ESE's works engine tuner

[senso]

Fantastic information Frits.

Makes me wish there was a book, keeping all that history for future generations, not just about the engines, but the people behind them.

[fatbastd]

Interesting stuff...

Was in a shed of a well-known collector in the UK a month or three ago, and he led me into a little room where he had about half a dozed Morbidellis and a grail twin...plus a set-meatl monocoque early TZ350 (ex-=Tony Rutter and nearly won the Junior TT one year, only to break down close to the finish), several 750's - TZ (several) and TR (2), other small stuff and his favourite - a ROC 500 Yamaha..

Not meany people get into that shed, so I was a bit shy of taking photos..

FB

[Frits Overmars]

Not many people get into that shed, so I was a bit shy of taking photos.

Taking photos without asking first is always a bad idea. And I can understand that people do not want it known to the world when they have a valuable collection.
But there won't have been many technical secrets around in that shed anymore, so that would not have been a problem.

In the previous century (and it feels like a century ago) I was a technical editor, always on the look-out for scoops in the GP-paddocks. The Japanese engineers of that era had strict instructions not to let anybody photograph their works machines, so they were understandably nervous when they saw people with cameras.
Once I walked into the Yamaha pit box and the first thing I did was to hand my camera over to the engineer in charge, for him to stow it away so he could have peace of mind.
One day later he called me and I was the only person allowed to photograph the machines without fairing. That is how friendships can start.

[seattle smitty]

Whenever you run into any of those old-timers, tell them that they have a little fan club that stretches around the world, and that we are asking about them and what they are up to these days. And urge them to join this site and tell us about their glory days.

[peewee]

now days im sure its impossible to keep anything a secret. for $35 you can get some glasses with hidden camera

http://www.ebay.com/itm/8GB-Mini-HD-...item23329a013a

[ken seeber]

NEW FOUR STROKE INNOVATION

A new variable squish, spherical skirt & lightweight piston design


I hope this doesn't mean an end to two strokes !!

[Ocean1]

NEW FOUR STROKE INNOVATION

A new variable squish, spherical skirt & lightweight piston design

Obviously an electrical fault...

[RomeuPT]

Here are some drawings to complement the above picture series. Left is the ultimate Garelli 125-twin pipe, right is a dyno comparison between the Garelli 125-twin (yellow) and its descendant, the thirty years younger Aprilia RSA125 single (blue). Solid lines show power, dotted lines show torque.
What made the Garelli invincible was not just the power but just as much the tractor-like torque. Jan Thiel accomplished this without a power valve, without a power jet and without a programmable ignition (we started testing with programmable ignition after the 1987 season).
Attachment 310233 Attachment 310234

125 twin with 47cv at 13600RPM, should have been such a fun little monster , is there a video anywhere?

[husaberg]

Obviously an electrical fault...

I pick it as being a loose oil fitting just like Raymond Roches at Mansfield that year.

[TZ350]

Garelli 125-twin ... What made the Garelli invincible was not just the power but just as much the tractor-like torque.

I hear 2Tempi was poking around in his shed the other day and stumbled across a complete Garelli 125-twin engine. The things that turn up in that blokes shed.

[fatbastd]

That shed only has a one way door though!

[F5 Dave]

I pick it as being a loose oil fitting just like Raymond Roches at Mansfield that year.

No 's' you plonker.

I was flagging and that happened out of the hairpin just approaching us.

[husaberg]

No 's' you plonker.

I was flagging and that happened out of the hairpin just approaching us.

Would have loved to have seen it that close he carried on for what seemed like a full lap after as well.
He was riding like a man possessed that race.

[senso]

More funny doubts, this time regarding the port-map of an aprilia rs 125(rotax engine) cylinder, this one is the cylinder without the boost ports, I have made a port-map and the single exhaust port measures 42mm maximum width, but going by the 75% convention, 75% of a 54mm bore is just 40.5mm, maybe this explains why so many of this cylinders always seize in the same way, the piston tries to escape through the exhaust port.

I have measured and eye-balled and both the boost + oval exhaust port and the single oval exhaust port cylinder share the same casting, the boost ducts are made with very little space, and in some points they can't have more than 2mm of wall between them and the water jacket.

The port map is attached below, if some one wants to print it, just print at 300dpi and it will have the real size:

[senso]

And some photos, first are the dreaded water circulation holes under/around the exhaust duct, as warned by Frits they have already been drilled to 7mm, much better now(no photo of that yet):


How little room there is to make some big boost port ducts, they use the boss for the screw as extra room, done is casting is easy, but hogging the ducts in a non boost ported cylinder seems like a challenge:


And finally boost port cylinder vs single oval: