Carb balancing problems

I tried balancing my carbs last weekend to sort out a lumpy idle and to see if the bike would stop popping/backfiring when idling. however i ran into problems.
I was using a set of carbtune gauges, basically the front cylinder pulled the rod right up to the top of the gauge and the rear cylinder hovered around 1/3 of the way up. no amount of adjusting made any improvement and pretty much just made the backfiring at idle worse.
Anyone got any ideas as to what could be causing it? i checked the hoses from the carbs to the gauge and they were fine.

[yorkie_chris]

See if theres loads of slop in the linkage arm, dizzyblonde had this problem where the pivot was worn to the extent that all the adjustment in the screw was used and the rear throttle was still shut tight.

Also, this is just a theory, but if the idle screw was set very low, and the adjustment very far in, then the rear pot would be opening and hence drawing air, with the front carb shut and just making lots of vacuum.

If you actually look at the throttles and check they are both open slightly when the throttle is closed then this should give you a bit of an indicator.

Please bear in mind that the above advice is given by me and may well be total rubbish

Chris

[Spanner Man]

Morning all.
Ditto Yorkies advice on checking the linkage for wear. Also make sure the carbs are correctly installed, as any air leak could give you the symptoms you describe.
He's right about the idle adjustment too (clever cloggs). I have seen bikes where people, thinking it was the idle adjuster, have adjusted a balancing screw to the point where one cylinder is actually not running due to the butterfly in the carburettor being fully closed. It's an issue more commonly found on multi cylinder bikes, but check it carefully all the same.

Cheers.

[yorkie_chris]

Originally Posted by Spanner Man

(clever cloggs).

But not that clever, can't even get mine to start...

[Spanner Man]

Morning all.
Still having trouble getting yours to go Yorkie? Have you bypassed the kill switch? & made sure that all connections (ignition switch etc) are clean, as don't forget that corrosion on terminals can allow voltage through, but not current. So your meter will read the voltage at say the ECU, but the corrosion will not allow adequate current through when under load.

Cheers.

[yorkie_chris]

Sorted it mate, exactly as you said, was a broken wire below the ignition switch.
No can on it at 11.30 saturday night, the exhaust full of fuel from trying to get spark and it fired up... muahaha ... nearly set my kecks on fire and mae my ears ring but sounded great!

Chris

[Spanner Man]

Evening all.
Good show Yorkie! I'm glad it's sorted at last
That explosion of fuel in the exhaust made you jump I'll bet! At least the neighbours didn't ring the bomb squad eh!

Cheers.

[yorkie_chris]

Originally Posted by Spanner Man

bomb squad eh!
Cheers.

My reputation preceeds me

late with the reply but it turned out the choke plunger on the rear cylinder was jammed, choke was half on all the time.
I stripped and rebuilt the carbs and took the opportunity to drop in a jetkit while i was at it. bikes running much better now, no more popping and banging at idle, although its harder to start in the cold now.

[yorkie_chris]

Just shows you can't assume anything (like that they'd be working), to tell the truth when I've seen SV's do this its usually been held open just a fraction, not much effect on balance just running rich.