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TOPIC: KZ650 Crankshaft Worn our of spec

KZ650 Crankshaft Worn our of spec 03 Feb 2019 08:06 #798114

  • Charleslabri
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Heyo! Just pulled apart my bottom end on a somewhat routine rebuild.
Found the main bearings and con rod bearings worn below limit.

What does one do in this position? Can you get NOS stock or used ones that aren’t worn? Checking around eBay I see plenty that aren’t measured for tolerance— gives me pause.


Thanks!

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KZ650 Crankshaft Worn our of spec 03 Feb 2019 10:52 #798129

  • Nessism
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Found this thread for you to review. It answers most of the various questions you may have. And be sure to download a factory manual for your bike...

www.kzrider.com/forum/2-engine/609309-kz...aring-source?start=0

www.zedrider.co.uk/service--owners-manuals.html

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KZ650 Crankshaft Worn our of spec 03 Feb 2019 12:16 #798133

  • DFIGPZ
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What Year 650 ? Peanut chain or HIVO ? I Pretty sure I have a good crank and rods from a 750 Turbo but its a HIVO style Chain.
1984 GPZ 1100
1170 wiesco 10.5 cr
Larry Cavanaugh head
Bored Throttle bodies
Web .415in cams
Kerker K2 with comp baffle
RC Hp inj
Pogue Adj Regulator

VITON VALVE SEALS $22.00 SET OF 8 SHIPPED TO LOWER 48 PM ME.

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KZ650 Crankshaft Worn our of spec 03 Feb 2019 13:19 #798135

  • Charleslabri
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This is an 80 kz650 hyvo.
I measured the bearings on cam and got 36.96mm on my caliper. So that’s leading me to wear.

Looking at it.. is the hyvo chain the one going up to the cams or the one going to the transmission?

Do the 750 cams fit?

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Last edit: by Charleslabri.

KZ650 Crankshaft Worn our of spec 04 Feb 2019 13:52 #798199

  • DFIGPZ
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Hivo Cam Chain.
1984 GPZ 1100
1170 wiesco 10.5 cr
Larry Cavanaugh head
Bored Throttle bodies
Web .415in cams
Kerker K2 with comp baffle
RC Hp inj
Pogue Adj Regulator

VITON VALVE SEALS $22.00 SET OF 8 SHIPPED TO LOWER 48 PM ME.

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KZ650 Crankshaft Worn our of spec 04 Feb 2019 14:44 #798201

  • TexasKZ
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I thought the 1980 and earlier 650s used a roller cam chain and then switched to the HY-VO cam chain in 1981.
1982 KZ1000 LTD parts donor
1981 KZ1000 LTD awaiting resurrection
2000 ZRX1100 not ridden enough

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Last edit: by TexasKZ.

KZ650 Crankshaft Worn our of spec 09 Feb 2019 23:28 #798417

  • Big Jay
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Measure journals with a micrometer, not a calipers
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KZ650 Crankshaft Worn our of spec 10 Feb 2019 18:17 #798460

  • baldy110
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What makes you think the crank journals are worn? Are they scored, burn't or galled. If not your way over thinking this, get new bearings or used ones and plasti gauge them. I bet you'll find it's just worn bearings. I've rebuilt well over two dozen KZ650 / 750 engines and never found a worn out crankshaft even on abused ones. Most didn't even need new bearings. I simply plasti gauge the old bearings and if they ars in spec I reuse them.

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KZ650 Crankshaft Worn our of spec 11 Feb 2019 22:38 #798523

  • Big Jay
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Actually the KZ650 had a soft journal surface. When these motors were subjected to big power boost, the journals would die. Back in the day, when people raced these bikes we would offer a service where we hard chromed the journals not make them live. It is the only crank we have ever had this service for.
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Last edit: by Big Jay.
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