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Hey Guys,

I am new here and thought I would pick your brains for some advice.

I recently got an 81 KZ750 4 cylinder from a friend. The bike was not running had an oil and a gas leak and he just did not want to deal with it so he gave it to me.

Now after a can of sea foam through the gas the bike runs like a dream. The gas leak I fixed and a bottle of stop leak fixed the oil leak for the short term (I know I will need to deal with that soon)

Recently I noticed that when the bike is cold it idles just fine but after riding a few miles when the engine is nice and hot it idles at around 3000 RPM's and the bike is REALLY heavy on gas I get about 70 miles on the 3 gallon tank before needing to fill up again.

Would you guys happen to know what could be wrong with this bike? Any ideas will be greatly appreciated.

You might want to do some maintenance on the bike to see if the situation improves. Clean the carbs properly and update the O-rings, adjust the valves, etc. The factory Kawasaki service manual provides a list of basic tasks. Look around on the internet and you can get a free download.

If the exhaust and/or air filter system has been modified there is a good chance the carb jetting is likewise modded. If someone threw some huge jets in the carbs that would explain the poor mileage.

Good luck

The manual here is not exact for your model but should be good enough for most things. mbsween.bike-night.com/kz750l3/manual.html
mbsween is a member
I use the manual he linked on the above site and also a Haynes. You probably need to do a really good service on the bike like Nessism says and the manual will help. Do you have original airbox or individual pods ?

Idle speed when warmed up should be about 1200 rpm. You can adjust idle speed with the knob below and between carbs 2 and 3

KZShipwreck wrote: Hey Guys,

I am new here and thought I would pick your brains for some advice.

I recently got an 81 KZ750 4 cylinder from a friend. The bike was not running had an oil and a gas leak and he just did not want to deal with it so he gave it to me.

Now after a can of sea foam through the gas the bike runs like a dream. The gas leak I fixed and a bottle of stop leak fixed the oil leak for the short term (I know I will need to deal with that soon)

Recently I noticed that when the bike is cold it idles just fine but after riding a few miles when the engine is nice and hot it idles at around 3000 RPM's and the bike is REALLY heavy on gas I get about 70 miles on the 3 gallon tank before needing to fill up again.

Would you guys happen to know what could be wrong with this bike? Any ideas will be greatly appreciated.

Hello, KZShipwreck, and WELCOME to KZr!

Would sniff-test the crankcase oil and examine its physical condition, being on the lookout for gasoline intrusion into the crankcase, which could explain the oil leakage and excessive fuel consumption.

Good Fortune!

JR wrote: The manual here is not exact for your model but should be good enough for most things. mbsween.bike-night.com/kz750l3/manual.html
mbsween is a member
I use the manual he linked on the above site and also a Haynes. You probably need to do a really good service on the bike like Nessism says and the manual will help. Do you have original airbox or individual pods ?

Idle speed when warmed up should be about 1200 rpm. You can adjust idle speed with the knob below and between carbs 2 and 3

Thanks for the info, I have the pod filters and I did check the carbs yesterday and they looked pretty clean to me. I do think I would need to do some serious maintenance on this bike... lol