QuestionI have a honda 90 1969 the shop has cleaned the carb. and now it is running to rich and they cant lean it out could this be a problem with the points or is this a elec. prob. I think it is a point or timing for they tried to fix and it gets worse and when at factory settings it gets better.
AnswerHi Shawn,
There are many reasons for a rich mixture
including symptoms that just resemble
a rich fuel mixture.
It is always good to start with the basics,
-check the air filter and intake for
obstructions.
Make sure the exhaust port and pipe are
not plugged up.
Make sure the timing is set on factory
"F" mark on the flywheel.
Makes sure your points heel is not worn down
preventing the points from opening fully.
Make sure the flywheel key is not stripped.
Check your compression as a worn engine
cannot burn the fuel properly.
Make sure the choke is opening fully
and carb float is floating and fuel level is correct.
Finally, there is an emulsion tube inside
the carburetor that has a small rubber o-ring
on it. If the o-ring is damaged or has not
been replaced then fuel can flow past
the emulsion tube and make the mixture too rich.
Picture here:
http://ep.yimg.com/ca/I/dratv_2167_104334530
Carburetor needle wear can also result
in a rich mixture. A smaller main jet
might compensate for wear but plug color
should be checked after changing jets.
Chart here:
http://verrill.com/moto/sellingguide/sparkplugs/plugcolorchart.htm
Use the correct heat range spark plug for your bike
and as you try different things always check
the plug color, this will tell you if it is running right.
Rich is a sooty black plug, oil fouling is an oily plug,
light brown is right on.
Good luck!
Wayne S.
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