get your carbs balanced

Originally Posted by northwind

...

Sure, under no load the revs can be all over the shot with very little adjustment but the throttle is virtually shut - so lets say that is an up to 10% deviance between butterflies?? … it’s actually really hard to balance them 100% as they are so sensitive (again, must only be fractions of a degree at the butterfly). I agree/accept balancing them DOES make them idle much more smoothly, even when you are just somewhere near it’s noticeably smoother. But under load and with wide throttle openings … I just can’t logically see how fractions of a degree is going to make any sort of ‘real’ differences

Perhaps its more noticeable with a V-twin? But at say 45deg and over opening, how is say 0.1 of a degree (so what 0.2%? (less as the opening becomes more)) deviance gonna make any real difference?? I mean surely you will get that much flex in the joints etc!?!

Also the sliders (which do the real work) are retained by springs ... are you seriously telling me they are that perfectly matched too?!?!

[northwind]

I've balanced 'em at 5000rpm, when my bike wouldn't idle (as I'd sabotaged the jetting ) and the effect is still there- revs rise and drop, and you can hear a shift in the exhaust tone much like loading and unloading. It's less obvious though, at idle it's night and day. I'd think it's possible that the effect is actually exagerrated at higher revs, but I've no clue if that's the case.

Still, I've reconsidered on the placebo effect, since there's probably a placebo effect in absolutely everything

Originally Posted by northwind

I've balanced 'em at 5000rpm

Even holding it at 5k it is still 'no load' as it is in neutral (presumably)

i.e. the throttle opening is very minimal with no load at idle OR 5k … it’s not so much revs but load … if you think about it, you can do 5k with a closed throttle downhill, but might need 3/4 throttle up hill

I am not arguing that balanced carbs don’t make the bike run smother, but at anything other than idle or no/low load, the effects are going to be pretty insignificant … certainly in a mid to high load (larger throttle openings) situation, in short I can't logically see how you can feel any power benefits at that loading!

Placebo Placebo Placebo!!

[Sid Squid]

Balancing at anything other than idle* does nothing and is irrelevant.
Think about it, the adjustment you're making is, as Blue says, tiny fractions of a degree of butterfly position, at tickover when the throttle opening is similarly small these adjustments represent a significant percentage of throttle opening, when the throttle is opened the same change of adjustment at a subsequently larger throttle opening represents a much much smaller change in gas flow. Anything other than setting balance at as low a throttle opening as is possible is meaningless.

*Or a dab above so as to smooth the intake pulses.

[northwind]

Originally Posted by Blue_SV650S

Even holding it at 5k it is still 'no load' as it is in neutral (presumably)

May well have had it in gear, not sure. Whatever, the difference from adjustments was still more than you'd expect from the trivial changes, I don't like to disagree with Sid Squid as it usually ends in looking silly but, the evidence of my own eyes contradicts here.

I'd agree with northwind here. But I think we're comparing different degrees of unbalanced carbs. My SV is in pretty good nick, but could be balanced better - and i doubt there would be any performance gain, ala blues argument.
But i think northwinds had an experience like my last bike which was badly out of balance. Its effect is very pronounced at any point in the rev range. After I'd balanced my carbs it felt like I had an extra cylinder!

Sorry to hijack/bump/derail....anyone any good at balancing the carbs on an 01 zx6r? It's running rough as a badgers since the new can fitted. Took it to the kwak garage who said the jets need cleaned and carbs balanced.

Oh it would help if within 30 miles of kinross

You want the jets cleaning first then. Balancing is basically the last thing you want to do. Would help if your passing through manchester :P

[Sid Squid]

Originally Posted by stuartyboy

Sorry to hijack/bump/derail....anyone any good at balancing the carbs on an 01 zx6r? It's running rough as a badgers since the new can fitted. Took it to the kwak garage who said the jets need cleaned and carbs balanced.

Oh it would help if within 30 miles of kinross

This is typical of Kawasaki low end carburation, and as such isn't specifically a balance question*, with a can on it it'll almost certainly be lumpy unless the pilot mixtures are set very carefully, and as they're fussy at the low end anyway it'd be wise to ensure that everything else is right first, ie clearances, plugs etc.

* Of course if the balance is off it won't be right anyway though.

[northwind]

Originally Posted by gettin2dizzy

But i think northwinds had an experience like my last bike which was badly out of balance. Its effect is very pronounced at any point in the rev range. After I'd balanced my carbs it felt like I had an extra cylinder!

Oh aye, maybe should have said that- I was fitting new carbs to my bike, so they were absolutely miles out. But, it's all matters of degree. Then again, sometimes when you scale a difference down it just stops mattering. Hmm. Right, I'm retreating to the fence Sufficiently badly balanced carbs will probably make a noticable difference, but how far out they'd have to be to cause that noticable effect I don't know, my example was a bit of an extreme when I think about it again.