Topic: PD50A carbs: 3 & 4 venting issues.

[my79650]

If anyone has been reading my posts on the issues i had with those carbs. Stock engine with airbox and baffled mufflers, stock jets in carbs. I have blocked the air cutoffs as they are overly priced to replace. Finally got the floats set up properly, i used clear tubing on the drains and got them right. When driving thru town up to 55mph i would notice a surging fit. At hiway speeds of 70mph and up it pulls great and i can't tell if its still doing it. I checked the vent line for 1 & 2 and it is working; 3 & 4 it's blocked. I just blew into the line for each side; 1 and 2 was fine i could hear air going through but 3 and 4 no dice.
The tank is cleaned and new inline fliter and gas line. I cleared the right side vent with compressed air and after a day it started doing the surging. I cannot  figure out why its only doing it on the 3 and 4 side of the rack. Vent T is in great shape no rot or kinks in the line. I had the bowls off of 3 and 4 to check them and everything is clean clearing the vents with compressed air they work fine on that side for maybe 40 miles. Any ideas on why it only does it on that side?

[lucky]

If anyone has been reading my posts on the issues i had with those carbs. Stock engine with airbox and baffled mufflers, stock jets in carbs. I have blocked the air cutoffs as they are overly priced to replace. Finally got the floats set up properly, i used clear tubing on the drains and got them right. When driving thru town up to 55mph i would notice a surging fit. At hiway speeds of 70mph and up it pulls great and i can't tell if its still doing it. I checked the vent line for 1 & 2 and it is working; 3 & 4 it's blocked. I just blew into the line for each side; 1 and 2 was fine i could hear air going through but 3 and 4 no dice.
The tank is cleaned and new inline fliter and gas line. I cleared the right side vent with compressed air and after a day it started doing the surging. I cannot  figure out why its only doing it on the 3 and 4 side of the rack. Vent T is in great shape no rot or kinks in the line. I had the bowls off of 3 and 4 to check them and everything is clean clearing the vents with compressed air they work fine on that side for maybe 40 miles. Any ideas on why it only does it on that side?

Two separate issues going on.

Vents on carbs and float height settings.
You need to MEASURE the floats the way the book tells you.
You only do that clear tube method AFTER you have set the float by measuring them.

[my79650]

I did set them then use the clear tubing to check. I pulled a float off and i got  some dirt. Was brown in color so must be rust out of the tank. I just came in from cleaning out the tank for the second time.  I used paint thinner and some nuts for cleaning; strained the paint thinner through a clean rag and got some dirt and rust. Did a rinse with a gallon of diesel then used some methyl hydrate for a final rinse. I took the tank to the gas station in the car to fill it with fresh supreme, now to check the carbs again.  If i had the cash i'd take them to the shop and let them deal with it! But i like to finish what i start.

[my79650]

Run like crap today, was missing almost all the way to work and halfway back home. I guess i didn't get all the diesel out of the tank when i drained it and the methyl hydrate didn't help much either. Must have got through it as when i went to the coffee shop iit came out of it and started running great above 35mph. When i put the carbs back together i set the air screws to 1 1/2 tirns this time. It still idles like crap but on the hiway it pulls great. Dumping some Seafoam in it after supper. Plan to run it a few days before i check anything else. 

[my79650]

After two days going to work and back running 50mph both ways i am still surging but not as bad. But enough to notice. I had the carb rack in a vice upside down then adjusted rack to be level before i set the floats to 12.5mm(1/2 inch) as the Honda manual states for these. I must not have found the sweet spot since i got to do it again.  Frustrating i tell ya!

[lucky]

After two days going to work and back running 50mph both ways i am still surging but not as bad. But enough to notice. I had the carb rack in a vice upside down then adjusted rack to be level before i set the floats to 12.5mm(1/2 inch) as the Honda manual states for these. I must not have found the sweet spot since i got to do it again.  Frustrating i tell ya!

Makes no sense. "I must not have found the sweet spot?
You just set the floats by measuring them. End of story .
There is NO "sweet spot"

Make sure you remove the idle jets and hold them up to
daylight and make sure they are clear.

[my79650]

Makes no sense? I did everything as the shop manual stated except getting the air screws right(didn't write down the turns on the teardown, should have done that) The float levels was not set up to book value when i first had the bowls off. I have blocked off the cutoff diaphrams; ever since then i have had nothing but problems. Got a set out of a cv rack for a 79 750 DOHC that's the same size as the ones for the 650s. The air passages are full of silver solder; will pull them apart and remove the solder then replace the cutoffs!  If that don't work then i'll just get another set from the salvage yard and take the best parts from both sets to make a complete running unit.

[my79650]

Actually screw it; get a set from the  salvage yard with clear cutoff passages then do a cleaning and rebuild, minus touching the float levels. Should have just left them alone in the first place!

[my79650]

Got a set of pd50e mechanical linkage; complete set for $100 from the local bike salvage. Needed a cleaning; i used all my good parts and jets off the rack i did the blockoff job to the air cutoffs. I did count and document the aiir screw turns this time. I used the floats  that was with this new set with my good needles. I swapped over all fuel rails; jets and emulsion tubes along with my good clean float covers. For cleaning all i used was wd40 and compressed air at 100psi. All 4 had excellent shape cutoffs which i removed and cleaned out all passages including the one under the cutoffs to the slow jets in all 4. Bench synced and replaced the air screw to the documented turns when i removed them for cleaning. replaced the cutoffs after cleaning.
These sat upside down at the salvage with gas in them; ran back and varnished up the throttle valve channels in the top. soaked overnight with wd40 and they freed up when i used pliers on the linkage to get them moving.
Installed on the engine, airbox connected. Started up after 3 or 4 twists of throttle. Idles good at 1400rpm. Ran level in the yard for a few minutes. Now to test drive to see how they perform.  Other than the number on the side stating pd50e these are identical to the pd50a series. Jets may have been different but i used the 50a jets i had that are clean.

[my79650]

I made sure all throttle vale assemblies and the channels were spotless. I put a dab of axle grease on the linkage shaft where it slid through all 4 bodies.

[my79650]

Ran to work and back last night 50mph both ways. preformed real good on the rural roads. Will pull plugs to check them. No gas smell when stopped, looks like i cleared up the rich issue i had with my original pd50 carbs(now for parts).