DR250S Won't run or start when warm

[MarlinHemi]

So i have an old run of the mill DR and it would start then run for a bit (half way round the block) and then die, so i replaced the coil and it still does the same thing! Could it be a stator or cdi issue? its wired pretty sketchily but runs when cold. I have also noticed that if i turn the bike off once its been running in the garage a bit it will not start again.

Cheers, Marlin

[MarlinHemi]

bump, still no idea

[OddDuck]

I'm not familiar with the DR's at all so this really is shooting in the dark...

Fuel? Is it getting fuel OK? Carb bowl filling up while the bike's at rest but being drained quickly once running?

Battery? Start the bike (cold I guess) and put a multimeter across the terminals, check the voltage while running. If the stator is doing it's thing properly you should see more than 12V across the terminals - 12-ish at idle, up to 14.4 max, then levelling off with revs.

HT lead/s and boot/s? What condition is the rubber and core wire in?

Vacuum leak? Old rubber on the vacuum side of the carb cracked, or is there an old compressed O-ring on the inlet manifold? Rubber shrinks when it heats up. An old O-ring could be making a decent seal while cold (just) but failing once it warms up.

Anyway, let us know how it goes.

[MarlinHemi]

Thanks for that, its getting fuel fine (first thing i checked). am not running a battery but will check the terminals to see what they put out cheers
Has new ht leads and boots so i doubt its that, will check for vacuum leaks tomorrow, thanks for the advice :)

[nzspokes]

Run it up and get it to fault, then quick pull the plug lead and chuck a spare plug on it and rest against the motor. Give it a kick and see if you have spark. No spark then check all contacts, crank pickup etc.

If spark then pull the carb, give it a proper clean out with air. Check everything in it is to spec. while its off check the inlet manifold for cracks. That should get it going. Also check for constant flow from the tank, dont forget the tank vent.

[slofox]

This is a long shot, but may be worth checking.

Years ago I had a similar problem with a fiat bambina motor. It would start cold, or within a minute of stopping, but if allowed to cool a bit, would NOT start.

Turned out to be valve clearances. As it cooled, the valve would lift off the seat thereby removing compression. Fixed clearances and fixed problem.

[MarlinHemi]

Thanks for that will give both of those a try, will check valve clearances as it is also a pig to start

[MarlinHemi]

Okay, so to narrow it down The Bike has no vacuum leaks and also seems to spark even when it wont run so the problem should be elsewhere so will try and check valves soon.

[Saarg]

So i have an old run of the mill DR and it would start then run for a bit (half way round the block) and then die, so i replaced the coil and it still does the same thing! Could it be a stator or cdi issue? its wired pretty sketchily but runs when cold. I have also noticed that if i turn the bike off once its been running in the garage a bit it will not start again.

Cheers, Marlin

I’ve just fixed the exact same problem, the fix was new stator.


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