[Stumac]

Enochs description is far more eloquent and expansive than mine.
Assuming you have a paddock stand, torque wrench, large sockets / breaker bar / impact gun and the requisite skill and knowledge to re-tension the chain and realign the rear wheel, and that you are contemplating modifying a new bike, which would infer you are already in the “competent” bracket, what exactly has Enoch spent his time detailing for you that you didn’t know already as someone experienced in changing sprockets, other than how to remove the sprocket cover on a bobber ( which is fairly intuitive)
just curious why if you can pretty much do the job already you would trouble someone to write you a guide on how to do it.

 

[Donner]

...
Assuming you have a paddock stand, torque wrench, large sockets / breaker bar / impact gun and the requisite skill and knowledge to re-tension the chain and realign the rear wheel, and that you are contemplating modifying a new bike, which would infer you are already in the “competent” bracket, what exactly has Enoch spent his time detailing for you that you didn’t know already as someone experienced in changing sprockets, other than how to remove the sprocket cover on a bobber ( which is fairly intuitive)
...

Jeeze, Stuey, that it is quite well the longest, well-composed sentence on the forum -- well done!
Now let's all get back to playing nice before somebody loses an eye.

 

[lopsided]

I'm considering installing the 39 on the rear now.

DO IT I would highly recommend everyone with Bobber / Speedmaster switch to at least 16/40 gearing. I am at 16/40 and I'm waiting on a 42 tooth rear. Top end RPM cruising is honestly not affected at any remotely legal speeds. Look at it this way 16/42 is fine for Speed Twin / Thruxton with essentially the same engine (I'm struggling to find out exactly what is physically different between 1200 HP / HT to be honest; as far as I can tell HP simply has a lower redline and different final drive gearing... but I need to compare the engine parts #s to be 100% sure)

It just feels so much more lively now and I love being able to get out of 1st gear ASAP.

 

[Stumac]

i haven’t read this - too much for me, but it may be of interest

 

[Enoch]

DO IT I would highly recommend everyone with Bobber / Speedmaster switch to at least 16/40 gearing. I am at 16/40 and I'm waiting on a 42 tooth rear. Top end RPM cruising is honestly not affected at any remotely legal speeds. Look at it this way 16/42 is fine for Speed Twin / Thruxton with essentially the same engine (I'm struggling to find out exactly what is physically different between 1200 HP / HT to be honest; as far as I can tell HP simply has a lower redline and different final drive gearing... but I need to compare the engine parts #s to be 100% sure)

It just feels so much more lively now and I love being able to get out of 1st gear ASAP.

The main difference between hp/ht is the cylinder head. and mapping of course. Pretty much everything inside the engine uses the same parts including crank, cam, piston rods gearbox etc..