Head Gasket Replacement

After a morning of running errands, I finally had the afternoon free to work on the head gasket leak that I had. The plan was that this would be a quick fix, just enough to slow the leak since I planned on taking the engine apart this winter.  As a background, Iím an amateur mechanic having never had an engine apart before, but how hard could it be?

I wheeled the bike out of the shed and into the garage since it looked like it might rain. Below is a shot of the bike from the right and left side, looks good from a distance but up close you can tell that its been ridden hard and put away wet by the previous owner(s).

Right Side

I received a head gasket, two rocker box gaskets and a couple O-rings for the push rod tubes from British Cycle Supply on Monday.  Armed with this, some gasket sealer, tools, some cleaning materials that I picked up that morning and the manuals I was already to take on what for me was a bit of a daunting task.

Left Side

The Right Stuff

Being a bit of a lazy guy I thought I would try to get the head off while taking as little off as possible.  I started with the air filter and carb, the manual says to take the slide out but I just disconnected it from the manifold and rested it on the floor by the bars, the cable holding it upright. Next were the pipes, one bolt where they attach to the heads and one holding it under the frame. So far things were easy enough.  Next were to remove the oil lines from the head, the right one came off easy enough but when I turned the left one the metal line started to bend a little.  I recall the manual stating that this can damage the line, so I frigged around with it for a while, but I didnít have a wrench or other tool that would hold the line still while I turned the nut holding it on. Finally I wedged a screw driver in between the line and the head and gave the wrench a quick hit, bingo, the nut turned and the line stayed in place.  This is probably not a recommended method, but it worked for me.

Finally the horn came off. At this point I started undoing the head bolts, my plan again was to leave the rocker boxes on and to remove it as one piece. Again, being an amateur the last thing I wanted to do was to have to mess around with anything other than replacing the gasket and putting it back together and starting it up, which may be a bit naive. I quickly realized that the tank had to come off, not a problem, two bolts and it was already disconnected from the carb.

Now Iím cooking, I can get all 9 bolts out that holds the head to the cylinder.  During this process I came to the realization that my engine doesnít sit straight in the frame, one of the bolts couldnít slide right out because it ran into the side of the frame under the tank, this is something Iíll have to look into some day. A little coaxing and the loss of some paint and all the bolts were out.  Great, now the head will slide up, Iíll remove the old gasket and slide the new one right in.  This is where things got ugly, Iím sure anyone whoís done this is shaking their head and thinking ďrookieĒ, and youíd be right.


Bad Idea

I quickly found out that the push rod tubes were going to get in the way, I couldnít easily get the gasket off.  I attempted to lift the head up so that I could angle the gasket out.  I finally got it out, but it was a bit bent, I realized at this point that I wouldnít be able to get the old gasket it cleanly.

Things got worse when I looked up and saw that the push rods were all out of sorts. There was no way that I could simply slide the head back down and have them seat properly.

Beer Break

Itís at this point that you sit back and think to yourself, ďWhat have I done?Ē  The only thing to do when you get to this point is to wipe your hands off and go grab a beer and think about the next move. Of course the beer is inside, giving the wife a chance to ask you ďHowís it going?Ē.  ďGreat.Ē I canít have her thinking I donít know what Iím doing. Of course, by the time Iím half way through my beer she has to come out to take a look, giving me the perfect opportunity to pose.

Bad Scene


Breaks over, beerís empty, 2 hours have gone by, the boyís nap is over, time to get back at it.  Itís obvious to anyone that at this point I have to resign myself to taking the rocket boxes off, itís a good thing I got the gaskets in anticipation of this. A couple bolts on the top of each and a few nuts on the bottom and they pop right off. My big concern with taking them off is that it probably means that Iíd have to adjust something when putting them back on.  I was also concerned with the guts of them falling all over the place was they were removed (hey, like I said, Iíve never been into an engine before).  Well I was wrong about the guts falling out, they came out as one piece, nice and easy.  Once the rocker boxes were off I was able to slide the cylinder right off with no problem.


The picture to the left shows just how dirty everything is, not mud and dirt dirty, but very worn looking. As long as it works...

Now Iíve got a nice easy access to the cylinder.  I little cleaning, add the new gasket, and Iím golden.

Easy Access

A quick inspection of the head and cylinder shows a lot of, what I assume to be, regular wear and tear. This winter will hopefully give me an opportunity to clean this out, but right now Iíve got my sites set on simply changing the gasket. Again, being lazy allows me the advantage of easily fending off the ďwhile Iím in here...Ē bug that tends to take hold of people tearing into an engine.  Itís easy to tell immediately from looking at the head that one of the sides in running leaner than the other, an interesting problem since there is only one carb. I may have to look at running a hotter plug in the other jug. As for the pistons, black and sooty, but I assume thatís to be expected, again, something I can clean this winter.

