What to Look for in a "found" 250 Motor

[Winter]

Hello.
I have just completed the rebuild of my 160 motor. Just completed it in time to find...a 250 motor in need of a rebuild (just the motor)

So sight unseen, apart from a photo on the "interweb", what are some tell-tale signs to look for as I review it in person and consider buying it?
Removing the side covers came to mind, look for seizure, the gear shift rod appears to be missing in the photo. Having read Henry H's "How to build a Ducati racer...." post, I pretty much have the itch to build it out and follow his advice on the cam, etc., and use the blueprint for speed as well.

I have an NC frame for the 160 since the 160 frame was bent beyond repair. So, it appears I may be building a custom 250 Single...

The advice and knowledge is appreciated.

All the Best,
Andrew

[Winter]

And the online picture. Only one there was.
Thanks,
Andrew

[Moto Chuck]

Exhaust nut threads would be easy to check. In addition to the side covers I would ask to check a valve cover. Screw adjusters here mean that the engine has a mild state of tune. Rockers with shim adjustment mean that the engine likely has at least a scrambler cam.

Checking the spark plug and the top of the piston through the spark plug hole can tell you quite a bit if you know how to read plugs. A lot of carbon deposits probably mean an oil burner. If you are lucky it will be a little oily and fairly clean meaning that someone oiled the cylinder before mothballing the engine.

The missing shifter shaft means that the cobbler has been there at some time. Pull the shifter cover. On narrow cases a broken chain could mean a trashed clutch lever mount requiring welding or more likely new cases.

Of course the biggest question mark on these engines is always the bottom end, which is the hardest thing to check. The engine has to be scattered and the crank taken apart to check it reliably.

These are a few things that come to mind on an engine out of the bike.

[Winter]

Thanks Chuck.
I asked the owner to provide some details:
"The number is DM250 89272. I think it is a scramber motor based on the alternator that was fitted. It is a spring head with shim tappet adjustment."
As for reviewing the top end and plugs, etc., that makes sense. I will try to roatate it and see if things engage. As far as the "cobbler" goes, the answer above would indicate that the owner is knowledgeable about these motors and I am a bit more optimistic.

Asking price is $550.00 CDN about 500.00 USD.

Best,
Andrew

[Bevel bob]

I would not follow the tuning article you refer to. This is for a RACE motor that will not be practical for road use. How do i know this?, I bought one.

[Winter]

I wanted to provide an update on this item.
The owner purchased it last year for extra parts to restore his DIana, but didn't require anything.

The items for repair include:
requires a rebuilt crank including bearings
stripped exhaust nut
general cylinder honing and maintenance
new rings.

It has an alternator and a scrambler cam.

I still think it's worth the project value. I also believe that these motors arte getting harder to find. Fair assumption?

All the Best,
Andrew

[double diamond]

$550 is probably the going rate for motors in need of a complete rebuild. I’ve heard tales of motors in such a state going for even more. Be prepared for a complete rebuild. If you’re fortunate, there won’t be any wear/damage beyond what a rebuild entails. You can never know how prior failures/repairs have compromised components until you disassemble, but expect it to be more involved than you imagine.