ESE's works engine tuner

[RAW]

[QUOTE=2T Institute;1130539530]Tried 90 and 180 deg phasing all you get is a numb bum. Back to twingle they go.

Hmmmm, so are you saying just re-phasing was a poor option because of the vibrations ?
Or are you saying that it was a poor option because you lost power ?
Or are you saying after addressing the balance issue it still did not produce a desirable effect ?

I'm still looking into this concept as its embedded in my deepest darkest thoughts, I desire to understand the required balance scenarios so I therefore may make a decision upon weather to invest the time, money & effort

[TZ350]

single port with the Exhaust opening 80 degrees ATDC 72% wide, Transfers 114 ATDC and Inlet opening 145 BTDC and closing 80 ATDC. Its a very easy bike to ride with a smooth flat torque curve. The carb is a taper bored 24mm OKO and is 30mm at the engine end and the rotary valve port window area has an effective diameter of 36mm.

I take the "Effective port diameter (mm)" to mean the chord width of the cylinder? Please confirm

If its the inlet rotary valve window area you mean. Then a port window that has an effective diameter of 36mm, means that the area of the oblong inlet window shape if squeezed round the diameter of the equivalent area would be 36mm.



The convention is chordal measurement.

For an exhaust port that is 72% wide, and 56mm bore the chord length across the port window is 0.75 * 56mm = 40.32mm

[chrisc]

If its the inlet rotary valve window area you mean. Then a port window that has an effective diameter of 36mm, means that the area of the oblong inlet window shape if squeezed round the diameter of the equivalent area would be 36mm.



The convention is chordal measurement.

For an exhaust port that is 72% wide, and 56mm bore the chord length across the port window is 0.75 * 56mm = 40.32mm

Sorry, by quoting that original post I meant the exhaust port as below:

[TZ350]

"Effective Port Diameter in mm) means, a round tube of 36.2mm ID would have the same area as that exhaust port window.

"Flow Width at Top" and "Flow Width at Bottom" give the Chordal width of the exhaust port.

Below is the Width % and on the left side is another important number, "Passage End Diameter" which is the diameter of the exhaust passage at the exhaust pipe flange. As a tuning trick, the pipe itself is sometimes made bigger than this.

[2T Institute]

[QUOTE=RAW;1130539803]

Tried 90 and 180 deg phasing all you get is a numb bum. Back to twingle they go.

Hmmmm, so are you saying just re-phasing was a poor option because of the vibrations ?
Or are you saying that it was a poor option because you lost power ?
Or are you saying after addressing the balance issue it still did not produce a desirable effect ?

I'm still looking into this concept as its embedded in my deepest darkest thoughts, I desire to understand the required balance scenarios so I therefore may make a decision upon weather to invest the time, money & effort

Made no more or less power and was basicaly impossible to stay on the bike even on the dyno. Would have had to spend a lot of time and effort just to get back to where it was with twingle firing.

[wobbly]

Been away at Tokoroa track for two weeks testing new junior class engines for Kartsport NZ, so havnt been on here for a while.
There are two questions that need answering , firstly, the reposting of my statement about free bowjobs to anyone that thinks they can get even close to 30Hp at 10500 from an Aircooled 125 bucket with 24mm carb.
This equates to a bmep at 12Bar , this is = to a 125 watercooled , full house Italian racing kart engine with 44Hp at 13,000 ( note the only slightly higher rpm, where all the wave action,both inlet and exhaust, is WAY stronger ).
So does anyone seriously believe that any bucket optimised at 10500 is going to get even close to a fully modern cylinder design with a 130 diameter pipe, that spins to 15000 rpm even with a 30mm carb and straight line ignition.
Thus the offer still stands.

The other is the possibility suggested about better cylinder cooling by reversing the exhaust port direction.
Unless I am missing something so obvious its invisible then the only thing possible to me would be less radiated heat from the header, a minimal advantage.
There is only one way to cool a racing cylinder, especially good if the case is cooled as well.
All of the coldest water should flow from the boost port,over the transfers toward the exhaust, with no exits above it into the head at all apart from an an air pocket bleed.
From there - the now warmer water should flow up into the head,from over the exhaust,and travel around the head insert to exit at the highest point to the rad.
This increases the volumetric efficiency by max cooling the inlet charge, as well as reducing the delta T across the inside and outside of the insert.
In a perfect world the head should have its own, much hotter circuit, such that the minimum of heat is extracted from the combustion space and sent - wasted - to the cooling stream.
Maybe Frits has a clevererererer idea.

