clearance.


Your bore is 80.04mm or 3.1511 manual says service limit is 3.1507 your clearance will
be .0004 ( .01016mm) larger than they specify but I would not worry about it, you
should have ordered the "A" piston part number 13101-HE0-010

Where in the UK you located?

A couple of the numbers are little mixed up, I think. Straighten me out please.

The piston cylinder clearance had an extra zero it would be .004 and not .0004, just a typo.


I think i got confused on the first part, if the bore is 80.04 and the piston is 79.50 that would be a clearance of .230 which is way bad, right? the second time it was 79.86 which would be more in line with a clearance of .090 a bit better but still way loose.

None of this matters if the bore is still good (crosshatch) and the new piston will give the proper clearance.

Are you checking the bore and taking the largest reading you get? What are you using to measure with?

My .0004 is correct and is not a typo that is the difference between 3.1511 and 3.1507
less than half a .001

From what I read, blown haed gasket, wont shut down by kill switch. It may be a good time to put new seals in it or the new piston may not last. Also if it ran that hot may need to check the head to see if warped a little. Using a flat bar and feller gauges. Seals at this point are cheap. Just a thought. Howes the reeds look. if stock may be a good time to replace them, sound like you have a lot of hours on them and may be a little weak.

Sorry for the new post. I was on my way to work when this thought jumped into my head. I think i read you just bought the bike. This happened soon after. This same thing happened to couple of motors I worked on. Some one stuck the cheapes piston in it to get it running and then sold it. That might explian the wieco piston. And to make a very long story short, I pose this.After several hours of rework, the problem on one was traced to an intake gasket and the other was a vacum hose to the fuel pump. Air check the motor (( Internal Combustion Engine ? )) in stages, first with cylinder and head on, this will check for seal damage. If ok then bolt up intake(reeds and intake boot),using vacum on this stage. This will check for reed cage gaskets and intake boot leak. If ok take vacum line off of pump put on cylinder then check through the vacum line the see if it holds. Be sure to right done all reading. Be sure to use vacume on the cylinder when reed cage is installed. If you use pressure it will cause the reed to shut indaciting a leak when the air ceapes through to the boot, vacume will open them and create a vacume through out the intire system this will show if the air leak if you have one is on the vacum side of the strock. Note, pressure can be used if one reed petal is removed from reed cage, this will make the numbers easy to compare. Note also drain the oil for non drive side of the case, and be sure to fill it back up when done. The thick cool oil on the seal and o-ring will make the detection harder to show up. Note, most seals will show up better under vacume then pressure( just my opion), due to that they leak when the motor (( Internal Combustion Engine ? )) is in its vacum state. Some times when the seal leak it very minenute, the pressure will seal up the seal by pushing the seal lip up tight to the crank surface.

Hoser,
I have put some more info on this on the other site you have contributed to. I have also posted a picture of the piston on the site that livewire mentioned. Wierd scratches.
I live in Harrogate in the UK which is in the north near Leeds, Yorkshire

Hoser,
I am sorry it seems that by searching for info, on more than one site I have created some aggravation for you. I will stick to this site from now on to prevent any more hassle for you. I am still waiting for the parts from Honda and will let you know the outcome when I get them.
Thanks again

The only aggravation for me is not being able to archive then recall tech post, on my old site (pilotodyssey.com) there is over 60k post lots of good tech info there too bad Kiowa never fixed the "super search" I never can find stuff I know that exist on that site using the search, I know there has been post lost on that site as I search for things I know that were once there are no longer to be found, I rather build a data base here if I can, I keep current backups and far as I know have not lost any info to date, my web page is 7 years old and growing its always up and ready to help others, so far here I have pretty good luck with finding stuff by searching, I need a search on the regular part of my web page too (PilotOdyssey.com), with over 600 html files I have a hard time finding stuff on my own page

Search all the Pilot Odyssey web pages read all you can they all have good info, more you read the better off you are, I like to read an average of 4 hrs a day of new material, I wish I had the internet when I was about 10 years old.

Let us know when you get the parts back and how you make out, I got a friend that lives some place in the UK but lost track of him lately..... I sent him a email will see if he replies.

Just an Idea for your website would to have a section at the beginning that lets us know when you
have added new info. And maybe show a date of when the new info was added. Just an idea, I love all of the tech info you have listed on your web page. Keep up the good work...

TA76455

Hi Hoser,
I have tried posting a picture of the piston to this site but it comes back with an error message.
I will keep you posted.
All the best

Hmm what kind of error?

Hi
It says picture cannot be posted to gallery Then "error executing imagemagickreturn value:1"
The file size is 175kb so I don't think its too big

Strange, I will play with it later when I get a chance, how about attaching a pic to this
post? at the bottom you click on "Browse" and navigate to the pic, slect it then click
on "add attachment" then "submit " like you normally do when you post a reply here...

Hope this works

WTF happen to that piston looks like hieroglyphics... Any other marks on the piston, you
have pics of all sides top bottom inside and out? Be nice to see the rest...

to me it looks like someone cleaned up the old piston that siezed in the bore with a bead blaster or scothbrite pad or something and then reused it!!! wtf! this is the one with the wacky tolerances right? that explains a lot.

the hardness/ minerals in regular, undistilled water or stream water will do that to alloys as well (like a side case or water port) but it would have to be sitting in it for a week or more

woah...did you have a bunch of dirt in it when you started it!?!??!

I have only seen vertical scratches on pistons before you got circles and half circles
something that was not caused by the piston going up and down.