Topic: 78 cb550 with PD carbs

[78whiteorbs]

Got a 78 I am waking up from a 12 year nap. Ultrasoniced the carbs and rebuilt them , new battery and cleaned and seal tank. Slapped the carbs on without the air box just to make sure no leaks or anything before tackling the airbox installation(trying not to have to do that to many times ) Fired it with choke on and runs on cylinders 1,3,4 but not 2 . Have good spark on 2 , pulled plug and it looked dry  so not fuel or oil fouled. Sprayed some carb cleaner down the throat on number 2 and I think it fired but couldnt tell for sure. gonna pull wires for 1,,3,4 today and spray 2 again to see if it is fuel problem on that cylinder. This should isolate it . Weird thing is that number 2 carb is the main one the fuel line runs into .l'd think it would be the least likely to be fuel starved.

These carbs are different from other 550's and I have read multiple accounts for setting the float hight. They looked around 16mm ish to me when I pulled them but I set them to 14. something (cant recall  but wrote it down.  Also I am guessing that without the airbox installed this bike would never run stock settings without the choke on, sound right .
This is a bone stock 78 with original pipes and everything but the seatcover was original.

[dave500]

ive test run heaps of 500/550s with open carbs,the only one that had a soggy unstable idle was the one with pd carbs,they went synced or anything though,but neither were the type ones,if your 100% sure the idles are clean try tapping that carb with a screw driver handle,have you opened its drain screw to check if it has fuel?if its an untouched engine after a long nap maybe that cyclinder has a #$%*ty sticky valve?maybe a quick comp check?

[mickwinf]

also check the little spring loaded pin on the float needle, on my k3 it stuck and caused me lots of head scratching!

[brewsky]

If you put some clear tubes on the carb bowl drains, then open the screws, it will tell you if
 if you have fuel level issues
The oem push in pilot jets are very hard to  tell if they are completely clean, as they can trap debris inside, and you can't see it. Did you pull them?  Clean or replace?