Warm weather & jetting
Been out on the G.P to Elvington today and the bike ran really rough right from the word go, i stopped several times doing a plug chop and the plug seemed ok, but the scoot really struggled in 4th with a slight cross wind. I realise there could be other issues here but could the warm/hot air today affect the jetting? Or am i kidding myself
My Imola runs sweet as can be through rain and cold or even pleasantly warm. But when it gets like it was today, temperatures up in the seventies. She starts to bog down at speed.
I can't be arsed to jiggle the jetting. I mean how often will we get this heat? :biggrin:
I can't be arsed to jiggle the jetting. I mean how often will we get this heat? :biggrin:
-
carlos fandango
- registered user
- Posts: 792
- Joined: Wed Jan 07, 2009 12:51 am
- Location: Stourbridge
- Contact:
I was just about to ask the same thing.
I think its to do with air density... the warmer the weather, the air is less dense....less air to fuel..... therefore the jetting will be richer.
But on a ride out today mine seemed to be running weak and another scoot siezed with a white plug definitely weak
So what is it warm weather up jet or down jet
I think its to do with air density... the warmer the weather, the air is less dense....less air to fuel..... therefore the jetting will be richer.
But on a ride out today mine seemed to be running weak and another scoot siezed with a white plug definitely weak
So what is it warm weather up jet or down jet
When i was young my Mom said "if you haven't got anything nice to say, say nothing at all " ..................... and people wonder why I'm quiet around them !
Humidity, rather than temperature, can make a big difference. The higher the humidity, the richer the engine will run, as the water vapour displaces air.
-
joeythescooterboy
- registered user
- Posts: 183
- Joined: Wed Jan 07, 2009 1:16 am
- Location: Chester
- Contact:
I thought it's more to do with the oxygen concentration in the given volume of air, it's oxygen that burns not air.
The easiest way to think about it is if you blow up a balloon and leave it outside in the sun it'll get bigger the warmer it gets, the amount of oxygen remains the same but in a larger volume so less dense. Allow the balloon to cool down and it'll contract so again the same level of oxygen but in a much smaller volume of air.
So theoretically you should downjet when it's warm/hot to keep the stoiciometric ratio (fuel to oxygen,) constant.
The easiest way to think about it is if you blow up a balloon and leave it outside in the sun it'll get bigger the warmer it gets, the amount of oxygen remains the same but in a larger volume so less dense. Allow the balloon to cool down and it'll contract so again the same level of oxygen but in a much smaller volume of air.
So theoretically you should downjet when it's warm/hot to keep the stoiciometric ratio (fuel to oxygen,) constant.
Nemo saltat sorbius, nisi infanus est.
-
adriang
- registered user
- Posts: 86
- Joined: Mon Jan 12, 2009 8:42 am
- Location: Brisbane, QLD, Australia
- Contact:
Couple of points to add here.. hopefully not to cause confusion.
I remember a long time ago reading an article in some bike magazine about GP bikes (in the 2-stroke days) experimenting with various environmental factors like cold air into the carbies. Don't think there were ways to consistently provide colder air without a lot of weight.
I'm now in Brisbane, Australia which is hot and humid. Really hot and sticky in the summer. Two of us have changed atomisers from AV264 to AV266 and our scoots run much sweeter. Mine is a PHBH rapido combo , other is an RB22 with the flatside delly AF advise except the 264 vs 266 atomiser.
I remember a long time ago reading an article in some bike magazine about GP bikes (in the 2-stroke days) experimenting with various environmental factors like cold air into the carbies. Don't think there were ways to consistently provide colder air without a lot of weight.
I'm now in Brisbane, Australia which is hot and humid. Really hot and sticky in the summer. Two of us have changed atomisers from AV264 to AV266 and our scoots run much sweeter. Mine is a PHBH rapido combo , other is an RB22 with the flatside delly AF advise except the 264 vs 266 atomiser.