Topic: Opinions on "Staged" Jet Kits

[mono]

I installed a MAC 4-1 on my cb550k and definitely need to rejet.  i need to run it with the choke open a bit or it sputters on me during takeoff and low RPMs.  after about 2500 RPMs it's all balls, though.

anyways, i was wondering what everyone thought about the Stage 1,2,3,etc rebuild kits that are "customized" for your specific setup.  I'm kind of on the fence about getting one.

the other thing i was wondering is if anyone knows a source to get a jet kit with a variety of jet sizes at a reasonable price.  i saw one on ebay the other day but it is gone.

[Bodi]

Sirius Consolidated has a jet kit CB550JK that includes 4 each 110, 115, 120 and 130 jets plus shims for needle height adjustment.
I haven't used a "stage" kit, it's pretty hard to evaluate what you need based on limited knowledge of your setup. If your bike has exactly the mods the kit was designed on then it should be good: different exhaust, intake, cam, porting, overbore... all bets are off.

[OneWheelDrive]

It is unlikely that just a MAC muffler would be causing your off-idle stumble.  Try richening up the air screws (screw clockwise) to see if that helps.  If you have the stock airbox, the exhaust wouldn't effect idle vacuum much.  That said, my 550 with 022A carbs and Kerker pipe and stock airbox really loved an upjet on the main from 100 to 105 and a richening of the idle air screw (3/4 turn out from seated). 

[lucky]

Jet kits have a lot of parts you will not need. Why pay for parts you do not need?
Most of those parts will not apply.

Based on the cumulative knowledge of the forum members and all of the years that have gone by and some of it during the internet there is sufficient info to get your bike running properly.
There are some forum members that have the same bike and same exhaust and can tell you what works.

You need to present this information to get the answer that you want.
LIKE THIS:

CB550
YEAR?
Intake system type?
Exhaust 4 into 1 MAC
Mac muffler?
idle jets?
main jets?
Needle clip position?
mixture screw turns?


Then you can get the info that you need.

[mono]

thanks guys - you're always full of good ideas!  sorry for the lack of info, Lucky - i'll fill it out below for y'all


Jet kits have a lot of parts you will not need. Why pay for parts you do not need?
Most of those parts will not apply.
  -- that was a concern - because i am trying to avoid spending money i don't need to spend (aren't we all? )

You need to present this information to get the answer that you want.
LIKE THIS:

CB550
YEAR?  1975
Intake system type? stock airbox, Keihin 022As (just rebuilt/cleaned/bench sync'd the carbs, replaced all o-rings and gaskets on the carbs and manifold)
Exhaust 4 into 1 MAC
Mac muffler? yep
idle jets? 38
main jets?  100
Needle clip position? unknown - i did not tear them apart that far as the needles looks sparkly, so we'll say "whatever is stock" since they don't look like they've ever been taken apart that far -- the tabs that hold the nuts in place don't look like they've ever been touched.
mixture screw turns? 1 1/4 turns out

[mono]

I'm going to try and get the carbs sync'd on a vacuum gauge this weekend.

[Rigid]

Why buy jets at all, most people have a drill set.

[Bodi]

1) Drilling a precision hole is not as easy as you seem to think. You need a precision drill bit, rigid jet holding fixture on a good drill press, correct drill RPM, cutting fluid, and correct spindle feed rate. And even then the hole you get will not be really precise. You would need to drill close undersize and ream to get a precise size. A good set of tiny metric drills - let alone reamers - will cost more than a set of jets.
2) The bad haircut problem - a barber can only fix that by cutting more hair off. If you drill too big a jet hole you can't make it smaller again.
3) marking - the drilled jet will be marked with a size it no longer is. Gets confusing.

[Rigid]

Pin drill while holding the jet in my hand.  It is brass dude, not inconel. Done dry, speed may vary.  I just file the numbers off.  Start small and work your way bigger.  Or use the chart I posted awhile back that showed drill size to jet size.  With the number of jet sizes being limited, and the number of drill sizes being what they are, it could be argued that my way is actually more precise.  Nothing anyone says to the contrary will change my mind one bit.  I have tuned far too many carb sets successfully.  Then you could argue that I don't know what real tuning is, or that I am settling for some less than perfect tune.  to that I say, whatever, and will still be drilling jets long after this post has faded into obscurity.

[adamlwvdc36]

Pin drill while holding the jet in my hand.  It is brass dude, not inconel. Done dry, speed may vary.  I just file the numbers off.  Start small and work your way bigger.  Or use the chart I posted awhile back that showed drill size to jet size.  With the number of jet sizes being limited, and the number of drill sizes being what they are, it could be argued that my way is actually more precise.  Nothing anyone says to the contrary will change my mind one bit.  I have tuned far too many carb sets successfully.  Then you could argue that I don't know what real tuning is, or that I am settling for some less than perfect tune.  to that I say, whatever, and will still be drilling jets long after this post has faded into obscurity.

+1  remember these bikes were made in the 70s before there were even cnc lathes and the like.  from what ive read, the drilling of the jets leaves a spiraling groove inside the jet that actually causes the fuel to flow more evenly and atomize even better.  Hell, after being chased around by some of the people on this site about what to do for a period of a week, I finally just did what my first instinct was:  (dont hate me) I took a propane torch nozzle reaming tool to ream my jets up to the size i needed them to be and the bike runs PERFECTLY. 

in other words, be a COWBOY, not a NERD!  youre riding an antique bad ass motorcycle for God's sake... Im adding that to my signature now.  LOL

[dave500]

lots of people have drilled jets,some people are ham fisted about it and others have more finesse,any grooves left from drilling wont affect anything as the jet is submerged,unless your the ham fisted one and really left a fine thread,i think its a job for myth busters?,i file the factory stamp off and scribe the new size on,its not a common activity i do though but i have done it.

[scunny]

I drill mine to find a rough base figure, then buy the jets a half size around that.

[adamlwvdc36]

i think its a job for myth busters?

+1