Mike brought me his Pilot he said he had problems with coolant getting burned as
the Engine ran like it was the head gasket leaking, when I took it apart the whole
bottom end was full of coolant.

The amount of coolant here has me concerned this amount had to seep in from the
coolant system but where, the cylinder was not exactly flat but I don't think it was
leaking or could leak that bad, enough to seep in when not under pressure, he still
had the coolant lines hooked to the carb so I will pressure test the coolant circuit
on the carb to ensure it is not leaking in to the throttle part of the carb, I will also
bolt the head on the cylinder and pressurize the coolant passages with air to see if
there is a leak between the aluminum and steel liner on the cylinder.

I painted the top of the cylinder with a blue marker then lapped it, the dark areas are the
low spots

The head was not bad all except for the little ring where the raised area of the head gasket
always leaves a dimple

A little more lapping and you can still see some areas of concern

Dam, what is causing this Hoser, you said the head is ok, the cylinder as well?

Ok I found the leak I had to finish lapping the head and top of the cylinder so I could
seal it up again, I then installed the head using one of my copper head gaskets and torque
it up, I blocked off the coolant openings with a hose and clamps then installed my
pressure tester on the small bypass line on the head.

I put 15 psi on it and it leaked out about as fast as I could fill it..

It took me a wile to find the leak but I found it on the roof of the
intake side of the cylinder.

I circled the area with a green marker the blue area is pointing where the crack or
poor casting is.

Another view

These are some pictures of the 'water damage' from the flood of coolant setting in
the Engine you can see how it etched the cylinder wall, this is why I suggest that
all lower end bearings be replaced...

Ok, now that the leak has been found, was the cause of it done by someone cleaning out the chambers,porting and polishing?Can that jug be used again if Mike finds someone to alumn weld it Hoser?I think also a good point here for all is that I would bet nobody pressure tests the jug prior to install, it may take us 2-3 minutes to do in the future but what a relief if we find the system has a leak before installation.Can that cylinder be used again ?would a bore or just honing get rid of the antifreeze pitting on the cylinder walls or is it a done deal, garbage?

Ok time for an update, I have the Engine assembled, new crank, bearings, seals, gaskets, piston, cylinder, etc. the Engine is installed and I am going through the radiator , carb, air box cooling system, I will take them one at a time I am not trying to embarrass or offend anybody so I will not sugar coat my findings after all my CSI's are a learning tool for all.

Time for the piston to cylinder clearance rant!

First I found the old piston to cylinder clearances at .014 yeah nuts huh, another ATV Racing botched job, yes there was wear on the piston and some wear on the cylinder (some cross hatch worn off) but .014 as found clearance, lets be generous here and say that the total wear on the piston and cylinder was .004 that means the piston to cylinder clearance was .010 when after the bore was completed my guess on the wear was .002 so again I am being generous here.

I just did the CSI on Pilotmans top end his piston to cylinder clearances were .010 ATVR strikes again

No matter who does your machining work you have to double check their work, NOBODY is 100% if you don't have the tools or are not sure how to measure the clearance contact me I will measure it for you for FREE if you send it out for a bore have them return ship it to me, I will measure then ship to you.

This piston was a Wiseco, correct me if I am wrong but the clearance for the Wiseco is around .004 depending on what size your piston is, they have a formula on the tech sheet that comes with your piston I don't remember the formula, when you send one to be bored you need to STRESS the finish clearances don't allow them to do this for you, over the years even the local mutts around me want to add clearance to what the manufactures recommend, the last one I took in the guy said "I always add .002 to .003 more than the Honda spec." heck if that is the case no need for me to bore my cylinder just buy a new piston since it would be running at less clearance than that mutt wanted to give me on my next bore!

If your not picky about your piston to cylinder clearances and .010 is ok with you then just buy a ball hone and do your own save the time and money of sending it out to be bored because your just pissing that money away when you get it back at .010+ clearance! Ask the guy that is going to bore your cylinder if he can give you an EXACT size not + or - .001 the last bore I had done I requested EXACTLY .0031 clearance and that is what I got. DO NOT let these morons do you a favor by adding unessasary clearances that just accelerate wear, rob your power, complicate tuning and waste money and time.


I found both of the vent lines on the carb plugged with mud dirt or sand (off-road crud) the air screw was 1/2 turn out probably compensating for the partial plugged pilot jet, the float was
set to high, there was a HUGE amount of oil and dirt in the rubber boot that goes between the air box and carb, your air filter feels like it was oiled with oil or maybe UNI filter oil? stuff sux, what happens is as the filter gets loaded with dirt the filter oil will actually flow through the carb and carry dirt with it, on a 90+ degrees day you can usually find the majority of the filter oil in the bottom of the air box, ever remove that drain plug and find it full of oil? I suggest you using a filter oil that is tacky, I use Maximia FFT Honda and Bel-Ray also make a "tacky" or "sticky" filter oil that works real good.

The radiator fins was about 30% plugged with off-road crud and as we thought with the cylinder and head gasket leaking in the past there was an oil film on the inside I flushed the inside with hot soapy water, the spot on the bottom of the radiator where the radiator fan ground connects to the radiator was corroded pretty bad I cleaned it up with a wire brush and sprayed battery terminal protector in the hole, I will inspect the connector and bolt when I put it back together.

Most of the stuff I washed should be dry so I will go back wrenching again, more later..

I matched the manifold to the pipe.

After, the edge was bent over to form a radius so the gas will flow over not run into

I took apart the fuel pump because it had been subject to the antifreeze just as I thought
it had coolant and crap in the pulse section of the pump.

After cleaning

I drained the gas tank then poured in about a quart of fresh clean and shook the
tank, what you see in the picture is what came out, the gas was clear like water
when I poured it in, I consider this about normal for this year tank...


It needs drained and flushed once a season...

I poured off the gas and you can see the rust and dirt left behind, my guess is about
1 tbl spoon probably as much came out the first time I drained it .

Hoser. Is Mike gonna have to remove and replace the filter for some time after the rebuild to catch the debris in there?Was the pump clogged or damaged by the antifreeze?is a new pump a better way to go than just cleaning?

I would remove the filter after a riding trip like ECJ and back flush it to see how
much crapola came out then work from there, the fuel pump did not look damaged
just dirty, sure new is always better then used...