Topic: 1977 550k Got my carbs in order now for some MILD jetting?

[Lostboy Steve]

Cb550k 1977. PD46 carbs. I have factory airbox with no lid and a uni "drop in" filter. Have 4 into 2 swept pipes pretty open. Right now I have it jetted stock and it runs great, but at high rpm I feel it getting lean (power drop off) and it pops a lot on deceleration. I had 105's in it but those were WAY to fat ALTHOUGH IT MADE GREAT POWER UP HIGH. I'm thinking of just bumping it up a tiny bit. Like a 95 or 100. I believe its 90 right now.

[harisuluv]

Hey again twisted.  I had pods and a mac 4-1 on my 78.  I had 105 in there and I can just smell it is running rich.  Seems to run well but if I had to guess I need 95 or 100.  They say to start bigger and go down but I just took a guess on the 105.  I'm thinking I want to just use the stock airbox on my bike and just go with stock jets--a lot of people are riding great with just a 4-1 swap.  Are you guys doing a lot of CBs over there nowadays?

[lucky]

Yes I would go down to 100 if the plug chop at WOT looks lean.

You are getting into fine tuning now.

The reason it may smell rich is at idle.
Remember though when it is rich at idle it is insurance.

You do not spend a lot of time at idle. But you want the transistion from idle and up to be smooth.

What about this....

 main jet #100mm  but raise the needle by lowering the clip on the needle to the 4th groove instead of the stock middle position. That could help with the lower part from idle to 1/4 throttle too and then you could cut that idle jet back to a #40

I have your last stats listed as:
Pods
4 into 1 exhaust.
needle stock position.
105 mains.
42 idle jets.
 and mixture at 1.5 turns. ( I thought that should have been 3/4 turn)
You said it ran good.

[harisuluv]

My bike does run good.  I am going to do a little tuning (suggestions noted) and I will get back to you.

[Lostboy Steve]

Lucky, I changed everything. It was running well before but I found a major air leak on my #1 Carb which lead to my misfire at idle. I have since rebuilt a set of 78 carbs with stock jetting and installed the factory airbox with a uni. It runs good just wot seems lean. I was never going for a "Full Cafe" Build. I like my sidecover's so why not utilize the stock airbox?


Harisuluv, No not many CB's around here. Infact, I never see any on the street. That 750 i did the exhaust on was on craigslist. It didn't seem ride-able to me. It was a beautiful build, but more of a show piece imo. I want to do a 750, a twin and possibly a cx if and when any of them come my way. I want EVERYTHING, but I hardly have enough time to ride 1 motorcycle.

[harisuluv]

Oh yeah I remember it vividly.  That exhaust was just what he wanted though.  The bike did not strike me as being a daily rider.  I never saw a pic of the completed bike though, post it!

[lucky]

Lucky, I changed everything. It was running well before but I found a major air leak on my #1 Carb which lead to my misfire at idle. I have since rebuilt a set of 78 carbs with stock jetting and installed the factory airbox with a uni. It runs good just wot seems lean. I was never going for a "Full Cafe" Build. I like my sidecover's so why not utilize the stock airbox?


Harisuluv, No not many CB's around here. Infact, I never see any on the street. That 750 i did the exhaust on was on craigslist. It didn't seem ride-able to me. It was a beautiful build, but more of a show piece imo. I want to do a 750, a twin and possibly a cx if and when any of them come my way. I want EVERYTHING, but I hardly have enough time to ride 1 motorcycle.