I don´t know about Bultaco Amal settings but a slide with no 1 opening.......That sounds incredibly rich. I think something between 2,5-3,5 would be normal. Throttle opening comes into effect just above idle and flattens out at approx 1/4 of opening where needle and needle jet is more important. I see Inmotion list thottle valves with 2,5 to 4 openings.
I don´t know anything about Yamaha clutches but generally speaking: Clutch centre and clutch basket must not be notched and clutch plates must be in good condition.
I think thin oil is better than thick oil. I use engine oil 0W-20 to get a drag free clutch
Carl
But... ..would not an Indian Bullet engine be considered as pre-65? I think they should. And to gain ground clearence you should cut the oil filter away.
Bullet forks are pre-65. I am not shure about the MZ forks?
For modern steering you need 20-22 degree headstock angle and a front wheel spindle that sits 60-65mm in front of headstock centerline. This will give you a proper rake with a 21" trials front wheel
You can use parallel yokes with (1)all offset in the yokes. (2) Yokes with part of the offest in the yokes and the rest in the lower fork legs (like modern bikes) or (3)nonparallel yokes.
Bultaco Sherpa use a combination of (2) and (3).
I use a modified (replica) Crusader frame (20 degree angle), Ceriani forks (1961 type) and my own nonparallel yokes for a front wheel spindle offset of 65mm and I think it steers well.
Carl
Hello
This is what I found in my Bing carb for my 199B
Idle 45
Needle jet 2,73
Main 123
Markings on throttle valve and needle are difficult to understand but needle was in 2nd position from top.
This is what I use mikuni vm26: Needle 5C23, throttle 2, main jet 140, idle jet 30, needle jet O3, needle first groove from top (French Trial Classics jetting). Air screw is 1 turn out
It´s easy to hit the electronic rev limiter. Even I do it sometimes. The very high steps you manage to master need speed. Perhaps you should change the gearing (larger front sprocket or smaller rear sprocket). Main jet 125-130 would be fine.
Inmotiontrials now stock something they call "The New IRC Tubeless Tyre". https://www.inmotiontrials.com/new-irc-tubeless-tyre-now-stock/.
Design changed?
Well, I have some experince of the PHBL carb. I see Dellorto UK list the D40 needle for Tiger Cub. Replacing the D40 needle with D34 will make the mixture slightly leaner at low throttle openings. Idle mixture screw at 1-2 turns out is perfect.
Needle chart is here http://www.dellorto.co.uk/wp-content/uploads/2015/05/E-D-Needle-charts.pdf
Someone know if there is any tough classic (or pre65) trials in northern Europe (Holland, Belgium, northern Germany) and apart from pre65 Schottish which are the ones in UK? I would like to attend a couple of them next year but don´t know where to go. Ventoux looks OK but it seems to be in southern France . What about Bilstain?