Blown head gasket

Hello I'm seeking some advice on diagnosing a blown head gasket on a 1982 kz750 csr. I bought the bike from a guy about an hour away from where I live, who told me he rode it frequently, I rode it around a little and got it through all the gears, which seemed fine. After about twenty minutes of riding home it started running like a tired dog ( struggling to maintain 55mph in fifth gear with the throttle open) It was backfiring with some black smoke and the guy said e had never cleaned the carbs so I threw some seafoam in the tank and it got a little better. About ten minutes from my house the bike died as I was riding and I rolled to a stop. When I tried to start it up the (new) battery seemed to have no charge and when I inspected the engine there was oil thrown all over Everything and a good deal of oil around the head gasket. Am I correct in assuming that I blew my head gasket? I have read that these bikes are notorious for leaking oil from that area.
Thanks
-colm

Not like that so soon. Why is the battery dead? Do a compression test. Do you have a manual? If not get one.
Steve

I have owned my KZ650 for 38+ years. The 4 cylinder 750's are the same basic engine. I have never heard of one blowing a head gasket, so I seriously doubt that is the problem.

You need to clean the engine. Then run it and see exactly where the oil is coming from. It could simply be the tachometer drive leaking as that is a common problem and a VERY EASY one to fix. Let us know exactly where the oil is leaking from and someone may be able to help.

Regarding the dead battery - you should check the bike's charging system. This is easy to do, but you need the Kawasaki Service Manual for instructions. You will absolutely need that manual anyway, so do yourself a huge favor and buy one before you start working on the bike at all. They normally are available on eBay. Be sure to get one for your bike's exact year and model as there are differences. Ed

Patton wrote: There are several different sources for oil leaks, most of which are are readily repairable.

Would thoroughly clean the engine, allow it to completely dry, spray foot powder onto suspected leak areas (all over edges of the cam cover and head gaskets, around the tach drive and exhaust clamps, etc.).
Should then look like a clean white blanket of freshly fallen snow.

Start the engine, and watch for appearance of darkening area where the oil is coming through the powder.

The source of leak is usually very evident.

Without the white spray powder coating, it's often more difficult to positively identify source of the leak.

Good Fortune!

Colm wrote: Hello I'm seeking some advice on diagnosing a blown head gasket on a 1982 kz750 csr. I bought the bike from a guy about an hour away from where I live, who told me he rode it frequently, I rode it around a little and got it through all the gears, which seemed fine. After about twenty minutes of riding home it started running like a tired dog ( struggling to maintain 55mph in fifth gear with the throttle open) It was backfiring with some black smoke and the guy said e had never cleaned the carbs so I threw some seafoam in the tank and it got a little better. About ten minutes from my house the bike died as I was riding and I rolled to a stop. When I tried to start it up the (new) battery seemed to have no charge
-colm

I'd wager your charging system is bad and you are "running off the battery" which kills it gradually and the ignition goes away as battery voltage drops.

The oil leak could be the tach cable.

First thing is to check compression.

Next, get it running and check battery voltage at 3k RPM (should be 14V)

Hey thanks for the advice everyone. I believe the problem is in my charging system. I charged the battery and dropped it in the bike and she started right up and ran fine for about ten minutes before the battery ran down.

The problem could be the battery. How old is it? Also, when charging a motorcycle battery you must use a charger that puts out 2 amps or LESS. Higher amperage chargers will shorten the life of motorcycle batteries, so if your battery had been charged at a higher rate in the past it may be kaput. Ed

Oil leaks are common if it's a 4 cylinder model. Cam end plugs, tach cable seals, orings between the head and cylinder, orings between the cylinder and engine cases. These are only a small sampling of the orings they used. They also were at multiple oil gallery orings that seal the 17mm head caps, three between the oil pan and cases, some more on plugs that seal the transmission shafts. They used a lot of rubber, and rubber is no good for sealing anything after it gets old. All the rubber seals go bad from heat and age. That was one very big problem with the design of a KZ650/750. They will leak and high mile examples are a constant flow of leaks. You will learn where all the orings are used on a KZ650 or KZ750 four by fixing leaks.The twins I don't know anything about.