or The Honda 500 4 & the mechanic that could
From: "Dave Ditner" <email@example.com>
Date: Fri, 30 Jul 1999
Started out high oil consumption, no smoke, and alot of oil found in the number 3 exhaust port.
Easy. Bad valve seal, right? Wrong!!!!!
It's a Honda 500 4, so off comes the cam cover/ rocker arm assy and spring removal. Lifted off what felt like a good seal to find parts of the valve guide inside of it. RATS!!!!!!
Now the head's got to come off. Okay, find a guide at the Honda dealer $13 and change. Give me two just in case. Oh, you want a valve? ONLY $59!!!! Finally found a valve for
$39 from a mail order house in the back of Motorcyclist. Got the guide put in, the seat retouched, and valve lapped, and started to put it together. First time, forgot the little O rings that seal the oil
passages from block to head. (Late at night, busy swatting mosquitos). Off with the head. Back on with the head.
OOPS, front cam chain guide in backwards. Off with the head. Fix the front chain guide. Back on with the head. Find TDC. Lay in the cam. Chain too short. Out
with the cam. Contemplate my navel. Chain tensioner looks wrong. Reset it to minimum tension as per the shop manual. Off with the head. Contemplate my navel some
more. Can't find anything wrong. Contemplate my navel again, this time with a beer. Back on with the head, back in with the cam. Chain still too short. Out with the cam, off with the head. Pull the
tensioner apart, and FINALLY, think I found the problem. The bottom of the tensioner sits in a rectangular hole in the tensioner in a little rubber pillow block, which it had come unattached from, and was sitting higher than it
should have been. With the motor in the frame and the cam chain channel directly below the frame backbone, It's almost impossible to see there. Took a dentist's mirror. Tonight the attack continues.
Hopefully with less navel contemplation, and more beer
Cuss, swear, contemplation, & beer
Part II final chapter
The final chapter in the tale of the 500 reads as follows. It needed a valve
adjustment, pipes, and tank for startup. Did it. Lit it. Decided to put new points and condenser in. Checked the advancer. A OK. Installed the points, condensers, set
the gaps, timed both sets, and was ready to kiss it good-bye when we saw oil running down the fins on both outside edges of the block. &^%%$#$%@%%$!!!! There are two oil passages through the block and into the
head for cam journals, rocker shafts etc. near the outside edges which have O rings that fit in holes in the head
gasket. Could have swore I put them in. Sure didn't look like it. By this time it's three o'clock Saturday afternoon.
The bike is due for a one week trip in a couple of days. "Let's take it apart and check. I'll say one thing for the third
teardown. It goes much quicker than the first. within an hour the head gasket was staring us in the face. WITH O
RINGS IN PLACE. While feeling better at seeing them in place, I'm really honked at the leak. Got my depth mics
and regular mics out and started measuring. The depth of the counter bore that the O ring fit in and the gasket
thickness added up to .087" and the O ring was >090" thick. Leaving only .003 for compression (the thickness of
a sheet of newspaper!) Iffy at best with smooth surfaces, but the bottom of the counter bore closely resembled the
surface of a small corncob. No metric O rings available in this small town on a Saturday, so found some with a
.125 dia cross section, and a 1/4" i d that were too big for the hole in the head gasket, stuffed them on a 5/16 drill
bit, took a file gently to the o d till they fit the head gasket and reassembled it again. More trouble with the cam
chain than previously. One notch in the sprocket is larger that the other and lets the chain move easily, but nobody
tells you this. Success was finally mine at about 8:00 last night. It rolled out of the driveway with my buddy's kid on it grinning from ear to ear. So was I.