ESE's works engine tuner

**Flettner** · 25th March 2013, 20:47

YZ 250 barrel

**TZ350** · 25th March 2013, 21:11

Originally Posted by wobbly

... oh shit, still detoes in the overev - WTF.

I know that's sarcastic bullshit from me that doesn't help at all, but surely the extra effort needs to be spent sorting the known basic issues, before flying off on another tangent ...

OK, the known basic issue is, that it detos in over rev. A few conventional things have been tried, compression, fuel curve, ignition curve, resistor plug, colder grade of plug, squish clearance, radiused exhaust port, lowered chamber pressure and a few tangents out side of the box, but all to no avail.

But don't sweat Wob, as you are free to suggest the pivotal solution if there is one and save me a lot of time.

Otherwise I will have to figure it out for myself, tangents and all. And at this point I suspect the restriction of a 24mm carb and subsequent lower crankcase filling is playing a part in my over rev deto problems.

If you join the dots of my posts you will be able to see where EFI combined with another tangental idea of mine and the better crankcase filling it will allow fits into things.

**TZ350** · 25th March 2013, 21:18

Originally Posted by Flettner

YZ 250 barrel

YZ250 barrel with EFI, this is something clever you are doing, please tell us more.

**speedpro** · 25th March 2013, 21:44

There's a Link G4 box in the background.

**Frits Overmars** · 25th March 2013, 23:33

Originally Posted by TZ350

YZ250 barrel with EFI, this is something clever you are doing, please tell us more.

Here's more:

**Frits Overmars** · 25th March 2013, 23:36

Originally Posted by wobbly

So now we will have a GP125 on EFI, with a trick variable computer controlled intake sytem as well, that, oh shit, still detoes in the overev - WTF. I know that's sarcastic bullshit from me that doesn't help at all, but surely the extra effort needs to be spent sorting the known basic issues, before flying off on another tangent - what happened to the super duper stinger bleed idea for example ,etc etc.

As I always say, Wob: everybody has to make their own mistakes. You can't say they're not trying! Let them fly off and who knows what they will come up with.
Personally, I must admit that in my younger years I learned as much from blundering as from analytical thinking.

**wobbly** · 26th March 2013, 06:34

In no way am I mocking TeeZees efforts, absolutely the opposite.
He is doing all this wrist slashing in public, and I admire the efforts, just trying to suggest concentrating the limited time, we all have, on a fix for the deto issue.
Variable inlet, EFI etc will for sure soak up a heap of R&D time.
I made the same ( negative, sorry ) comment about CVT, but shit, if you think im starting to hold hands with SS90 on here, then I will shut up.

**Flettner** · 26th March 2013, 06:57

EFI is not a waste of time and variable valve timing works for me. I'm starting to wonder after reading about so many EFI disasters on two strokes that I've just been lucky, muddling along with just enough knowledge to be dangerous. All I know is when EFI comes into play the design rules change. You can do a lot of things a carb will never do. I certainly won't be using a carb ever again. That Bighorn is running sweet now but it's not been easy.

**Flettner** · 26th March 2013, 07:25

Here are all the computers cuddled up under the Bighorn seat. Link Atom G4 and Ignitec ignition.

Flywheel and triggers, 12 minus 1 pins.

The G4 could do ignition but the Ignitec was already set up and is running the vairable rotary valve housing so I decided to leave well alone.

Servo for vairable housing ( R1 ). All very messy but it works, one day maybe I'll clean it all up or not.
After all it is an " Enduro bike " or at least that's what the 1973 advertising says.

**Flettner** · 26th March 2013, 07:36

Here is the other end of the R1 servo, this is where the cables attach to the vairable rotary valve housing. 55 degrees valve closing under 4000 rpm then starts moving and at 6500 it's fully open, at 9000 the rev limiter cuts in. Micro switch is to run a light on the handle bars to tell me when the housing is fully open, I didn't trust the mechanism at first.

**Flettner** · 26th March 2013, 07:40

Wobbly is right there is a lot more to be had from the "standard" twostroke yet but it is fun having a go at different ideas as well. Especially if you get results.

**Flettner** · 26th March 2013, 07:47

Here is a pattern being made up for the next EFI engine, 360cc reverse cylinder, water cooled, power valve, computer controlled rotary valve housing / throttle ( fly by wire or should that be crash by wire )
to fit in a modern YZF 250 frame. Will run on E90 like the Bighorn.