125H problems

Lambertini era singles (125 and 250 - half v-twins)
125H
Posts: 59
Joined: 30 May 2018 18:36
Location: Loughborough UK

125H problems

Post by 125H »

Has anyone gotten to the bottom of the 125H problems as yet, I have one from 1975 which I rebuilt completely, it looks great but does not want to run.
I can start it on about an eighth to perhaps quarter throttle and it runs OK if I hold it there, but even a slight deviation from that and it will stop.
Sometimes it will rev away if I get over the stop point but then its over revving and I have to shut it down. I have tried two different carburettors to no avail, the transducer I was recommended a 323921 is producing a good spark and a good belt if I get anywhere near the electrodes so don't think that's the problem, I have wasted most of the summer trying to find the problem but nothing seems to work, don't know if its modern fuels, valve timing or ignition timing.

Any suggestions are most welcome.
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themoudie
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Location: Perthshire

Re: 125H problems

Post by themoudie »

Aye 125H,

What settings, jets, do you have fitted in your carb and what number is it?

As for the electrickery! :evil: Typical Italian 1970's - '80-'s rubbish. If you have read my hijack of 'andygrew's' original question, you will see the lengths that I have been going to, to get the little perisher to run, hence it's "Morini the Minx" by-name, as well as the colour scheme.

Link_to_125_with_no_spark_thread

I have taxed the patience of Benjy Straw, Mark Bridger, and Paul Compton, who latterly has offered to put my entire ignition system on his testing rig to see if he can locate a potential fault. However, I had received an offer from a person specialising in Ducati Electronica Lambretta and Vespa ignition systems to run some tests and had despatched my complete ignition system, when Paul's generous offer was made.

So, at present my ignition system is being diagnosed and possibly repaired, depending upon what is diagnosed. I will update the "125_with_no_spark" thread, with the results of the tests and all other information.
I have wasted most of the summer trying to find the problem but nothing seems to work, don't know if its modern fuels, valve timing or ignition timing.
You have my commiserations, as my ongoing battle has lasted 15 years and with some intensity the past 5 years.

My Ducati 450 took 20 months to sort out, as it would blow the carb off the inlet stub, with sheets of flame. In the end, a change to an Electrex Hall effect ignition system rectified the problem that appeared to be the vibration harmonics of the crankshaft upsetting the mechanical AAU! :twisted: Unfortunately, because the ignition system on the 125H is unique amongst the Moto Morini models and is essentialy a bastardised 2 stroke scooter system firing a 4 stroke engine, nobody has produced a reliable alternative, YET! If necessary I may have to research Lambretta or Vespa scooter alternatives. The scooter systems run with little or no advance and with modern fuels benifit from some retard from the 'standard' ignition timing. Whereas, we are looking for 36°spark advance BTDC at 6,000rpm, with our engine.

Maybe the Moto Morini Club Nederland article commenting on many Morini's lying in the back of workshops due to ignition failure reflects our 125H's Achilles heel.

If you acheive a satisfactory outcome, please post it, so that a resolution is available to others.

Good health, Bill
125H
Posts: 59
Joined: 30 May 2018 18:36
Location: Loughborough UK

Re: 125H problems

Post by 125H »

in regard of carb settings it was suggested that I lean this out, so fitted a 43 pilot the standard atomiser 260U standard choke 50 standard needle E4 but in the top notch and a number 5 slide instead of a 4.

When I do get it to run, with the above settings it does not stink the garage out so much but the problem persists in as much as it will start on approximately eighth to quarter throttle and runs, but any slight deviation from that with the twist grip and it stops. If I very gently open the throttle and it does not stop, then it revs like as banshee and I have to shut it down.

I am from my own experience and reading all these posts, forming the opinion that a 125H is a white elephant, little wonder they were never officially imported into the UK.

I have tried two carburettors as above so do not think there is a fault with carb body, the only issue apart from ignition and I have had the stator rewound and a new pickup fitted may be the atomiser, 260U is no longer available but may try and find a weaker size that fits but this is probably clutching at straws and only adding to the money pit! If anyone does come up with a solution please let me know, the dust sheets gone back on!
125H
Posts: 59
Joined: 30 May 2018 18:36
Location: Loughborough UK

Re: 125H problems

Post by 125H »

with the ongoing ignition problems I wonder if the generator rotors have any bearing on the issue.

