Aye 125H,
You are not alone!
I'll try and answer your queries from my experiences to date.
BUT remember that the ignition system, stator, rotor, CDI/HT coil, are away from me at the moment and I despatched the original low tension coil and trigger coil in the package for testing and future reference.
CARBURETTOR
Model: VHBZ 24 BS
Main jet: Fitted 74 (#6413.74) Factory fitting: 72 (#6413.72)
Pilot jet: Fitted 48 (#11486.48)
Starting/choke jet: 50
Float jet: 200
Float: 14 grammes, one piece assembly (#7450.2 gr 14)
Float level: Carb body, carb intake side down, float pivot posts below float, body flange to outer edge of the float = 24mm +/- 0.5mm (Dellorto manual)
Carb body, carb intake side down, float pivot posts below float, body flange to mid point of the float = 10mm (Moto Morini 'Blue' manual)
Slide: 40 (#7447.40)
Needle jet: 260 U (#8203.260 U)
Needle: E4 (#2343.04 E) N.B. Mine only has 3 grooves and I run it with the clip in the middle groove
Slide/idle screw: 3 turns in from lightly seated against the slide
Pilot jet/air screw: 1 turn out from lightly seated
ENSURE THERE ARE NO AIR LEAKS EITHER AROUND OR FROM THE INTAKE/MANIFOLD RUBBER! This would cause a weak mixture and an inclination to rev without control. Spray WD40 over the manifold and see if the engine revs change/drop, or any cracks become apparent.
IGNITION
Generator rotor: Internal diameter over the magnet segments = 94.05mm (#31.96.91 stamped clearly on the outside of the rotor)
Generator stator: Overall diameter over the stator poles and the trigger coil poles = 93.75mm (No part numbers stamped onto stator plate)
This gives an air gap between the stator poles and the rotor segments = 0.15mm (0.006")
N.B. This is being investigated at present!
CAM PUULLEY/TIMING
Cam pulley fitted to my engine is stamped with a 'C'. I suspect that a 125H engine was built using 'A', 'B', 'C' pulleys, so as to conform to the tension requirements of the timing belt. These timing belts, on all Moto Morini models, are being run at the upper range of their design speed and load!
Hence, the need to check that the maximum deflection from the outer edge of the belt, on the forward side of the pulleys, does
NOT EXCEED 6mm and
is less than 3 years old
However, I find that there is no need to purchase the 'lettered' belts, providing the belt that you use remains within the maximum deflection limit (6mm) and is less than 3 years old. I purchase quality generic timing belts (#124L075) from my local bearing supplier, for the princely sum of £7-36 inc. 20% VAT each, rather than the £30.00 + plus P&P being asked for the specifically measured and labelled belts.
I am sure that if you entered "timing belt" into the "Search" window in the top right of the forum screen, you will find earlier threads on this subject, mainly the concerning 350's. I also used to own a 1982 K2 350 and used the same timing belts on it, with no problem.
I hope this answers some of your questions and clarifies others that you may have? I will post on my "Ignition" thread the results and progress or otherwise that is made, with the ignition on my "Minx"!
Good health, Bill