Topic: More PD46 carb adjustments. (For Lucky's database.)

[Lostboy Steve]

I'll save you the gory details but I still haven't taken a LONG ride due to lack of confidence in my tuning so far. So what I've been doing is small adjustments and then a ride around the block. (About a 1/3 mile.) So here we go again. I feel like we need to incorporate a few other things like freshness of carbs / engine, and obviously bore size.

77 CB550K
Fresh Top End
Stock Bore
PD46C carbs Fresh and New Jets
4 into 2 Exhaust (looks like a niche cycles job but who knows)
Uni Pods Oiled with Uni Spray Oil
Stock Needle Position
105 Main Jets
42 Slow Jets
Currently screws are pulled out 1.5 turns

Bike runs good. Has really good power and smooth transition. At idle I still get a bit of smoke which smells like hell. Much less than when I had the screws at 2.5 turns out. Still, definitely rich. I'm wondering if I should try turning those screws in another half turn. Other wise I guess its time for a 40 Slow jet if I can get them or should I just jump down to 35? Again, the bike runs so well that I feel terrible messing with it. Some say not to oil and it will lean out the mixture, but the whole point of the foam filters are to have them clean and well oiled. Also I think I should recheck my valves now that I've gotten it hot a few times.

[Blitzburgh207]

How are you running smaller mains than stock w/ pod filters?  Have you opened the throttle up?

[lucky]

How are you running smaller mains than stock w/ pod filters?  Have you opened the throttle up?

He is running #105mm mains and the stock size is #90mm.
Stock idle jets were #38mm.

I would stay with the 42mm idle jets, turn down mixture to 1 turn out.
Should be fine.

[Lostboy Steve]

Yes, and it runs extremely well even with my misfire. A little rich if anything.

[lucky]

Yes, and it runs extremely well even with my misfire. A little rich if anything.

It is a new engine. a little rich is good insurance for now. Try that mixture screw at 1 turn out instead of 1.5

[harisuluv]

My bike has a very similar setup to yours.

78 CB550K
Fresh Top End
Stock Bore
PD46C carbs Fresh
4 into 1 MAC exhaust (megaphone variety)
Uni Pods Oiled
Stock Needle Position
105 Main Jets
42 Slow Jets
Currently screws are pulled out 1.5 turns

Seems to run good, but I have not had it out a whole lot, as I am finishing up putting it together still.

[lucky]

My bike has a very similar setup to yours.

78 CB550K
Fresh Top End
Stock Bore
PD46C carbs Fresh
4 into 1 MAC exhaust (megaphone variety)
Uni Pods Oiled
Stock Needle Position
105 Main Jets
42 Slow Jets
Currently screws are pulled out 1.5 turns

Seems to run good, but I have not had it out a whole lot, as I am finishing up putting it together still.

Thanks for that report, Harisuluv.

Can I add that to my database?

[cabrala]

Quick question here is reference to the carb part numbers and bike year...

The '77 had PD46A and the '78 had PD46C. Is this distinction actually meaningful? Am I just wrong in general? Or do you have a '78 rack on a '77?

Having both years of the bike, I'm just trying to get my s*%t straight.

[lucky]

Quick question here is reference to the carb part numbers and bike year...

The '77 had PD46A and the '78 had PD46C. Is this distinction actually meaningful? Am I just wrong in general? Or do you have a '78 rack on a '77?

Having both years of the bike, I'm just trying to get my s*%t straight.

77 or 78 WHAT Cb550 or cb750?

Got to be clear.

[cabrala]

We're talking about 550's in this thread, right? 

At least that is how it was started and what I was looking for clarification on.

[Blitzburgh207]

How are you running smaller mains than stock w/ pod filters?  Have you opened the throttle up?

He is running #105mm mains and the stock size is #90mm.
Stock idle jets were #38mm.
 
I would stay with the 42mm idle jets, turn down mixture to 1 turn out.
Should be fine.

Oops I misread....thought it was a 750 thread  my bad

[lucky]

Quick question here is reference to the carb part numbers and bike year...

The '77 had PD46A and the '78 had PD46C. Is this distinction actually meaningful? Am I just wrong in general? Or do you have a '78 rack on a '77?

Having both years of the bike, I'm just trying to get my s*%t straight.

The PD46C was the 1978 CB550K.
The X46A   was the 1977 CB550K.

[Lostboy Steve]

Lucky, my 77 cb550k has pd46c carbs and to my knowledge they are original as the bike has never been screwed with until i pulled it out of a barn.

[cabrala]

This is what I was trying to understand. From the little I know, '77 and '78 were different from the '74 to '76 years. I believe fuel efficiency regulations moved Honda to refine the carbs and within those two later years, they were similar but had different identifying numbers...

Lucky references the '77 as X46A, but I have known them to be PD46A. I am not sure if the designation is different in terms of "X" or "PD". The '78 is definitely PD46C, however.

Could it be possible that you have a '78, if the bike has indeed never been modified?? 

[Lostboy Steve]

Well, the side of the carb is stamped PD46C and the head tag on the bike is 1977. It is also registeded as a 77 and has the candy brown paint of a 77.

[harisuluv]

Lucky of course you can add my info.

As far as the 77 bike with pd carbs instead of x___ carbs, maybe your bike was built in late 77 like sept or later and they were already doing next years model.

[Lostboy Steve]

That's what I think happened. It was built late.