The 3-prong Attack: An Inquiry Into Increasing Horsepower

[shisoshin]

rusty, in this there are 'experts' and 'expert experts' and...

read aufitt response as simple correction of terminology
being initial correction before further flow of meaning..

analogy - eating food for energy; relative amount of food ingested
= potential energy,, this large stomach aids ingestion of more food..
restricted mouth/throat determines how much food enters stomach..
impacted bowel similarly effects ongoing elimination thus process..
type of food eated, calories etc etc, effects energy potential of system..

valves/multiple valves thus also camshaft lobe shape = how much fuel
can enter, speed of entry and 'swirling' patterns as fuel enters..
analogous to mouth/teeth/tongue/throat for biting/chewing/swallowing food..

valve function esp at high revs also depends on precise fast opening and closing
[for max flow-thru of fuel/air] thus valve spring efficiency a factor, unless
valves are closed mechanically as for ducati desmodromic system..

bore and stroke ratios of piston/cylinder effect potential valve size/number
also speed of piston up and down thus time for sucking in more fuel..
compression ratio = how much bang you get from the system,
depending on type of fuel used to get the bang..

details of it include tuning fuel/air intake, also length etc of exhaust,
thus 'shape' of exhaust pulses exiting thru exhaust, which may
help suck fuel out and also may help restrict escape of fuel once in..
[thus exhausts themselves, rather than simply dumping it out
directly thru valves to atmosphere in racing applications,,
as some, restriction, helps retain fuel air in combustion chamber]

there is always some trade-off in designing internal combustion engines,
esp for typical engines in typical road vehicles, where small gains here
may mean large costs [in $, noise, etc] there..

as for your friends scooter engine, it comes down to that formula..
design engineers have already designed it according to their formula
which includes typical road use, incl economy, servicing and engine life..
you can always improve on the engine, in small ways [spark plugs etc]
but dont expect to greatly enhance a 161cc scooter performance
with typical engine add-ons.. [get her a cbr250r ]

[BBRMotosports]

Rusty, you are putting wayyy to much thought into this. Its a scooter! The stuff is dirt cheap, If you want to big bore it than do it. If you don't like the outcome put a head on it. If you still don't like it then pipe it. I say sscrew the neighbors and do it all. just my .02

[Rusty Shackleford]

Shisoshin: I love your digestive system analogy. It's so obvious but I never thought of it that way. Thanks. As for Aufitt, I like him just fine. I just poke at him every now and then for the slight tone of condescension we all know and love, much the same way I get busted on for over analyzing things from time to time. He's a knowledgeable dude.

BBR: I know what you mean. Just trying to research and plan before spending. In your defense, it would be a lot easier to "screw the neighbors and do everything" indeed!

[shisoshin]

obviously youre interested in it, the process and the subject,
so no harm in feeding your brain another type of knowledge
which [like learning language, music etc] increases actual
brain mass by stimulating increased synapse connections..

so theres that, together with the 'fun' of playing with engines..
if you dont see it as fun, probably best leaving the hands on
aspects of it [big bore kits etc] to trained mechanics
for better outcomes on the day to day level

[shisoshin]

[ps - on the neighbours; had a honda 750/4 potentially loud
4into1 exhaust, but even so, it could be started up quietly,
and ridden away fairly quietly and not offensive..
so your scooter no doubt similar]

[MotoMike]

Originally Posted by Rusty Shackleford

Just trying to research and plan before spending.

Let's cut to the chase... how much $$$ are you talking to do all three - big bore, head, pipe, and labor (if you're not doing the work yourself)?

How many ponies will you gain?

Aftermarket horsepower generally costs more than factory horsepower. That's just how it is.


If it's worth it to you go for it... if not, save your dough and put it towards a bigger scoot.

[mdma946552]

i am no expert but more cc need bigger exhaust, not noisy just bigger

[Will 250]

How do you know the aftermarket can would be that loud? Are there any you can get that increase flow without dramatically increasing the noise? I know leovince do an evoII model for the CBR250 that is meant to flow almost as well as their really loud GP2 system.

Having said that, I reckon MotoMike is right. Trade the scoot for a PCX 150 like sendler's and problem solved.

[NSU]

Originally Posted by MotoMike

Aftermarket horsepower generally costs more than factory horsepower. That's just how it is.

Now more than ever, unless you have a factory turbocharger. Chiptuning works magic.

If you're DIY, I would do the scooter bore kit just for the experience.

[Rusty Shackleford]

Originally Posted by MotoMike

How many ponies will you gain?... ...If it's worth it to you go for it... if not, save your dough and put it towards a bigger scoot.

Should be around 1.5hp for the big-big kit alone, but that's a jump from 9.5hp to 11hp. As for the second part, she wants a Vespa GTS300 (22hp) after she graduates college, but they're $6,400 right now in 2012.

Originally Posted by mdma946552

i am no expert but more cc need bigger exhaust, not noisy just bigger

This is true, though the only ones I know of for the Buddy 125 are made by NCY and Prima, both of which are high flow in the "noisy" way.

Originally Posted by Will 250

Trade the scoot for a PCX 150 like sendler's and problem solved.

The Buddy 125 is an unusually fast 125. With me on it, it tops at 61mph GPS, and slightly higher with my girlfriend (who's the primary rider). The PCX150 isn't much different and my lady likes the vintage styling of the Buddy. I personally like the PCX a lot.

Originally Posted by NSU

If you're DIY, I would do the scooter bore kit just for the experience.

I certainly feel capable of trying, but I don't want to get into a situation where I have the thing apart and don't have the tools I need to get all the way through the job. It'd make a good "hot coffee in the garage on a Saturday" type project over the winter.