Saturday, February 13, 2016

dnepr k750 part 1

A week of so ago, John drove up to Appleton to pick up a 1967 Dnepr K750 that was pulled from a barn in Manitowoc. He brought the Russian made bike to my studio and we set to work inventorying parts and looking at the overall condition. The bike was complete minus the wheels (but the brake backing plates and rear diff is there. The motor was seized, but I was hoping that it was something minor. There were tons of these K750 Denpr made at the KMZ factory in Russia. The design has roots from the original BMW R71 military based motorcycle and the K750 was produced in large numbers for the Russian military. They are famous for their off-road capability and two wheel drive sidecar setup. That said, the manufacture quality of the later Dnepr models was questionable and they have received a bad reputation due to "kit bikes" that are sold from a mash up of surplus parts, worn out machines, and Chinese CJ750 knock off's. I was hoping that by this being a late sixties machine and the possibility that it was built for military use that it's quality would be a bit better than average. As I tore down the engine, I did not discover the typical stamped "star" on any of the castings that denotes military production machines. That said, I did discover that these machines are robust and they're "built like tanks". I believe this K750 is a civilian model. It's a bummer that it didn't come with a sidecar and the 2WD differential. 

John and I decided to tear the engine down to see what was keeping it from turning over. This K750 is a sidevalve/flathead model which I am highly intrigued by. The design of the engine just seems so simple and reminds me of an old Briggs lawnmower engine. John set about getting a lot of caked-on grime off the outer case of the engine and I worked on popping the heads off. The pistons seemed to have a bit of wiggle so I wasn't convinced that they were seized in the cylinder. We popped the cylinders loose and slid them off the pistons which revealed some broken oil rings. There was some scoring on the piston skirts too. The cylinder surfaces weren't horrible but I believe they will need a rebore (which I am going to attempt on the Bridgeport as I've been reading up on this). John ended up having to leave, and about 5 minutes after he left I de-coupled the trans and realized that the clutch/flywheel was frozen to the inner wall of the engine casing causing the engine to not turn over. Since discovering this, I've been working on refurbishing parts and cleaning things up. I think this bike should clean up rather easily though. Parts are readily available via the Ukraine and other European sites and the parts are cheap. There doesn't seem to be many of the older bikes around the US to source spares from, but it's possible to find odds and ends. I'm still curious how this late 60's K750 got into the states during the cold war. I'm guessing this bike came to the US via Poland or one of the other communist countries into Wisconsin via immigrants that had relocated to the area. Who knows though...


Charles Collins said...

Wow! There's something beautiful under that mess! I can't wait to see it!

Frankie Flood said...

I hope there is something beautiful in here, because I'm knee deep in grime!!!