Hi everyone! I am working on my new to me DS650 and it is acting up. I am only getting 95 psi of compression. If I drip some oil into the sparkplug hole it doesn't change. Do yall think a valve adjustment would cure this? Thanks!

 

I would start with the valves. They may be tight. Does it start okay? Any smoke at all? Could be worn rings but valves are much easier to check...

 

I am going through the same thing. (I have mine figured out, though.. bad cylinder/broken piston)

Aceisback, correct me if I'm wrong but the DS has a centrifugal compression release that hangs a valve open slightly on starter cranking. If this is true, how does one get a good compression test done?

 

You are correct. There are leak test procedures starting on page 03-03-1 of the repair manual. You will definitely have better compression once you replace that broken piston. I just had a DS running well very well but noticed it starting to smoke a little on one trip to Dumont and then two to Glamis. Broke it down after the last Glamistrip and it actually had chunks missing out of the piston. One was an inch+ long. The piston and the head were beat all to hell but it was still ripping the dunes. The rings and cylinder wall were unscathed, amazingly.
Putting another 11.5/1 back in it but hopefully this one last a little longer. Guess four years wasn't too bad though. Lots of hard hours and miles over that time period.

 

Ended up tearing into the motor. I wanted to go through it anyway as the oil was milky white. Replaced the water pump seals, ordered a JE 11.5:1 piston kit and a cometic top end gasket kit. I will be sending the jug and head out for machining as soon as the piston arrives. Currently in work on the OMR carb mods and trying to figure out if I have the stock exhaust.