Scooterotica

I don’t normally share my YouTube videos on here, but I’m convinced this one will be of interest to most here (I could be wrong, wouldn’t be the first time).

Established ‘tuning’ methods thrown into disarray?

Let me know what you think: https://youtu.be/SxQV0xz4q6E

I've often wondered do a gas and liquid flow in the same way? Maybe traditional tuning makes a mistake by assuming they do? Matching openings and removing edges which obstruct a pathway definately helps a liquid flow along that pathway better. Smooth edges are good for liquid flow. I'd love to see an experiment where the casing transfer inner surfaces and the transfer channel surfaces up the side of a barrel were given a dimpled non smooth finish just to see if it made gas flow with less drag and maybe make more power. I"ve often wondered where pistons don't clear inlet ports at the bottom of stroke or anywhere the piston edges interupt flow, is it deliberate on the part of the manufacturer to aid piston cooling? Did the matched cylinder/piston set up run hotter or cooler?

This is very interesting and I admit my knowledge on tuning is limited but a question for me is the SSR and it’s huge transfers or is this a whole different conversation due to how this kit is designed

I found it really interesting- makes sense from the power angle.
What didn’t seem to be considered though is the long term efficiency Of the system..
Power increase may be negligible in a Dyno or the road - but run the bike for a 1000 hours and see If their is a difference in fuel consumption.

All restrictions cause pumping losses- The losses may have no appreciable effect on measured instantaneous power, but they will reduce a systems efficiency in the long term.
Is the long term payback from reducing the small losses worth the time/cost effort is a balance.

On a race scoot that does 10 laps - probably not
But on a mile munching rally machine it may have some payback.

Consider. ( and these are just figures I’ve used to make the numbers easy)
Increasing efficiency by 0.01% ( in scooter terms that’s 0.12hp based on a 12hp machine), I’d be surprised if a dyno picked that up.
But in a machine that runs for 1000 miles , that’s 10 extra miles at no cost . ( a gallon of fuel + 2 stroke) .

so are you saying there isn't enough room to make enough of a difference, or if 43bhp can be acheived with no matching, are the ports already bigger than they need to be - has a margin already been built in? good article

Of course what we are all waiting for with baited breath, are Darrell’s secrets of what DOES produce his big power gains

https://flic.kr/p/WqMVME
is this overtuned then, i matched the size of the cylinder transfers to the ports on the cylinder, its a rotax cylinder from a snowmobile

Wasted Tuning? At the moment, its an intertesting observation but until a reason is established and proven I'd say its too soon to say!

coaster wrote: ↑Fri Jun 19, 2020 2:27 pm Wasted Tuning? At the moment, its an intertesting observation but until a reason is established and proven I'd say its too soon to say!

In the video mr clare alludes to knowing, something about 1000% of a ratio. But it seems DT wants to keep his hard-earned tuning secrets to himself. Fair play to him if that's the case.

paul d wrote: ↑Wed Jun 17, 2020 2:10 am I've often wondered do a gas and liquid flow in the same way? Maybe traditional tuning makes a mistake by assuming they do? Matching openings and removing edges which obstruct a pathway definately helps a liquid flow along that pathway better. Smooth edges are good for liquid flow. I'd love to see an experiment where the casing transfer inner surfaces and the transfer channel surfaces up the side of a barrel were given a dimpled non smooth finish just to see if it made gas flow with less drag and maybe make more power. I"ve often wondered where pistons don't clear inlet ports at the bottom of stroke or anywhere the piston edges interupt flow, is it deliberate on the part of the manufacturer to aid piston cooling? Did the matched cylinder/piston set up run hotter or cooler?

I think the crux of the matter, is that these tuning principles (as outlined by Bell, Jennings, Robinson etc) do work. But as Darrell Points out in the articles, is that you should never assume that what works on a 50cc rotary valve, liquid-cooled, 14000rpm GP race bike, will also apply to a 7000-8000rpm 252cc reed inlet, air-cooled, vintage machine, which has vastly different restrictions and design limitations. The question isn't 'do these tuning methods work'... the question is, WHEN do they work. On what applications?