ESE's works engine tuner

[Patrikh]

....... The throttle body MAP sensor is connected to the exhaust port and samples the pressure during blowdown. I’ve set up a 2nd fuel table in the ECU with a multiplier for when the pressure is above a threshold, corresponding to the cylinder firing. When the exhaust pressure is high, the main fuel table is unchanged, when low, it is reduced by 50% (will need to be dialled in for various RPM, but seems to work so far). The main fuel table is tuned with the wideband when the motor is firing, then extrapolated into the non-firing low throttle/overrun area. On closing the throttle, once the motor stops firing, fuel flow drops to match the airflow, so the motor doesn’t flood. On opening the throttle, the mixture is correct to initiate firing, then after the first fire fuel flow goes back to the main table value.

I think with some tuning I should be able to get the transition pretty much seamless. At the moment I'm working on getting the fuel table just right around the transition area, then I'll work on the switch threshold and multiplier values. That said, it's pretty decent already, but I'm a perfectionist.

Nathan

Hi Nathan!

I'm running an almost identical setup as you but on an 82cc engine, and i'm experiencing the same thing as you. Since it is a pure dragrace machine i thought i would not need the low throttle leaning, but i feel it would be nice to be able to ride it back from a run without going wide open throttle.
I have a map sensor now that i use just for baro correction at start up, do you use youre exhaust map sensor for baro correction? I was thinking if i would need another one or could use my existent one for both purposes.
Do you have any advice for the setup in Microsquirt or any other dos and don'ts?

Regards
Patrik

[RSC]

I was reading an article the other day that said one of the reasons why Honda opted for reeds for the NS500 was that it was easier to start,and judging from race starts I've seen that seems to be the case.So is a Reed valve 2 stroke fundamentally easier to start than a disc valve ,and why?

[peewee]

Alternative cause for deto could be simply elevated combustion temperature after ignition, because heat loss path via piston top was blocked.

thats what i was wondering. what happens to the heat if it cant go to the piston top, to the rings, to the bore walls ?

[wobbly]

2Ts are hateful things but do in the end respond to some sort of logic.
The ceramic coated piston was a disaster,but change the coating so that only the dome is insulated,and the squish area is left stock - then the deto instantly goes away.
One has to assume that the heat that isnt absorbed by the piston has to go either into the combustion gas, or a % of it is transferred into the water via the insert.
When I tested this the egt did rise,about 1/2 a jet size,so not really significant,but if you coat the combustion chamber ( not the squish area ) the temp rises another
whole jet size and the pipe then reved on a worthwhile amount.
As it turns out, i prefer now to mirror polish the piston ( much cheaper than ceramic ) and that works even better.
But you have to keep on cleaning it as oil burns onto the surface.
The coating in the chamber is a real "hidden trick " and doesnt cost much at all.
It increases the combustion gas heat retention and the water temp drops, a win win.

Have a think about the process and what is needed by different parts of the enclosed combustion space.
We want to keep heat out of the piston and in the gas - so polish the piston so it reflects the heat back.
We want to keep heat out of the water - coat the chamber.
We want to effectively cool the plug body - get water right up to the threads.
We want to keep the squish area boundary layer and thus the trapped end gases cool - you work it out, I have but aint telling.

Re the TM Ex duct - I have the cylinder CAD file so I remodeled the duct,reducing the height and added the ears all the way down the side right thru the spigot to the header.
The exit area is smaller again than the C model, and as per usual it made best power in the sim at 75% of the effective total Ex port area.
Franco has the file,and has promised to make the special sand cores for a cylinder in the next manufacturing batch - " just to make me happy ".
As Jan said,I think he will be surprised, but for me it enables a bigger scope of new pipe design critera with alot more front side power and overev capability.

