Pod filters, Carpy exhaust and jetting - CB550k

[haddock]

Hi all!

I'm pretty new in the whole motorcycle business, but every day I learn a little more.
I've bought a old Honda CB550k3 from 77' some months ago, and my goal is a nice cafe racer.

Some days ago put some Uni pod filters on the bike, and exhaust from Carpy - now it's a lot harder to start the bike. My guess is the jetting is all wrong bacause of the modifications.

Can someone please help me out here? Where do I buy jets (I live in Denmark, so in Europe would be lovely)
Which size jet should i try out?


My carbs look like this: - think they are called Keihin PD carburatores right?

Kind regards
Jannick

 

[focusinprogress]

if memory serves, you should have 38 pilots and 100 mains? On the same bike with pods and 4-1 exhaust I was at 112.5 main jet and stock pilot, but had adjusted the mixture screw to richen it up.

 

[haddock]

if memory serves, you should have 38 pilots and 100 mains? On the same bike with pods and 4-1 exhaust I was at 112.5 main jet and stock pilot, but had adjusted the mixture screw to richen it up.

This FAQ says the main jet is 90 for an 1977 CB550K3. Maybe I should try buy some different sizes and do it the slow way.

 

[focusinprogress]

This FAQ says the main jet is 90 for an 1977 CB550K3. Maybe I should try buy some different sizes and do it the slow way.

that is ALWAYS the best way. Anytime I've looked up online what the common jetting is, it's always needed adjusted from there. I always buy two sizes either side of recommended so I have room to tune.

 

[haddock]

that is ALWAYS the best way. Anytime I've looked up online what the common jetting is, it's always needed adjusted from there. I always buy two sizes either side of recommended so I have room to tune.

So maybe some 105, 112 and 120 in size?
And do you have any recommendations of where to buy them? Saw power-barn.com had some, but don't know if there is a better online shop.

 

[focusinprogress]

So maybe some 105, 112 and 120 in size?
And do you have any recommendations of where to buy them? Saw power-barn.com had some, but don't know if there is a better online shop.

cheapest I've ever found was Z1enterprises.com

http://www.z1enterprises.com/ItemDetails.aspx?itemDescription=Keihin+99101-393+Type+Round+Main+Jets+%23105&item=SIKHM-110105

 

[danker16]

So maybe some 105, 112 and 120 in size?
And do you have any recommendations of where to buy them? Saw power-barn.com had some, but don't know if there is a better online shop.

highly unlikely you'll need a 120, id get sets up to 115, and very likely with both pod and exhaust mod you'll need a 40 or 42 slow jet if you stock is 38

 

[haddock]

A short update.
I've got the 110 jets mounted today, and took it for a short ride. It was indeed better, but when i'm turning the throttle for a quick acceleration it't feels like it doesn't gets enough gas.

And its "farts" (whats the english word for that?) when I release the throttle.

What is my next step now? I'm kind of a newcomer here, and looking for tips and tricks.

 

[focusinprogress]

If you are abruptly cracking the throttle fully open, it will always respond with a bit of a lag and hiccup. The carbs can't compensate at such a quick rate, the throttle is meant to be rolled into rather than smashed open. Try riding around about half throttle on fresh plugs and then pull them to check tip color

 

[haddock]

I'm just bringing this topic up again.

Does somebody know where to find slow jets for the Keihin PD46 carburators?
Would love it, if I could find some from Europe.

 

[focusinprogress]

if you can't find in europe....

http://www.power-barn.com/press-fit-pilot-jet-for-honda-oem-keihin-carburetors-xl100-xl185-cb550-cb650-cb750-cbx1000-trx200/

 

[haddock]

Hi again.

I pulled the slow jets out today. Found out that it was a size 42

My spark plug looks like this after a have driven the bike for some hours.

Should I go up some sizes in jets?

 

[8ball]

It really depends on how you were riding. Most riding is done at mid throttle, which is regulated by the needle. The correct sequence would be to get the idle mixture right, first. That is the slow jets and the air fuel screws to fine tune. Then get the main jets right by doing wide open throttle plug chops. (Go to a place that you can accelerate wide open for a distance, then pull the clutch, and shut the bike off. Coast to a stop and pull the plugs and look at the color......you want to start with clean plugs) Once you get the main jets, you can move to the needle adustment. The needle goes in the main jet circuit and is affected by the size of the main jet, so adjusting the needle range (1/4 to 3/4 throttle) before getting the main jet range (3/4 to full throttle) right is fruitless. Adjusting the needle is done by removing the slides, taking out the needle and moving the e-clip that sets its height. Lower the clip to raise the needle and richen the mixture.

Yes, from what I can see of your picture, it looks lean, but as I said, reading that plug is dependent on other information. Also, you generally read plugs down closer to the base of the ceramic cone. The higher the RPM, the deeper your read on the cone.