Scooterotica

Meds1 wrote: ↑Fri Jun 19, 2020 9:56 pm - but are they worth recovering on our scooters

I think you hit the nail on the head there...

There is a lot of THEORY that applies to two-stroke engines, some of it is so intricate that it's mind-blowing, but whether a 12hp GP200 and a power station have anything in common at all is another matter altogether.

Adam_Winstone wrote: ↑Sat Jun 20, 2020 2:59 pm I do love DT's testing, testing, testing and conclusion from measurable results, rather than the guesswork of pre-dyno days, where road testing to determine results way a long winded and less obvious affair.

Few people test in the volume which he does, even fewer share those results.

coaster wrote: ↑Sun Jun 21, 2020 1:01 am But Wasted Tuning is a provocative statement Dan so bound to draw the inevitable comments

Provocative? Some people might say that, but I couldn't possibly comment...

mick1 wrote: ↑Sun Jun 21, 2020 8:24 am Is it possible he obtains the high readings using these methods ? then alters them to more conservative settings for road use ?

Possible? Well yes, anything is possible.

Likely? No, not at all. He produces some of the fastest and most powerful Lambretta engines on the market, each different package tailored to suit. I've absolutely no idea what the end-use of the 43bhp RB252 engine was for, but from what I have witnessed, Darrell does everything he can to maintain set standards and repeatability. So you'll often see people ride his motors to dyno day shoot-outs etc or other events, and the hp matches what it says on the tin. I don't get the impression that he is in the business of fluffing figures, I really don't.

But that, I guess, is a separate conversation to the old 'matching and flowing' debate which this video sparked off, isn't it?

Fair point, just thinking aloud.

Is it also possible that the charge entering the combustion chamber (under primary compression) is restricted by the actual volume of the combustion chamber ? Therefore more charge would not physically be able to enter, unless the primary compression was increased ? so widening transfers would not be beneficial without more pressure to force it into the chamber ?

I like the way Darryl has approached this methodically, with a scientific mentality. Make a change, check it's effect. Make no assumptions, even if it means ruffling a few feathers.

He must be confident in his results to go against decades of ingrained wisdom

mick1 wrote: ↑Sun Jun 21, 2020 10:51 am Fair point, just thinking aloud.

Is it also possible that the charge entering the combustion chamber (under primary compression) is restricted by the actual volume of the combustion chamber ? Therefore more charge would not physically be able to enter, unless the primary compression was increased ? so widening transfers would not be beneficial without more pressure to force it into the chamber ?

I doubt it. The engine's job is to act as a pump, and the pipe facilitates that by drawing the charge through and then stuffing it back in at the right moment. I think most of the work is focussed around controlling the direction, velocity and amount of charge at various points in the engine.

been enjoying the recent series of youtube vids youve posted especially the carb ones , there was some irony in your praise for the humble 30mm dellorto only for your targa to have punctured floats! .

like most from the 80s generation of scooterists ive owned stage 4s ,ts1s i dont pretend to understand the art of tuning . but if you can repeat something an get the same results well thats science to me an il believe it . besides whats not to like about saving cash when an engine builder says youll need to have this or that done you can point them towards this an say no thanks .

Be interesting to see what other Tuner/Dyno Operators Views are as well on Darrell's results

wintermod65 wrote: ↑Mon Jun 22, 2020 10:58 pm been enjoying the recent series of youtube vids youve posted especially the carb ones , there was some irony in your praise for the humble 30mm dellorto only for your targa to have punctured floats!

Yup, nothing is perfect.

Glad you enjoy the videos.