[diesel62]

2Ts are hateful things but do in the end respond to some sort of logic.
The ceramic coated piston was a disaster,but change the coating so that only the dome is insulated,and the squish area is left stock - then the deto instantly goes away.
One has to assume that the heat that isnt absorbed by the piston has to go either into the combustion gas, or a % of it is transferred into the water via the insert.
When I tested this the egt did rise,about 1/2 a jet size,so not really significant,but if you coat the combustion chamber ( not the squish area ) the temp rises another
whole jet size and the pipe then reved on a worthwhile amount.
As it turns out, i prefer now to mirror polish the piston ( much cheaper than ceramic ) and that works even better.
But you have to keep on cleaning it as oil burns onto the surface.
The coating in the chamber is a real "hidden trick " and doesnt cost much at all.
It increases the combustion gas heat retention and the water temp drops, a win win.

Have a think about the process and what is needed by different parts of the enclosed combustion space.
We want to keep heat out of the piston and in the gas - so polish the piston so it reflects the heat back.
We want to keep heat out of the water - coat the chamber.
We want to effectively cool the plug body - get water right up to the threads.
We want to keep the squish area boundary layer and thus the trapped end gases cool - you work it out, I have but aint telling.

Re the TM Ex duct - I have the cylinder CAD file so I remodeled the duct,reducing the height and added the ears all the way down the side right thru the spigot to the header.
The exit area is smaller again than the C model, and as per usual it made best power in the sim at 75% of the effective total Ex port area.
Franco has the file,and has promised to make the special sand cores for a cylinder in the next manufacturing batch - " just to make me happy ".
As Jan said,I think he will be surprised, but for me it enables a bigger scope of new pipe design critera with alot more front side power and overev capability.

On that note does a skirt coated moly piston slow the heat transfer between piston and barrel.

Sent from my SM-G900F using Tapatalk

[wobbly]

[QUOTE=diesel62;1131051284]On that note does a skirt coated moly piston slow the heat transfer between piston and barrel.

I dont know how you would measure that, but I have never seen any evidence of piston overheating on coated pistons.
All the papers I have seen on the subject state that the vast majority of heat transfer is thru the ring to the bore.
And in jetski racing with very big overbores I know of one famous tuner who " fixed " piston overheating issues by simply adding a second ring.

[diesel62]

[QUOTE=wobbly;1131051287]

On that note does a skirt coated moly piston slow the heat transfer between piston and barrel.

I dont know how you would measure that, but I have never seen any evidence of piston overheating on coated pistons.
All the papers I have seen on the subject state that the vast majority of heat transfer is thru the ring to the bore.
And in jetski racing with very big overbores I know of one famous tuner who " fixed " piston overheating issues by simply adding a second ring.

Thanks

Sent from my SM-G900F using Tapatalk

[Nath88]

Hi Nathan!

I'm running an almost identical setup as you but on an 82cc engine, and i'm experiencing the same thing as you. Since it is a pure dragrace machine i thought i would not need the low throttle leaning, but i feel it would be nice to be able to ride it back from a run without going wide open throttle.
I have a map sensor now that i use just for baro correction at start up, do you use youre exhaust map sensor for baro correction? I was thinking if i would need another one or could use my existent one for both purposes.
Do you have any advice for the setup in Microsquirt or any other dos and don'ts?

Regards
Patrik

I use a separate sensor, you could use the same sensor, but if you have a power interruption with the engine running the baro correction value will then be incorrect, might go lean, might go rich. You can just get any sensor, then calibrate it from the main sensor.

Microsquirt set up is pretty self explanatory with MSextra firmware, I haven't had any issues with it so far.
What are you using as a crank trigger? Port injection? How many injectors?

I should probably be using 2 injectors, or a bigger injector at least. 75% injector duty cycle, not enough time for the injector to close fully at 10,000rpm.

[F5 Dave]

I was reading an article the other day that said one of the reasons why Honda opted for reeds for the NS500 was that it was easier to start,and judging from race starts I've seen that seems to be the case.So is a Reed valve 2 stroke fundamentally easier to start than a disc valve ,and why?

So what year did they move from push starts to clutch starts? Certainly relevant to NS500. I remember reading about the diminutive Paul Lewis (angry ant or summit like that) struggling to start the RV RGB .

I have limited experience but have tired myself out pushing a Rotax 256 bike that would start real nice with 2 people and not so flash with just one inexperienced Muppet (me).

