ESE's works engine tuner

[2T Institute]

I found with my system it would never clear once it bogged, just 100% dead until the revs dropped. They must have been using some method of clearing it.
I guess that's why injected snowmobiles and boats don't have the issue, as soon as the throttle is cut the revs drop.

A prop will never drive the engine once the throttle is chopped, sleds have a CVT so the engine is always in band. The other thing in common is on/off throttle no trailing no feathering no half off pipe throttle.

[Nath88]

Thanks Nathan, you have shown me a very different approach. Use a 2 bar MAP sensor to measure the pressure changes in the expansion chamber to determine bulk changes in air flow through the engine. Good idea, wish I had thought of that ages ago.

Measuring the blowdown pressure pulse rather than the negative (since they should be proportional) gives you a head start on getting the fuel in. I have the pressure sample window set to 140-170° ATDC. The peak moves with RPM, because of the delay along the hose to the MAP sensor, so best to keep it as short and close to the port opening as possible. I have the injection start 10° after the sample window, so the latest pressure value is used to calculate the injector pulsewidth.

I suspect the pulses develop to full strength over a few cycles, as the return wave strengthens the combustion, so probably no need to get all the fuel in on that first cycle after measurement.

I am measuring through the powervalve vent, so my pressure values are only indicative for firing or not. With a proper exhaust port measurement you could adjust fuelling based on the pressure rather than just firing/not-firing.

You could even use a firing/not-firing approach based on the sound from the combustion chamber to switch maps... More time to sort the fuel for the next cycle.

Will be complicated on a multi-cylinder when one cylinder kicks on before the other... Will have to separate the signals from each cylinder, two switched map sensors?! Maybe have the spark output for each cylinder activate the MAP input for that cylinder? So it flips back and forth? Ughh.

Will you try it?

[TZ350]

Will you try it?

Yes.........

[husaberg]

I found with my system it would never clear once it bogged, just 100% dead until the revs dropped. They must have been using some method of clearing it.
I guess that's why injected snowmobiles and boats don't have the issue, as soon as the throttle is cut the revs drop.
Nice article on the Cagiva too, I hadn't seen that one.

Exactly my problem too.

Same problem everyone else, from Cagiva through to Suter last year at the IOM the longer time at full throttle the worse it will be.

That overlay from the ECU on the video is uber cool

My initial thoughts would be Auto blip throttle control, MGP bikes have it.
Ages ago I posted something Jennings wrote that came from John Brooks who was the macolloch pumper carb guru.
https://www.kiwibiker.co.nz/forums/s...post1131005018
From memory they fixed the pumper carb by closing off the circuit when there was i think no air pressure on the upstream side of the venturi
maybe that’s what the Fuel injection needs the Air pressure sensor on both sides of the throttle body and the truth table to compare them.
I don't think the Microsquirt could react fast enough to the sudden decrease in revs to control it that way.

Cagiva alluded it could be tuned out, but not sure if that actually involved GPS mapping which was one the cusp widespread use at that time.


Foggy refused to ride it at the Brit GP due to its behaviour.

I have never heard it mentioned as being a problem with either the fuel injected NSR500 or the EXP400 Honda that were also throttle body injected.
Riley Will was having some good results last time i looked with a kart motor.

[Flettner]

That overlay from the ECU on the video is uber cool

Yes I like that too.

[41juergen]

your doing good job . will your exh exit be 75% of exh area at bore face ?

Yes, at least best as I can. The Problem is that I can't make a real oval as I would get into the water jacket, so I try to make the aux tunnel as far and "wide" as I can... Also I will put the stinger nozzle in, EngMod predicted a nice power increase behind peak. So let's see what the dyno will tell

[TZ350]

Well, for something different, Paul and I spent the last few evenings playing with a Bucket EFI 4T, as you do, playing with motorbikes instead of spending time with family and loved ones. We found extra hp by advancing the cam 6 deg, and carefully shortening the inlet 10mm at a time. Anyway 151 runs latter, 23 hp. In the end there was still a cyclic series of humps, interesting, no idea how to smooth them out.

Really looking forward to getting back to my 2T EFI project and exploring Nath88's idea of using the strength of the exhaust suction pulse on over run to adjust the strength of the next injection cycle.

[shnaggs]

I just read that KTM was going to run EFI on their 125 gp right when the moto 3 rule went into play. Wonder if that was TB injected???


Here: https://www.motomatters.com/analysis...long_feud.html

[jonny quest]

Are there any pics out there of KTM'S parallel twin 250 gp engine? I tried searching with no luck

[Martin1981]

Does anybody know if there is a good heat and fuel/oil resistant liquid rubber a carburetor insulator boot could be made of?

[senso]

Silicone, or RTV?

[190mech]

Polysulfide compound,its used as fuel tank sealant in the aviation world,search for PRC PR 1422 or 3M corp EC801,its a 2 part system that dries tuogh and flexible.Sold at Aircraft Spruce..

[Frits Overmars]

I just read that KTM was going to run EFI on their 125 gp right when the moto 3 rule went into play. Wonder if that was TB injected?

Not likely; the 125 cc KTM GP-bike already had an injector in the crankcase that injected through a port below the exhaust port.
They used it instead of a powerjet and it would only have been logical to use the same setup for full EFI.

[Frits Overmars]

Are there any pics out there of KTM'S parallel twin 250 gp engine? I tried searching with no luck

Here you go Jonny.

[mr bucketracer]

don't know about fuel but at work we made soft stuff out of rotomoulding pvc , here is a small clip of baby heads been made https://www.youtube.com/watch?v=TSyZY6aFJZ0