Topic: Help finding vacuum on a morgan carbtune

[gloken]

Hi,

I've been in the process of getting a CB500K back on the road... should be done by the time it snows at this rate.

I had to tear down the carbs and clean them out, so now I have to tune them. I bought a Morgan Carbtune online and hooked it up according to the manufacturer directions... but I'm not getting any movement on the readings, they all sit at zero.

Is it possible for a vacuum leak to leave all of the meters sitting at zero? My gut says that a vacuum leak might affect one carb, but wouldn't affect all four like that.

Really trying to figure out why all of the meters would read zero, the bike sits at a decent idle, so it's obviously got enough vacuum to run the engine. Does anyone here have experience running this tool on a similar bike?

[greenjeans]

Is the carbtune assembled correctly ?     The rubber tubes each have a clear tube that join them - don't remember which end is shorter.

[gloken]

Yeah, I had to cut the tubing and insert the clear damper tube into each one. I did that, and put the damper tube on the engine side, not the tool side. 

Sorry, I know this kind of thing is really hard to diagnose via the internet.

Here's a picture of the carb with the adapter spigots screwed in to each unit, just to show that I'm not totally insane.

[TwoTired]

What year bike and what country?

Those are PD carbs, right? 
If the engine runs, there has to be vacuum in the intake runner and the portions of the carb between intake valve and the slide.


Hold a tube up near your ear that is connected to port fittings.  You should be able to hear it suck.  If so, then look into a problem with your morgan tune.

[gloken]

She's a 1977 Honda CB550K, and runs at a high idle... but seriously needs a good sync, obviously.

I suppose I'll indeed have to inspect the tool. Thanks for the advice.

[RevDoc]

You will find in the Carbtune directions that some bikes have a vacuum level that is too low for the usual vertical assembly and reading. Simply flip the carbtune upside down and use the level, whatever it may be, for the #2 reference carb as your synch level. Just keep the proper tube to cylinder reference in mind!. Discovered this with my '78 cb550K. Works out fine.

[dusterdude]

Um,does this mean i dont want to buy a morgan?if not,what brand?sorry for the hijack

[flybox1]

nothing wrong with the carbtune, duster, i've used one, and eventually bought this, and it works great.
http://www.saber-cycle.com/store/product859.html

[dusterdude]

Thanks flybox,ill check it out

[gloken]

Buy one, it works very well and the staff there were very helpful.

Is this where I admit that I didn't read the manual as well as I thought?
 

If you flip the tuner upside down it catches a lower pressure range... and that did the trick for me. Once I had it working the tuner was really easy to use.