Not Bent Valves! Head Gasket Issue!

PLUMMEN wrote:

ive seen plenty of motors with cooked valves and bad rings that ran,some of them ran suprisingly well! :laugh:

Me too.

I had a kz900 motor a guy brought in one time to have the timing set on. It was in a sand drag car. Timing was off a couple of degrees. I had it on the money in about 1 minutes time.

Guy looks at me and says Ok but listen to this. He grabs the throttle and holds it about 5000RPM. Breaking up and popping something terrible. Let it idle and just lightly rev it and it sounded not too bad.

This thing smoked a bit when you let off on it and thats all! Pretty typical hard run KZ900 motor IMO.

Then I spot the Nitrous fittings but no bottle. I ask the guy about that. He confirmed he had run it on juice for a while. I check compression and one cylinder had 50lbs. The others were about 90 PSI.

Guy takes it home and tears it down. I stop that night on my way home to see how he made out.

GET THIS - When he took the block off, most of the ring lands for the top rings on all 4 pistons fell off in little pieces :huh:

True story..swear to God..

Nitrous blew the ring lands to pieces but nothing could go anywhere so it kept running. :laugh:

Broken rings.... Ahhhhhhh, reminder as kids growing up on 2 stroke dirt bikes.... :laugh: :laugh:

Frigging thing would be rattling and pinging all over the place... not to mention smoking like a bitch but ride on.... Get me home old girl... :laugh:

Ah, miss the days.... :blink:

HEY GUYS IT TURNS OUT THE VALVES ARE NOT BENT...... MISS-COMMUNICATION!

It does however have a "blown" head gasket. Which I kind of had a feeling was a problem anyways because there is a tiny bit of oil around where the head meets. So the guy "adjusted" the valves, and "freed" up the "advancement".

The bike runs much better it doesn't have the sputter and hesitation that it had before. The problem is though it heats up way too hot and way too fast.


How much would it realistically cost me to replace the head gasket? Should this in theory eliminate my over heating problem?


Thanks Again Guys!

not sure on the price of parts for your bike.
yes the head gasket being blown can(will) cause overheating.

leon holmes

your probably looking at a couple hours labor if that is the only thing you need to get it going again.

If not already done, would perform compression test to help confirm diagnosis of blown head gasket, and a leak down test also if feasible.

Would also assure correct ignition timing by using a strobe type timing light. And also watching advancer move back and forth with rpm changes when blipping the throttle.

Would remove spark plug and examine color at business end (plug reading).

Over heating can result from several different reasons besides blown head gasket, such as issue with carb, fuel mixture, floatbowl fuel level, oil quality, oil level, oil pressure, incorrect spark plug, excessive rolling drag (brake, wheel bearings, drive chain, insufficient tire air pressure), air filter, clutch slipping, air leak, etc.

What appears to be oil seepage between head and jug might upon closer examination be traceable instead to leakage of valve cover gasket, tach drive, exhaust gasket, etc.

And the head nuts might simply need to be torqued to specs.

Good Luck!

To add what Patton was hitting on...

freed" up the "advancement. The problem is though it heats up way too hot and way too fast."

When freed did he re-set the timing?
Resoning I ask, if your timing is advanced even a couple of degrees it will run hotter as well...

Just a thought... Now I'll shut my pie hole....

OMR