Topic: Carbtune issues

[Frostyboy]

I think that if they are not new and they are on backwards, that is worth checking. Since you had so much trouble getting them on...

Good thought, but I happen to have 4 new 16211-323-000 rubbers in readiness to reassemble my 550F and they are the same depth from either end. There doesn't appear to be a front & back so to speak.
Comparing my old ones with the new all I can say is I'm really glad I got newbies. The 'ridges' inside the rubbers which engage on the grooves of the manifold & carb bodies virtually don't exist on my old ones. I've had them off a couple of times over the years, but not sure how many times by PO.

[cookindaddy]

I see. Mine is a 750K with what looks like the same Keihin carb and my insulators are definitely different at both ends. The head end is thicker rubber and slightly smaller ID. They are possible to put on backwards (I did with one by mistake) but it is extremely difficult, like he said it was. I'm looking again at the pics he posted way at the beginning of this thread and what he is using looks to be different at both ends? Anyway, I made my point. Hopefully he will figure out whatever it is that is causing his vacuum leak.

[Frostyboy]

I see. Mine is a 750K with what looks like the same Keihin carb and my insulators are definitely different at both ends. The head end is thicker rubber and slightly smaller ID. They are possible to put on backwards (I did with one by mistake) but it is extremely difficult, like he said it was. I'm looking again at the pics he posted way at the beginning of this thread and what he is using looks to be different at both ends? Anyway, I made my point. Hopefully he will figure out whatever it is that is causing his vacuum leak.

Aha, maybe that's the answer Cookindaddy. Perhaps they're the wrong rubbers on there

[cookindaddy]

Frostyboy: Why don't you post a pic of your new official parts for him? So he can see what he is supposed to have? The ID at both ends is the same? You mentioned the depth, but not the ID.

[Brian G]

This is better than a movie  

I happen to have 4 new 16211-323-000 rubbers in readiness to reassemble my 550F and they are the same depth from either end.

My understanding is that the '77 & '78K carbs are different. I have mine off right now, and when fitting the insulators back onto the carbs was surprised to find that they were a very loose fit. I then realized that I was fitting the head end of the insulator to the carb rack.

The fact remains, there must be vacuum present for the thing to run, so it must be able to be read on your gauges. Check the holes are clear anyway.

There's nothing for the gauges to read! All the air for combustion is being drawn into the engine from downstream of the sync ports so there isn't enough vacuum at the carbtune to lift the indicator columns. What little fuel/air mixture is being drawn through the carbs is enough for a (crummy) idle but is so lean it causes popping & backfiring when the load goes up.

Stu's pictures tell it all. And what else in the induction system would affect all four gauges?

Hth,
Brian

[MRieck]

This is better than a movie  

I happen to have 4 new 16211-323-000 rubbers in readiness to reassemble my 550F and they are the same depth from either end.

My understanding is that the '77 & '78K carbs are different. I have mine off right now, and when fitting the insulators back onto the carbs was surprised to find that they were a very loose fit. I then realized that I was fitting the head end of the insulator to the carb rack.

The fact remains, there must be vacuum present for the thing to run, so it must be able to be read on your gauges. Check the holes are clear anyway.

There's nothing for the gauges to read! All the air for combustion is being drawn into the engine from downstream of the sync ports so there isn't enough vacuum at the carbtune to lift the indicator columns. What little fuel/air mixture is being drawn through the carbs is enough for a (crummy) idle but is so lean it causes popping & backfiring when the load goes up.

Stu's pictures tell it all. And what else in the induction system would affect all four gauges?

Hth,
Brian

  Stu's pictures tell it all. I agree.  And what else in the induction system would affect all four gauges? Maybe from time to time the laws of physics cease to exist in CB550's.

[Sam Green Racing]

I think I've got a HEAD ache, anyone know a good HEAD doctor? 

Sam.

[Bob Wessner]

Might I direct you to the healthcare thread? 

[Sam Green Racing]

Heads suck as much as carbs Bobby for some

Sam.

[Nikkisixx]

I think I've got a HEAD ache, anyone know a good HEAD doctor? 

Sam.

I don't always understand your accent Sam, but it sounds like this is where your HEAD is:
[youtube=425,350]<object width="480" height="385"><param name="movie" value="

name="allowFullScreen" value="true"></param><param name="allowscriptaccess" value="always"></param><embed src="

type="application/x-shockwave-flash" allowscriptaccess="always" allowfullscreen="true" width="480" height="385"></embed></object>[/youtube]

[Sam Green Racing]

The English sence of humor Nik  I'd rather be in NC though 

Sam.

[Nikkisixx]

Sam, the weather is good and the drag racing is better!   

[Sam Green Racing]

That's why I'd rather be there, and the nice girls

Is there much bike racing going on at Piedmont these days, don't here much about the place since Mike sold it.

Sam.

[Nikkisixx]

Sam, I've only been here in the Carolinas for 18 months, but have been to Farmington, Z-max, and Rockingham.  We've some great dragstrips here! Haven't made it to Piedmont yet - I'll put it on the list 

[TwoTired]

To clear up confusion about the couplers, I offer these pictures and some dimensions.
The couplers (and manifolds) for the PD carbs are significantly different from the earlier style and are used on K model CB550 in 77-78 model years (US models)
In the 1st picture, the left is the earlier style and right is the PD style.
77-78 couplers are shorter in length and wider in width.  They also have two molded ridge lines which orient toward the carb side connection.  The second picture is a snap of my 78 CB550K, showing installed orientation. (My 78 runs, btw.)

The early couplers have the same internal dimension for both carb side and manifold side.
The PD couplers have a different internal dimension on each end.
For the couplers I have in the parts bin, they measure 33.9 mm on the ridge lined end and 31.5 mm at the other end.
These are, however, old and hard and may have shrunk.  So, those dimensions are only ball park.

Cheers,

[Sam Green Racing]

Sam, I've only been here in the Carolinas for 18 months, but have been to Farmington, Z-max, and Rockingham.  We've some great dragstrips here! Haven't made it to Piedmont yet - I'll put it on the list 

Seems they have bikes at least once a month, only 1/8 mile but a well prept track.

http://www.piedmontdragway.com/schedule.html

Sam.