'26 JD motor restoration

[swest]

I have a nice set of matching number JD cases. I would like to start collecting parts to rebuild but I need an information source so that I search for the correct parts. When I look on ebay, everything is listed as J/JD. I need to know what the differences are. Any help would be greatly appresiated.

Thanks

[rwm]

innards are the same flywheel rods pistons heck you can't see um so who cares .cylinders get tricky i belive 26,27, and 28 take a larger intake manifold . 23,24 and 25 take a smaller intake manifold .26 thru 29 will work fine. the 29's you can tell them by the price ,i have seen the 29's sell for $5000 a pair.but don't worry you'll find ones you need .find terry marsh on ebay he's in oregon his ebay items have his phone #. he claims to have bought about 2 dozen cylinder for j models that he will be selling soon

[mootch]

jd or vl transmission

i just listed a tranny on ebay # 120501612497.....i do not know if this can help your project or not..........................

[Tommo]

To tell the difference between J 1000cc and JD 1200cc cylinders count the fins above the exhaust port 5 for a J, 7 for a JD.
The only other major thing you need to worry about is the cylinder base stud hole spacing as the earlier ones have a narrower stud pattern on one side than the ones you want.
Get yourself a compression plate with your stud pattern and take that with you to make sure you get the right cylinders
So long as the cylinders are a pair you will be ok and I wouldn't get too hung up on exactly what year they are because if the USA is anything like here cylinders are very hard to come by.
Probably the most important thing is to check for cracks between the exhaust valve seat and the cylinder wall. If they have bad cracks they can render the cylinder unserviceable so you don't want to pay top dollar for something that may be beyound repair.
If you,re lucky enough to find some of what the factory called E or Fast Motor cylinders you can tell them by the fact that they have taller inlet cages so therefore the pocket the cage fits into is taller.
In most cases the large dia inlet manifold only requires a inlet nipple change so you can in generally fit either the large or small inlet manifolds by just fitting the corresponding inlet nipples
As rwm stated most of the rest of the engine is common to both models
Hope this helps

[swest]

thanks to all for the info.

[23JDCA 808]

There is a site dedicated specfically to the J and JD's. They have helped me pick the right parts for my 1923JD. ...bill in oregon
http://autos.groups.yahoo.com/group/harleyjd/

[Chris Haynes]

J = 61" Battery ignition.
JD= 74" Battery ignition
F = 61" Magneto ignition
FD= 74" Magneto ignition
H behind the other letters = Two Cam

[2camtom]

another pocketvalve engine number

Found this motor 17 years ago in Denmark.Has anyone an idea of what bike it was??
The best bid til now is that it was made for roadracing in europe. The cams are different to what you see in 28-29 H engines- much "steeper", it has another flywheel- longer stroke, and the displacement is 1400cc +/-.

Regards tom

[rwm]

tom do you have this motor .i could realy use the measurements of the valve pockets.

[sludge]

Three good sources of info and or parts for JDs are in no particular order:

The book "Inside Harley-Davidson" Subtitled - "An Engineering History of the Motor Company from F-Heads to Knuckleheads 1903-1945" by Jerry Hatfield.

Competition Distributing Company www.competitiondist.com (they make/sell lots of JD parts).

www.Linkcycles.com (makes quality reproduction parts and sells original parts, does a lot of eBay sales Good Guy Mark is).


Hope this helps.

[2camtom]

valvepocket

Hello Rob

Enclosed is a photo with the measures.
For the ex I modified valves from a Ul and for the in I think it was from an evolution.

[rwm]

thanks tom .that will help a lot what do you run that 2 cam in?

[Tommo]

Rob
Just a bit of trivia. The vanes in the centre of the inlet slot are handed so therefore the cages are either front or rear.
The vanes are engineered to start the incoming gases rotating in a circular motion around the valve head in an effort to try and get a bigger charge into the cylinder.
I'll try and post some pictures of a pair of cages side by side so you can see what I mean.

[rwm]

tommo they above pocket doesn't look like it has a center vane. my 27 has f and r stamped on the pockets i am a little confused as to what i need the measurements tom sent me are exactly like my stock 74 ci jd i need measurements for 61 jL or jh with the tappered fins

i need it for cylinder on the left

[Tommo]

Rob,
Perhaps I did'nt make myself clear enough.
I'm talking about the inlet cage that sits in the cylinder pocket.
If you look closely at the image of the cage posted by 2cam tom and study the central support you can see that it isn't a straight bar but is in fact more like a small wing/vane.
The rear cage has a vane that swirls the incoming charge in a clockwise rotation and the front cylinder swirls in a anti-clockwise rotation.
I've seen these cages put in the wrong way round and guys wondering why the motor didn't go as good as it had gone previously. When you show them why they are generally amazed and say that they hadn't even noticed the vanes.
If they are put in the wrong way round the swirling gases are trying to block the incoming charge in the inlet manifold and destroy any of the benefits that are obtained if they are fitted correctly.
If my explaination is still not clear enough please ask again