Mv 125tr -
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post #1 of 2 (permalink) Old 04-24-2018, 03:25 PM Thread Starter
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Join Date: May 2017
Location: Oxford
Posts: 4
Mv 125tr

Hi all,
On a bit of a whim, i bought a 1955 MV 125TR last year. The idea being to take it to Italy and ride the Milano-Taranto event with a friend on a ‘64 Garelli and another on a ‘57 Motobi.

I rode it when I bought it and, though it seemed to need a bit of a tweak, it was fine and rode as I expected. Of course the minute I got it home it wouldn’t start again!!! Further investigation revealed that the mixture screw was missing from the carb (it might have fallen out) which has now been replaced.

It now starts, then runs well for a few minutes, then gradually seems to die out as if it was running out of fuel. The problem is, there seems to be plenty of fuel getting through to the carb.

Anyone got any thoughts? Is this anything anyone has come across before? It feels like fuel but friends keep saying check the electrics (which, of course, are 6 volt no battery).

Any help gratefully received, and if anyone has any other suggestions to aid reliability and ride ability in modern traffic I’d be interested in hearing them.

Cheers David.
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post #2 of 2 (permalink) Old 04-25-2018, 09:22 AM
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Join Date: Sep 2017
Location: UK
Posts: 43
Hi David, It certainly sounds like fuel starvation. These old bike accumulate rust in the tank, partly due to ethanol now being in the petrol. So I'd start by checking fuel filters, both in the tank (part of fuel tap) and in the carb.
My MV wouldn't idle when I got it as the drilling where the pilot screw goes was totally blocked with white aluminium corrosion. I cleaned it with a very fine wire and it now idles perfectly.
Also check the carb jetting as you didn't know what has been changed in its earlier life.
One final thought is to check the petrol cap vent. These usually leak but could be blocked in yours.
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