Carb won't balance - slide won't adjust. Help!

[Dan]

Hi,

I've just tried to balance my carbs to get rid of a knocking noise at tickover and seem to have opened up a can of worms.  Three of the carbs were fine but I just coudn't get a reading on #3.  At first I thought I may have an air leak and tried spraying WD40 on and around the carb-head rubber to see if that would help but still no vacuum reading.  The only way to get a reading is by pushing down on the adjuster for #3 but that would stall the engine.

So... I've whipped out the carbs and I can see that the throttle slide on #3 is sitting about 1 to 1.5 mm higher than those on the other carbs and there is not enough adjust ment to correct this.

Before I start taking the carbs apart, can anyone point me in the right direction?  I know the previous owner had the carbs apart so could he have reassembled them wrongly?  Could the needle height be set differently on this carb and would that affect the throttle slide anyway?  Any suggestions welcome.

Oh, and Happy New Year everyone 

Dan

[Bryanj]

Have you tried unadjusting the main tickover screw to lower number 3 then adjust the others up?

[Dan]

I will try that Bryan when I get home again from visiting family for New Year. Thanks, I will update in a day or so.

[Dan]

Ok, so it took longer than a day or so but I'll blame that on the cold weather :-)

I stripped and cleaned the carbs and after trawling the internet decided to try and set up the carbs to suit the Marving exhaust that is on the bike. I raised the needles 1 notch and opened up the main jets with a #84 drill. Finally I visually balanced the slides to match the carb that I was having trouble with initially.

This afternoon I refitted the carbs and fine tuned the balancing. Result! No more knock and engine runs sweet. I had it in the back of my mind that the knock was something more major like a worn primary drive chain but that's not the case.

Thanks for the advice Bryan, it has since been suggested to me that Honda carbs are set up around either number 2 or 3