Yamaha DT50 won't start

do not rule out the plug i have had them not work under compression before, try another new before doing anything else
 
Whealie said:
How easy is it to replace all the wiring and upgrade to 12v anyway?

A 12-volt conversion is pretty standard on old Vespas.
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In theory it should be possible as the only things that determine that the system is 6 volts are the voltage regulator and the battery. Finding a replacement 12 volt battery should not be a problem, but I think finding a 12 volt regulator might be. I could be wrong mind.

You would, of course, then have to change all the bulbs for 12 volt versions. The flasher relay might be happy enough, but it might also need changing.

All rather academic at the moment mind.
 
Since you do have a spark, I would still tend to think that this is a high voltage problem, as we don't know how strong the spark is. As Phil says, the HT lead could be breaking down. Easy enough to check if it can be replaced. If, on the other hand, it is one of those all moulded into one jobs, then it will be a case of replacing the ignition coil. Is it the original 30 year old coil?
 
I have no idea what is original and what has been replaced. It's 32 years old. Am tempted to replace it all.
 
I had a DT175 in the early 80s and a common problem on these (and other Yam 2 strokes) were the windings on the alternator (or is it generator - the magnetic/ coil thing at the end of the crankshaft) going iffy. Main symptom is a weak spark at best and no spark at worst. I had this rewound on the DT and later on an RD350 and both times cured difficult to impossible starting. There was a way of testing but can't remember what it is (30 yes ago) but you will need a puller or something to get the generator off.

Just my ramblings and vague memories trying to be helpful.


Sent from my iPhone with a smile :)
 
Update. New ignition coil (with HT lead, trimmed to fit), new plug cap and new plug fitted - total cost about £23 - and she fired up first time. Hoping for a dry patch bank holiday Monday to take her out for a ride as Molly passed her CBT on a school bike last week.

Miserable out there today. Not sure it's the best conditions for Molly's first road ride on a geared bike.
 
Good stuff! Yesterday was a bit of a write-off weatherwise, but today (Monday) is looking a lot better :thumbsupanim:
(And congrats to Molly on the CBT pass ... the fun begins :ride-bumps: )
 
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