Topic: 1977 750 Supersport Lean Carbs - Help

[mikeb4]

I just changed out to pods on a used bike I recently bought that ran fair before the change, also it has the Mac 4 into 1 exhaust.  It seemed lean at idle since I bought it with the stock airbox since it would not run cold for 5+ minutes without the choke fully on then fair when warm.  I cleaned out the carbs real well, added new needles and seats and 120 mains with 4 turns out on the mixture scews with the new pods. 

It started but ran really crappy so I pulled the carbs again and moved the needles to the 2nd position from the lowest.  Presto, different bike with decent lower through top end but it still seems lean at idle.  I also get light popping on decel in gear and it runs poor at idle until fully hot.  I do not see pilot jets, rather it looks like brass tubes with a hole in the end like a set sized pilot jet with only the screw for adjustment.  How do I get more fuel at idle?? (2,000 RPM and below) 

[Badboy]

If it has air bleeds give it less air.If it has an idle mixture screw[ where is the idle adjust screw] give it more fuel [turn it conterclockwize] Clockwize if it is an airbleed] Can you post a picture of your carbs?

[mikeb4]

The screws appear to be fuel screws since they are callled pilot mixture screws in the manual and they are on the manifold side, not the airbox side.  The bike will not run well at all with the screws in less than 3 turns so that confirms they are richer when turned out.  I assume any more turns out than the four turns I presently have (as a general rule on mixture screws) will not help, especially since a couple more turns and they are falling out.  Thanks!  any ideas?

[Terry in Australia]

Blocked pilot jet/s is my guess, my F2 wouldn't idle properly until I attacked the buggers, I carefully pulled them out (they're pressed in) with vice-grip pliers, and they were all cruddy, but #4 was blocked completely.

Now normally I use welding tip cleaners to clean blocked jets, but the holes in F2 pilot jets are so small, I had to find some really fine copper wire to poke all the gunge out, then soaked them in carb cleaner for awhile before I put them back in.

I'm only running 110 main jets with the needle on the second lowest position, with the idle screws 1.5 turns out, and it seems to run very well, and idles fine. The F2 carbs do run a little lean normally, (an EPA requirement back then, apparently) but make up for it with the accellerator pump when you crack the throttle open. Cheers, Terry.