[husaberg]

The other is the possibility suggested about better cylinder cooling by reversing the exhaust port direction.
Unless I am missing something so obvious its invisible then the only thing possible to me would be less radiated heat from the header, a minimal advantage.
There is only one way to cool a racing cylinder, especially good if the case is cooled as well.
All of the coldest water should flow from the boost port,over the transfers toward the exhaust, with no exits above it into the head at all apart from an an air pocket bleed.
From there - the now warmer water should flow up into the head,from over the exhaust,and travel around the head insert to exit at the highest point to the rad.
This increases the volumetric efficiency by max cooling the inlet charge, as well as reducing the delta T across the inside and outside of the insert.
In a perfect world the head should have its own, much hotter circuit, such that the minimum of heat is extracted from the combustion space and sent - wasted - to the cooling stream.
Maybe Frits has a clevererererer idea.

Mr Waynewright, the question for you and Mr Frits it was about air cooled cylinders with rear facing ex port.
I didn't word it that clear though, so my fault.
With air cooled (or water cooled for that mater)I can see how the straighter ex would be beneficial the weight distribution can be improved the sheilding of the exhaust pipe can be beneficial.

But i have often seen it written that the cooling of the cylinders is better and more uniform with the rear facing exhaust on a air cooled cylinder

Which is counter intuitive to me as the hotter part of the cylinder around the ex port would receive preheated air, so intuitively it seems that the cooling would be less uniform. With the cooler part of the cylinder getting better cooler airflow with this set up

But this isn't the case..... or is it?

[TZ350]

Thought I should get the tape measure out and compare the RS and NSR chassis.

Rob that 800mm, Is that with the NSR's forks still compressed vs the NF4 rs125's

With the forks compressed both the early RS 795mm and NSR 810mm from the front axial to the swing arm. With the forks at full extension the NSR was 860 and RS 810, there may be a hint right there about why the RS handles better tipping into and changing lines in a corner.

For good measure I made a quick and dirty measure up of a later model RS too.

Post 95 RS front axle to swingarm 730mm swing arm to rear axle 520mm total 1250mm
Pre 95 RS front axle to swingarm 810mm swing arm to rear axle 460mm total 1270mm
NSR front axle to swingarm 860mm swing arm to rear axle 525mm total 1385mm (All quick and dirty ball park figures.)

So it does look like up to 100mm could be cut out of the NSR frame if needs be.

[F5 Dave]

. . .
There is only one way to cool a racing cylinder, especially good if the case is cooled as well.
All of the coldest water should flow from the boost port,over the transfers toward the exhaust, with no exits above it into the head at all apart from an an air pocket bleed.
From there - the now warmer water should flow up into the head,from over the exhaust,and travel around the head insert to exit at the highest point to the rad.
. . ..

Thanks.

So it amazes me when one looks at an RZ350 or the aftermarket responce like my CPI 496 that the approach is more or less to treat it like a bucket of water, aim a hose at the back of the bucket & put an outlet at the other side.

[fatbastd]

Yep, my modest collection of old Yamaha road-racers is the same as the RZ - all this makes me wonder if there are practical gains to be made, while making the engine look like a plumber's nightmare.

[speedpro]

Excellent news about the preferred cooling circuit. I had thought about a separate circuit for the head and the cylinder. The only issue would be 2 of everything unless I do a tricky bypass thermostat system. 2 of everything would probably be easier using electric pumps like I have now. Of course it's only waterjacketed down to the top of the ports.

[wobbly]

The Yamaha TZ,LC,RZ,Banshee are all complete crap, as is the CPI clone setup.
All it needs is a fitting on the rear of the cylinder, below a plate that will be welded to the deck as this will accommodate the longer stroke as well as hold the water flow within the cylinder.
Then the coolant flows up over the exhaust, into the head, and out the stock entry at the back, the front thermo being blocked off.
No plumbing nigtmare at all, it even auto bleeds on startup.
This is what will be in the Frepin copy TZ400 to blitz the field at Philip Island next Jan.

No drama to arrange a hotter head circuit, just restrict the flow at the head exit, such that you can overcool the cylinder, but overheat the head, with parallel circuits entering and exiting.
Of course you will need two sensors, at the exits to home in on the correct flow regime - and thus temp exiting from each.

[Grumph]

Are you sure those reed boxes are big enough ? What'cha got in there ? 6 petal blocks maybe ?

Fred would be salivating....

[husaberg]

My money's on CR250 but what model are the rubbers? TRX?

[wobbly]

The reeds are 8 petal VF3 to suit a CR125 that have enough area to support over 50 Hp per cylinder.
Those rubbers are aftermarket units from England to suit CR250 as used in 250 National Karts over there, but I redrilled the stud pattern to the CR125 - same as RS125 etc.
These manifolds will have 40mm Lectron HVs fitted with solenoid powerjets - all perfectly legal in pre 82 Post Classic Junior here, but will have to run in class 5 - 500cc at PI.
A huge crossflow radiator is being made now in Taiwan, as well as a new pump impeller ( thanks Niel at Autoflight ) to hold the temp at 50C, unlike the idiot Yamaha system for the TZ350 that has the temp at around 70C, throwing away probably
8 Hp ( 10%) easily.