ESE's works engine tuner

[twotempi]

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.

Not quite true !!

It is a MBA Morbidelli 125 twin but with some important parts missing.

I have a Sanverno gearbox "kitset" but have not confirmed if this will fit. does Frits know if it is the same ??

Also the primary gears are missing. I can reverse engineer this but if any one has any drawings that would help immensely.

[fatbastd]

'Manfeild' would also have 'e' before the 'i', as the name is a contraction of 'Manawatu - Fielding' and that's the correct spelling of Fielding..

[husaberg]

'Manfeild' would also have 'e' before the 'i', as the name is a contraction of 'Manawatu - Fielding' and that's the correct spelling of Fielding..

lol
I found this when trying to find the clip Hailwood.

[Frits Overmars]

It is a MBA Morbidelli 125 twin but with some important parts missing. I have a Sanverno gearbox "kitset" but have not confirmed if this will fit. does Frits know if it is the same ? Also the primary gears are missing. I can reverse engineer this but if any one has any drawings that would help immensely.

In case you want to google it, the correct spelling is Sanvenero. And although it's a 125 cc parallel twin, it differs from the Morbidelli, MBA, Minarelli and Garelli twins.
For example the Sanvenero crankshaft is bolted to the upper crankcase half by means of saddles (a bad solution, as it turned out).
But if you need Morbidelli gearbox parts, you don't need to look very far: try Yamaha TZ 250/350 parts; most of those will fit.

[breezy]

Not quite true !!

It is a MBA Morbidelli 125 twin but with some important parts missing.

I have a Sanverno gearbox "kitset" but have not confirmed if this will fit. does Frits know if it is the same ??

Also the primary gears are missing. I can reverse engineer this but if any one has any drawings that would help immensely.

http://www.bonhams.com/auctions/20924/lot/467/

[Dutch Fisher]

Calculated, 1 cylinder.

Calculated ! I'm intrigued

If you don't mind a bit of peer review Frits, pls feel free to publish your variables and their values.

Frits, did you miss my post. You might be interested, I spotted an error (or two)

[Frits Overmars]

If you don't mind a bit of peer review Frits, pls feel free to publish your variables and their values.

Frits, did you miss my post. You might be interested, I spotted an error (or two)

Do I mind a bit of peer review? Not at all.
Did I miss your post? No.
Am I interested? Yes.
Can I find the time to discuss the subject? Alas; the racing season has broken out....

[twotempi]

That shed only has a one way door though!

The door opened both ways when you had the use of one of the bikes !!

[TZ350]

Page 1150 .....

But if the engine NEEDS the smaller crankcase volume? And the rsa engine also has smooth crankwebs that do not help stirring?Edit: okay, if ANY engine needs the smaller crankcase volume? the banshee engine obviously doesn`t need it.

With the RSA/ RSW Most of the volume is concentrated in the transfer ducts. Then there is the volume inside the piston of course, and the 1 mm shear-avoiding clearance at all surfaces of the crank.
But that is not nearly enough volume. If you take another look at the Aprilia crank below, you will notice that the space between the crank webs is the same as the space needed for the big end bearing. In other words: the crank webs have flat insides, good for another 60 cc or so, if I remember correctly.
Attachment 310767
Additional benefits: the con rod has an easier time pushing the mixture aside as it moves between the webs, and the big end bearing gets a lot more cooling and lubrication because it is not shrouded in any way.
Because there are no overhung bobweights, the crank webs are stuffed with tungsten to get the balance factor right.
In the RSA125, the con rod was lengthened from the RSW's 115 mm to 120 mm to create even more crankcase volume.

The paddling is a mixed blessing; it creates aerodynamical drag but it also greatly improves the homogenity of the mixture.
Smooth, full-circle crank webs have the advantage that there is little mixture hiding in nooks and crannies. An example of it's importance: in a certain engine there were 20 mm spaces between the crankshaft bearings and the seals. these ill-accessible volumes acted as pneumatic dampers on the crankcase pressure fluctuation. Filling those volumes with plastic bushes gave a measurable improvement.

Summary: you need a large crankcase volume. Ideally all of this volume should be situated in the transfer ducts. In real life you will also need to lodge part of this volume between crankshaft and piston, i.e: use a long con rod. Avoid nooks and crannies. Crankshafts should be small and smooth. Big end bearings must never be shrouded by recesses in the crank webs or by stuffers.

