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XR 750 CAMS

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MOLDTHREAD

Posts: 121

Joined: Fri May 04, 2007 5:46 am

Location: BRANFORD, CT

Post Tue Jul 01, 2008 7:16 am

XR 750 CAMS

Hi All,

I'm looking for some help.

I just got a set of XR 750 cams that I'm going to measure and start reproducing. I would like any information on these cams that anyone can give me as to aprox. date, who they may have been made for, what racers may have used them, what type of tracks they were used on, and where they fit into the XR development history.

These were made by CR Axtel, with lobes welded to the gear clusters, all lobes are stamped 055, one of the gear clusters is stamped on the lobe side "79" which I am sure is factory stamp and is preceeded by letter? "I" or "J", hard to tell because weld starts to overlap.

Thanks for any help,
Bruce

PEEK Seals & HOT cams for flatheads
http://www.enfieldracing.com
Bruce Argetsinger
AHRMA Dirt Track # 67J
www.enfieldracing.com
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JohnR

Posts: 146

Joined: Sat Nov 13, 1999 1:01 am

Location: Utah,USA

Post Sat Jul 05, 2008 8:29 am

Re: XR 750 CAMS

If those cams are from an Iron Head XR 750 then they are from a model of which very few were ever produced.
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thefrenchowl

User avatar

Posts: 584

Joined: Fri Mar 10, 2006 3:18 pm

Location: Crewe, Great Britain

Post Sat Jul 05, 2008 10:58 am

Re: XR 750 CAMS

Hi, Bruce,

Iron XR used the "A" grind, probably a "PB" XLR grind adapted for smaller stroke.

Early alloy XR are "E" grind from memory, -72R set, listed in parts books as having the following opening/closing: Intake 33-54, Exhaust 67-18.

New grind in 74, "no letter stated" but -74R set, Intake 33-54, Exhaust 64-24.

The "J" grind is -79R set, Intake 43-57 1/2, Exhaust 67 1/2-29

No mention of lifts anywhere...

Hope this helps,

Patrick

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