crankshaft flywhheel
Road Master
Joined: Apr 2008
Posts: 1,012
Likes: 285
From: Alva Florida
If the crank in question is the one from the sig, it looks like you have the makings of some HP. How long is a hard question to answer. Best indicator is to have the crank run out measured. That will give you some idea how it is doing currently. But how long depends on a lot of factors, HP/torque, riding styles, all play into the equation.
Big Kahuna HDF Member
Joined: Feb 2010
Posts: 20,530
Likes: 2,305
From: texas panhandle
What actually leads to a crank failure? Bearings could fail and lead to crank failure. I'm not very informed on this issue, but a crank shouldn't fail on its own unless excessive torque is exerted on it.
Last edited by jmorganroadglide; Dec 7, 2015 at 06:54 PM.
Intermediate
Joined: Apr 2015
Posts: 49
Likes: 0
From: Orange County, CA
Almost always excessive heat for extended periods of time. Most failures can be traced back to overheating of motor components.
Club Member
Joined: Jun 2007
Posts: 45,429
Likes: 2,898
From: Bedford UK
Many years ago a local dealer had on display a con-rod with the bearing journal jammed tight in it, removed from the flywheels. I think it was out of a Matchless single; the rollers had ground down against each other, then climbed over each other until the whole lot welded itself together. The owner had ridden his bike until it finally stopped, engine seized thanks to that rod bearing. Despite that the engine was dismantled and rebuilt, the flywheels were fine!
Going back to Greg's crank, ride it until the engine obviously needs attention. That can be any of a number of things, for example burning oil, making a lot of noise, vibrating, etc. Your question is rather like another common one - how long does a belt last?! There really is no easy answer, but a very long time, if you're lucky - in both cases.
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Cruiser
Joined: May 2012
Posts: 149
Likes: 2
From: worcester massuchusetts
I ride hard but I don't beat it no burnouts or dumping the clutch just like to have fun with the throttle and some speed.. I'm burning a little more than a quart every 1000 miles so I'm thinking of tearing it down and going with a Revolution 107 kit but have question with the lower end. If I have to redo it I'm going with sending my crank and cases to revolution to rebuild balance weld and upgrade to timken bearings.
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Seasoned HDF Member
Joined: Dec 2005
Posts: 5,464
Likes: 624
Measure the TIR on the crank when you tear it down and make a decision at that time. For reference, my 07 103" TIR has been at .005 since I built it almost 7 years ago. No issues so far.
Zach
Zach
I ride hard but I don't beat it no burnouts or dumping the clutch just like to have fun with the throttle and some speed.. I'm burning a little more than a quart every 1000 miles so I'm thinking of tearing it down and going with a Revolution 107 kit but have question with the lower end. If I have to redo it I'm going with sending my crank and cases to revolution to rebuild balance weld and upgrade to timken bearings.
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Seasoned HDF Member
Joined: Sep 2009
Posts: 17,148
Likes: 6,170
From: SE Michigan
If the crank in question is the one from the sig, it looks like you have the makings of some HP. How long is a hard question to answer. Best indicator is to have the crank run out measured. That will give you some idea how it is doing currently. But how long depends on a lot of factors, HP/torque, riding styles, all play into the equation.
I'd say if his crank scissors, it would have anyway.
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Cruiser
Joined: May 2012
Posts: 149
Likes: 2
From: worcester massuchusetts
I spoke with Revolution yesterday I'm going to send them the cases and crank they are going to replace the crank pin rod bearings balance and weld it and upgrade to timken bearings. I'm not going to screw around with a motor with 100,000 miles