KZ440 engine knock and won’t rev past 4k

  • JimmBuzz
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KZ440 engine knock and won’t rev past 4k

18 Oct 2019 08:30
#812661
Not my bike but a friends. He put 87 octane in the tank and then rode on the high way and it developed a knock and wont rev past 4K. The bike burned a little oil before the knock. We replaced the spark plugs and the old ones were oil fouled but otherwise normal. The exhaust on the left side leaks an oil and gas mixture. My guess is the ignition timing is out of sync. I’d appreciate any suggestions on what could be wrong/ what to check. -Thanks

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  • TexasKZ
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Re: KZ440 engine knock and won’t rev past 4k

21 Oct 2019 12:15 - 21 Oct 2019 12:16
#812823
Based on the description, I will be surprised if ignition timing is the culprit.

Has the bike been properly maintained? Is the engine oil level correct? Is it the correct oil for the engine?
A leaking valve seal may have caused so much carbon buildup on that exhaust valve, that it can no longer close. Worse, the head of the valve could be broken off.
Where is the oil leaking from the exhaust? At the head? If so, that can contribute to the knocking sound, and is easy to fix. At least the exhaust leak is. The oil coming through is a different matter.
Have the valves been adjusted in the last few decades?
Are the carburetors properly adjusted?
Any modifications, like no air filter, chopped of exhaust system, et cetera?
Yes, there are many possibilities. More information will help board members make useful recommendations.
1982 KZ1000 LTD parts donor
1981 KZ1000 LTD awaiting resurrection
2000 ZRX1100 not ridden enough

www.kzrider.com/11-projects/620336-anoth...uild-thread?start=24
Last edit: 21 Oct 2019 12:16 by TexasKZ.

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  • JimmBuzz
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Re: KZ440 engine knock and won’t rev past 4k

19 Dec 2019 09:36
#815611
Thanks. It has stock air box and stock exhaust. Oil has been monitored and changed regularly. Valve clearance has been checked. New spark plugs. It did burn oil before.

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  • JimmBuzz
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Re: KZ440 engine knock and won’t rev past 4k

19 Dec 2019 09:52
#815613
I attached a video of the tapping. Looking at it from the rear the left side appears to have more smokey exhaust, so I'm assuming that's the side with an oil leak. I will double check valve clearances.

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  • TexasKZ
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Re: KZ440 engine knock and won’t rev past 4k

19 Dec 2019 15:18 - 19 Dec 2019 15:20
#815622
Are both cylinders firing? An easy test is to spray a little water on each exhaust pipe near the head. while the engine is running. The water should immediately sizzle and quickly evaporate. If one side is much slower, that cylinder is probably not firing.

Next on my list would be a compression test, or even better, a leak down test.
1982 KZ1000 LTD parts donor
1981 KZ1000 LTD awaiting resurrection
2000 ZRX1100 not ridden enough

www.kzrider.com/11-projects/620336-anoth...uild-thread?start=24
Last edit: 19 Dec 2019 15:20 by TexasKZ.

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  • Nebr_Rex
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Re: KZ440 engine knock and won’t rev past 4k

19 Dec 2019 17:30
#815632
That is a rod knocking.


.
2002 ZRX1200R
81 GPz1100
79 KZ1000st daily ride
79 KZ1000mk2 prodject
78 KZ650sr
78 KZ650b
81 KZ750e
80 KZ750ltd
77 KZ400/440 cafe project
76 KZ400/440 Fuel Injected

www.dotheton.com/forum/index.php?topic=39120.0


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  • JimmBuzz
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Re: KZ440 engine knock and won’t rev past 4k

20 Dec 2019 07:12
#815641
Now that you mention it. Yeah that sounds like a rod knocking. rip

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  • baldy110
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Re: KZ440 engine knock and won’t rev past 4k

20 Dec 2019 08:27
#815644
Yep thats a rod. There is no fixing that without a complete teardown.

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