the carburetor catastrophe
|8/6/2012: about two months ago i decided to try and
fix a small problem with the idle that had developed hoping that it would
also cure the problem that had been around since i had become the owner.
the small problem: after about 10 or 15 minutes into a ride when i came to
a stop the bike would die. it took a few tries to start, and it seemed that
if i was downhill, the bike was harder to start. but, it started and it
did not ever die a second time. the rest of the ride was fine be it a half
hour ride, or a 3+ hour ride.
that was annoying. the bigger problem i hoped to solve was the initial start
and warming up. choke was useless while starting. i had to open the
throttle about one quarter or more. then i had to sit and hold it at
2000 rpm for 5+ minutes until it had warmed up a bit. really, it was best
to hold for nearly ten, but i found that i could take off at 5 minutes and
when i came to a stop give it a bit of gas so it would not die. by doing this
i did not have to sit for 10+ minutes warming up the bike and after about two
minutes on the road all was fine (until stopping at the 10/15 minute mark <g>).
while first testing this out i
blew the end cap off and tried fixing
it. the end cap fix has worked well. i took the baffle out just in case that
was the cause of the problems that started to develop...
once everything was put back together the bike was basicallhy a PITA to start.
i honestly don't remember what the symptoms were at the time. but i ended
taking the baffle out, cursing, and cleaning the carburetor. once this was
done everything was theoretically clean and the jets and floats were set back
to spec. it should work... then when i started it up everything seems ok
until it got warmed. when i revved it, not only did it not fall back down,
it climbed to about 4000/5000 and hung. i could turn the idle screw and this
would make it decrease, but then it would die.
the first thing that pops into everyone's mind is the butterfly shaft valve
seals! but these were replaced last summer! then, the boots. no cracks,
soft, pliable and they seem fine. i tried spraying WD-40 and found no rev
increase anywhere. something was not right! when i took the spark plugs out
the body was very dry and black, just like being rich. but the ground strap
was white! it must be lean.
with a bit of futzing i was able to get it to idle, but usually this involved
strange things like the idle screws being 3 1/2 or more turns out, the idle
jets being larger than the OEM 42.5, or the floats being in a non-standard
position. on top of this the plugs would be jet black and the bike would
not really idle smooth.
ok, after starting i found you are suppose to
start from the top down: wide open throttle, 1/2, 1/3, then idle. but,
at this point i could not even get the bike to
idle well without dieing!
it was somewhere around here i decided to try the balloon trick to see if
the carb was sucking in air since i could not hear any change using WD-40.
i didn't want to use anything else in case the seals were fine and end up
ruining them. it didn't look very good...
left side before
right side before
left side running
right side running
there was definately an air leak. after a bit more messing around i decided to use
carb cleaner to test the seals again to see if i could make it rev. i was going to
order new ones anyway, so it would not matter if they were destroyed. interestingly,
the carb cleaner made it rev! could it be that because it was so rich, WD-40 did not
have the same effect? or maybe carb cleaner causes a higher rev and is just easier
when ordering the new butterfly shaft seals i also decided to replace the choke
gaskets. i usually see them referred to as "dust seals", but at this point i decided
that even though they were a loose fit, i did not want to take the chance of them
leaking air as well. gaskets and seals can collapse when malleable, but after more
than 30 years they tend to harder up a bit. <g>
they were a bit hard
by this point i had replaced almost everything i could think of and cleaned and cleaned
and cleaned and cleaned... the carb was back to speck, except for the main jets. the
bike has pods and everyone on
the forum who has posted carb info i remeber
reading about uses one size larger: 132.5, so that is what i put in. the hope was one
less thing to change.
i put it all back together, on the bike and fired it up. bang! it started off pretty
darn well for a 97 degree day. while it warmed i adjusted the idle screw a bit since it
was still in the previous postion. the revs all fell back down and did not hang! i
was very hopeful. then it was time to stop.
another issue caused by the leak that seems to have been solved was a temperature
difference. i have one of the hand held laser temperature devices and i was using
it to try and make sure the bike would not overheat (really, i do not know how hot
is bad, but if it gets really hot despite the fan, i would turn it off). i would
take the reading of different places, especially the exhaust. doing this i notcied
that the number three exhaust was 150+ degrees cooler during idle than the other two.
when revved to 2000+ it was about equal. after the seals were replaced i found that
the temperature on all three are about equal whether idling or revving. interesting...
the next round of testing began. once again it started fairly easily and warmed quickly
compared to before. when i revved it, it did not linger, but fell quickly back down.
i synced it and took it out for a test run! the ride ended up being only about 40 miles,
but it was great! no hesitation! it did not die! and when i got back i took the plugs
out to see what state we were in:
after about 40 miles
i did not stop along the way, this is just a look after the ride. but,
according to everything i found, these should actaully be about normal!
we will see if the problems are cured, but i have high hopes!
i will probably decide to do a bit more testing, but for now it's
finally time to ride again!