ESE's works engine tuner

[TZ350]

I think it was Sonic-V who told me about a twin carb kart engine his dad successfully ran.

It had one carb opening before the other, that way he could vary the inlet tract cross section area for better carburetion, also it could be arranged to vary the inlets closing point too, also one inlet tract could be longer than the other.

The problem for me using this idea is the 24mm carb or equivalent area class rule which maybe makes two small carbs too flow restrictive and impractical, interesting though, and first time I have seen a twin carb cover, it looks a very good idea.

[sonic_v]

Two of these carbs (bored out to 16.97mm) will give the same venturi area as one single 24mm carb. However they have a 20.5mm bore thus should flow considerably better than a straight through 24mm carb.


http://www.tillotson-racing.com/carb...rburettor.html

[Henk]

1998 TTR600 Belgarda I had a while back (the one with the Ohlins shock) had a strange twin carb set up. The primary was a straight pull and the secondary a CV. I have no idea why they did this but it seemed to work OK.
It would probably only add to the complexity and setting up problems but if you were to go for two carbs there is no reason they would heve to be the same.

[husaberg]

Attachment 249188

1998 TTR600 Belgarda I had a while back (the one with the Ohlins shock) had a strange twin carb set up. The primary was a straight pull and the secondary a CV. I have no idea why they did this but it seemed to work OK.
It would probably only add to the complexity and setting up problems but if you were to go for two carbs there is no reason they would heve to be the same.

The first bike I can remember with the 2 stage carb set up was the Villiers Starmaker stuff I poster further back.Yamahas had a big play with them in the mid 80's to 90's TT and XT etc. Honda with the XR series in the Mid 80's one thing they all have in common is they all went back to single carb set ups.The (TTR way be an exception to this rule)
2 carbs in my opinion = twice the drama.
I have enough trouble tuning one as it is.

Picture of updraft carbs on MZ and Suzuki 60's bikes a pic of the DKW 250 supercharged Twingle and lastly a Binks mousetrap variable venturi carb I had heard of them but I had never seen a picture of one.

[TZ350]

Two of these carbs (bored out to 16.97mm) will give the same venturi area as one single 24mm carb. However they have a 20.5mm bore thus should flow considerably better than a straight through 24mm carb.http://www.tillotson-racing.com/carb...rburettor.html

Thanks for that, I will have a look at them, and I guess that there is no reason for them to both be the same size, the low speed one could be smaller.

2 carbs in my opinion = twice the drama. I have enough trouble tuning one as it is.

Me Too, but I am starting to get the feel for tuning my HL-360 pumper,so tuning two pumpers at a time may be the next challenge.



I very much like the look of the split inlet, I think if the inlet is say 50deg wide and closes 85deg ATDC then by closing the front carb at lower rpm you can advance the closing point to say 60 deg ATDC and as a side benefit this will also automatically increases the crankcase volume by the volume of the inlet tract to the back of the throttle plate of the closed front carb.

This extra volume exits during the suction and induction ramming phase but the extra volume is lost when the rotary valve closes the port off during the transfer phase so it doesn't help with bulk transfer.

One carb with two complete inlet tracts where one tract can be closed off was one of the ideas that Thomas and Bucket had come up with for varying the crankcase volume. With only one inlet tract open to the carb and the other left open to the crankcase this should give an apparently larger crankcase volume when filling (for less spitback) at lower rpm and then both inlets open to the carb and tighter crankcase volume for higher rpm.



Ok so its a reed Kart engine. But an idea suggested by Wobbly is to have the carb(s) angled up on my GP engine, looks like a good idea.

[TZ350]

I was looking for something to independently drive a turbocharger for an F4 engine and started looking at pulse jets. I am not sure how good they would be for that but they sure look fun. http://www.pulse-jets.com/pulse3.htm

[Ocean1]

I was looking for something to interdependently drive a turbocharger for an F4 engine and started looking at pulse jets. I am not sure how good they would be for that but they sure look fun. http://www.pulse-jets.com/pulse3.htm

Couple of points.

They're hideously fuel ineficient.

They can be amazingly light for the thrust they deliver.

Oh, and if you show too much interest in the subject you'll be added to a long list of potential threats to national security by certain elements of the worlds security services. No joke.

[husaberg]

Couple of points.

They're hideously fuel ineficient.

They can be amazingly light for the thrust they deliver.

Oh, and if you show too much interest in the subject you'll be added to a long list of potential threats to national security by certain elements of the worlds security services. No joke.

Walter Kaaden was kind out involved with them in a way. After all they are just another use for an Expansion chamber. Edit they have Reed valves too.
http://forums.cycleworld.com/showthread.php?t=249421

Junkyard wars did one with ss exhaust bits and a Propane tank and a spark plug. It was loud and sounded like a V1. Funny that.

Interestingly enough the net is full of videos of people making Turbo's into turbojet engines. Reverse of reverse engineering perhaps.
http://www.youtube.com/watch?v=BZoymnZRBVc
http://www.youtube.com/watch?v=gNnSq...feature=relmfu
http://www.youtube.com/watch?v=FIuHb...eature=related



Check out the carb on this 1958 MZ but Honda ran Flat slides in the 60's too I think on the 250/4 or 6 Edit at least as early as 1959

http://www.motohistory.net/news2008/news-jan08.html
http://www.cyclechaos.com/wiki/Honda_RC166
http://www.cmsnl.com/classic-honda-g...l_media1Page=1

[Ocean1]

they have Reed valves too.

