ESE's works engine tuner

[husaberg]

[/URL]


No surprise that a 500ccm engine does not give more power than a 125ccm gp engine if the cylinder is mistreated like this. "The power valve ports are slightly smaller...." So why using a 500ccm engine if you don`t let it breathe? unbelievable...

It pays to consider that they also have a carb smaller than a 125 gp bike and were built to be ridden my lesser mortals on surfaces that offer less grip.

[Dutch Fisher]

My source:- Page 429

Originally Posted by wobbly
As we were talking about Yamaha and their lack of results here is an interesting story. Harold did the CNC anemometric flow testing on the BSL cylinder for me that I had lithographed in plastic. He showed me the dyno curves of his cylinder Vs Yamahas on the 125 when he was running their team with the Japanese rider Ui. Yamaha wouldn't let him use his 50.2 Hp set-up on the bike - even though their cylinder only managed 44.

Here is the preceding story, Wob, as told to me by my recently-passed friend Cees van Dongen. Cees was working on his son's Yahama TZ125 which was no match for the Honda RS125, power-wise. Cees changed the stroke from 50.7 to 54.5 mm and put a Honda cylinder on the Yamaha engine. Problem solved.
Bartol, facing the same problem while he was working for the Kurz Yamaha team, noted the dutch solution. Bartol also had a good connection with the factory and offered to develop a better cylinder for the TZ125. The Bartol cylinder turned out to be an exact copy of a Honda cylinder. Yamaha was not pleased...

[Martin1981]

It pays to consider that they also have a carb smaller than a 125 gp bike and were built to be ridden my lesser mortals on surfaces that offer less grip.

no question, husa, you are right. the 500ccm engines are discriminated where ever possible!

[wobbly]

Well of course Harold failed to mention to me that his Yamaha replacement cylinder was an exact Honda copy, and I had no reason to suspect it was
due to his access to the Czech machine.
Yamaha certainly didnt fall into the flattery by copy trap with the Y2K cylinder for the 250,as obviously Harolds influence was somewhat tarnished for them at that stage.
But if I over reacted to your sarcasm Mr Fisher, then I apologise unreservedly.
Try as I might though, I have never been able to get any idea what was inside a KTM, has anyone out there ever got any good pics.

[husaberg]

Yep, the concept of the system used by Team Roberts was admirable, but as Dave points out the dynamic squish in reality varies with rpm and I will add, bmep.
Making the head retract as the cylinder pressure increases against a set pressure above the insert is clever, but as is the usual case, no free lunch.
Squish clearance needs to vary with rpm ( and by default bmep ), so having the chamber fixed in space to the cover, and the squishband area moving independently
seems a really great lateral thought process that ticks all the boxes.
Minimising the end gas volume at all rpm, via a variable squish height, but having a fixed chamber would then give high com and high squish at low rpm ( bmep )
then translating into slightly lower com, along with low squish volume at high rpm ( bmep ).
Dropping the com as the engine comes onto the pipe, maximises the energy distribution as we know is actually needed, but at all times the squish volume is minimised - brilliant.
Having the close tolerances needed along with O ring seals wont affect the temp gradient we want ie a cold squish area, and a warmer chamber, if the thought process of the really effective squish cooling
scenario I have alluded to is used as well.
Hey, hey, maybe a small step for Dave, a giant step for 2T technology, good shit.

The system was the sort I posted earlier lol I had forgotten about that.....

Raineys Yzr is left

[RAW]

Well of course Harold failed to mention to me that his Yamaha replacement cylinder was an exact Honda copy, and I had no reason to suspect it was
due to his access to the Czech machine.
Yamaha certainly didnt fall into the flattery by copy trap with the Y2K cylinder for the 250,as obviously Harolds influence was somewhat tarnished for them at that stage.
But if I over reacted to your sarcasm Mr Fisher, then I apologise unreservedly.
Try as I might though, I have never been able to get any idea what was inside a KTM, has anyone out there ever got any good pics.

Follow the link Wob
http://www.pit-lane.biz/t118-gp125-c...tiques-ktm-frr

Let us know your thoughts would you

[husaberg]

Follow the link Wob
http://www.pit-lane.biz/t118-gp125-c...tiques-ktm-frr

Let us know your thoughts would you

For those who are not signed up to the pitlane forum.
http://www.kiwibiker.co.nz/forums/al...p?albumid=4857

[wobbly]

Well I do like the chamfer/flat top on the piston edge ( ha hah,I showed Harold that idea when I designed the BSL500, and it ended up in the Swiss Auto,Pulse, as well ) but it also appears to have a radius,that now, we have
VHM using to make better power from KZ2 engines.
But if Harold copied a certain Honda cylinder, then it for sure wasn't a late model A Kit as they ALL had very a oval Exhaust exit shape at the cylinder face that transitioned
into a round within the flange to mate with the header - no step = alot more power.
Honda even issued a tech bulletin that said you would loose alot of power if you ground the cylinder round to match the very old design spigot on the 125 customer bikes.
The best power I have ever got from a T port 125 cylinder was with a 41 wide by 32 high oval, and that was tested back to back starting at 40 round and progressively inserted/
welded and ground smaller and smaller in the cylinder and spigot.
The final design with the 41 by 32 dimensions used as cast in the cylinder - and CNC machined in the spigot made another Hp over my welded test pieces.
But shit Harold, every dumb arse could see that shaping the tang below the boost port was worth some power, allowing better flow from the reed cavity into the case area.
But no - so just maybe Mr Fishers sarcasm, and Frits tacit agreement are worth noting.

