This update has a number of YouTube clips that basically
detail what I found after coming home from the Easter weekend away directly
after rebuilding the fuel tank petcock which I covered in my previous
blog. When I came home and got out
of the car in the garage the first thing that I noticed was that the garage
smelled like gasoline (not a good sign).
Upon further inspection I found that there was a slow leak from the
petcock down various components to the floor. The first video is a (somewhat tongue in
cheek) word of warning on petcock rebuilds.
The best advice I can give you regarding rebuilding your
petcock is to not assume that just because you put all new parts in that everything
will be fixed. That is the mistake I made
the first thing that I did after rebuilding my bikes petcock is take it for a
spin and then fill the gas tank. THIS IS
A BAD IDEA! You definitely want to make sure that the petcock is functioning
properly before you do such a thing. The
next most important piece of advice I have if you do what I did and fill the
gas tank and have a petcock that is letting fuel flow freelyor if you just find
out that you have a leaky petcock for the first time; is to bite the bullet and
empty the gas tank rather than try to remove the gas tank and tilt is perfectly
so that the gas is not spewing out the lid or out of the petcock to do your
work.
Yes, you still have a little spillage when you put the drain
tube on the fuel fitting of the petcock but the mess will be much smaller.
It’s pretty easy to see what I did in the above picture but
to detail it out, I set up a 2.5 gallon gas tank (an important note is that the
1979 GS 425L gas tank does not hold only 2.5 gallons the full capacity is 3.7
gallons so plan ahead with two containers or on that will hole the entire
contents) on a 5 gallon bucket on the right side of the bike so that when I
rant the drain tube to the petcock that it wouldn’t have to make any hard
turns. You can see a closer look below.
After spending some time letting the
problem marinate I let decided that the only thing that I did not change when I
rebuilt the carb was the spring and decided that it must have weakened over the
last 32 years.
I talked to some of the old codgers at Motorcycle Performance who suggested
that remove the petcock, take it apart again, use an eraser to burnish the
contact points and the valve nipple, and stretch the spring that pressing the
valve nipple into the contact point.
Which I did, after doing the work, I had to figure out a way to do test
the work I did without re-filling the tank and making a huge mess in the process. In the video below you can see what I came up
with.
I put about a quarter of a gallon into the tank and set the
petcock to reserve to allow flow from the lowest point in the tank results
follow in the video below.
FAIL! As you saw that
did not go well. True it isn’t spewing
out as bad as it was before but that was about but that was with a quarter
gallon in it if you think about adding another 3.45 gallons into it the amount
of force being put on the valve with the added weight of the gas could have had
it spewing out just as badly. I decided
to leave that sit and look into why the gas was coming out of the float bowl overfill
tube on the left carb when the carb float should be shutting the gas flow off.
That
meant taking the carbs out again, so off they came!
I basically run down the findings in the video below. The surprise finding was that the o-ring between the spacer and the carb boot was sheared in a section, if I’m honest due to me being lazy and not fully removing the carbs before installing the gaskets and when I slid the spacers back into place the tight fit cut the gasket into two places.
When I took the spare set of carbs apart I found some interesting
things, see below.
After getting the good float’s height set I basically put
the carbs together and that was it for the day.
I needed to find a source for some intake boot seals and find a cure for
the issues with my petcock before I could move forward.
Check back to see if I have any luck! More to come soon!
No comments:
Post a Comment