ESE's works engine tuner

**TZ350** · 6th November 2009, 19:55

Originally Posted by SS90

Just as a matter of interest Teezee, what cylinder head design are you using on the new cylinder?

Hi SS90 at first I am planing on using my favorite copper head,, mainly because I have it and to try something else means I have to source suitable 56mm, domed, 16mm pin, thin ring, race quality pistons, may be, something like late 80’s YZ125 Wiseco pistons.

I have a welded up head that I could machine out into a squish configuration and I also have a spare standard open chamber head. If the engine does peak at about 9,500rpm or less, then I think the open head would be worth a try at the lower rpm.

I remember you talking about the benefits of an open chamber head like a std GP has and if the engine works out as planed definitely the next step will be to try an open chamber head on the new configuration engine.

.

**TZ350** · 6th November 2009, 20:43

.

The current challenge is to get more air into the engine through the 24mm carburetor. A carburetor is basically a simple venture. Thomas and I have been looking into how the flow through a venture can be improved.

Picture-01 of a traditional venture (A) and a low loss flow tube (B) where the maximum pressure recovery (flow) occurs when D2/D1 is between 0.6 to 0.7.

Picture-02 a short flow tube (C) with a length 4.5 times its diameter flows more than a carburetor of the same size. Now it would be very handy if the fuel could be atomized into the air before its sucked through the flow tube.

This could be achieved by sticking the flow tube into the rear of a bigger carburetor (D) and then you would have a high flow 24mm carburetor.

Picture-03 It turns out that the optimum ratio is a 24mm flow tube pushed into a 38mm carb.

Picture-04 is a 24mm flow tube/nozzle, press that baby into a 38mm carb body and you could have super efficient 24mm carburetor.

Well that’s the theory anyway and something we plan on trying out sometime.

.

**TZ350** · 6th November 2009, 21:19

.

Anyone have a 38mm power-jet Keihen carb of an RS125 for sale or any jets and needles?

.

**xwhatsit** · 7th November 2009, 11:35

Originally Posted by TZ350

Picture-02 a short flow tube (C) with a length 4.5 times its diameter flows more than a carburetor of the same size. Now it would be very handy if the fuel could be atomized into the air before its sucked through the flow tube.

That's the trouble, isn't it -- I thought the point of a venturi in a carb was to keep flow rate up over the top of the jet. If you put the flow tube in the rear of the carb, flow rate might be high through the flow tube but afterwards it'll slow down once more with the bigger volume, won't it, and prevent good atomisation of the fuel? Or did you mean stick the flow tube after the carb?

Still think somebody needs to try fuel injection in a bucket. Take a flow tube, a simple rotating choke throttle, and an old injector.

**bucketracer** · 7th November 2009, 15:58

.

A bit of info on flow tubes and what they look like in theory.

http://www.cranemfginc.com/PDF/Ventu...0CATALOG-2.pdf

And a picture of what they look like in practice. TeeZee you will need a trailer, they are a bit heavy for a bucket racer.

.

**bucketracer** · 7th November 2009, 16:27

.

Randy Norian's thoughts on tuned inlet design for Motorcycles and still air box design.
http://www.saltmine.org.uk/randy/airboxdesign.html

Randys Home page
http://homepage.mac.com/rg500delta/RandysAddiction/

.

**Buckets4Me** · 8th November 2009, 08:56

Originally Posted by F5 Dave

Well clearly that was a PT by Mike, Kart engines & parts aren't legal (aside from where free rule like pistons, ignitions).

Also no gearbox losses.

so there is the problem you cant buy the parts you need to make them
and knowing TZ350 that means money

and time

**TZ350** · 8th November 2009, 14:47

.

20,000rpm some how I don't think I will be going there.

27-30 hp at the crank might be possible as people (with dyno graphs) have claimed 20-22-25rwhp for their F4 100's

But 27-30hp with a 24mm carb, don't think so.

.

