Is this an XLR motor.

Racing K Models

Is this an XLR motor.

Postby JerrryR » Sun Jun 28, 2020 9:20 am

My friend would like to know how to tell if a motor is really an XLR. What are the unique features to identify one?
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Re: Is this an XLR motor.

Postby Maxcapacity » Sun Jun 28, 2020 10:30 am

Hi Jerry- An XLR should have 10 bolts for the primary and an "R" casting number on the left case. The right case should be machined for a horizontal mag at the generator boss. The hole in the boss will be enlarged and be machined/tapped for the mag mount. Also the belly numbers won't follow the standard production pattern. They'll be a 2-3 digit number with no year indicated.

If it has its original heads the spark plug boss will be raised instead of flush with the surrounding casting like a normal ironhead. 58 is very early for an XLR BTW.
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Re: Is this an XLR motor.

Postby No side stand » Tue Jun 30, 2020 12:12 am

Hi Jerry. I was thinking that a some of the XLR/KR aficionados would have piped in. Maybe all the action is happening in private messages. :D
Aside from the vin pad being cleaned for a picture, the engine number looks great and has the correct R with serifs. It has the small diam sprocket shaft and looks to have the original alloy clutch drum. Here’s a picture of a couple of orig xlr left cases for reference on the R casting number that was mentioned above.

XLR left case.jpeg
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