Effect of humidity and air temperature on carb performance

[drunkmunkey6969]

I'll drop the pilot and see how it goes

I'd leave that to Joan Armatrading.

you'll have to explain that one to me Dan

[coaster]

HUMIDITY................
humidity ....is water vapour,..........
In a given amount of air it displaces oxygen content ,making the air less dense,as a result the engine takes in less oxygen ,and its output is reduced.
for eg,......on a hot day at sea level high humidity would cause a scoot to run rich.........

.......

Surely water vapuor is made up of oxegen and hydrogen molecules, wouldn't they count? Also I seem to remember water injection kits used on high performance cars some years ago although that might have related to lowering the temperature of the charge??

Not arguing, just trying to prove/disprove some old ideas stuck in my head

[156 D]

.

[coaster]

156 d will be along shortly to put you right on this.......................

o....O.......... no he won`t.........not this time!........i like it here!!!...........

No!!...........i won`t be tempted?..........

...........................................

Come on, you know you want to really

[storkfoot]

I feel like dropping the whole scoot, never mind the sodding pilot When I posted this, thought I only had a mild issue, however, today [quite warm here and a bit damp] the scoot was running like the proverbial bag of sh1te_____bogged out badly a couple of times when under load, so badly, I had to pull over, turn the fuel tap off, open the throttle to full and burn off all the excess petrol and vapour.

I've tried raising the float, no difference. The air screw made precious little difference which, to be honest, I thought might be the case as I'm pretty certain the 42 pilot is right. Indeed, I tried a 38, 40, 45 tonight and they all made matters worse.

Clearly I need to look at the whole carb tuning again, especially the needle. Any thoughts as to whether my needle setting may be too rich or too weak ? I know there's a significant overlap between the main and needle, but I sometimes struggle to get my head round whether "bogging" is as a result of there being a lean spot in the carb progression, or because of spitback.

Any thoughts gratefully received

[coaster]

What needle are you using Storkfoot? I have found the GJH needle works better for me its a bit weaker and has vastly reduced the 4 stroking that used to occur on mid throttle.

If you are weak in the mid throttle position it will hesitate and jerk, a bit like fuel starvation but it will clear as yo go through the week spot. If its bogging to the point of having to stop then its definately too rich. Have you cleaned you filter lately?

[joeythescooterboy]

Ah Ha, at last somewhere I can impart a little of my knowledge...........
The water cooler that Coaster is on about is to cool down the compressed charge from the turbo. The turbo compresses and heats the air, a charge air cooler cools and condenses the air allowing more into the cylinders creating more power!
Not a spotter on these things just something I had to teach when I was D&M instructor on Challenger Tanks!

[elgarra]

Try giving that ram air filter a good clean, or at least dry it out the next time you have this issue, as i have a suspicion that may be a major factor in your problem.

In fact, out of interest, take it off and see what how the motor reacts before you mess about too much with jetting etc.

[elgarra]

"coaster"Have you cleaned you filter lately?

F**k, I'm an echo.

[coaster]

"coaster"Have you cleaned you filter lately?

F**k, I'm an echo.

I gave my engine a blast with the jet washer the other week then next day set off for a bike show. Only got half a mile before I realized I was in trouble, engine was bogging at about 30mph and dying. Turned round and returned home, fitted spare remote filter and all was well again