Mugello Jetting query

[scootcoot]

I had a similar set up and had lots of trouble trying to dial the 25mm in ,i ended up ditching it and getting a 26mm del and had it set up in less than an hour !

[olliewtf]

Please explain Daggs

The plug colour is mostly influenced by top gear running rather than tickover or when accelerating through the gears.

I find this interesting as ive always found jetting in a bit hard, mainly because i have no patience! Could you explain why this is? how is it different then, say, holding half throttle in second as opposed to fourth?
also, how long would people recommend you hold it at any given throttle position?
There seems to be alot off differing opinions on this most necessary and basic of procedures, I even read on FB the other day someone saying that their best practice was changing the plug for a new one everytime they took it out of the head! now that is mad....

[Daggs]

Please explain Daggs

The plug colour is mostly influenced by top gear running rather than tickover or when accelerating through the gears.

I find this interesting as ive always found jetting in a bit hard, mainly because i have no patience! Could you explain why this is? how is it different then, say, holding half throttle in second as opposed to fourth?
also, how long would people recommend you hold it at any given throttle position?
There seems to be alot off differing opinions on this most necessary and basic of procedures, I even read on FB the other day someone saying that their best practice was changing the plug for a new one everytime they took it out of the head! now that is mad....

Perhaps i didn't phrase it well? I was suggesting most time checking the jetting is when out on the road, getting into top gear to keep the revs down, because presumably, the engine is being 'run-in' at the time.
You are correct to say there are many differing opinions. Twelve years ago i had never 'jetted' a two-stroke carb. I built up an Imola engine with a 28mm Dellorto and suddenly found out i needed to know how to do it. So i asked around, listened to advice even if contradictory and worked it out for myself. It was a long process of learning but i got there. I wouldn't call myself 'expert' but i am now 'capable' of 'jetting'

[olliewtf]

that makes more sense, id find it surprising if your choice of gear mattered... although i suppose you do have to consider load, and jetting for on pipe and off pipe... this is where my head starts hurting and i just whack a bigger main jet in

[paddyfitz]

On those 25mm carbs - I like the 266 tube with a D29 needle a little better.
Might be worth a shot.

[Tractorman]

I am working on which main jet I need for my set up, which the same as TSI-200's, by doing plug chops. I started at 96 which is recommended by Cambridge and have worked up to 100 which was just on the weak side so I have 102 in and waiting for the wind to drop to test it.

I have settled for a 104 main jet, the plug colour look about right.

[TS1-200]

Right, upped the main to 115 , 266 atomiser, 70 pilot, scoot runs fine but still looks weak. just something I didn`t mention Is its using a manifold for a 30 mm delly with a stepped carb rubber, I have now got a manifold for a 25mm and will be running through the airbox, will be fitting this tommorrow, and will start all over again, and will report findings.

[Tractorman]

Sorry, forgot to mention I am running through airbox and filter.

[TS1-200]

Looks like the reason for weak running was the original 30mm manifold was leaking(faulty gasket) where it attached to the cylinder, replaced with a 25mm manifold and have had to alter all the jetting back to something a bit more likely.
105 mj, 50 pilot , 45 slide, 266 atomiser, D22 needle 2nd clip and it runs well I`ll do a few miles and check do more plug chops.