carb adj question

 

I've got an 85 VF700 Magna.  Just bought it a few weeks ago.  The dealer I
got it from said they rebuilt the carbs.  The bike hasn't been running as
well as I think it should so I got a repair manual and begain the carb
adjust process.  I found that adjusting the pilot screw on carb #2 does not
affect the running of the engine at all.  I can screw it all the way in or
out and it continues to idle at the same rpm.  The other 3 carbs will cause
rpm changes when I adjust the pilot screw.

I really don't want to take it back to the dealer since its over an hours
drive away and I really don't want to pull the carbs either.  Any
suggestions on things to try?  Could there be trash in the carb causing this
problem?

thanks for the help.

Richard

 

Richard Slay wrote:

Inspect the idle mixture screw's tip to see if it's damaged.

Buy a can of Berryman B12 Choke and Carburetor Cleaner in the 15 ounce liquid
form. Pour 4 or 5 ounces of B12 into a full tank of gas and go for a slow
ride to make the engine suck the B12/gas mix through the idle jets.

If you're riding along at low speed and the RPM increases, you know the B12
is working.

If three tanks of gas with B12 doesn't solve the problem, you'll need to buy
the aerosol can of B12 and spray it through the idle circuit.

The single idle port that is controlled by the idle mixture screw, and the
three transition ports that are controlled by the bottom edge of the throttle
butterfly
get their gasoline through the idle jet in the float bowl and they get the
idle air they need through the pilot air jet, which may be in the intake of
the carb or under the rubber diaphragm.

If you spray B12 through the pilot air jet, it has to come out through the
idle mixture port, the three transition ports and the idle jet or the carbs
aren't clean enough for good throttle response.

--
Message posted via http://www.motorcyclekb.com

 

Richard Slay wrote:

Pull carb #3 and give it a thorough cleaning with spray carb cleaner.
Remove the pilot screw and pull the float bowl and float off and then
remove the jets and shoot cleaner through the passages and the jets.

When reassembling you should refer to a full assembly part breakdown to
ensure that you have all the right parts in the right order.  I've heard
of mechanics reassembling without an o-ring or washer and it causing
havoc.  If you don't have a drawing compare parts of the bum carb with
one of the good ones.
--
-Fred W

 




Don't want much, do you?  ;-)
If you ever want it to run right again, ONE of the above is probably
required.
Sorry, no miracles today!

 



 >> I really don't want to take it back to the dealer since its over an
 >> hours drive away and I really don't want to pull the carbs either.


Ha, well it doesn't hurt to ask now does it?