When my 125H was stripped down, we also stripped another engine for spares( I needed a new cylinder head) I think it was the later KJ model and I may have used the rotor from that instead of the one that came with the bike.

One rotor is numbered 31 96 90 the other one which I think is the later one is numbered 31 96 91 not much difference but would it have a different line up with the pick up on the stator plate?

Perhaps these are just part numbers? Before I pull the rotor off to check can anyone confirm.

Over a 40 year period parts can get swapped around which may be causing problems. This ignition system should work it looks very simple and motor scooterish why it does not baffles me completely, but then I'm from the magneto era.

I also noted that the timing pinions (crankshaft) had the punch dots in the same place, so its doubtful these engines were set up individually at the factory more likely they were put together from bins of parts already marked with an approximate cam timing built in.
125H
Posts: 59
Joined: 30 May 2018 18:36
Location: Loughborough UK

Re: 125H problems

Post by 125H »

and further more - just been digging in my box of spares and found a different cam pulley marked C.

does anyone know if a 1975 125H should have a C pulley or a B pulley and of course the appropriate C or B belt.

If anyone with with one can check its much appreciated.
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themoudie
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Location: Perthshire

Re: 125H problems

Post by themoudie »

Aye 125H,

You are not alone! :wink:

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! :twisted: 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"! :twisted:

Good health, Bill
125H
Posts: 59
Joined: 30 May 2018 18:36
Location: Loughborough UK

Re: 125H problems

Post by 125H »

Hi Bill,

thanks for the extensive info I will check it out against my 125H and keep a copy for reference.

I have looked for an alternative ignition system but since VAPE stopped making one for the 125H there are none available.
My friend in Germany Karlheinz is of the same opinion so for the time being we have what we have as far as that's concerned.
I suppose it would be possible to have a new system made from scratch by a specialist engineer they are being made for motor scooters and other lightweight bikes so its possible, but the cost would be quite astronomical for such a small batch as we would require.

Thanks again for your input.
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themoudie
Posts: 119
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Location: Perthshire

Re: 125H problems

Post by themoudie »

Aye 125H,

Just been on the 'VAPE' website and note that no 125H kits are available. However, I am not giving up on the wee beastie yet.

"Man maketh, so man can repair/rebuild!" :wink:

I will await to see what can be diagnosed, with my current set-up and have a conversation and then see what might be possible, yet affordable. I am no looking to make a silk purse out of a sow's ear!

Good health, Bill
125H
Posts: 59
Joined: 30 May 2018 18:36
Location: Loughborough UK

CAM TIMING

Post by 125H »

can anyone give me some pointers on valve timing, I noted today that my 125H is blowing petrol/vapour out through the carburettor inlet.

I may have set this up wrongly, after the rebuild. I have fitted the cam wheel it can only go on in one position as its keyed onto the camshaft, then turning the timing mark to the top in line with the crankcase mark and then aligning the crankshaft pulley marks produces this effect.

at top dead centre on the compression stroke with both valves closed, (clearance at 010) the timing mark on the cam pulley is then at 6 o'clock if I then align the marks as before, cam pulley mark at approximately 12 o'clock and crank shaft pulley aligned with the lower crankcase mark then there is no clearance in the valve gear at all. Does this sound correct, how accurately do the timing marks have to align?

I have ordered a timing disc to see if I can achieve the specified degree values and to see if the timing marks will then align exactly. I have some photocopies of a workshop manual that describes moving the crank pulley around on the shaft and using the belt as a guide and then stamping new punch marks and although I have fiddled around with the pulley settings the lower timing marks then appear way out.

Any suggestions?
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themoudie
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Location: Perthshire

Re: 125H problems

Post by themoudie »

Aye 125H,

SNAP!

Sounds as though you have the cam timing out by 180°. The timing marks need to align, 'dot' puch mark on the cam pulley at 12 o'clock and the 'dot' on the crankshaft pulley aligned with the 'dot' made by the factory on the crankcase. On my engine the crankshaft pulleytiming mark aligns with a tooth on the pulley and the crankcase mark is at 2 o'clock from the vertical plane through the crankshaft.