[husaberg]

This is the bulliten Wob is referring to.
http://www.kiwibiker.co.nz/forums/at...6&d=1308200871

as above found this on Honda rs125
Space bar now working again

[peewee]

honda used a oval for a brief time on their mx 250 cylinder. most guys had no clue why it was there and figured it must of been a manufacturing error and grinded it round . yamaha still uses a oval style but i think they been using the same casting for nearly 10yrs or so.

[richban]

A question while there is talk on honda barrels.

In the pic below is a machined NSR150 sp barrel that is used to make up the NSR300 kit. I keep looking at the bridge between the ports and wondering it this should be cut lower. In the other pic is the view from inside the case's when I first started cleaning them up.

I suppose I am wondering if cutting this down (red line) and adding a radius instead of the sharp edge currently, would aid flow into both ports?

[ken seeber]

Transfer passage entry obstruction

This is a picture of a TM KZ10B cylinder with the piston at BDC. The transfer cut out in the piston protrudes around 4.5 mm below the level of the side entry into the cylinder. Surely this must create a significant flow disturbance and loss of flow. Particularly so, as I am lead to believe, that the maximum mass flow rate occurs around BDC. In addition, it has been pointed out on how important it is to have a radius at the edge of the cylinder at this level.


So, what are the options?

1. One could modify the piston a bit by blending, but there is a limit, particularly under the A ports, where only a mm or so of material removed will expose the aux exhausts to the crankcase at TDC. The picture shown this done a bit, but it is still far from perfect in terms of a relatively smooth junction


2. Lower the level of the side entry into the cylinder so that it matches the level of the cut-out in the piston, ie adding a nominal 4.5 mm of material, effectively adding cylinder bore length at these points. Could look something like the yellow plasticine addition in this pic. Unfortunately I don’t have a set of crankcases to see if this could possible affect other aspects of the transfer flow entry into this area.


3. Fit a longer rod in conjunction with a piston with a correspondingly lower compression height. Current engine has a 109.8 rod with a 29 compression height

4. Others ????


At the CIK/KZ level, it looks like 1. is the only option as the rules disallow any fundamental additions, visual and dimensional changes.

At the fresh or cleansheet design level though, I would think either option 2. or 3.

So, if you clever blokes had the choice, which one would you go for or is it just a non issue?

[richban]

Transfer passage entry obstruction

So, if you clever blokes had the choice, which one would you go for or is it just a non issue?

Now I am wondering how much air/fuel flow is actually happening at that moment of BDC?

[wobbly]

Killing two birds with one stoner is easy.
Forget the bridge Rich, its a fuckup, so get to work on the bore/duct interface.
Get a really big ballnose on there, copy Mr Thiels flow bench and championship winning methodology.
And as I have seen on a piston from a Euro Cup winning TecSav KZ10B the radius on the piston works as well - that guy doesn't grind Jack Shit for no reason.
The duct ballnose is worth at least an easy Hp in a 125, the piston mod is done by Savard for a reason, but I havnt quantified that yet, wont be long though - the Nationals are at Easter.
Makes it a bit harder when the KZ2 rules specifically forbid adding material, grinding the right bits is the black art.

BDC flow is where it all happens - the negative pressure ratio at the Ex port/cylinder junction is the deepest value and widest duration at this point, if the diffuser is designed correctly for peak depression
around BDC at peak Hp - as it should be.
Get the point - the port area is the greatest, the pressure ratio is the highest, what naturally follows is power making FLOW, and one of the biggest influences on FLOW into a duct is the entry geometry.

[richban]

Killing two birds with one stoner is easy.
Forget the bridge Rich, its a fuckup, so get to work on the bore/duct interface.
Get a really big ballnose on there, copy Mr Thiels flow bench and championship winning methodology.
And as I have seen on a piston from a Euro Cup winning TecSav KZ10B the radius on the piston works as well - that guy doesn't grind Jack Shit for no reason.
The duct ballnose is worth at least an easy Hp in a 125, the piston mod is done by Savard for a reason, but I havnt quantified that yet, wont be long though - the Nationals are at Easter.
Makes it a bit harder when the KZ2 rules specifically forbid adding material, grinding the right bits is the black art.

BDC flow is where it all happens - the negative pressure ratio at the Ex port/cylinder junction is the deepest value and widest duration at this point, if the diffuser is designed correctly for peak depression
around BDC at peak Hp - as it should be.
Get the point - the port area is the greatest, the pressure ratio is the highest, what naturally follows is power making FLOW, and one of the biggest influences on FLOW into a duct is the entry geometry.

Nice one. Thanks for that. When I pull the engine down and get stuck in I will post progress.