**TZ350** · 8th November 2009, 17:35

Details and pictures of someone fitting TZ barrels to a RG500 the big brother of the GP125.

http://homepage.mac.com/rg500delta/D...verallanalysis

The spacer plate idea is what we are trying with the RGV cylinder conversion on one of our GP's

.

**sonic_v** · 9th November 2009, 01:06

Originally Posted by TZ350

.

20,000rpm some how I don't think I will be going there.

27-30 hp at the crank might be possible as people (with dyno graphs) have claimed 20-22-25rwhp for their F4 100's

But 27-30hp with a 24mm carb, don't think so.

.

They certainly give a minimum of 28hp but there are very good reasons for this, most of which cannot be applied to a motorcycle. These engines are the old world championship class "ICA" until about two years ago.

features

1/ Intake uses a diffuser after the carb choke.
2/ High trapped compression ratio - Over 10 to 1.
3/ High crankcase compression ratio.
4/ Static Ignition but with a lot of advance.

The only reason that karts can get away with this setup is the fact that they spend such a short period of time in the power band. Note that even though the engines rev to 20,000 rpm peak power is in the 13,000 rpm range.

**TZ350** · 9th November 2009, 06:33

Originally Posted by sonic_v

They certainly give a minimum of 28hp but there are very good reasons for this,

1/ Intake uses a diffuser after the carb choke.

.

Hi Sonic, thanks for your input, carb's and diffusers. Can you tell us more? A picture or discription would be very helpfull. I am very interested in how this is done.

Here is a picture of the carb parts that Thomas has been playing with to try and improve the mass flow through them.

.

**k14** · 9th November 2009, 07:13

Originally Posted by TZ350

.

Anyone have a 38mm power-jet Keihen carb of an RS125 for sale or any jets and needles?

.

You don't need a power jet. What you want is a carb off a 95-96 RS125. Didn't have power jet, those were the last years that the bikes were setup to run leaded fuel. If you get the powerjet carb you'd be looking at $1500+ because you then need to run tps, the full loom and cdi. You can't just block the powerjet off because then it cocks up the whole fueling of the thing!

**SS90** · 9th November 2009, 12:45

Originally Posted by sonic_v

They certainly give a minimum of 28hp but there are very good reasons for this, most of which cannot be applied to a motorcycle. These engines are the old world championship class "ICA" until about two years ago.

features

1/ Intake uses a diffuser after the carb choke.
2/ High trapped compression ratio - Over 10 to 1.
3/ High crankcase compression ratio.
4/ Static Ignition but with a lot of advance.

The only reason that karts can get away with this setup is the fact that they spend such a short period of time in the power band. Note that even though the engines rev to 20,000 rpm peak power is in the 13,000 rpm range.

I'm not too sure I would subscribe to the idea that a Kartsport engine spends little time in the peak power range there Sonic.

I am of the opinion that it is quite the opposite actaully!

One of the many things a Kart does well is hold it's corner speed!

You point out that they run "a high Crankcase compression ratio", what do you consider "high"?

Because, what I consider "high" is pretty much anything over 1.45:1 (and for most applications, I would go further to say that over 1.3:1 to be "detrimental" to over all power spread.

Of course expansion chamber design has as much to do with that as anything else.

I am pretty sure that most "fixed gear" Kartsport engines run around 1.25:1, for the very reason that a longer spread of peak power is desireable.

I realise that some Kart engines are very particular about set up (I have minimal experience with these), but i have never heard of a moder 2 stroke engine that revs 7000 RPM over it"s peak power, and has a static curve.

Why would a 2 stroke engine that revs to 20,000 RPM have high advance, when the peak pressure point at 20,000 RPM come a lot sooner that at 14,000 RPM?

do you have some dyno graphs for these engines?

**TZ350** · 10th November 2009, 15:17

.

Will this 50 make it to Taupo? and is the front brake big enough?

To be able to use a better piston than the original I have to use one that is 2mm oversize. And to stay within the 50cc limit I have had to de-stroke the crank 3.5mm, thats shift the pin into the center by 1.75mm. I found I could do this by using an Apprilia rod kit but the bigend pin cuts into the main shafts which could be a problem.

.