What Are Harley Js? Harley Js Discuss What Are Harley Js? in the Classic Harley Motorcycles forums; OK, I know a bit about the newer Harleys, and a little about the Pans, Knucks & Shovels, but what's a Harley J? Is it a flathead or ? Sorry ...

[BaggerDad]

OK, I know a bit about the newer Harleys, and a little about the Pans, Knucks & Shovels, but what's a Harley J?

Is it a flathead or ?

Sorry if this is a dumb question, but I'd like to know.

Not a dumb question. J models are i.o.e. engines. Intake Over Exhaust. The intake valve sits on top of the "head" and the exhaust valve is in the side of the cylinder, like a flat head. The cylinder and head is cast in one piece. This type of cylinder is called a blind cylinder. The push rods and rocker arms for the intake valve are exposed and can be seen operating when the engine is running. The right side gas tank is notched out so the rocker arms have clearance to operate. The J model engine was the first 74 cubic inch engine for Harley in 1921 or 1922. If memory serves me correctly the first true V twin ioe came out in 1911. I know that the ioes ran until the end of 1929. The earlier V twins , 1909, had the intake valve operated by atmospheric pressure???? In my opinion these are the coolest engines to watch run. Hope this helps.

[JayDee]

Thanks for the info. I don't know much about the older Harleys but am interested in learning more.

[shovelmike]

Jay-Dee, look around at Borders, Barnes & Noble etc. You can find nice coffee table size History of H-D type books for $20 or so. Nice glossy photo's and informative text. Will get you right up to speed on the subject.

[47knuck]

[BaggerDad]

How long were Harley Js made and how popular were they?

[Bargain Hunter]

They were made from the teens until 1929. Very fast bikes, especially the JDH. V-twins with one sidevalve and one overhead valve per cylinder.