Moto Morini 125H tick over problem/general running

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125H
Posts: 97
Joined: 30 May 2018 18:36
Location: Loughborough UK

Moto Morini 125H tick over problem/general running

Post by 125H »

I wonder if anyone can help with this matter, before lockdown I bought a 125H which was not in too good a condition, I spent many hours rebuilding the engine and refinishing the frame and chrome, when I start the engine it will start easily but does not want to tick - over it will not tick over unless the throttle screw is right in, the spring compressed. The mixture screw has very little effect at all, it was suggested I try a number 5 slide and that the timing may be too retarded. I set the timing to full advance and fitted the new slide but still no improvement it ticks over with the screw fully in then there is a burst of revs and I have to shut it down. I feel the problem is carburation but not too sure, when I bought the bike the original carburettor was damaged and was stripped for spares, it should be a VHB24 but I could only find a VHB25 the carbs look the same but the original had a brass bush in the air bleed to the atomiser the bush having a small hole drilled through which I assume cuts down on the airflow to the atomiser? It sits at 6 o'clock near the front of the venturi. Eurocarb tell me its not a Dellorto part and they were fitted at the factory, Are 125H's that critical of carburation i.e. 1mm extra in bore size even when jetted the same. Or am I barking up the wrong tree does this issue indicate another problem.

If anyone can help I will be pleased to here, give me a call on 01509 856563 or email leonard,gant@btinternet.com or reply to this post.
Any assistance or advise is much appreciated, I want to be a Rider but am stuck in the garage.

Leonard Gant.
norbert
Posts: 750
Joined: 15 May 2007 15:15
Location: Lübeck/Germany

Re: Moto Morini 125H tick over problem/general running

Post by norbert »

Have a look at the peak of the little mixture screw. Is there a fine peak? Is there a little O-ring behind a small washer?
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Daddy Dom
Posts: 512
Joined: 16 Nov 2006 19:48
Location: Auckland, New Zealand

Re: Moto Morini 125H tick over problem/general running

Post by Daddy Dom »

They are very helpful at dellorto.co.uk. I would just cut to the chase and ask them for advice.
DD
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acemorini
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Location: Uckfield, East Sussex.
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Re: Moto Morini 125H tick over problem/general running

Post by acemorini »

Hello Leonard,
I also have a 125 H, and in my experience no they are not to critical on carburation. As you say you have checked the timing, new slide in the right way ? No air leaks ?
I do have a Dellorto VHB 24 D carb body, but from memory I think the the thread is damaged in the carb body where the fuel bango and filter fit, it may just clean up, you are more than welcome to borrow the carb to see if it makes any difference.
Regards Pete.
125H
Posts: 97
Joined: 30 May 2018 18:36
Location: Loughborough UK

Re: Moto Morini 125H tick over problem/general running

Post by 125H »

Hi,

thanks for the info, I have covered all of those topics but cannot get a result, I will have to go through it all again and see if I can find the problem, without pulling my hair out!

Thank for your responses.
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