EL to FL...

[ajvague]

Would like to find out if 74" wheels will fit in 61" cases w/o modifying them...
If not, what all is involved?
Have the opportunity to buy a pretty clean EL, and am wondering how practical 61" displacement really is in today's world. Not trying to ride it to work everyday, but I do want to ride it and I don't live in the country.
Thanks, Anthony

[john HD]

anthony

i just finished a 47 el for a buddy this last summer.

a 61 goes down the road just fine! pretty snappy to boot!

john

[Bigincher]

I am admittedly not an 'expert motor guy', but my 41 EL was built as an FL--- well before I got it so many years ago. Besides the flywheels, the cylinders and pistons must also be FL. Not sure about heads, but stands to reason also. Robbie will surely know all the details.
I saw a discussion recently about the pros and cons of converting a 61 to a 74, and the general consensus was that the EL was snappier, with less vibrations. I have no first-hand experience on that, however.

[Bosheff]

If I'm not mistaken, the 61 wheels are the same diameter as the 74's, difference being the crankpin location. The 61's were lower compression than the H's so todays watered down fuel is O.K. If the motor is right, you should have a good putter to play with....bosheff

[ajvague]

Thanks for the reply's everybody...
Can anyone give me a general idea of cruising speed for a stock 61", without winding it out, mph at a safe comfortable rpm for the motor?
I really don't know, just going on the more cubes is better line of thought.\
Thanks again

[panz4ever]

Crank pin size is different, same size flywheels but crank pins are positioned differently. Different cylinders, intake manifold, and carb. Also different cam. Think you also have to modify the oil scraper clearance in the cases.

[Sir_Rat]

A stock EL will go plenty fast enough to get killed on....how much faster do you want to go? I'll take a long slow ride on backroad over a long fast run on the highway anyday. How fast can it cruize will depend on your final drive ratio. I don't know the actual numbers but someone here does, find out from them what a good ratio for the city would be. I'm sure that just about every variation of ratios has been tried by someone here on this site. The smaller EL will be really snappy in town and with the right gearing you should be able to ride through town all week and still be able to hit the freeways for some longer weekend rides. If you stick with the stock set up or close to it you should be geared just about right. Good Luck

Aloha,
Mike

[Bosheff]

With the diameter of the flywheels being the same as 74's, there should be no need to modify the oil scraper....bosheff

[Cotten]

With the diameter of the flywheels being the same as 74's, there should be no need to modify the oil scraper....bosheff

True for 61" Panhead models, but not all 61" models.

Ajvague asked:
"Can anyone give me a general idea of cruising speed for a stock 61", without winding it out, mph at a safe comfortable rpm for the motor?"

They were designed to be 'wound out', not lugged!

My 1937 61" proved it could pull a sidehack across Illinois on the Interstate at 70 mph.
(And got better fuel and oil mileage than my wife's '65 with the same hack, over the same route.)

But generally they should be considered ideal as a solo machine.

....Cotten

[RUBONE]

ajvague,
As has been noted it is a pretty straightforward conversion. But it begs the question, why? Most EL's are very smooth and fine runners, easy starters and generally all around nice bikes. The flywheels from '40 on are the same casting so no internal modifications are needed, the earlier flywheels were smaller diameter. The cylinder bore is different but also the overall length so they would need to be changed. Because they are shorter the intake manifold is also shorter as the distance between the heads is less. As Cotten said his '37 EL ran very strong. 61" Knuckleheads are inherently stronger runners than the Panhead versions. Some of it has to do with thae same camshaft being used for EL and FL. Not the case with Panheads. Also the early small port Knuckleheads seem to do particularly well. If you decide to do the conversion (a mistake in my opinion!), you merely need to use FL flywheels, an FL or FLH cam, Cylinder and piston assemblies in the compression ratio you prefer. The heads are the same. The intake manifold should be longer for best sealing. depending on which carburetor you have, you can use it or upgrade to a larger one. There are no other differences other than an increase in power with a corresponding increase in vibration.
Robbie

[ajvague]

OK thanks for the input everybody...I do appreciate it.
I haven't gotten the bike yet, but the opportunity is there and maybe a deal will be made.
I've never rode a 61" motor, Pan or Knuck and wanted to find out more. I don't think I'd change a thing at this point.
It's a '50, if I didn't say so before.
If I end up getting it, I'll post back about it and see If I can post pics on this site.

[partshunt]

One other point I might add. Converting an EL to FL could devaluate it some day to a fussy purist buyer since the last 61 was produced in 1952 making the 61" EL panheads a bit rarer than FL's. All the numbers on the cases would stay true blue. Sitting in a museum wont have any effect on power and speed if it was to ever end up there someday. My thoughts.....Joe.

[joe]

I have heard from some old timers say that the 61 was a smoother ride and easier to start. Why not just stick with the 61?