panhead 48

[pan 48]

good morning, I am French and my translation is poor, I am sorry
i have a panhead 1948 with piston/cylinder standart +0.6
i don't want to put piston 0.7
i want to put cylinder /piston 74 ci because cylinder standart 61ci are impossibble has find.
is it possible to do this operation ?
my bike come back USA

[steve_wood]

Tu veux dire que ton moto est presentement 61 ci et tu veux le changer au 74 ci?

(Do you mean that your motor is currently 61 ci and you want to make it 74 ci)

[pan 48]

oui , ton français est meilleur que mon anglais

[pan 48]

yes

[steve_wood]

So does anybody know? Is the crankcase the same for 61 ci and 74 ci in 1948? Are the connecting rods the same?

Of course the pistons, cylinders and heads are different. Anything else? Primary chain gearing perhaps?

[RUBONE]

Crankcases are the same. Only difference above the cases is cylinders and pistons. Heads are the same. However, due to crank difference (Stroke is different) the cylinders are not the same length. So either a 74 crank needs to also be installed (rods are the same), or the cylinders need to be shortened, which ruins them for any other use. The only good part about running the 74 bore is the engine becomes a 68 incher, one of the best running combos ever!
Robbie

[panz4ever]

Robbie what about running SV wheels and stroker plates? Couldn't you just about get the same results?

[pan 48]

where can i buy cylinder and piston panhead 61 " ci standart???

[panz4ever]

where can i buy cylinder and piston panhead 61 " ci standart???

Here is a place to start... http://www.billscustomcycles.com" onclick="window.open(this.href);return false;

[pan 48]

thank you

[RUBONE]

Robbie what about running SV wheels and stroker plates? Couldn't you just about get the same results?

No, not really. Sidevalve big twin flywheels are 4 9/32 stroke, 74 OHV is 3 31/32, 61 OHV is 3 1/2.
SV flywheels create a stroker motor which is big on torque and doesn't rev all that well. They also tend to shake more.
61 OHV with 74 cylinders is close to "square" dimensions, ie; the bore and stroke are the same or nearly so. This creates an engine that revs well and is inherently smooth.
So the end result is a radically different feel to the engine. A stroker has that Kick in the pants feel, but a 68" is all day comfortable.
Robbie