The picture below shows, wait for it, an RSA125-crank with stuffers...
After Jan Thiel went into retirement in 2008, some geniuses at the factory grabbed their chance to 'correct' the errors that Jan left behind, without even testing the result because 'everybody knows the smaller the crankcase volume the better'. But they never could understand why a 2011 RSA125 was slower than a 2007 model (just look at the 125 cc top speeds on any GP-track). O, the joy of working with Italians.....
Attachment 310768
Frits Overmars 2012


In theory enclosed cranks are good. Jan Thiel did some experiments at Aprilia with a kart engine that had its reed valve at the front: the incoming mixture had to move against the direction of crank rotation. And although the crankcase stretched over the crank webs, reversing the direction of rotation brought another HP. So the crankshaft does have an influence.
But in practice, if you reduce the distances between crankshaft and crankcase walls to less than 1 mm, the viscous friction of the mixture between the surfaces really costs power at high rpm. And if you make the clearances so tight that lubricating oil can no longer reach the big-end and crankshaft bearings, it will also cost engines
Another negative aspect: any volume with a narrow 'entrance' between the crankshaft and crankcase surfaces acts as an hydraulic damper on the Helmholtz-resonance in the crankcase.
Aprilia has avoided this by making the space between the crank webs as wide as the big-end bearing. As a result the crankcase volume of the 125 cc RSA engine at TDC is about 650 cc,(or 675 maybe) so the exhaust pipe really has some volume to breathe from.

Crank stuffers? An Aprilia RSW125 has a TDC crankcase volume of 650 cc. An RSA125 has 675 cc and a bit more power. See where this is going?

So much for the fairy tale of high crankcase compression

I remember Jan saying that the crankcase volume of the Derbi reed valve engine was even larger than that of the rotary engine. And after Jan had laid his hands on it, that reed valve engine was the strongest 125 cc reed valver ever.
You see, the volumes of the transfer ducts and the volumes between the crank wheels and inside the piston are largely equal, and the volume of the reed cavity is a lot larger than the volume of a rotary inlet duct.

Frits has also mention previously that the Reed Valve Derbi that produced 49 (I think) HP after some work by Jan had an even larger crankcase volume than the RSW and RSA.

A technical explanation? Nah, too much to do today. But since you were kind enough to post that picture of your sex six sisters, I will show some curves of my own.
When Jan Thiel went to Derbi to design the bike we now know as the Aprilia RSA125, he encountered the 125 cc reed valve Derbi ridden by Lorenzo the previous season. Jan played around with the reed valver as well, because he wanted to find out the differences between reed valve and disk valve power. He managed to extract 2 HP more from the reed valver than anyone else had ever done before (never mind the fairy tales of reed valve 125s producing over 50 HP; those Horses must have been Shetland ponies, probably measured at the piston ring).
My graph shows the power curve for the Aprilia RSA, the Aprilia RSW and that best-ever reed valve Derbi. It's not quite in the same league as the rotaries, hmm?

EDIT: Shame on me; I discovered that I posted a wrong graph (and I do not have the correct one at hand here in Holland). Power curve DERBILOR shows the reed valve Derbi as Lorenzo rode it. After Jan finished playing with it, it had 49 HP. Still, the best-ever disk valver produced 10 % more power than the best-ever reed valver.

Well 41 or so of the words are mine. I wonder if there is any job opening for a Physicists secretary. Click on the pics to make them bigger

Husa, thanks for your post. a rotary valve engine needs a big crankcase volume, i know that jan thiel and frits told us many times. but ask wobbly if a reed valve engine also needs the bigger the better crankcase. and the banshee engine IS a reed valver.

For sure bigger case volume is better,but I think Jan Thiel said on pitlane that you need the most of the volume to be on the transfer ducts on the cyl and case transfers,will bigger volume between the crank webs help on BDC??
Plus,can tranfers like the RZ's handle a very big volume in the cases and also a fat Aprilia type exhaust?
Cheers

It has been my experience with many reed engines that do NOT have any where near all the design elements correct ( like the Derby did after Jan )
for making big bmep numbers - that going under 1.3 CCR yields no better power.
As always there is alot more to this than meets the eye, as I have recently done a little more work on a KZ10B kart engine.
I spent hours stripping and machining 5mm off the reed face on the case and enlarged the trenches for the reed block screws to make it fit.
Now this ( my ) engine makes 47 Hp at 13,000 so must have most of the ducks in a row - but it now has a 5 mm spacer behind the reed.
So a blanket statement that claims big cases make more power in reed engines is over simplifying rubbish.
But as part of that test session I fitted some experimental plastic plugs to the piston and ground the Aux around to bore centre with
nice radial pockets on the rear entry walls.
This added 3.8 Hp at 14,000, a 10% increase in power over the stock setup at that rpm - now thats a result.

Off the pipe you want a reasonably small crank case, on the pipe it almost can't be too big. Assuming a good pipe and port design.
You kind of need dual cankcases volumes.

ok and that spacer BEHIND the reed keeps the intake tuned length correct?

Jan did not enlarge the crankcase volume on the Derbi reed valve engine; it was already big; a reed case has a lot more volume than a rotary valve duct.

