SOLD! - complete crankcase for Ariel MK II Sq 4

List any Ariel motorcycle parts or accessories for sale. Please include a quick description of part in the subject line.
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phil.auldridge
Posts: 43
Joined: Sun Mar 04, 2018 9:59 pm
Location: Austin
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SOLD! - complete crankcase for Ariel MK II Sq 4

Post by phil.auldridge » Sat Mar 10, 2018 7:12 pm

This crankcase was the original in my 1953 Sq 4 MK II. It suffered a rod failure due to oil starvation. A hole was NOT knocked in the crankcase, but there was a small crack, and on disassembly it was discovered that a previous repair had been done, certainly from a previous rod failure.
I spent some $500 with my local machinist who properly and professionally repaired the small crack in the drive side case bottom.

In the interim, I managed to source a complete, undamaged case on eBay, so I have opted to go with that one for my engine.

I believe this case will make a suitable and usable case for another bike that may have suffered similar mishaps. It has been beautifully polished, and ready to go. My machinist tells me the case mating surfaces need to be slightly shaved for a good fit. Then shim gaskets are available from Paul Ackerman (contact info in the Ariel club newsletter) can be utilized to make up any difference.

Other than that, this case can make a fine alternative for a damaged engine.

A sharp eye will notice that the bridge web on the drive side case is missing. When I opened the case after my "incident", the web was nowhere to be found, so clearly it had been broken with the previous failure. Numerous machinists and experts have opined that this bridge was there merely to assist at the factory with alignment while boring the crank bushings, and that its absence doesn't detract from structural integrity. On the other hand, if an owner wanted to replicate that web onto this case, I do have listed (separate post on this forum) another spare drive-side case half which does have the bridge web intact.. that could be removed from the one case and welded to the other if deemed wanted.

I will include a pair of brand new timing-side crankshaft bushes with the case at no additional cost.

$375 for the case, including crank bushes.

Phil Auldridge
512 517-0055
or email: http://www.arielnorthamerica.org/wordpr ... webmaster/
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Phil Auldridge - Austin, Texas
1953 Ariel Square 4
1997 Honda Valkyrie
1972 Norton Combat Commando
1978 BMW R100/7
1980 Honda CBX
2014 Indian Chief
1975 Moto Guzzi 850T

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