Well, that's a matter of opinion. And i'll probably do it gradually-
my builds- the little 50 especially- is centered around keeping it all lightweight-
I've got a lightweight cruiser frame, alloy bars and stem, 700 c wheels that are fairly narrow on 3/4" rims, alloy 3 piece crank, lightweight 415 trike chain with NO TENSIONER, alloy handbrakes, even titanium bottom bracket spindle bolts- Use the smaller tank too.
I haven't weighed it yet, but whatever a 50 kit would add, I've already reduced that a couple of pounds, and the bike really sorta even rides like a road bike now- even with the motor on. I was doing a track stand on it the other day, Rolls forever-
So if I can get it down further I may take a year to do it but I still want it light, and I'm stilll pushing it up a flight of stairs. I doubt if anyones got a lighter one- at least using a cruiser frame still- and I use that for clearnces
There are after all 12 heavy steel bolts just on the flywheel and magneto and clutch covers
Now if only someone started making some lighter fiberglass ones!
My BMX alloy stem has 4 fairly large bolts- probably WON'T compromise on the wedge bolt!- but I've priced them out on ebay- and it looks like that would run about 20 dollars for the $18 stem- but would take some heavy metal off.
The nine regular rag bolts on that one I've reduced the number of bolts from nine to the six inner bolts by drilling the hub and bolting- they are still M6 but the commercial alloy sprock that Kings sells has inner bolt drilling for M5- even smaller! So that also cuts out the weight of 3 bolts and nuts, the heavy steel backing plates and the rubber.
It does add up- but yes- some expense I won't do all at once. I can actually get a much lighter head jug- I had one and something got in and scoured and I ended up putting the original heavier one on- just the way it came as opposed to what Boygofast sells now as replacements- much lighter than the kit from two years back. And then i can put a billet back on a have better carburetion- LONG STORY
So I may do that first- but no hurry- wear this one out a little
I'm sure this bike is well under 50 pounds already