True, Neil. Off the pipe you need a pump with the minimum amount of dead volume; on the pipe you'll want the engine to breathe directly from open air (mixed with a bit of fuel and oil). But that oil has to pass through the crankcase to keep the bearings happy. Hence my 24/7-setup

There are several issues involved with the reed engine and its case volume - that has effects not seen in an RV setup.
The bigger the case the less are the pressure swings from piston movement and the pipe action ( assuming the same depression at the Ex port created by the pipe )
around BDC.
This changes the tuned frequency of the case vol, but this also requires thinner reeds to get them open fast and far enough.
Of course changing the reed stiffness then changes the intake tuned frequency,they then hit the reed stops and flutter uncontrollably - and so it goes on and on.
I tried machining the KZ10B case back to make the volume smaller as I already had the 5mm laser cut spacer from a test making the case bigger by pushing the reed block outward.
This failed miserably, so of course you then go the other way - this also failed,but only partially in that I did not then try differing reeds to compensate as I should have.
Adding a spacer behind the reed block HAS NOTHING to do with the intake length, this is already as short as it can be, with the rubber manifold recessed into the reed stuffer.
All I can say is that from a huge amount of sims and real world reed engine testing, that a very well tuned engine with good power capability ( bmep ) likes the case down near 1.3.
An engine with less power ( bmep ) capability ( for whatever reason ) tends to respond better to the case closer to 1.4.
When you are making 8 Bar and or 14 Bar BMEP of course these exceptions to the norm tend to prove the rule of thumb.

Might get to try that soon, the sleeve engine cases are not too far off finished. First I will be running just normal reeds.
You may have seen earlier, LM13 plates well. I've had all my Heat Ranger cylinders done. I sent them an offcut from the casting process to test first. FOS pattern has stalled due to having to get these Heat Ranger engines out.

this is why i was thinking you could stuff the voids near the big end pin (but not shroud the big bearing) on these twin cylinder cranks like the pic i posted, either with carbon fiber, the material that wobbly suggested or simply using plastic like ktm has done for years, then of course just screw the stuffer into the side of the cheek. then the lost volume from stuffing the voids, you can gain that volume back via longer conrod. if my thinking is correct, this would now put all your volume above the crank cheeks and at the transfer entry, rather than have voids down low in the crankcase during the transfer phase. maybe the performance difference wouldnt be much but atleast you would end up with a rod ratio probly around 2.15-2.2 ( just guessing as i havent calculated it), which doesnt seem like a bad thing for high rpm

But by adding the stuffers into the crank you loose more volume than you gain by adding 115 long rods ( that fit straight in )

from my calculations i think your right but who said anything about using 115 rods . theres even longer rods that fit right in . might even be something around +120mm that would fit right in, or require just a alittle machine work, i havent looked into this option yet though. just eyeballing the size of the stuffers needed, im guessing somewhere around 120mm is what would be needed to be at 1.33ish, this is just a guess though. i had it written down somewhere but with 64 bore,58 stroke, 118 rod and 513 series piston (standard wristpin location), it was 1.31 if i recall, ill try and find my notes. i do have a crank sitting around i could check the volume of the voids and get a pretty good idea what length of rod would be needed to recoup the stuffer volume, based off my previous calculations. ill have a answer in the next few days as im curious to this

Something Wob I think and Grumph had said about the Reed valve Hondas having the shorter rods with the reed valve engines.

Long vs Short rods

I think (if I have got this right if I haven't the panel will fix it and burn me later at the stake)

Short rods have a higher acceleration rate away from and until about 90 degrees either side of TDC and BDC. This could be an advantage with a reed valve engine.
Conversely after 90 degrees either side of TDC or BDC the longer rod then actually accelerates more but then slows again nearing either side of TDC or BDC. Dwelling for longer.

Honda stuck with shorter rod despite huge amounts of R&D money with I guess was thrown about.
I don't know the rod length of of the Yamaha and Suzuki Cagiva GP500's but none of them seem that long either

Note I believe The longer rod should have less thrust friction as most of the this acceleration occurs with the piston and rod in a more parallel position though.

I note RAW on a Superkart has noticed the carburation is very different when he went to longer rods but I guess the burn will be different and so would be the optimum carb and especially the ignition timing.

I'm sure you've grasped it Husa, but the way it comes out of your keyboard indeed deserves burning. And your and is simply wrong. You might damage the younger brains here!
Short rods have a higher acceleration rate approaching and leaving TDC but a lower rate approaching and leaving BDC. That is all there is to it.
I posted the graph hereunder before, but it may not have sunk in with everybody, so I made an additional sketch.
Attachment 310781 Attachment 310783

When the crankshaft rotates away from TDC, the big end pin pulls the con rod downward. But because the rod also has to sway sideways, the small end drops more than the big end. The sketch (made with MS-Paint, so everyone can understand) shows a crankshaft with a 100 mm stroke, rotated through an angle alpha of about 70°.

