ESE's works engine tuner

[Fabio15]

I've seen a lot of mention of water temps being between 50-60 C. Where exactly is the measurement being taken? ( I assume this is after the radiator before entering the engine?). Also, where is the most ideal spot to place a temp sensor on 2 strokes?

[Frits Overmars]

I've seen a lot of mention of water temps being between 50-60 C. Where exactly is the measurement being taken? ( I assume this is after the radiator before entering the engine?). Also, where is the most ideal spot to place a temp sensor on 2 strokes?

The quoted temperature should be the highest temperature of the water in the cooling system, so it should be measured directly after it exits the cylinder head.
Often the sensor is mounted in the head which gives about the same reading.

[wobbly]

There is an answer on here somewhere about inlet piston porting for reeds.
As there is no intake flow until the timing edge approaches TPC, the piston skirt position should be as high as possible ( greatest port duration ) and
the holes should be as low as possible to promote the initial start of the intake process.
The 250G we were talking about had the whole port lifted, to straighten out the duct ( a good mod to earlyer TZs as well was to recut the flange face
thus steepening the carb angle - and thereby reducing the abrupt downward bend at the face ).
Then the piston skirt on the G was shortened to get the correct timing with the higher floor position.

Re water temp, its near on impossible to have too much radiator, or too much water flow.
The KZ2 125 kart engines are fastest down at 45* exiting the head, but its very hard to achieve this with ambient above 20*.
And PS - Flettner has nearly finished the bypass thermostats that several readers are waiting for.

[JanBros]

Frits a few years ago you mentioned playing with a Kawasaki KR1
Did you window the piston?
I was looking at a cylinder map picture the other day, i noticed it had a odd port arrangement?
With what is by the look of it a blind gully port?

That port map of yours doesn't look like the KR1S I worked on.

that might be correct Frits, as that is a KR1 cylinder map, allthough probably from a tuned cylinder. the give-away is the port underneath the C-port. probably the one that makes Husaberg wonder if you windowed the psiton.

here is an original KR1S map, and as you notice : from the S onwards, they ditched that port (S cylinders are supposed to be the cylinders from the racing kit of the KR1)



anyone have any idea about the purpose of the port under the C-port ?
as a sidenote : on mine the brigde between both (C and below) got missing (damn you Woessner ), so I removed it in the other cylinder also, never noticed any difference in performance.



edit : you don't happen to know CR ratio/squish ratio and height/... of that engine Frits ? How many rev's to get those 73HP ?
I use YZ125 '89 piston's in mine for the same reason, as they also have 1mm less compression height

[ief]

anyone have any idea about the purpose of the port under the C-port ?

wob > to promote the initial start of the intake process.

Perhaps?

Didn't work I guess

[wobbly]

It depends upon the C ports duct and the flow regime below the entry from the case.
In the early Rotax twins it was found that a big " 1/2 moon " cylinder cutaway under the C duct along with a hole in the piston gave a good power increase.
Rotax didnt believe our dyno numbers till we sent a heavily ground sample along with the new JL pipe I did for them to test.
Very quickly the factory engines added this idea, but put a tall 1/2 moon in the piston skirt instead of just a hole.
That cylinder 1/2 moon cutout idea even survived into the Aprilia.
Several other engines like RM125 have a long slot in the piston that allows thru piston flow easier access to the C duct entry.
I even tried cutting slots thru the all transfer inner walls and the piston on a Rotax,thinking that the boost port idea would work on all of them.
Sadly all it did was cost my boss a weeks wages ( at Zipkarts ) and a new cylinder, it was the trickiest thing I have ever seen that worked so badly.

[Hemi Makutu]

Arctic Cat features piston slots, see here: http://www.snowgoercanada.com/review...new-600-c-tec2

[Muciek]

Wobbly what was the difference in power using that JL pipe and rotax vsk that was made by factory, to go that year with engine?

[Hemi Makutu]

Want to have a go at a DIY? See here: http://www.engapplets.vt.edu/fluids/...le/cdinfo.html

[Hemi Makutu]

[JanBros]

It depends upon the C ports duct and the flow regime below the entry from the case.
In the early Rotax twins it was found that a big " 1/2 moon " cylinder cutaway under the C duct along with a hole in the piston gave a good power increase.

in the KR1, piston's didn't have any sort of hole or whatever that came in front of that port below C-port

[wobbly]

The so called JL "Silverstone " single rear cone pipes for the Superkart twins made an extra 4 +Hp at peak.
Best of all though was the overev power,they made some 14 Hp more at 13,000 with usable rev on to 13400.

This was the pipe that we spent months at JL in England, trying to get a blown version of to replicate the power made by the cones.
No matter how we went about it, including using a clam shell bridge to hold the dwell to size, we could never get closer than
4 Hp down nearly everywhere ie the blown pipe made the same peak power as the Rotax VSK design.
Hines used them to win his World title, and then sold those pipes exclusively for something like 1800GBP.

[peewee]

And PS - Flettner has nearly finished the bypass thermostats that several readers are waiting for.

just in time as ill be needing it

[Hemi Makutu]

I even tried cutting slots thru the all transfer inner walls and the piston on a Rotax,thinking that the boost port idea would work on all of them.
Sadly all it did was cost my boss a weeks wages ( at Zipkarts ) and a new cylinder, it was the trickiest thing I have ever seen that worked so badly.

Good on ya for trying it in metal though, W.

Not all R & D ideas are gonna pan out, but the worthwhile ones need hard work too.

Have you ever tried, or seen done - transfer ducts with full or partial - internal lateral flow fences
( for aero, not structural reasons), air-straightener honeycombs, venturi-type cross-sections/organic nozzle shapes
- or boundary layer control devices - such as dimples/vortex generators & /or director vanes/Coanda effect?

[adegnes]

Have you ever tried, or seen done - transfer ducts with full or partial - internal lateral flow fences
( for aero, not structural reasons), air-straightener honeycombs, venturi-type cross-sections/organic nozzle shapes
- or boundary layer control devices - such as dimples/vortex generators & /or director vanes/Coanda effect?

Laminar flow nozzles in the transfers and exhaust? Like used in water fountains. I was thinking about it a while back. Maybe not so good for a/f mixing, and hard to make enough room(and keep enough volume), especially in the transfers.