paulnobodyimportant wrote:Feedback Update.
Only got round to re-jetting my carb as I mentioned on page 1..................
Then I found this snippet from Mark Broadhurst
“A basic guide is if you get to your top clip position, you may require a smaller atomiser (needle jet). And, if you get to the bottom clip, then a larger atomiser is required.”
............But to conclude, it does look like you change the atomiser first, or it did in my case.
Unfortunately, the simple truth is.....it's not that simple.
A) in ref to the MB segment above, it's all relevant to what needle and atomiser you are on really isn't it? If you are on an AV262 and an X2 needle (top clip)....you'd come down on the needle. But if you were on AV268 and X7 (top clip) you'd come down on the atomiser.
B) If we were all riding factory built/jetted Yamaha RD350 bikes and we fitted a set of Stan Stevens pipes, then chances are you could say: up-jet to XXX main jet, and this would work. Due to standardisation of parts and information........ But scooters are like a massive combination lock, with each cipher effecting another area. So this scooter responds to ABC, but that scooter responds to XYZ.
There are of course some basic 'rule of thumb' and set principles to follow, but quite often it boils down to testing, knowledge, experience, testing, information, testing, results, testing, equipment, testing.....and so on.
As far as the area of jetting carbs is concerned, I have to add up: cylinder + crank + pipe + carb + known faults + unknown faults + who built it + jets already in it + ignition timing + fuel tap/flow + comp ratio + squish + ethanol + safety margin + weather/temp variances + rider/owner technical ability + Dyno chart readings from 3 different runs.........and then make an assessment, change a carb component, and re-test. Asses info, and continue until desired result is attained.
So the rule is ........there are no rules. Just information and decisions.
