ESE's works engine tuner

[bad'rule]

Hello everyone,
I've joined KB for sometimes now and have read everything ESE thread.(I think I didn't missed any pages . I love to be accepted in KB ,TQ again)

Seems that, I couldn't find any talks here in KB ,regarding bore thickness meassures.

A question on Air-cooled 125cc engine.
What would be the good thickness cyl.bore for any given piston?

I know the facts that, the bigger the piston gets, the thinner standard cyl bore wall will be and at some stage of the size they loosing power easily when engine get hot .

Here in SEA country, the best sleeves we can only easily get is "disel sleeves" .

TIA.

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[husaberg]

Despite it raining 170 mm the day before and the Grey river being in full flood with all 4 roads leading to the coast being shut the day before with slip, flooding ,rock falls and snow.
If that wasn't enough in the first practice a diesel bucket oiling the whole track leading to the whole track having to foamed then be washed off by the fire brigade.

Greymouth put the 35th annual street race without it even raining.

Live feed
https://www.facebook.com/watch/live/...48924202180366

Those observant will notice there is one one left corner the rest being the laeast favoured right hand bends
This was due to the original officials wisely noticing it would be far too fast in the traditional rotation.

[wobbly]

bad'rule , my choice would be a 5mm aluminum sleeve pressed in, and welded in at the top and bottom.
Then get it plated after final porting - check with the plater what type of alloy is suitable.

On another topic re drag racing in Thailand and Malaysia , the EngMod users FB group are thinking of doing a pipe design shootout , as a means to help people to learn
how to use the code more effectively.
One suggestion was to use an engine that isnt " common " like a 125 or 250.

The KR150 seems to win everything in Thailand/Malaysia as it was built there ,so I thought that would be a good choice.
Do you have access to a stock one of these that could be measured and entered into a sim.
The other one would be a TZM150 , but I believe these were made in only in Vietnam as I have done several of those , but all bored and stroked.

[bad'rule]

Thank you Wobbly for your answers ,even tho it was for water cooled engine. Still good to have that information in hand.

Thailand is the best in our region here for racing thingy even in the past they beat us on race machinery .Im not so into drags anymore, mates still race them. Things get very costly for us over here nowdays actually.
It Would be great to know and watch your works race Wobbly.

I was hoping an answers for Air Cooled Engine if any one know,please
,TIA

-Badrule-

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[wobbly]

The 5mm sleeve would work just as well in an aircooled, even better in fact as the thermal transfer thru the plating and alloy would
be far superior to a cast sleeve.

[bad'rule]

Okay Wobbly, i will just follow your suggestions then ,ThankYou again.



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[Haufen]

I would love to see a typical power curve of those bikes. Has anyone seen something by chance?

And does anyone happen have to a KR150 EngMod Pack file they would share?

The KR150 seems to win everything in Thailand/Malaysia as it was built there ,so I thought that would be a good choice.
Do you have access to a stock one of these that could be measured and entered into a sim.
The other one would be a TZM150 , but I believe these were made in only in Vietnam as I have done several of those , but all bored and stroked.

I was wondering the same in April. No luck so far, unfortunately.

I think there was a Mota Shootout on another board about 20? years ago. I don't remember much about it, except that it was fun and didn't turn into a pissing contest.

[jamathi]

The 5mm sleeve would work just as well in an aircooled, even better in fact as the thermal transfer thru the plating and alloy would
be far superior to a cast sleeve.

In 1974 I made a conical sleeve, Morse cone. It was very easy to fit and remove, worked great!!!
No welding needed, just a light press fit. I pressed it in about 2mm.
I got the sleeve material from MAHLE, so I was sure it could be plated... MAHLE 138
Once I had to make a cylinder in a hurry, no time to get it plated.
So I bought a plated Kreidler cylinder, and made a conical sleeve out of it...
It gave good power, and won a lot of races!!
First I made it without aux ports: insufficient power....
As it was easily removable I took it out and added aux ports: +2.5 HP...
Less than 1 hours work, my client was very happy, and won a Dutch NMB championship with it.

[Frits Overmars]

I am very happy too as that cylinder now has pride of place in my cabinet, together with a cylinder of the world champion Suzuki RK67 50cc twin and a cylinder of the Garelli 125cc twin, good for six world titles, all given to me by Jan.

[Mollihead]

Hello everyone,

I‘m a longtime reader of this thread and appreciate a lot the experience which all of you share to keep 2 strokes alive!
I‘m living in Germany and during corona time I started tuning my 1976 Zündapp 50cc moped. Ended up with 64cc aircooled and reliable 18,5HP.
Now the next step is 98cc (50mm x 50mm Bore x stroke).
Target in the range of 25HP.
There are not so many cylinders out there - so I have to use one with a T shaped port.
Many times I could find pictures of ideal shape of a single port but nothing about ideal T-port dimensions.
Can somebody explain the ideal shape? Is it a horizontal line? Or should it be lower towards the sides to prevent damage of the ring?

[wobbly]

All the GP Honda A kit cylinders had a dead flat timing roof , but years ago I did a test by reversing the normal shape and had the outer edges opening first.
This gave a good power increase , with the same timing as previously.
The reasoning was that the initial exiting wave front , that would normally be smeared out in time and amplitude , due to the considerable path length differences
would be helped by the geometry change - it worked.
Ring damage isnt an issue , as the center bridge gives support no matter what the shape.
The bridge relief is very much an issue though.

[Mollihead]

Thanks Wobbly!

I have seen your post about outer edges opening first.
For now I will try the horizontal line.

Another topic is the maximum width of inlet port with a bridge in the Center.
My last try seemed to be too wide and in the end I had a crack in the piston skirt.
Is there a rule of thumb like xy % of bore width ?

[TZ350]

There are not so many cylinders out there - so I have to use one with a T shaped port.
Many times I could find pictures of ideal shape of a single port but nothing about ideal T-port dimensions.
Can somebody explain the ideal shape? Is it a horizontal line? Or should it be lower towards the sides to prevent damage of the ring?

Team ESE has run exhaust T ports with a center divider and tried all sorts of configurations. Currently ours is higher on the outside and lower at the bridge.

The theory is, when you get it right. With a head start, about 2deg . The gases from the outer edges arrive at the exhaust duct nozzle at the same time as the gases from the lower bridge area as they have a shorter path.

It is hard to be definitive, but it does seem better. Or at least runs better. and 2deg might not be the ideal, more experimenting is required.

NSR250 MC21 Cylinder.

May or may not be ideal but it has done a few furious races and is still going strong. So mechanically an OK idea at least.

[Mollihead]

Hi TZ,

That’s very interesting.
The theory is, when you get it right. With a head start, about 2deg . The gases from the outer edges arrive at the exhaust duct nozzle at the same time as the gases from the lower bridge area as they have a shorter path.

This is a little bit confusing to me since the exact same theory didn’t worked with triple exhaust port and ended with having auxiliary ports lower than main port !?

[Wos]

In 1974 I made a conical sleeve, Morse cone. It was very easy to fit and remove, worked great!!!
No welding needed, just a light press fit. I pressed it in about 2mm.
I got the sleeve material from MAHLE, so I was sure it could be plated... MAHLE 138
Once I had to make a cylinder in a hurry, no time to get it plated.
So I bought a plated Kreidler cylinder, and made a conical sleeve out of it...
It gave good power, and won a lot of races!!
First I made it without aux ports: insufficient power....
As it was easily removable I took it out and added aux ports: +2.5 HP...
Less than 1 hours work, my client was very happy, and won a Dutch NMB championship with it.

Mahle 138 should be AlSi18CuMgNi 😉