Hi guys. I just recently bought a 2000 Ds650 because it was a deal i couldn't refuse ($1000). So far it just needed a radiator. I want to perform some tests on the motor and electrical to see how reliable it is. I especially want to do a leak down test, But I am having the hardest time finding the TDC position of the piston. I took the two plastic screw caps off of the right side cover and assumed that there should be some markings in there for TDC, but I can't find anything. Could somebody help me. I appreciate any help.

 

Remove gas tank, then remove head cover. the gasket is rubber and reusable.
After removing the head cover you will see both cams, and the sprockets have marks on them. Align the marks on both sprockets and you are at tdc. Having all 4 cam lobes facing out away from each other will give you tdc of compression stroke.
You will need to disable the automatic decompressor on the end of the exhaust cam for a compression test - without disabling it you will get approx. 120psi for a stock piston in good condition.

If you ever do any top end work, like valve adjustments, and remove the cams, the crank can be locked at tdc. Looking at the left side of the motor, locate the perimiter of the clutch cover - there are 6mm bolts (5mm allen wrench) all the way around it. Directly beneath the clutch cover locate one 8mm bolt head (requires 6mm wrench). This bolt has a copper washer under it. Remove this bolt (have crankcase oil drained first) and insert an 8mmx50mm bolt in its place. There is a hole in the side of the crank that this bolt can be screwed in to reach, and lock the crank from rotating so that it remains at tdc for reassembly.

 

Thanks HighTower. I knew that I could find top dead center that way but I was hoping not to have to do all that work. On my yamaha warrior you could just remove the plastic screw on side cover and turn the crank by hand to TDC. Well I guess I should just take the cover off anyway and see all of those components are in good shape. SO what are those plastic screw caps for on the right side cover of the ds650? Thanks

 

the center one is where you will put a t-handle hex key in to turn the crank. the other one is pretty much useless - no distinguishing marks on the flywheel that I could find, contrary to most other bikes like you said.
Since you just got it, you need to inspect valve clearances too, while the cover is off.
Have fun!