Motorcycle Repair: NOT STARTING, honda xr 500, air fuel mixture

Question
1979 HONDA XR 500

I HAVE NO HISTORY ON THE BIKE. I REBUILT THE CARB AND CLEANED OUT THE TANK. THE BIKE STARTS ON 2 TO 3 KICKS COLD TO WARM. VERY HOT IT WON'T START. I ADJUSTED THE VALVES AND DECOMPRESSION LEVER. SPARK IS GOOD. WHEN IT WONT START STARTER FLUID DOES NOT HELP. I GAVE IT A COMP. TEST AND IT WOULD NOT GO OVER 75PSI (I HAD TO KICK IT 30 TIME TO GET IT HERE)I HAD TO RIG THE COMP. TESTER TO THREAD INTO THE ENGINE BUT ALL SEEMED TIGHT. ADDING OIL TO THE TOP OF THE PISTON HAD NO CHANGE. WHEN RUNNING THE BIKE RUNS GREAT. THE SPARK PLUG GETS A POWDERY CARBON BUILD UP ON IT. WHEN I KICK IT IT SEEMS TO HAVE ALOT OF COMMPRESSION.

THAN YOU FOR YOUR TIME
BOB  

Answer
Hi Bob,

You'll need to get an accurate compression reading. I also recommend a cylinder leak-down test.

Plug indicates a rich air-fuel mixture.

Need at least 100 lbs of compression for it to run properly.

Valves may need readjusted, too tight.

Keep me advised.

mshively1@woh.rr.com

Respectfully,
Mark Shively