New 2 stroke piston design. ESR CEO

Is it the piston, or the big bore? I like to build big bore bikes, as my buddies know lol. The power feels so much better the stock. Would like to see test vs stock bore.

Been around for years, also makes a 345 kit...

racingfortheson wrote:

Is it the piston, or the big bore? I like to build big bore bikes, as my buddies know lol. The power feels so much better the stock. Would like to see test vs stock bore.

It is the big bore kit that increases the power, not the piston design so much.

ESR has been around forever from the micro sprint days in the 90s. We were taking CR250s and bore and stroking them on methanol . Clutch gone, power valves gone, huge pipes and replaceable domes and a host of other shit. Was getting close to 90 HP out of a 270cc honda engine. They still race them back east.
It's all in the squish... ( post piston to dome clearance)

Monk wrote:

Been around for years, also makes a 345 kit...

It is the piston design that is completely new.

"Powerband feels three times wider"... if it sounds too good to be true....

Not saying it can't happen, but that's a pretty big claim.

YZ ESR 325 is awesome, similar to a 450 but not as broad of a power band!




Might be worthwhile to upgrade.

ESR 325 Engine

Setup:

Yamaha YZ Eddie Sanders Racing (ESR) 325 Build (2007)

Purpose - Motocross and Off Road rider – Intermediate Level

-Eddie Sanders Racing (ESR 325 - S7 (Woods Porting), Race Gas Dome (use 50 Pump/50 Race Fuel) ($900)

-No - Fly Wheel Weight - None

-Race Tech Suspension ($600)

-Moto Tassinari Reed Valve ($250)

-Rekluse Clutch - Core EXP 2.0 ($900)

-ESR Expansion Chamber ($200)

-FMF Q Silencer ($100)

-Vortex Ignition ($250)

-Dunlop MX 3S 90/21 Front, MX 33 Rear - 120/19

-TU-BLISS -Traction Control System ($200 Total)

-Geared 14 – 48

-Jetting 165 Main, 42 Pilot (Works in 500” to 4,000’ Altitude)

$3,500 Used 2007 YZ 250, plus parts $3,450 = $6,950

Interesting: Concave Piston

I wonder what the head shape is - Flat, or curved to mirror the piston profile, or any number of other designs?

I signed up to his newsletter, as I'm interested in the PV Cylinder he's got coming for the CR500. I'm not sure of his design - perhaps (well, likely) it's the CV / Diaphragm type I so liked on my Maicos. Or, better still, just vacuum without a diaphragm. Simple, though, of course, far more complicated than just a plain port . The basic simplicity of my 500 is it's great appeal to me, but a PV like the Maicos (and many others that used non 'mechanically linked' set ups) , just scoots into the simple / basic side of the ledger for me.

goinrcn44h wrote:

ESR has been around forever from the micro sprint days in the 90s. We were taking CR250s and bore and stroking them on methanol . Clutch gone, power valves gone, huge pipes and replaceable domes and a host of other shit. Was getting close to 90 HP out of a 270cc honda engine. They still race them back east.
It's all in the squish... ( post piston to dome clearance)

This. My neighbor, across the street, has a wall full of melted pistons from his old 270. Methanol sure makes power...but those dirt track boys sure do scatter a bunch of engines.

SDTony YZ ESR 325 wrote:

ESR 325 Engine

Tony - I've been in contact with Eddie the last couple of yrs. as I've been contemplating picking up a 325 kit for a 02/07 CR250. The production date has been pushed back a few times in that span, but it shows mid Nov. 2018 on the link above. I've been unable to get in contact with him since this thread got started probably due to the holidays.

With his kits, Do you know if a 250 pipe can be run or do you need the ESR pipe I see on your list of mods ? Can the standard 250 38mm carb be run or does it need to be tapered for a bigger bore size to a 39mm ?
I would think the mods above would help to get optimum performance out of his 325 kits..

etccb wrote:

It is the piston design that is completely new.

And how is it supposed to improve the way the engine works?

SDTony YZ ESR 325 wrote:

ESR 325 Engine

H4L wrote:

Tony - I've been in contact with Eddie the last couple of yrs. as I've been contemplating picking up a 325 kit for a 02/07 CR250. The production date has been pushed back a few times in that span, but it shows mid Nov. 2018 on the link above. I've been unable to get in contact with him since this thread got started probably due to the holidays.

With his kits, Do you know if a 250 pipe can be run or do you need the ESR pipe I see on your list of mods ? Can the standard 250 38mm carb be run or does it need to be tapered for a bigger bore size to a 39mm ?
I would think the mods above would help to get optimum performance out of his 325 kits..

Yes the stock or FMF pipe (I had the Works and Gnarly) works great with the ESR 325.

The ESR pipe is about 40mm longer and maybe slightly larger diameter, it works better for a 250 or 325 than the FMF, maybe by 15-25% better, not a huge difference but noticeable.

Stay with a 38mm Carb, changing this will complicate things. Stock jetting on a YZ 250 was 170 main, 48/50 pilot, but the ESR 325 sucks harder (33% larger piston) and therefore you go down in Jet sizes. I tired a lot of sizes, but in the end 168 main and 42 pilot.

Monk wrote:

Been around for years, also makes a 345 kit...

etccb wrote:

It is the piston design that is completely new.

GODZILLA wrote:

And how is it supposed to improve the way the engine works?

Godzilla, mine is the current technology, which is outstanding. I am waiting to see the photo on ESR as well, we will see, ESR has been around for over 25 years.

Obviously the top of the piston is concave...
Don't have a clue what it does, lol...
Neither with the hollow side.
Any good 2 stroke tech around?

GODZILLA wrote:

Obviously the top of the piston is concave...
Don't have a clue what it does, lol...
Neither with the hollow side.
Any good 2 stroke tech around?

1988-1989 KX125 OEM piston 13001-1266 used a concave crown, there have been others that use this design

It's pretty simple. The head is either flat or has a reduced chamber volume. The piston needs a dish to get the desired compression ratio. It's not rocket science.

BobPA wrote:

Loop charge, cross flows, inverted domes, all different names for the same basic idea...

This the current Piston and Head.

Sorry here we go again.