Thread: Carb Balancing

Hello Terry,

My Eurosport is having carburetor issues again; I know for a fact the carbs are perfectly clean because they have been rebuilt twice in the last six months (my fuel tank was having some liner disintigration issues).

However, I am not sure that my carb synchronizer is not a complete piece of shit, and as such causing the problem. If I follow what the synchronizer is telling me, the bike runs like a one legged Special Olympics hurdler with Tourette's Syndrome.

If I dial it way the hell out of "balance" (according to the tool), the idle gets higher and runs like Jessie Owens.

Thoughts?
(P.S.- no leaks, tested it with ether)

Tim, I am not familiar with a Eurosport, I do remember that the CX's had metal slide diaphragms that would wear out and cause balancing/running problems. I actually worked on 2 that had bad worn slides, replaced with new ones and they both ran great again. Hope this helps. Oh, slides came with carb tops.

Originally Posted by R1-Limited

Jimmie is right, the diaphragms can crack or not seat correctly, if they are a tad worn, there can be air leaks, if rebuilt these should had been replaced, if not then bad on the rebuiler.

Syncing them if I remember is vacum based not just feeling the slides, like todays sport bikes the throttle tubes can become out of sync causing issues like you describe. Most people dont even notice. Get em sync'd

John, they are aluminum, can't crack at all. Think piston (slide) and cylinder (carb top) the slide and card top wear and the slide can actually bind in the top.
Here is a picture of a CX/GL slide and carb top

Hi Jimmie,

The slide diaphragms are fine, polished and pretty. No binding at all. This does remind me of something that the rebuilder mentioned though, I'll have to see if he actually did something about it. . .
didn't think about it until you mentioned it.

Warning Will Robinson, Do Not Use Welder Tip Cleaners!!! The little serrations on the wires WILL resize your jets to an unknown size . . . Always use a smooth wire, preferably a tool like the Honda Jet Cleaner like I use #07JPZ-001010B.

The carbs were both completely stripped down and each port, emulsifier, tube, jet, needle, seat, and passage, was checked and cleared. Twice.

It has something to do with the idle circuit only. On gas (especially full throttle), it does run fine.
The spark plugs both are a nice light brown.

That's why I am so stymied, I would be suspecting the spark system otherwise.