After the Motor Rebuild – KZ440

After I got the motor rebuilt with the used parts (about 6 hours total work time) I put in some fresh gas and BAM, fired right up, and I’ll be damned if it didn’t run great. I checked the compression and each cylinder was now 140+!! It was amazing. I went from a completely toasted motorm to a good running motor with great compression and I didn’t spend a single penny. Just goes to show what you can do with a little crazy in you.

The next day I loaded the bike with a couple bags and drove it straight down the highway 430 miles to Rochester, NY. It ran incredibly well the whole time. I had it on the highway, in the freezing cold, wide open throttle, for about 8 hours solid. I rode it on and off for several days in NY then drove right back home. Over 1,000 miles in a few days in the cold (26 degrees) on a bike I just bought the day before and rebuilt the motor.

And for those who are curious, no, I didn’t spring any leaks through the old gaskets. Once I got home, I listed the bike for sale real cheap and had it sold the next day.

Mission accomplished.


By ef

Hey, I'm Evan and this is one of my motorcycle sites. You can find more about me on my homepage, or visit me on Google Plus: +Evan Fell


  1. nice job on the kz440. I just bought one for a couple hundred and it is getting spark on both cylinders but the right side exhaust is not getting very hot just warm left real hot.What could this be?The right plug has slight oil residue but no gas smell.It has 30000 miles on it. Oh and oil is leaking from right below my gear selector have to see what seal it might be next day off.


  2. Hi Alan,

    Congrats on the purchase. I say with all honesty, the KZ440 motor is an incredibly nice platform. It has the perfect mix of size, power, and convenience. They are excellent little bikes that will do anything you throw at them.

    30,000 miles is a lot for a small KZ440 aircooled twin. First thing I would do is a compression test on that right cylinder. Generally when a header doesn’t get hot (if you lick your finger and touch the header it should sizzle) it either means that the cylinder is not getting gas, spark, or is WAY out of tune. If there was gas in the cylinder it would either burn (causing the header to get hot) or it would pool (causing the spark plug to get coated in gas). Since you have neither of those traits I’d guess the carbs need a cleaning. You can check out my guide on Cleaning Motorcycle Carbs for a hand with that.

    However, that said, if you have a serious compression problem from a worn piston/cylinder or from valve damage that will also cause the problem you are having.

    Keep me posted. Thanks for reading.


  3. Wow sounds exactlty like my story. Same thing Luke warm right exaust. But that was after full carb rebuild. Points. Condenser. Valve timing. Compression is 148 r. 152 l. Going out to ohm out my coil as soon as I send this that has to be intermtant as it will run better at high rpm. 1980 kz440 a1


  4. @Rydplrs –

    How did the coils check out? Is your exhaust stock? If the baffles in the mufflers are worn it can cause some erratic running behavior on these bikes.


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