Idle mixture by exhaust temp?

I gave it a go today as I had to do the carbies again, fitted new Iridium plugs & she ran badly.
I warmed her up, took shots of the headers in roughly the same places & got a wild range of temps, Cyl 1 185, cyl 2 300, cyl 3 150 & cyl 4 150.
I hooked up the guages & cyl's 1 & 2 were out badly & way off to cyl's 3 & 4. Cyl 3 & 4 were close to each other.
All that started to match the temp readings. When balancing carbies, 1 & 2 get done to match each other then 3 & 4 get matched then the centre screw is used to match the 2 pairs together, another amazing piece of carby engineering.
I balanced all 4 to each other & got all excited about going out for a ride to test it that I didn't re take the temp readings.
I'll do it on Tuesday, DOH. cause I want to know too.
I can't do it now cause Dad took it home,
& yes it went like a dream,

 

Awesome work will

 

Yes I understand, sorry for the confusion.
I'll adjust the mixtures according to the temperature readings & see what happens.
It'll be interesting to see what the temp's are like with the carbs balanced perfectly & also to see if mixture adjustment affects temp's, they are all set at 2 turns out which is 1/2 a turn more than usual on advice from another.
I should say that the bike is a 94 ZXR750 with a full Hindle S/S race exhaust, a K & N intake filter & a Factory Pro jet kit, valves are freshly adjusted so the readings should be fair, I'll post the results tomorrow night.
Initially set the carbs with a single strand of copper wire like a feeler gauge to get the butterflies close then fit them, balanced the carb's with a set of vacuum guages.

 

Ok had a fiddle with the mixtures & shot the temps with the thermometer.
It's a bit hard to follow, with rising engine temps, I did get her up to running temp, fan cuts in etc
Now that the carbs are balanced the temps are closer, cyls 1,3,&4 are about 180 - 190 deg but 2 is still higher, 270 -280 so about 100 deg hotter than the other 3 so I worked on it first & screwed the mixture screw out a turn & seemed to get a 20 deg reduction but thats where it stayed even with another turn out.
I made 1/4 turn adjustments on the other one that was a bit out but nothing really changed.
There are variables that could effect things like wall thickness of the headers, the inner 2 should be hotter as they are shouldered by the outer 2.
In my mind adding more fuel should increase the heat as there more energy going & being burnt, in 2 strokes we richen mixtures to cool the engines when they start to get up but that has to do with having the oil lubricant in the fuel it's not a air fuel adjustment.
I need to have the vacuum guages attached to see if there is any change & fiddle around more. Thats a job for the weekend.
So at this stage I'm not convinced it's a reasonable measure for setting mixtures.
A gas analizer is the way to go if possible in the persuit of excellence, but for a road bike it might be just a bit eccentric,
I'll have to get into it again this weekend cause the mixtures are all over the place now.
I have to say though she sounds a bit sweeter at idle & responds well to throttle at low revs.
If you were serious you'd buy an oxygen sensor that can read all four, weld in the 4 probes at the start of the headers & you'll get excellence, but it'll be expensive, something necessary for serious racing, too much for the road I think..

 

I'll give it another go, 260 may be achievable & I'll watch the vacuum guages at the same time to see if anything changes & adjust to keep all the moons in alignment.

 

The wire I use to set the butterflies = 0.16mm & it always suprises me at that tiny setting it idles up at about 3000 rpm or more & has to be wound back.
I balance my carbs at idle, am I wrong ? I havent ever read them at higher revs, maybe I should in the future.
I didn't have to make much of an ajustment on the balance screws but like you say that will effect the butterflies.

 

But on the exhaust stroke the valves are open, the piston & worn rings etc is just pushing the burnt gas out under no pressure, I know it's all happenning quickly & there'd be some pressure but were talking compression on the firing stroke when were talking about compression readings.
When I got the carbs balanced with the guages she levelled out & sat there ticking over beautifully, you could hear the difference when they came into balance.
At this stage, till I do the mixtures again, I still think the vacuum guages hold sway over the temperature but I'm open to anything new & better or old & better. I'm in a happy place right now with the tune so any improvement will be extacy.

 

I'm on it.
The position at the moment is cyl 2 is hotter than the other 3 by about 80 deg, you say 260 could be the mark, looks like I need to get the other 3 up a bit from 190, those 3 have the mixture screws set at 2.5 turns out, cyl 2, the hot one, is at about 3.5 turns out.
The only unknown will be the compression, I haven't got a gauge that'll fit down into the plug holes, don't know much about the engine except that the bores still have hatching, it's not the original motor but one bought from a wreckers & we guess it was out of a bike that was crashed early in it's life, everything in it is still fresh like new, so compression is expected to be as good as can be.
The Princess is going to the tennis on the weekend so there'll be plenty of time to test without any disruptions. I'm having trouble deciding what to do first, anything I want to anytime!
The

 

Further to this I changed the pilot jets just like in the article, & changed them as per the Factory Pro recomendations, can't remember the sizes, but it did make a sweet difference to the low - mid rev range, she pulls hard from down low eliminated the lowish rev range lag she had before. It's no trouble to get the front wheel to lift in any gear around 8 through 11 k revs no matter the speed & I'm 110 kgs. So tomorrows testing has everything in it's favour as comparible to the article.

 

Well it's done, sadly no result, I couldn't the the temps to move up.
The second, hot cylinder is at about 250 now & the others are just over 200.
I went to extreme with the mixture & closed cyl 1 to almost closed & the temp dropped to 85 deg
Ive set them back at 2 turns out until another time, when the skin on my hand has grown back from the burns & I've replenished some patience
Is it what I thought, more fuel = more heat. I'm going to ask an expert about all this & see what he says, It'll cost me a dozed top shelf beers but now I'm frustrated not getting a clear result
I'm gunna do the FZR next.
Oh & the mixture adjustments don't affect the carb balance, I was pleased to see thay were still in perfect balance & she's been ridden a couple of times.

 

Yes, that's the way I was taught.
Watch the revs rise with mixture or more often listen to them rise to their highest the back the mixture off a tad.
I could hear & see the zxr rise with adjustment, but the temps were still out & thats what we were chasing.
I did the CBR mc22 yesterday & at the end of the ordeal I shot the temps & they were around the 180 - 190 deg mark but again one was hot, 230 but I'm not sure, can't recall exactly, I had the FZR on my mind.
It's got no tubes to connect the vacuum guage to so I'll have to drill out the centres of 4 bolts & I'm off the the hobby shop today to see if I can get some copper tube to weld into the bolts.
Nothing is ever easy!
I expect the FZR will be way out of balance so I'm eager to get the guages on her, I was suprised the CBR was almost perfectly balanced & all it got last time was the wire under the butterflies, just lucky I suppose, the FZR gets the same so we'll see.