On the right there is a 220 mm rod. Because of the swaying the small end has dropped an additional 4,8 mm.
On the left there is a 110 mm rod. Because of the swaying the small end has dropped an additional 9,9 mm, although the angle alpha is the same on both sides of the sketch. It's as simple as that.

Frits, you said that the best rotary valve engine has 10% more power than the best reed valver.

can you also tell us how much better is a case reed engine than a cylinder reed engine (in%)?

Nope. The 10% was not a calculated but a measured value; it was based on Jan Thiel's work with the reed valve and rotary valve Derbis.
I doubt if we can persuade Jan to come out of retirement and start tuning a cylinder reed engine for us (he doesn't like reed engines anyway).

Long rods that affect the case volume then influence the carb tuning dramatically as well.
I did a Rotax 257 single years ago for sprint kart racing, filling the crank webs with that UHWMP stuff.
This raised the case com form down near 1.3 up to about 1.35.
It needed complete rejetting and the main dropped from a 185 to a 165 due to the much stronger signal across the jets.
Going the other way on a 250 tandem twin by fitting long ( 120 ) rods and making full circle ( no pockets ) cranks, the jets then need to be huge
in size by comparison.
Honda used the short rod for years in the customer engines, but when push came to shove the final version used to win the last 250GP title used a long rod, for a reason obviously.
The big reed boxes that design had from day one, gave a relatively big case volume by default.

In my experience if a case reed is done as well as it can be ( look at a TM - KZ10 ) then there is very little difference in power if a cylinder reed
is also done properly with plenty of intake STA via piston cutouts and big Boyesens or floor ports.
The only real difference is that the boost port duct does not have a proper inner wall, and thus the flow regime is not as well controlled.

Nowadays an engine needs a large crankcase volume, all the port area you can cram into the cylinder circumference, good ducts for efficient flow and directional control, an exhaust that sucks and blows hard at the appropriate moments, and cooling, cooling, cooling.

[TZ350]

Well, that was the F4 and F5 Gp and the Tokoroa cup. Lots of great people from all parts of the North Island. Good weather for Saturdays practice, Wild Partying Saturday Night, Rain all night and Sunday morning, drying track late morning with more rain forecast in the afternoon making tyre choice a tricky gamble. Some very brilliant riding, with a spot of bad luck followed by a controversial re-interpretation of what was a pretty clear safety rule, all the drama you could wish for.

All in All a brilliant weekend of racing at a great track.

[NSR143]

Well, that was the F4 and F5 Gp and the Tokoroa cup. Lots of great people from all parts of the North Island. Good weather for Saturdays practice, Wild Partying Saturday Night, Rain all night and Sunday morning, drying track late morning with more rain forecast in the afternoon making tyre choice a tricky gamble. Some very brilliant riding, with a spot of bad luck followed by a controversial re-interpretation of what was a pretty clear rule, all the drama you could wish for.

All in All a brilliant weekend of racing at a great track.

Not sure what the re-interpretation was, none of the officials on the day changed the rule in any way? Damn good weekend though!

[kel]

Not sure what the re-interpretation was, none of the officials on the day changed the rule in any way?

You are taking the piss. The rule was clear, but it seems rules no longer apply. Its now open season in buckets!!!!!!
Your post really pisses me off Steve. The call was bullshit and you know it!

[seymour14]

Not sure what the re-interpretation was, none of the officials on the day changed the rule in any way? Damn good weekend though!

I thought most of us were told in no uncertain terms that bikes would need to be scrutinized if they hit the deck, and we would be marched if we failed to follow those very explicit rules. Not sure that a "made up" penalty was a good result for a blatant mistake. Pretty sure if Regan had hit the deck and then got up and carried on, that the shit would have hit the fan.

It's history now, but plenty more will be said about this I'm sure.

[NSR143]

You are taking the piss. The rule was clear, but it seems rules no longer apply. Its now open season in buckets!!!!!!
Your post really pisses me off Steve. The call was bullshit and you know it!

well well well... out of the frying pan and straight into the toilet. If I(we) thought it bullshit we would not have called it that way would we? I suspect a few people do not have the full facts to hand have misunderstood the situation. I would be happy to explain the full situation if you are interested in listening to it carefully and thoughtfully.

[kel]

well well well... out of the frying pan and straight into the toilet. If I(we) thought it bullshit we would not have called it that way would we? I suspect a few people do not have the full facts to hand have misunderstood the situation. I would be happy to explain the full situation if you are interested in listening to it carefully and thoughtfully.

Toilet or fry pan I couldn't care.
You don't need to explain it, I was there. I saw him go down, I saw him choose not to come in, I saw you guys hand him the trophy. You called it wrong, he should have been black flagged.
Its supposed to be one rule for all Steve. Bad call, very bad call.