ESE's works engine tuner

[TZ350]

It might pay to spell out to the others that your new engine is a complete reversal of your previous incarnations of the ESE125

From memory the top end is completely Standard road NSR the pipe is a stock 93ish RS Honda.

Normally you would have had a cylinder with hundreds of hours work and development. yet you are close to matching the best output obtained with the previous incarnations. Is this correct?

Yes you are right, this current engine is pretty stock and with Wobs suggestions they may be the equal of my previous best efforts with the Beast.



Team ESE have two of these GP/NSR 110cc engines running and more in the process of being being built.

All have 48mm de-stroked cranks.

The Standard production engine has no real additional tuning and is as simple as possible. Basically it is just fitting a NSR250 cylinder to a GP100 bottom end.
1978 Suzuki GP100 engine.
Std Suzuki GP 24mm inlet tract and carb. Polished but not ported.
Inlet RV closing point increased from 65 to 80 atdc.
Yamaha 115mm c/c RD400 con rod.
Re plated std road going Honda NSR250 cylinder and head. 12:1 CR
Cylinder position adjusted so the Exhaust opens 80 ATDC.
Transfers then open 115 ATDC. (This is just the fortunate way it works out with the shorter stroke.)
Std Honda RS125 pipe. NF4
Modified 1975 TS125 5 speed gearbox.
Ignitec Digital Ignition.

A Team ESE basic GP/NSR110 in a NF4 RS125 chassis.

27 RWHP as measured on a DynoJet.

These so called standard production Team ESE engines are basically as standard as possible to keep things simple and this is the engine that Wobbly has been simulating and developing a pipe and nozzle for.

The Beast H2o 110cc engine has more bells and whistles:-

This engine was originally a 1978 air cooled Suzuki GP100, latter run as an air cooled 125 which made a reliable every day 28 RWHP. (31 on the dyno).
And now has:-
Kawasaki KE175 rotary valve with 32mm inlet tract.
Inlet opens 140 BTDC Closes 85 ATDC.
EFI fuel injection with 24mm throttle body.
48mm de stroked crank.
55% balance factor, was aiming for 50 but stuffed up.
Yamaha 115mm c/c RD400 con rod.
Massive crankcase volume.
Re plated road going Honda NSR250 cylinder. Exhaust port shape modification to make it look like a RS125.
Cylinder position adjusted so the Exhaust opens 80 ATDC.
Transfers then open 115 ATDC. (This is just the fortunate way it works out with the shorter stroke.)
VHM head with torroidal head insert. 14:1 CR
Std Honda RS125 pipe. NX4
Modified 1985 TS125 6 speed gearbox.
Eight plate clutch.
Dry sump gear box with oil mist spray.
Ignitec Digital Ignition.

the Beast. MC18 chassis.

31 RWHP as measured on a DynoJet. I felt it was a lot of work for not much gain over the std 27RWHP Team ESE engines.

I will keep the "Beast" as a EFI development donkey and all out tuning test bed, just for the fun of it.

I expect that the std setup with Wobs suggested improvements will make great advancements to the keeping it simple approach and will be the way to go for the team bikes.

So here is the pack file of Robs GP-NSR110 Mod by me, to generate the power curve as published previously.
Rob or anyone can ask for details on any input for explanation.
As I said the ports ( including the RV ) are all "stock " as set up originally.
First page to explain is the Engine.
I went for 12 Bar at 12500 as this is what the STA say the ports are capable of.
Thus we have a fairly low bmep, and on AvGas this will happily take the 16.5:1 com input, used on short kart tracks where acceleration between corners is far more important than overev power..
This is proven by the TuBMax output with the stinger size optimized and a "normal " ignition curve that starts at 25* under the pipe
then heads for 15* at peak power.
The Ex length input is 10mm, to look at the Mach in Pipe 2 = the stinger nozzle.

Robs GP-NSR110 Mod (1).zip

[TZ350]

Attachment 336559. .

By golly, that factory NF4 racing cylinder is not very symmetrical is it!

[Vannik]

By golly, that factory NF4 racing cylinder is not very symmetrical is it!

Can that be because the photo is not in line with the bore center line?

[TZ350]

Yes I guess so.

[Muhr]

Thats a good point Frits.
The min allowable volume is 13cc TOP.
But I know the magic number to shoot for is actually 13.6.
Below this you loose overev, above this the mid ( 10,000 ) is compromised.
So if I can do a toroid that measures 13cc on the bench, but actually has 0.6cc trapped as air above the threads we could have a winner.
Onto the CAD right now.
Cheers Big Ears.

just an explanation for others who may not be used to karting 11cc + 2cc thread insert

[Tim Ey]

Thats a good point Frits.
But I know the magic number to shoot for is actually 13.6.

10,19:1 Really?

[jbiplane]

Comparison of transfer port angles between a Honda RS125 NF4 and NSR250 MC21 cylinder.

I have 3d scanner and can make precise 3D mesh of cutted cylinder if someone sent me
This mesh can be used to make precise 3D CAD model if someone will spend time for.

[F5 Dave]

10,19:1 Really?

No 11.8, as said includes plug hole for easy measurement.

[lodgernz]

Can that be because the photo is not in line with the bore center line?

This is a better view, but the picture is much worse. The B ports are not too bad, a bit too much kick at the back perhaps, and the right-hand A port is spot on I think, but the left-hand A port front edge is kicking way too far back. Maybe two minutes with a port grinder could have made quite a difference to that engine.

[wobbly]

Yes the rules state 11cc actual combustion chamber volume, and a standard gauge is used that has 2cc added for the plug threads.
So 13 cc to the Top Of the Plug hole.
I use a digital burette and depending upon the tune and track,mostly shoot for 13.6 = 11.6 chamber vol.
This is due to the idiotic straight line PVL homologated ignition, so the engine has way too much advance past peak power,.
To to combat this the pipe is very short and you can run less static timing or less cc to get extra overev capability.
Minimum track rpm is about 10,000 with peak power at 13500,and it must rev to around 14800 to enable short gearing and to eliminate extra gear changes between corners.
We must use pump fuel here, in Europe its 100 octane unleaded race gas.

[TZ350]

This is a better view, the right-hand A port is spot on I think, but the left-hand A port front edge is kicking way too far back.

It might be that the cut is not perfectly square and we are seeing the remains of the curved part at the front of the A port. If the cut is not square horizontally one front edge of the A port will lean forward more than the other. I will have to check.

[jfn2]

Also I don't think your lines are showing the top of the ports. If you look closer I think you can see where the real tops are pointing. I think your lines are only showing the beginning of the flow side surface or the end of the flow surface so to speak.

[Pursang]

Perhaps the offsets can put a bit of 'swirl' in the rising column, rather than an inertia free "dead" lump of charge.

Swirl is a big deal in the poppet valve world.

Cheers, Daryl

[lodgernz]

Also I don't think your lines are showing the top of the ports. If you look closer I think you can see where the real tops are pointing. I think your lines are only showing the beginning of the flow side surface or the end of the flow surface so to speak.

OK, I've moved the line a little so you can see better. Think I got it right.

[TZ350]

Good spotting, symmetric port shape is important. You might be onto something.

I will have another look at the original piece, maybe face it back a bit in the lathe so the cut is definitely square.