Engine rebuild of a 78' 650D SR

I'm looking for some advice about rebuilding the engine on this bike. I have had her for almost 10yrs and I will never sell. I love this bike. I bought it from the guy who bought it out of the crate. He only put 4,000 miles on it then kept her in a garage for years. when I bought it, she was in pretty bad shape. For the next 3 years (part time) I restored her top to bottom (all except the engine which I was told was in great shape). She's got 70k on her now. last winter I rebuild and rewired her (thanks to those you who helped on that project). I have yet to do anything to the engine and it's really not running right so I think that it maybe time. I know my way around a wrench so i'm looking forward to it but it's a bit intimidating i'd like to be as prepared as possible.

What is the best way to go about it, top end only or total overhaul?
When i'm getting ready for it what besides the kit (gasgets, rings and seals) should I get?

Do you have the KHI Factory Shop Manual? It will have torque specs, tolerances, etc. etc. for the motor and will take the guess-work out of deciding when and how to rebuild. If you do have the factory manual, it will have a listing of all those tools you'll need to do a rebuild...you can decide which tools are necessary, which you can fabricate yourself, and which you can do without. Plan on a top end overhaul but with 70,000 miles be prepared to do rings and cylinders also (although there are a number of KZR members who have far exceeded 70,000 miles without dealing with rings/pistons/cylinders).

Before even considering top end work, would first perform compression test, assure valve clearances being to specs, repeat compression test, AND perform a LEAKDOWN test.

This should give a good idea about engine condition and any problem area. And imo may be helpful even where tear-down is a foregone conclusion, toward better knowing what to look for when getting inside.

Good Fortune!

I would have to echo the statements of Patton. A "decent" compression tester and leak down tester are available from Harbor Freight for fairly cheap. Or find a buddy who has them and borrow.

Great ideas gents thank you! I'll do the tests next week and post the results to see what you think. Thanks

If the compression and leak down numbers are okay, still check those valve clearances especially if it hasn't been done for some time.

Also, be sure the ignition is in time and up to snuff before going round and round with the carbs.