ESE's works engine tuner

[2T Institute]

Found this in Bert's links


GRP125 made into a 170 and home built EFI. Made 29hp, not extensively ported/tuned.
Unfortunately a lot of the earlier image links are dead but I think it was a carb replacement type injection rather than a transfer port injection type.
Have a look, I haven't trolled the thread much yet but man there are some idiots on that forum.

http://www.125ccsportsbikes.com/foru...c=63480&st=320

125cc sportbikes is just for 16yr old dreamers

[F5 Dave]

you mean the forum. I used to frequent the Derbi 50 one years back. but not for long when I realised who was posting

[tonyed]

Yea maybe a bit like Beck poking his tongue out at Clapton, a respectfully intellectual exercise .

But in a dissimilar vein here is some pervage for the boys,this isnt on track, its on the rubbish tin - and yes I know the floor needs sweeping.
Pre 82 Classic Frepin copy frame I have FEA corrected with TZ400 and S model fairing Billy is hoovering up now.
Coming together for Philip Island next January.
Late model Yamaha blue - tank/fairing will be a bit like Roberts colours.

I have the original Peter Pinion Frepin. It has a couple of extra tubes in it at the rear engine mount and between the top frame tubes. It houses a TZ350 G spec motor with G forks, ARE front wheel and a SMAC at the back (could not afford Campags).
I gather Peter bought the frame, swinging arm and tank back to England to have them copied, left them at a frame builder and never surfaced again. It has been round the houses a bit since then and at the Stafford Classic Bike show a couple of years back I talked to a previous owner who found the frame etc at the frame builders and bought it, not knowing anything about its' history. Built it as a 250 and raced it as a Yamaha in the TT. He said then he fitted a 350 engine and did the frame mods as the rear engine mount broke.

Murray DeLacey has one and some replicas.

Also a NZ contact was going to email me some photos of his but never did.

It always draws attention at shows and will be at Stafford again next weekend (26/27th April)

[2T Institute]

you mean the forum. I used to frequent the Derbi 50 one years back. but not for long when I realised who was posting

Yes no amount of experience or logic is equal to a cut n paste of the internet

[TZ350]

... cut n paste..

"Cut n Paste" ... replica of a 2T concept originally posted by Frits ....

how can we prevent a scavenging column from toppling over to the exhaust side like the leaning tower of Pisa? Not by pushing against its basis, but by pushing higher up.

Follow the link to read the whole story and see the original pictures.

[wobbly]

Does anyone know if Pinion is still with us.
One of the frames I have came from Fred McLeans estate I believe, but I have never had any info re Peter.

[Grumph]

Does anyone know if Pinion is still with us.
One of the frames I have came from Fred McLeans estate I believe, but I have never had any info re Peter.

My impression is that Fred was based in ChCh around that period - i may be wrong. I'll ask a couple of oldies i know not on here who may have some info on PP. At least one had a Frepin - and i've got the tank.

[TZ350]

Unlike finicky carburetors, with fuel injection there is not the over enriching problems you get when the inlet stream bounces back and forth several times in the inlet tract. Passing the carbs needle jet several times and picking up fuel on each pass. With EFI I don't have to be so conservative with the rotary valve timing and can experiment a little.



I have cut the top valve to have the same area but with a soft opening and closing effect.



Soft Opening - Fully Open and Soft Closing.

With the inlet opening at the bottom of the port first I am hoping to encourage the flow to adhere to the port floor, that way I think there will be a greater total flow through the port.

Opening at the inlet port floor first is an idea that Jan Thiel talked about, I hope I can make it work for me. Looking at the Aprilia pictures it looks like Jan offset the RV a little sideways in relation to the inlet port and that way he was able to cut the RV so it opened from the bottom first much more neatly than I can manage with the GP.

And soft closing at the top because I think the bulk of any blow back will follow the inlet port floor. And having the valve close the bottom first will block it.



Looking into the inlet tract you can see how the boost bottle directly feeds the inlet port as the RV starts to open it.



All the fuel injectors, hoses and plugs fit, thank goodness... ... I was a bit worried.

Anyway I have no real idea if any of this will work but I guess the dyno will tell us soon enough.

now to figure out all the wiring.

[wobbly]

As I understand it Pinion and McLean did the Begg F5000 cars and the Frepin was a sideline.
But I would like to nail down the history and chat to the horses mouth if possible.
Even the butchered frame I have that had a 500 in it is mirky in that I have also heard the motor was a 700, but again - who rode it
and who did the crap job of fitting it together.

[wobbly]

TeeZee, I spent days on the dyno at ZipKarts running a Rotax tandem 250 trying all the ideas we had seen with various rotary valve opening/closing scenarios.
I tried convex and concave opening and closing edges, singly and tandem curves in all manner of combinations - initially all with the same timings of 140/88 but
later when getting no results I tried curved edges with less and then more timing as well..
Several ideas changed the full power egt and this was re jetted for, but none of the weird shapes made any more power, many made less.
Then years later, Ii read that Jan had said somewhere when asked about the RV shapes being used on the leading edge only of the Aprilia
that the angled shape had nothing to do with power, but helped ameliorate the rapid wear on the case that was caused by the unsupported
valve being pushed against the open port area by the inrushing column of air.
This may have changed later, but I sure could not find any hidden horses but ruined a heap of perfectly good discs.

[F5 Dave]

Thus stimulating the Austrian economy and promoting world peace, so not a total loss.

[TZ350]

I sure could not find any hidden horses but ruined a heap of perfectly good discs.

Thanks for the heads up, I had to give it a go but will only try this one then maybe re fit the original one and save face by calling it a back to back test....

Ii read that Jan had said somewhere when asked about the RV shapes being used on the leading edge only of the Aprilia
that the angled shape had nothing to do with power, but helped ameliorate the rapid wear on the case that was caused by the unsupported
valve being pushed against the open port area by the inrushing column of air.

Makes sense.

[wax]

TeeZee, I spent days on the dyno at ZipKarts running a Rotax tandem 250 trying all the ideas we had seen with various rotary valve opening/closing scenarios.
I tried convex and concave opening and closing edges, singly and tandem curves in all manner of combinations - initially all with the same timings of 140/88 but
later when getting no results I tried curved edges with less and then more timing as well..
Several ideas changed the full power egt and this was re jetted for, but none of the weird shapes made any more power, many made less.
Then years later, Ii read that Jan had said somewhere when asked about the RV shapes being used on the leading edge only of the Aprilia
that the angled shape had nothing to do with power, but helped ameliorate the rapid wear on the case that was caused by the unsupported
valve being pushed against the open port area by the inrushing column of air.
This may have changed later, but I sure could not find any hidden horses but ruined a heap of perfectly good discs.

bad results are still good data. Im glad to hear the results you got it saves me trying what I had in mind

[chrisc]

I thought I had read that same info re the soft opening Rob. What you say wobbly makes a whole lot of sense though. I wonder if others have had the same experiences re the shapes.

[Drew]

Unrelated question. Do two strokes drink enough oil, to pump it in through the crank and run shell bearings?