[goodoltup]

I took a swingarm welding jig from another project and repurposed it for an engine stand. I removed the engine from the bike, removed the head, and replaced the cam chain with the DID 219T, 88 links. I thought that maybe 86 links was too short, but to be fair 88 seems a bit long. But the tensioner makes good contact although it's at the end of the adjustment. Engine back together, on the stand, AND THE SOUND REMAINS.

If you are interested, have a look at the videos below and tell me I'm crazy and that there is no noise. To me, the noise is a kind of chuffing noise.

Also I bought a replacement crank, that is next.

- YouTube

 

[goodoltup]

Good news. On Sunday I tore the engine all the way down, swapped the crank, built it all the way back up, and installed it in the bike. Started up, the noise is gone. Unlikely as it was, it must have been the two inner crank main bearings, or big end bearings, that were making the noise. That is the only thing that was different when the engine was built back up. Amazing.
I now have exactly what I set out to create, a CD175 with 12v electrics, electric start, 200cc, and a 5 speed gearbox. While retaining the original CD175 head and carb.
So, case closed. I'll post links to some videos of it running. I hope that this thread was interesting to you the reader and possibly even helpful. Cheers

 

[goodoltup]

IMG 8631
IMG 8632

Above, two videos on YouTube showing the engine all installed and running great.