Now itís time to reverse the process, I clean all the areas where the gaskets are going to go and start putting it back together.  Fortunately the rocker box gaskets are the ones with the holes for the push rods, makes it easy to slide them down and have them stay in place as I place the rocker boxes back on.


Piston s

The re-assembly is fairly straight forward and uneventful, however I think itís worth mentioning, in the event that someone wants to correct me, but to make sure that the push rods are in the right place I opened the inspection covers on the rocker boxes and turned the engine over using the kickstart.  All the rockers seemed to move up and down without any problem, I took this as a good sign and finished tightening everything, making sure to alternate the head bolts so I didnít do all one side and then the other.  As for gaskets, the head gasket is copper and can be reused if annealed, something I didnít bother to do, I simply used a new gasket since they were only 5 bucks.  Iíll anneal the old one and keep it as a spare. The head gasket is not supposed to be installed with the aid of any gasket sealer, but Iíve been told that the rocker box gaskets need all the help they can get, so I used new gaskets and gasket cement for this.

One thing I found that is nice about working on such a ratty bike, scratching paint off the frame and whacking the pipes back on with a wrench doesnít bother me. This will likely change if I ever get a chance to clean it up and paint/powder coat/chrome a few parts. The re-assembly took about two hours, as did the tear down, part way through the rebuild I had someone show up who needed to do a little work of there own on their three wheeler. Fortunately they didnít need any of the tools I was using, and occasionally felt the need to hand me a screw driver or run off with the roll of electrical wire.  I think he was adjusting his seat from the looks of where he was sticking that screwdriver.

My next step was to put the tools away and then try to start it up. It didnít start easily and sounded a lot louder, not as smooth sounding as before, and a couple backfires. I only ran it for a couple seconds, then I realized that with gasket sealer being used in some locations that I should probably wait until tomorrow before really checking it out.


Working hard

Follow-up: After posting this I got a couple suggestions before I tried to start it the next day. What I didnít do after putting everything back together was to check the valve clearence, something I neglected the day before. Englishman, from The Horse BC, (have I mentioned that I got this bike off the swap meet section of their web site for $900, a purchase I could be happier with) mentioned that even though the push rods seem to be in there ok, and move up and down as I menitoned, doesnít mean theyíre in the right way.  One step that he suggests is to try to but them back in the order and attitude in which they came out, I did this for the most part.  Checking the valve clearence to also help you determine if the pushrods arenít seated correctly.

Valve Clearance

My valve clearance was off but not by too much, the intake was measured at about 0.010 inches, the manual suggests 0.004.  A seemingly small amount, but still twice what the manual recommends, and now that I re-read the manual I see that the intake should be 0.002 and the exhaust should be 0.004, looks like Iím going back in, fortunately the access caps make it an easy procedure. [Take a good look at that fuel line, thatís gotta go]

Ride Report: So with my valve clearances not set quite right, which I didnít realize at the time, and a newly recharged battery, I started her up with a minimal of effort.  The bike was sounding much better than the day before, no smoke, no odd smells, things were looking good.

Now Iíve been working on this bike whenever I get a chance, which hasnít been very often, since I got it last year. Various issues have kept me from taking it for a long ride, but today was to be the day. Being a rookie mechanic I decided it would be prudent to have the wife follow behind with the pickup, just in case.  It wasnít long before I noticed that black gas was all over the primary, an inspection while riding showed that it was coming from the exhaust clamp, which made sense since the bolt was dancing around in the hole.  I was forunate that the clamp was positioned so that the bolt didnít just fall to the ground after coming loose.  I pulled over, got the wrench out of the truck and tightened the bolt down, my problem now was that I had black gas all over the cyliner and head, this made it hard to see if the head gasket problem was fixed.  Oh well, I had yet to have a chance to ride the thing for any distance so I decided to continue on once the bolt was tightened.

The bike doesnít have any low end power to speak of, probably a result of the short, slash-cut pipes, but it still ran pretty good in 1st and 2nd.  Switching from 2nd to third is another story, seems like there was a huge ratio difference and once in third the bike really bogged down. It almost felt like it was going right from 2nd to 4th, the backroads I was on didnít give me an chance to try to get it into 4th from 3rd (assuming I was actually in 3rd).

Aside from this lack of power the bike seemed to run ok, the occassional backfire but nothing serious. At least it did run ok until I got to a stop sign, at which point the bike sputtered for a bit and then died. A quick look showed that the lights were out, nothing at all, and this was with the battery on. LUCAS!!! I pushed the bike to the side of the road and the wife and I pushed it up onto the pickup. Next issue, tackling the charging system.

As a side note the pictures were taken with an HP 812, just got it through work a few weeks ago and seems to work quite well, very happy with it.  Tud

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