Topic: Hi

[cado007]

Thanks for adding me to the group! I really have enjoyed all the knowledge here. I recently acquired this 1978 Honda cb 550k.
I have previously worked on a 1973 cl 350 but I always wanted one of the 70's 4 cylinders. This bike has pd46c carbs with 90 mains - 38 slow jets and the needle clip is the 2nd notch down from the top. I think these were factory settings. I ride with gentlemen that have 70's cb 750's and they recommended fully disassembling the carbs which I did. Then I joined this forum and it recommended never to derack. Oh well too late. I was able to install new felts which were basically gone. I know this has been talked to death and I have been researching Two Tired and Harisluvs posts on these carbs but I do have some questions. What is the float height? I set them to 14.5 but I have seen 12.5 and 14.5 . 3 of the floats were way low like 8mm. The motorcycle has 22000 miles on it. It ran but it needed the choke on. The choke mechanism seems like a poor design. I have it working  but it seems like it could fail easily. Also I bench synced ( I think) the carbs. I matched the  all slide heights to carb 2 height. I used a large sewing needle not sharp end as guide it is probably 1/16th of inch but its what matched the #2 carb. Before doing this sync I could move the throttle shaft spring with my finger. It was stiff but doable. Once doing this bench sync I have to pry with screwdriver to move is this normal.  Lastly which throttle cable push or pull goes on the top of the mechanism on the carbs. I have downloaded from this site the manuals for the 1978 Honda cb 550 k but they seem to be lacking or confusing for this year and it seems there were many different configurations. Again mine is 1978 Honda cb 550 k with PD46c carbs - 90 mains 38 slow jets. needle 2nd notch down from top of needle. - stock airbox and stock mufflers in great condition

[willbird]

I cannot imagine why it would be bad to de rack. If I had an ultrasonic big enough to do a whole rack (I do not) it would not gain anything to take the two screws on my round tops and take them our of the rack, but with what I have I can only clean the carbs in the ultrasonic if I take them out of the rack. I can clean the rack itself but I have to flip it around several times and only parts of it are underwater.

[cado007]

That is what I did  as I too have a 3 liter ultrasonic cleaner- then I found out one of my riding group has an ultrasonic big enough to do the whole set of carbs. They definitely needed a cleaning and I learned a lot- I guess Ill find out if it was a success when I reinstall them
Thanks

[MauiK3]

I took mine all apart, the shafts and parts were pretty much in need of attention. All went well.

[willbird]

I took mine all apart, the shafts and parts were pretty much in need of attention. All went well.

I guess those are quite different than round tops tho, I could see where a ham fisted individual could make a hash out of your type LOL.

[bryanj]

The PD carbs are very cold blooded and need choke for quite a while after starting, your symptom is typical of blocked pilot jets and passages. The jets are a press in fit but can be removed by gripping carefully with vice grips then pulling and twisting at same time, refit with a light tap from nylon hammer.
The only place i have ever found jets is Sirius Consolodated in Canada and their website is horrible to navigate

[cado007]

Hi Bryan
I have already cleaned and rebuilt them -photo attached is after rebuild and clean-and plan on reinstalling this week.
these are PD 46c - I have the floats set to 14.5mm - do you think this is the correct height?
Thanks

[Stev-o]

these are PD 46c - I have the floats set to 14.5mm - do you think this is the correct height?

I no longer have my 550K but according to this thread, float level should be 12.5mm. 

Are you aware of the "clear tube method" to set them?

http://forums.sohc4.net/index.php?topic=152261.0

[HondaMan]

Hi Bryan
I have already cleaned and rebuilt them -photo attached is after rebuild and clean-and plan on reinstalling this week.
these are PD 46c - I have the floats set to 14.5mm - do you think this is the correct height?
Thanks

PD42c should be at 12.5mm float depth: at 14.5mm they will be very lean and won't idle for beans, if at all, without choke assist.
The only PD42c I have seen with the #38 pilot jets were smog-limited versions from California (back in the day), and their air screws were set to 1.75 turns instead of the normal 1.5 turns out. The normal pilot jets were #42 in most of them. However, I also noted that in those with the #42 pilot jets there tended to be a flat spot in the performance right around 3500 RPM, probably because the mixture was leaning out with the #2 clip position on the needles right about there. The sparkplugs tended to run quite lean (white) in this version of the bike in hiway use, prompting some I know to install larger mainjets. This tended to make the bike then bog right at 3500 RPM instead, so try to avoid that merry-go-round if you can? This was an early version of the CB650 lean-burn (i.e., anti-smog) configuration, so it was a little 'bumpy' in mixtures versus RPM.

[BenelliSEI]

Welcome to the Forum. Lots of good advice here, you’ll have it running sweetly soon! My 1978 cb550K was my first Honda SOHC4. Perfect weight, size and great looking. Smart choice; good luck.

[bryanj]

The reasons not to derack are
1 have to drill out the choke flap screws
2 complicated sping mechanism(s) on throttle linkage andjoints
3 i hate those carbs with a vengence
4 gazillions of small bits that need more tiny fingers to replace than a human has
5 did i mention i hate them!

[willbird]

The reasons not to derack are
1 have to drill out the choke flap screws
2 complicated sping mechanism(s) on throttle linkage andjoints
3 i hate those carbs with a vengence
4 gazillions of small bits that need more tiny fingers to replace than a human has
5 did i mention i hate them!

yea that is a far more complex task than de racking round tops :-).

[MauiK3]

Sounds like no fun

[bryanj]

Why do you think items 3 & 5 are on my list

[Deltarider]

Why do you think items 3 & 5 are on my list

Come on, Bryan... gotta wear this.

[bryanj]

Nope, never. PD carbs are utter #$%*e and the work of the devil