Balancing Triple Carbs

Spub

Spub

Hero member
Location
Pasadena, California, USA (Left Coast)
Being obsessive about balanced carbs, I have been fiddling with that bell crank balancing mechanism on my Jota for the past two days. There must be a better method than the one I have been using, which is to loosen both adjust screws so there is no contact, adjust the middle carb to one of the outers at idle with the idle screw, then adjusting the other outer to the middle, then tinkering by raising to 2500 rpm and making sure all three rise together, which is a bitch.....the twins are MUCH easier......so who has a better method....if one exists....
 
Don't understand- is your method to avoid using a set of carb balancing guages?  Don't you just balance the outer two to the centre?
 
Spub,

Just get yourself a set of guages...

Wear in the linkages can and will eventually drive you crazy, eliminate all play by replacing the bushes and linkage shafts if necessary.  Balancing then becomes a 5 minute job.

The slightest wear in the bushes will throw any balancing efforts out the window, open the throttle twice and your previous results will be gone.  The dellortos seldom open evenly, the bracketry is a bit weak to keep all three carbs properly in synch.  I loosly assemble the carbs, clamp the centre one in the vice and tweak both brackets till they open as closely to another as possible.  Easy to see; adjust the closed slides with just a tiny opening visible.  Open to WOT and usually at least one slide will be off by 2mm...  either tweaking/bending the brackets or bell cranks will eventually get you at least quite close to perfect.  There is also quite a bit of play in the slide bell crank that you can use to advantage.  Loosening the fixing screw allows an additional few degrees of adjustment.

Thus pre-adjusted carbs usually require a minim?m of adjustment once mounted on the bike and checked with vacuum guages.

HTH,
piet
 
Yup, have been using gauges to balance. Piet points out my issue, getting to balance and then keeping adjustment. Did not realize ham fisted bending of the bracketry was allowed, but if it works, I got more than enough ham fistedtry in me to go down that path....
 
Once tried a triple cable splitter on the carbs, wasn't really happy.  Quite a bit of friction in the system, and the cables do need regular service/lube. 

A blob of thick oil in the linkage bushes every now and then keeps them in shape for a very long time, no particularly big load on them.  Should be a "must do" during every service.  But, in reality, they are totally neglected, they wear quickly once dry, and take out the shafts whilst doing so.

piet
 
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