Re: New 750f2 owner, member intro & few ?'s.... Carb issues for now

Posted by Matt Story on Aug 28, 2012; 3:46am
URL: http://vintage-and-classic-hondas.81.s1.nabble.com/New-750f2-owner-member-intro-few-s-Carb-issues-for-now-tp4026717p4028170.html

Bit of an update.  Over the last couple days I finally got to spend a few hours on the bike.  It now has a really good initial tune on it.  New needles and float adjustment really did the trick.  Unfortunately, the needle seats on this bike aren't removable, and the #2 and #3 seats were corroded pretty badly.  They needed a good lap and polish to seal.  I used small bits of adhesive backed fine grit sand paper stuck to the end of a wood dowel and just twisted and twisted until the shoulder was polished smooth and flat.  Probably only took off a few thou.  Then I took another dowel and ground a point on it and twisted that around to polish the sealing corners clean.

I was worried that I might not get a good seal with the new needles and the reworked seats, so I foolishly set the floats about 2mm low to get a stronger seal.  Fortunately, they did seal up.  Set-up like this was the best it had run for me yet, but still not good.  I rechecked the timing, set the valves, and did a quick carb balance.  That was better but still not it.

I took the carbs back out and carefully reset the floats in the middle of where they're supposed to be.  Put them back in, and re-synced again. WOW!  Now it will idle down to about 850rpm once warm.

I was pleased to see that when I checked my static time job with a timing light, it was really close - at idle and at full advance.  It close enough that I'm not going to bother readjusting with the strobe light.

A couple years ago I bought a hand held electronic tachometer.  I used that to check the accuracy of the bikes tach.  It looks like the bikes gage runs almost 200rpm faster than the pocket gage.  Tomorrow I'm going to use the hand held tach to check and set the idle mixture screws.  Will adjusting the idle mixture screws have any effect on the carb balance??

Above, I asked if the 75-76 rear master cylinder kit would work on a '77.   The earlier kit comes with the spherical ball stud where the later one doesn't.  I kin d of rolled the dice and bought the early kit because my ball stud was rusted up.  Now I have it, and everything looks compatible.

After a little more carb tuning, all I have to do is rebuild the the brakes and the bike will be on the road!  Just a few more hours of work and I'll be riding.