Re: carb rebuild issues

Posted by seestheday on Jun 05, 2013; 3:12pm
URL: http://vintage-and-classic-hondas.81.s1.nabble.com/carb-rebuild-issues-tp4041611p4041842.html

Maybe they were partially clogged prior to you cleaning them?  

Is there a k72 stamped into them or are you measuring them?  A 35 jet should be .35mm or 0.13 thousands of an inch (this is why a .10 guitar string is perfect for cleaning them).

Theoretically here is what I think could happen with massively over sized idle jets:
- When first starting, bike will run very rich.  It will allow lots of fuel, but not much air will get in because it is being restricted by the throttle plates and the CV slides stay down.
- For it to run at all, you need to turn the high idle screw up a lot so enough air can get in around the throttle plate
- When you blip the throttle air rushes in (along with some more fuel) and you finally start to get decent vacuum coming from the pistons.
- The vacuum coming from the engine keeps the CV slides up, allowing for more complete combustion of all of the fuel the big idle jets are dumping into the engine.
- The revs stay up because they're getting lots of fuel, and some of the air they need (I still suspect it'll run rich because the throttle plate is mostly closed).
- Because the high idle is so high to start with you are getting enough air for it to stay at 4K rpms.

This also explains why the choke has no effect (you're already running super rich)