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Valkyrie Riders Cruiser Club > General > 1500 Tech Board > What could cause a "rod knock" sound on cylinder #6?
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Author Topic: What could cause a "rod knock" sound on cylinder #6?  (Read 1462 times)
Momz
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« on: June 21, 2013, 11:16:44 AM »
My motor has been apart and everything is within spec. The rods were checked for straightness, bearings and piston pins were well within tolerance as well as piston to bore clearances, and crankshaft end play was also OK.

Expert engine opinions would be appreciated.

Thank you.
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97 Valk bobber, 98 Valk Rat Rod, 2K SuperValk, plus several other classic bikes
Patrick
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Largo Florida
« Reply #1 on: June 21, 2013, 11:29:42 AM »
Was the engine taken apart due to this noise ?
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Momz
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« Reply #2 on: June 21, 2013, 11:33:55 AM »
Quote from: Patrick on June 21, 2013, 11:29:42 AM
Was the engine taken apart due to this noise ?

Yes, and after a hydrolock fix.
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97 Valk bobber, 98 Valk Rat Rod, 2K SuperValk, plus several other classic bikes
John Schmidt
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a/k/a Stuffy. '99 I/S Valk Roadsmith Trike

De Pere, WI (Green Bay)
« Reply #3 on: June 21, 2013, 12:14:55 PM »
George, these flat engines will knock like crazy if the carbs are out of sync real bad.
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Oklahoma_Valk
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Central OK
« Reply #4 on: June 21, 2013, 01:25:43 PM »
Keeping with John's advice,

If one cylinder is not getting fuel, and the rest ARE getting fuel, the lean cylinder will knock. Im assuming your valve tolerances are correct as well.
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Patrick
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Largo Florida
« Reply #5 on: June 21, 2013, 01:53:34 PM »
I'm also wondering if there could be a problem with one of the starter drive gears.
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Momz
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« Reply #6 on: June 25, 2013, 08:29:49 AM »
Quote from: Patrick on June 21, 2013, 01:53:34 PM
I'm also wondering if there could be a problem with one of the starter drive gears.

It seems that you may have a point.
Would seem rather odd with the motor components in spec, and #6 cylinder closest to the starter drive mechanism.
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97 Valk bobber, 98 Valk Rat Rod, 2K SuperValk, plus several other classic bikes
Momz
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ABATE, AMA, & MRF rep.
« Reply #7 on: June 25, 2013, 08:34:48 AM »
Quote from: John Schmidt on June 21, 2013, 12:14:55 PM
George, these flat engines will knock like crazy if the carbs are out of sync real bad.

Carbs were synced less than 600 miles ago. They were rebuilt and rejetted, then synced after reinstallation.
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97 Valk bobber, 98 Valk Rat Rod, 2K SuperValk, plus several other classic bikes
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