getting the 78 cb550k running proper

[screemn2]

have a project ive been putting together 78 cb550k with the pd46c carbs....the only things that have been changed are uni pods and a mac 4 to 1 exhaust system ....so far ive only been able to get it to run while on full choke or fluttered slightly ...it will die if the choke isnt on or if you really give it and throttle at all ...any info is appreciated thanks

 

[frogman]

Running on full choke enriches the fuel mixture. IF you have to do that to get the bike to run, then you need to start ADDING fuel to the mixture by changing jets in the carbs to larger sizes, you may have to change both primary and secondary jets to get to run correctly. Any time you change intake or exhaust on a carbureted engine you will/may have to change jetting to compensate for better/poorer air flow through the system.

Pods are overrated IMHO, they are almost all your issue right now. Put the air plenum back on the bike and find one of these K/N adapter kits or make one. Old school speed parts for these bikes, I have one on mine.

 

[Tune-A-Fish]

have a project ive been putting together 78 cb550k with the pd46c carbs....the only things that have been changed are uni pods and a mac 4 to 1 exhaust system ....so far ive only been able to get it to run while on full choke or fluttered slightly ...it will die if the choke isnt on or if you really give it and throttle at all ...any info is appreciated thanks

So what, the Mack didn't come with baseline "suggested" jetting?? Magine that. start with 40/105's 1.25 turns out PODS? brand? if they cost !00's of dollars they were pre-oiled, if foam... oil with filter oil, in a Ziploc and then wring out ALL excess... it's sticky and will perform fine and better than cotton IMO... If cheapo junk no name... toss em and get smarter... NEW plugs, fire it up full choke, run (if it runs) until it starts to idle back... hot out 30 secons or so cold 2 minutes or so... open the choke twist throttle slowly up to 2K and then whack it! if it winds up... ride it... do a set of chops, read here: (not your carbs, but the information is good) http://www.amckayltd.com/vm34-36.pdf

The thing is with jetting, you have to time the thing and make sure all the other stuff is done right first the PDF is an awesome read even if you don't follow by the letter... No bike is the same so no one here can give you the magic jet to fly, only a baseline. Dyno and sensor method is always best.

 

[panzerhell]

I run 110's and dropped the clip on my needles. All good, anyone who says pods are a bad idea doesn't know how to tune carbs. Pods and a free flowing exhaust are a great idea.

 

[jryftc]

The choke provides a temporary rich mixture. So if shes running with only the choke on / dies with throttle, sounds like she may be running too lean

 

[barnett468]

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i would just raise the needles and go up 3 sizes on the small jets and try that.

if you hold your throttle around 1/8 open and spray wd40 into a carb and the engine rpm increases, it is definitely lean.