Bikernet Blog Search Bikernet
Ride Forever -
Sunday Edition

How to build the 45 Magnum Engine

Completed by Yankee Engineuity

By Duncan Keller, Yankee Engineuity

Share this story:

Check this out. We are building a similar engine with a K-model top end for our Bonne Belle 45, 2012 Bonneville effort. Duncan Keller is helping Lee Clemens through the engine build process.


Duncan is the master of the Magnum engine. Enjoy the tech:

Click on the banner for more info.
Click on the banner for more info.


Share this story:

Back to Tech

Reader Comments

I have tried (Dec 2023) to contact Duncan Keller thru the numbers you have, his facebook page and thru Paughco. PaughCo and a friend of his on FB said they would try and have him contact me. I'm not sure if he was contacted, but if so, I respect his desire for privacy and to not respond. I have a chopped trike project bike and the major parts for a 45 Magnum; 45 cases and cam cover as well as complete front and rear 900 cc ironhead Sporty jugs and heads w/valves.

With all that said, I don't have the skills or tools to build a 45 Magnum myself. Is there anyone (or even Duncan, if he hasn't yet been told I'm trying to contact him) who could help?

Lonnie Dean Adkins
Tuesday, January 2, 2024
Editor Response Hey Lonnie,

I reached out and Duncan responded. I'll let you know what he says.
Hi, would like to know if Duncan is still in business building motors. I have a 45 to do a magnum motor. If so what is his current number. Thanks Bob

Bob Marcuccelli
Friday, May 19, 2023
Editor Response Try 408 307-4714
I recently bought a hardtail frame that came with, what will probably be, the only magnum 45 engine here in Belgium... The guy I bought it from started work on it. Already has the WL case welded up and partially machined, but apparently lost interest and is now selling me a half-finished Magnum 45!

As I do more research on it, I'm excited to tackle it! Also bought a small mill and lath a few months ago. I'll be trying to do most, if not all the machining myself. but just wondering, since my experience level is not that great, is there a more extensive "how-to" manual available somewhere, with exact measurements and pictures and all?


gent, Belgium
Wednesday, March 22, 2017
Editor Response Doubt if there is a manual, but I would highly suggest reaching out to Duncan Keller of Yankee Engineuity. He knows the complete drill and will help you.
Would very much like to contact Duncan Keller to build both my 45 magnum projects (K model and Ironhead). Have bulk of components for both projects. Any help you could provide would be appreciated.

Know Keller is most knowledgeable person on this subject. Please, please help me achieve my objective.

Marty Gibson
Comanche, OK
Wednesday, September 16, 2015
Editor Response Try calling 408-307-4714 or Duncan Keller . He's a great guy to work with on any project.
Page 1 of 3 (11 items)

Your thoughts on this article

Your Name
Anti-Spam Question:
Please enter the words you see in the box, in order and separated by a space. Doing so helps prevent automated programs from abusing this service.