Re: Mototrans 250 Scrambler restoration: she's a runner!

[Ventodue]

... the discs are available on line.

Or in extremis make your own. Just need an old CD, a print out off Tinternet (e.g. https://www.pinterest.com/pin/315674255131381893/) and a bit of glue ...

[themoudie]

Aye ventodue, thanks for the link.

I still think that it's the CDI playing silly bu88ers! But, if Saches aren't forthcoming, they are just blotting there own copy book.

I have received the Morini 125H stator back today, so will see if the polarity change, if that was the issue, has made any difference?

Aye A.I.M., one step at a time! The flooding out east was horrendous! North Esk over 60cm higher than previous records and the South Esk over topped/ destroyed the flood defences in Brechin that are only 6 years old, with the maximum flow remaining unrecorded as the recording station was inundated.

Good health, BillR

[A.I.M]

Thanks Colin, Mark, Craig & Bill, I'm working through mustering together all the equipment & knowledge (not forgetting the courage as this is stepping out of my comfort zone) to check ignition & valve timing. It's school holidays here, so my time is not my own for a couple of weeks.....
That link is going to be useful, thanks Craig. Am I correct thinking the female thread on the left end of the crankshaft is M8 (I think that is what Colin's 8mm bolt/12mm studding & nuts indicates).
I do suspect I'll find something amiss with timing, I'll let you know....
The compression was tested during the rebuild and was "ok", but more specific than that I don't know. I hadn't heard of a drip test before, good to add that to my knowledge bank
The UK weather was truly terrible last week, especially around the Brechin area, I heard that the river rose over 5 metres in places! I hope no-one on here was badly affected.
Cheers,
Al

[A.I.M]

She runs!
I got my head around checking the timing:
Valve timing was fine
Ignition timing was 5° too advanced. The Sachse system I fitted should be set with static ignition timing at 0°, not the 5-8° of the conventional ignition. The advance logic then applies 5° advance at idling speed and increases with engine speed depending on the curve chosen (of 3 possible curves). So that is now reset.
At the same time I fitted new main & needle jets to the carb and applied grease to both faces of the carb/inlet flange gasket.
First 10 km run, the engine was running much better, pulling strongly, although not idling very well. However I could only find two gears: the selector box was installed 180 degrees out, and I was only getting 4th & 5th gear with a false neutral between them. No wonder I thought the bike gearing was too high! I sorted that and now I'm getting all five gears. Thanks to an old post by Jordan this was fairly easy to diagnose & fix.
The spark plug was too black after that first run, so I warmed-up the engine with another 10km run and adjusted the pilot air and idling stop to get a smooth idle.
I noticed that the footpeg nuts had rattled loose, so they got some thread-lock and nipped-up.
After that I took her for a 30km run and all seems to be in good shape. A couple of small oil weeps to fix. The only thing puzzling me is a high-frequency buzzing noise on over-run with a closed throttle, I haven't been able to find the source of that yet.
This bike is so much fun on the road, even while respecting (at least trying to) running-in limits.
Thanks to the help of this community, another one of these great singles is back on the road after 42 years I can't overstate how grateful I am for all the expertise I've found here.
Cheers,
Al

[Duccout]

Well done Al,

Sometimes it is the small things that matter. You will be kept busy - you know the old saying: 'Ducati, making mechanics out of riders for 50 years'


Cheers,

Colin

[Ventodue]

Good stuff, Al! well done for persevering and many congratulations.

They are good fun, these Scramblers. And delightfully counter-culture up against the modern offering from Ducrappi.

Have fun!

[A.I.M]

Hi folks,
Since my last update :
- The bike has been running really well, huge fun on the country roads here. This despite the engine been burning a LOT of oil.
o I might post a new thread about carburation oddities and discrepancies between original and new replacement (from Burlen) Amal carbs.
- France introduced a requirement for a Controle Technique for motorcycles in 2024
o with the amount of oil being burnt mine would not get through the emissions testing.
- The resin lining of the petrol tank has been dissolving, presumably due to ethanol in modern petrol.
So, I have removed the engine to check / replace as necessary valves, seats, guides and stem seals, and whether a rebore and new piston would be needed (and anything else I find with the engine open). I'm now wishing I had done this before - isn't hindsight a great thing!
And I plan to remove the old tank lining and replace it with something that will tolerate ethanol.
Hopefully back on the road for summer.

Al