I use a dab of 'Tipex' liquid correction fluid to highlight my timing marks.

Are you using the 'PMS' mark on the flywheel rotor to check your valve timing and the 'ANT' mark on the flywheel rotor to check your ignition timing? The 'PMS' mark and the cam pulley 'dot' should align through the camshaft centreline and the crankshaft pulley (providing you didn't strip this off the crankshaft in the rebuild) 'dot' should align with the crankcase 2 o'clock 'dot'.

Do you have the Moto Morini workshop manual "Blue book"? If not I can forward you a good scan in pdf format, if you PM me with your email address via the MRC forum.

Have you watched Paul Compton's "evguru" YouTube videos? They are specifically using the 350 v-twin as the demonstrator, but the principle is exactly the same as that used on the 125H single. It being the same as the front cylinder of a twin. LINK: Paul_Compton_Cambelt_change_on_a_Morini_350

I hope that this helps.

Good health, Bill
125H
Posts: 59
Joined: 30 May 2018 18:36
Location: Loughborough UK

Re: 125H problems

Post by 125H »

Hello Bill,

thanks fore the info, I think that's how I have set it up but will check again.

tell me one thing though - with your 125H if you align the top mark on the crankcase the one at 12 o'clock with the punch dot on the cam wheel and the mark on the crankshaft pulley with the crank case mark at 2 o'clock ready for fitting the belt - do you have any valve clearance at that point?

I can only get valve clearance when the mark on the cam wheel is at six o'clock this is TDC on compression with both valves closed using a plug gauge to check TDC.

My flywheel is an early one, it just has an arrow which I think will be TDC and an A which I suspect is the timing mark (I am not confusing this with the ABC marks on the pulley for belt size) these mark are on the generator.

Although I have picked up a later one which is marked PMS and ANT but don't know if it will suit my engine will have to check the key slots are in the same place.

If you have some info please email to leonard.gant@btinternet.com look forward to hearing from you.

Regards
Leonard.
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Ming
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Re: 125H problems

Post by Ming »

Don't forget that the markings on the rotor are in Italian. So PMS = punto morto superiore = Top Dead Centre. ANT = anterior = front (for the twins). And that Ignition in Italian = accensione. So your "A" mark is the ignition timing point.
Also, on early V twins, the PMS reference mark is at 9 o'clock on the crankcase web, rather than 12 o'clock . I don't know if the 125H is similar, though.
MickeyMoto
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Re: 125H problems

Post by MickeyMoto »

Ming,

Only pre electric start 350 has the timing mark at 9 O'clock. To adjust ignition timing on a 125 the stator is loosened and rotatated.
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Ming
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Location: Central France

Re: 125H problems

Post by Ming »

Oops.
OK, notwithstanding the risk of being wrong again, I just came across this link to a French site with a possible (if fairly drastic) option. https://www.kennedy.fr/morini_125h.htm
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themoudie
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Location: Perthshire

Re: 125H problems

Post by themoudie »

Aye Ming,

Thank you for your persistance and interest.

The link that you have posted is for the fitting instructions for the VAPE (Czech) company who used to make this conversion kit! :( On the kennedy.fr website and is dated 2011

The VAPE website VAPE_Moto_Morini_generator_ignition_systems shows a range of systems for the older 50cc, 125cc, 150cc, 175cc and Franco Morini singles, but when I enter the #73 04 999 00 for the Moto Morini 125H system described by kennedy.fr in the posting, the VAPE search engine gives a negative return.

Also, when I search the current kennedy.fr website kennedy.fr_Morini_generator/ignition_upgrades_2022, they too are now only offering the VAPE older 50cc, 125cc, 150cc, 175cc Moto Morini conversions. They do not now appear to have the Moto Morini 125H or the Franco Morini conversions in stock and I suspect that they are the French agents for VAPE.

I haven't contacted my scooter ignition specialist, yet, but depending upon what he says, I will contact VAPE directly to see what they have to say or offer.

Good health, Bill
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