They don't have to. Everything you never wanted to know about pulse jets: http://aardvark.co.nz/pjet/

[husaberg]

I was looking for something to independently drive a turbocharger for an F4 engine and started looking at pulse jets. I am not sure how good they would be for that but they sure look fun. http://www.pulse-jets.com/pulse3.htm

It would never pass a noise test anyway TZ
I had posted this somewhere else But thought it should probably belong here.

I could remember seeing these donkeys years ago. See attachments below
Delay boxs, old tech piggy back to CDI units.
This company is still in business too.
It was meant at the time to be a common Mod on proddy bikes.

I have an article bellow that explains how they work and how to basically map an old style cdi unit. Attachments below
The Ignitech is the obvious top self bees knees set up, but it may be possible to provide a lower tech solution.
I seem to remember JayCar having a adjustable delay circuit.

http://http://www.jaycar.com.au/images_uploaded/LM555.PDF
http://http://www.ehow.com/how_4827785_build-time-delay-circuit.html

Here is an exert off the net from a guy that builds Ignitions He mentions Buckets on his site to in regards to a Ignition he makes for the Honda 4 stroke single.

Engine revs Timing advance
1000rpm 26.0 degree
2000rpm 27.0 degree
3000rpm 25.5 degree
4000rpm 23.5 degree
5000rpm 22.0 degree
6000rpm 21.5 degree
7000rpm 20.0 degree
8000rpm 18.0 degree
9000rpm 15.5 degree
10000rpm 13.5 degree
11000rpm 11.5 degree
12000rpm 9.5 degree
"But the advance and retard goes the wrong way!?" you say. (Well one or two of you have.) I queried this with Rex, as I also thought that engines were supposed to advance the timing as the revs progressed, not retard it.
Rex replied:
"Since the early '80s much two stroke research has focused on electronics. We have seen the introduction of power valves to control the point of opening of the exhaust port. Initially this was performed by mechanical means, then designers found that to enhance the power band a control by an electric motor, itself controlled by a computer gave far more scope for power increases, especially in the midrange, just where you need to accelerate from a corner. Part of the search for midrange power focused on the ignition timing. It was found that beneath the power band created by the tuned exhaust system, more ignition advance could be given than could be tolerated at the peak horsepower rpm. A study of a MK 3 TZ350 curve will illustrate this. (Diagram to follow)
Then it was found that a further retard of the spark timing caused the exhaust pipe to run hotter, which affected the speed of the sound wave in the pipe. The net result was the pipe stayed in tune longer after peak horsepower by keeping the torque up.
We have found that retarding a fixed timing setup, by say 2-3 degrees, will give more power after peak horsepower, but there will be a drop in power on the climb up to peak horsepower. There a tailored ignition curve can give gains over the fixed timings we were used to in the early days of racing two-strokes. With limitations in engines by piston crown temperatures it pays to approach the design of the curve with care and dyno testing sometimes has to be verified with actual track testing. The same applies to other settings on the engine and the whole picture is usually a blend of art, science and experience, with failures on the way, such as holes in pistons! Hopefully this will give a brief explanation of why the general two-stroke ignition curve differs from a four-stroke curve which normally has a rise in ignition advance with a rise in rpm. Further study is recommended by reading books on the subject such as "Basic Design of Two-Strokes" by Doctor Gordon Blair and " Two-Strokes Performance Tuning" by Alexander Graham Bell."
So there you are. Years of research and hard work summed up in on or two paragraphs, supplied totally free to all of you people out there....thanks Rex.

There is also a Kiwi that makes ignitions too. Here http://www.pazon.com/ignition/ignition-products/

[wobbly]

Two strokes like an ignition curve approximating to an inverse of the power curve.
With around 28* in the mid range, that ramps up from an easy kick starting 10* at idle to about 1500,2000 rpm.
Then as the bmep rises and the pipe gets in sync with the port we pull out timing in relation to the dynamic compression created by the wave action, to prevent detonation in the end gasses.
Most engines like around 15* of timing at peak torque, we then drop this away after peak to increase the heat released into the pipe.
We have a finite amount of heat energy to use to heat trapped combustion gas,heat the water, heat the piston/head, or release it into the pipe.
The ignition delay sets the amount dispersed into each element and how much this creates power at the crank is set by the interaction of each component part.

[Buckets4Me]

just to show TZ what has hapened to his old number #9
before
halfway threw

no after as it's having a bowel implant

[TZ350]

just to show TZ what has hapened to his old number #9

Looks better in Red and I think it will go well in F5 with the Honda100, I hope young Rob will have lots of fun with it.

[chrisc]

Anyone ever played with T125 lay down twins? Are they worthwhile/alright engines or dogs? They have twin carbs, anyone know if they're too big for buckets?

Any comments on the bikes in general is welcomed too.

I found a picture of an old racer:

[husaberg]

Anyone ever played with T125 lay down twins? Are they worthwhile/alright engines or dogs? They have twin carbs, anyone know if they're too big for buckets?

Any comments on the bikes in general is welcomed too.

I found a picture of an old racer:

Ask Pete Sales but they are 5 speed piston port iron cylinder points ignition and quite collectable.
There has been two on Trademe lately that have been raced.
I have a weakness for them and Wolfs but It would be a big ask.
They could be made competitive on a open track with MB5 cylinders but would need two of everything.
The carbs are odd and possibly oversize for the rules which would need to be equivalent to a single 24mm carb Which would be around 17mm I guess.
No doubt it could be done and it would be a hoot. They handle good even in stock trim and they would be beautiful done up as a replica of the 60's GP race bikes. But given how collectable they are now.
Should they be done?