Topic: Carb Jets for 74 cb550

[danjwsu]

I've got a 74 cb550 that I am "rebuilding".  My question is, I put individual air filter pods and an open 4 into 1 exhaust on it, so what do I have to do with the jets.  The jets on the carbs were size 100, and I have heard that you need to increase that by 25%.  Has anyone made this mod and could help me out, thanks.

[KB02]

On my 750. I ended up going two sizes bigger than stock when adding pods (Staying with stock exhaust). I think it's a little on the rich side now.

As a general rule, when making the mods you have, you will generally want to increase the gas flow since you have increase air flow. That being said, every bike is different, so the only way to tell is trial and error, really. I doubt you're going to need 125s in a 550. I'd start with 110s. Ride it for a little bit and do some plug chops and report back as to what you've found.

[tbone]

Yeah, 100 to 125 is a drastic jump. Start with 110 or 115 and follow what KB is saying.

[danjwsu]

ALright, thanks alot guys.  I'll try that and let you know how it runs.  KB02, what kind of monster do you have?  I have a 01 S4 and was just wondering.

[mmtsquid]

Where is the best source for jets?
I've just ordered pods myself, and strongly suspect that I will need jets as well.
I have a 77 550K, stock jets, with 4-2 exhaust.

[jalfonso]

The main jet has been addressed, but what about the slow jet or idle jet....or whatever it's called.  Will those jets need to replaced as well? 

[danjwsu]

This is the question I asked

"I noticed you had a beautiful cb550 with air pods and what looks like and open can.  This is the same setup I am trying to use on my 74 550.  what size jets did you use to make up for the extra airflow.  Thanks alot
Dan"

Here is the answer

Hi Dan,
I've put the megaphone exhaust back on the bike. It was simply too loud, and I was running a bit lean. I stayed with the stock jets the whole time. I got the pods at http://www.crc2onlinecatalog.com/. They claim that Twins and 550 and smaller Honda forus usually do not typically need jetting. My bike ran fine afterwards. My 750 however needed to be rejetted. Does this help?

Thanks kuyarico

[physician]

if i remember right, my 78 550 with pods and a 4-1 cheapo exhaust run on 115 mains. on your older carbs, you can play with slow jets to

[Porscheguy912]

Hay man, I have he same year and setup.
I rebuilt the carbs and used 110 mains.
I have 4-1 open pipe and k&n pods.
The bike screams! And i even get in the neighborhood of 50mpg too!
I bought my jets from some canadian company.
They are big on ebay, if i remember the name i will repost.
good luck!

[clarkjh]

Hay man, I have he same year and setup.
I rebuilt the carbs and used 110 mains.
I have 4-1 open pipe and k&n pods.
The bike screams! And i even get in the neighborhood of 50mpg too!
I bought my jets from some canadian company.
They are big on ebay, if i remember the name i will repost.
good luck!

This the place?
www.siriusconinc.com

Good place to deal with.

James

[edbikerii]

Porscheguy912:  do you have a 78 or a 74 CB550?
What about your needle position?
Can you accelerate smoothly all the way to redline with no bogging?
Any flat spots or bogging?
Did you oil your pods?
What is the code on the side of your carbs?  PD series?

I'm working on my 77 CB550 with PD46C carbs.
Pods, MAC 4-1, 114 mains, and the bike is bogging out over 7k RPM at WOT.  I think it is too rich, but plug chops show no changes on my plugs no matter what I do.  The plugs always look perfect!  I'm also running Dyna ignition and coils.

Thanks

Hay man, I have he same year and setup.
I rebuilt the carbs and used 110 mains.
I have 4-1 open pipe and k&n pods.
The bike screams! And i even get in the neighborhood of 50mpg too!
I bought my jets from some canadian company.
They are big on ebay, if i remember the name i will repost.
good luck!

[Porscheguy912]

Clarkjh: Yes thats the place. Funny thing is that i remembered that name yesterday when i posted, but i was not sure it was right.

Edbikerii: I have no idea what my needle position is. The bike is at my moms house. (she has a garage) I will check this weekend, although it needs to be changed. Last year when i made all the major changes to the bike i never put in new points or condensors.
So this spring i did that and i noticed a marked difference in idling.
The bike will idle at near 1200rpm so smoothly that i can hear each cylinder fire and i i can even hear the carbs squeak! Before if it was below 2000 rpms @ idle it would die and it sounded like it was mis-firing.

Anyway, now that i have new points and condensors i have problems in first gear if i rev it past 7-8k @ WOT. But in all other gears i can cruise all the way to 11k on the dial no prob.
I'm figuring that i just need to to adjust the carbs a little because i adjusted them to run on the old points and condensors. Or perhaps The timing is off.
I will get you all the other numbers from the carbs you wanted and post this weekend o next week.
And i have a 1974 CB550F.
CHEERS!!

[Wink]

Hi All,

I was hoping you could help me out.  Recently I purchased my first motorcycle, a CB550F - so in advising, remember, I'm a noobie  .  It had mainly been stored for the last 10 years except for rides around the previous owner's block.  For some reason, he thought it a good idea to remove the muffler.  The bike as you might guess is running extremely rich.  This week I purchased a muffler from Dennis Kirk:

http://www.denniskirk.com/jsp/product_catalog/Product.jsp?skuId=25660&store=Main&catId=4&productId=p25659&leafCatId=&mmyId=6201

The muffler is designed only for the 550F 75-76.

No performance-altering modifications have been made.  I know that the carbs definitely need to be synched and adjusted.  But since this is similar to the OEM muffler will I need to re-jet it? 

Further, how can I tell if it just needs to be synched and adjusted or if it's not running correctly due to the incorrect Jets for the new muffler?

Thank you for your insight!

[Gordon]

If the carbs have not been altered from stock by the PO, putting on an aftermarket muffler will probably make it run better.  Give it a good tune-up and then see what the spark plugs look like with the new muffler installed.

[Wink]

Thank you, I appreciate that your suggestions!  I will give the bike a tune-up once I've put the new muffler on.  Do you have any suggestions once I have the muffler installed, how I can tell if it needs to be carbs re-synced/adjusted and adjusted or jetted?

Thank you again!