CB550sc Exhaust and Carbs

A

alee9476

New Member
Hey guys I have a couple things. First off I'm new here, but I got a 1983 CB550sc I'm attempting to convert into a custom cafe racer and I need a place for some advice. Second, I was thinking of doing an undertail exhaust, not exactly traditional, but it seems like a challenge and I personally like the look. The only issue is I don't have a huge budget. Is there any inexpensive muffler ($25-30 per can) that anyone knows of that will give this bike a great sound (I'm thinking similar to more modern inline 4's with yoshi's) without being too loud or obnoxious? I've seen the 12" and 16" shortys on DCC but i have a feeling those might be a little too loud/ not the sound I'm looking for. Anybody have experience with these? I'm keeping it a 4 into 2 by the way.

The other thing is carb jetting. I have what appear to be Keihin VE carbs? I've never heard of them, but I bought a set of pod filters because my airbox was beyond salvagable. Does anyone have even the slightest clue as to how to rejet these with the new filters and a new, possibly more open, exhaust? would it be maybe 5-10 up on the main and 5 up on the pilot? Sorry for the long post and I'm hoping I have this in the correct section.
 
I have never rejetted that particular bike, but I'll give you a couple pointers of where to start.

Those jets are in increments of 2.5. Five points on the jet number is only two jet sizes. A good starting point would be five jet sizes larger, therefore the jet number would be 12.5 larger.

For pilot jet, start with one jet size larger.
 
What jets are in there stock?
About 10~15% increase should be starting point
Set float level at least 1mm higher than stock
They will probably need further work, it's a long term project in itself jetting CV carbs
 
As best I can tell, the bike comes stock with #110 for main and maybe a #35 for pilot. I'm assuming the carbs on the bike still have stock jetting, but I can't remember what they were when I broke it down to clean it. And is that 10-15% recommendation for just the pod filters? or would an exhaust system that's more open than stock require a larger jet to run properly?
 
10% for pods, 5% for exhaust.
It's just the starting point, you will probably need different jetting after testing plus other adjustments.
Check service manual for stock jets
 
Alright great, I don't think I'll start that until I weld up a new exhaust though. I'm expecting this is going to take a long time to get right
 
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