ESE's works engine tuner

[ken seeber]

Isn’t life so interesting. A couple of centuries ago when I was a kid, having twin carbies on your old pommy Morris or Prefect, you were hot.

Well nothing has changed. Yep, I’m hot. Moving onto twin carbies for the DCI engine, or even triple if you count the original.

Finally got them and made up some adapter blocks and some fiddly throttle shaft arms and connected these to a cable splitter. Good to know is that the Chinese supplier has pre-set the jet screws to the correct DCI requirements. No worries there.

In between times, made a shitty vid of some action. https://www.youtube.com/watch?v=iAf1gbWztT8

The DCI passage does in fact communicate with the cylinder in two ways:

1. Direct to the upper cylinder, with, in this case, the same duration as the original transfers and the existing B ports with a duration of around 120 degs.

2. Connecting to the crankcase when the piston is near TDC. This was unavoidable with a standard piston with the usual side cutaway that exposes the transfer port to the crankcase. In this case the duration of the DCI connection to the crankcase is a mild 114 deg, compared to the original piston port inlet duration of 160 deg.

Some possible subtle interactions going on, but there you go. Maybe do a piston with filled in sides to prevent the crankcase communication.

Anyways for now, give the two carbs a try.

More to come.

[Frits Overmars]

...Moving onto twin carbies for the DCI engine, or even triple if you count the original.
The DCI passage does in fact communicate with the cylinder in two ways:

1. Direct to the upper cylinder, with, in this case, the same duration as the original transfers and the existing B ports with a duration of around 120 degs.

2. Connecting to the crankcase when the piston is near TDC. This was unavoidable with a standard piston with the usual side cutaway that exposes the transfer port to the crankcase. In this case the duration of the DCI connection to the crankcase is a mild 114 deg, compared to the original piston port inlet duration of 160 deg.

Some possible subtle interactions going on, but there you go. Maybe do a piston with filled in sides to prevent the crankcase communication.

What's wrong with crankcase communication Ken ? You'll need it anyway, you wouldn't have to find a special piston (although that wouldn't be too hard in your position) and you could omit the original carburetor. KISS, you know?

Come to think of it, a fully closed piston skirt might be helpful in establishing whether opening the DCI carbs increases the revs due to the increased transfer time.area or due to the increased intake time.area, or both.

[jonny quest]

KTM puts the injectors in the throttle body on their factory race bikes. Apparently they're leaving the TPI in place to give the impression that they are still running them.

[lodgernz]

I should know the answer tothis:
My 2T goes noticeably better out of corners on a cold race day than a warm one. What does that say about my carb settings?

[diesel pig]

I should know the answer tothis:
My 2T goes noticeably better out of corners on a cold race day than a warm one. What does that say about my carb settings?

Your mid range carburate setting is a bit lean? I may be wrong I have been before.

[Frits Overmars]

My 2T goes noticeably better out of corners on a cold race day than a warm one. What does that say about my carb settings?

Not much. A two-stroke with perfect carburation for cold circumstances will produce more power in those cold circumstances than a two-stroke with perfect carburation for warm circumstances will produce in those warm circumstances. Yes, two-strokes like cold air.

Cold air is denser than hot air; even if the mixture is too rich for cold air, the engine will burn a larger percentage of this fuel and thus produce more power in cold circumstances.
In your case the mixture can be too rich for cold air, perfect for cold air, or too lean for cold air but still too rich for hot air. In any of those cases cold power will be higher than hot power.
Only when the mixture is too lean even for hot air, the differences between cold power and hot power will disappear (and your engine will notify you by refusing to start when cold).

[TZ350]

2Stroke Stuffing. A bit of CNC action in this one. The supercharged engine is taking shape.

[TZ350]

.


My original issue was, that when I shut the throttle after a hard run in top gear with fixed ignition and WOT. The engine picked up for a bit after I partly closed the throttle. I was able to replicate it on the dyno. WOT = Blue line, partly closed = Red line. The consensus seemed to be that the fuel curve went rich at WOT and needs straightening and the ignition retarding at peak RPM to enjoy the benefits of some over rev power.

I have modified the carb for replaceable air correction jets. And have wired in an Ignitec ignition. Ignitec's are available here in New Zealand from "Fast Bike Gear" in Auckland.

I have a DCCDIP1-Race version. https://www.ignitech.cz/en/vyrobky/d...cdip1_race.htm

The great thing about these DCCDI units is that they generate their own CDI spark from 12Volts. So they can be powered by a 12-14 or 18Volt battery. Mine draws only mA's when idling and about 1.25A at full RPM.

My version can also be powered direct from the bikes AC generator.



The Ignitec I have has a mapping option to pulse a solenoid power jet, PWM at 10Hz. So I got one of these little air solenoids, hopefully it can handle fuel without melting. The plan is to use it as a power jet to richen up the mid range and lean off the over rev.

I have finished the wiring and got the bike running ready for fiddling with on the dyno. Just in time for New Zealand to be plunged into "Lock Down". The Govt went hard and early, hopefully we can beat the virus again and get back to enjoying our freedom soon and the relativly good economy we have.

Anyway I am now confined at home and will have to wait a week or three before I can get back to work to work on the bike.

[lodgernz]

Not much. A two-stroke with perfect carburation for cold circumstances will produce more power in those cold circumstances than a two-stroke with perfect carburation for warm circumstances will produce in those warm circumstances. Yes, two-strokes like cold air.

Cold air is denser than hot air; even it the mixture is too rich for cold air, the engine will burn a larger percentage of this fuel and thus produce more power in cold circumstances.
In your case the mixture can be too rich for cold air, perfect for cold air, or too lean for cold air but still too rich for hot air. In any of those cases cold power will be higher than hot power.
Only when the mixture is too lean even for hot air, the differences between cold power and hot power will disappear (and your engine will notify you by refusing to start when cold).

Thank you Frits.
So basically, the higher you go the fewer, and the rest of the other the same, as my mother used to say.

[ken seeber]

All plumbed up and ready to go. Made up a blanking plate (good idea Frits) for the original inlet for when that carb is removed for part of the initial trials. Included a phallus, attached to the inside of the plate, to fill up most of the inlet passage volume..

[ken seeber]

The pics:

[TZ350]

2Stroke Stuffing



First Start. As Dr. Frankenstein said to Igor, "IT'S ALIVE".

[HalfStrokes]

2Stroke Stuffing


This would be my favourite watch on Youtube, this guy and what he has tried and thinks about has to have 2stroke oil for blood.

[TZ350]

KTM puts the injectors in the throttle body on their factory race bikes.

If you can find a photo or two I would love to see them as I am very much interested in 2S EFI.

[husaberg]

If you can find a photo or two I would love to see them as I am very much interested in 2S EFI.

You just look in Neils pics form a few years ago if you wannt to see what KTM will do next