[lodgernz]

So what year did they move from push starts to clutch starts?

About 1980 in NZ I think, maybe a year or two earlier. I always had to push-start my CR125 road racer, but I don't ever remember pushing my RD250LC.

[Grumph]

About 1980 in NZ I think, maybe a year or two earlier. I always had to push-start my CR125 road racer, but I don't ever remember pushing my RD250LC.

Canterbury club changed in 71/72 season. Pretty sure the GP was clutch start that year too. But canty were in advance of most...We had guys coming back from the US who were converts.

[Patrikh]

I use a separate sensor, you could use the same sensor, but if you have a power interruption with the engine running the baro correction value will then be incorrect, might go lean, might go rich. You can just get any sensor, then calibrate it from the main sensor.

Microsquirt set up is pretty self explanatory with MSextra firmware, I haven't had any issues with it so far.
What are you using as a crank trigger? Port injection? How many injectors?

I should probably be using 2 injectors, or a bigger injector at least. 75% injector duty cycle, not enough time for the injector to close fully at 10,000rpm.

I run a homemade 24-1 trigger with a VR-sensor. It is a modified 38mm throttle from a gsxr600 or something, with one port injector and another one upstreams pointing straight down the funnel.
With them fully staged I think there where like 40-50% duty on both, so i would recomend two injectors!

[RSC]

So what year did they move from push starts to clutch starts? Certainly relevant to NS500. I remember reading about the diminutive Paul Lewis (angry ant or summit like that) struggling to start the RV RGB .

I have limited experience but have tired myself out pushing a Rotax 256 bike that would start real nice with 2 people and not so flash with just one inexperienced Muppet (me).

I think 1983 was the last year that they push started the bikes.

A patent from Nomura here
suggests that reed valve engines were hard to start as well,but they retarded the intake port open periods and they took advantage of the added flow of the boost ports to overcome the problem.So why would a disc valve be any different?

[husaberg]

So what year did they move from push starts to clutch starts? Certainly relevant to NS500. I remember reading about the diminutive Paul Lewis (angry ant or summit like that) struggling to start the RV RGB .

I have limited experience but have tired myself out pushing a Rotax 256 bike that would start real nice with 2 people and not so flash with just one inexperienced Muppet (me).

That might be because the rotax 256 also fires both pistons at the same time. I would wager a reed valved bike with a similar set up would be hard to start as well.

I think 1983 was the last year that they push started the bikes.

A patent from Nomura here
suggests that reed valve engines were hard to start as well,but they retarded the intake port open periods and they took advantage of the added flow of the boost ports to overcome the problem.So why would a disc valve be any different?

i have it in something i posted previously (that i will find in a minute) but it was in the NSR era arround 87 ish i think.
https://www.kiwibiker.co.nz/forums/s...post1130224117
(Yes 87 was the first year third attachment)
The use of reeds instead of discs in the Japanese bikes was more likely because for them they could cross pollenate with the MX bikes tech.
the reed at first allowed a more user friendly power delivery as evidenced by the superiority on the 500's plus also up to the mid to late 90's on bumpy and tight tracks, even on the 125's and 250's.

[RSC]

i have it in something i posted previously (that i will find in a minute) but it was in the NSR era arround 87 ish i think.
https://www.kiwibiker.co.nz/forums/s...post1130224117
(Yes 87 was the first year third attachment)
The use of reeds instead of discs in the Japanese bikes was more likely because for them they could cross pollenate with the MX bikes tech.
the reed at first allowed a more user friendly power delivery as evidenced by the superiority on the 500's plus also up to the mid to late 90's on bumpy and tight tracks, even on the 125's and 250's.

That is of course true.The only experience Honda had with 2 strokes stemmed from reed valved MX bikes, Miyakoshi himself was project leader in the development of many of these.So of course they would use tech they were familiar with,given that unlike with the NR,this time they had to succeed quickly.

Still,it would be interesting to know if reed valved 2 strokes are fundamentally easier to start than disc valved.