[GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 4)

i have engmod but my experience with it is only a fraction of the experience that wobbly and some other people have. the blowdown sta is what matters. exh area below the transfers is unimportant like frits says and certainly i dont think you want to enlarge the lower portion of the port for this very reason. some people even reduce the exh area below the transfers, this i believe is part of the reason the engmod indicates the blowdown sta is great but the total exh sta is low, because the lower portion of the port is fairly small in comparison to the area above the transfers.

frits thats great you are joining forces with neels. im sure engmod will only get better and be capable of calculating many more variables with your help

Paul Olesen a écrit:

Frits Overmars a écrit:

Paul Olesen a écrit:

Frits, do you have any experience working with the EngMod software Wobbly is using? I've done some simulation work in EngMod however I often rely on it for looking at STA values and power estimates. My understanding is that blowdown area is the biggest factor in how much power the engine will make and exhaust STA is less critical. When I'm trying to determine how much power I can reasonably expect from an engine I focus on optimizing blowdown, transfer, and intake STA. When I do this the exhaust is usually left "short" on STA and the numbers indicate the exhaust area would have to increase to achieve the desired power. Have you seen a trend in relation to blowdown and exhaust STA.  For example on some of the porting setups I've observed from Wobbly's engines I see the the exhaust is between 80 and 90 percent of the achievable blowdown power number. So if blowdown power was estimated at 100hp the exhaust estimate would be somewhere around 80 or 90hp. There must be a point at which the exhaust does become the limiting factor?

Paul, I am corresponding with Neels van Niekerk, the man behind EngMod. He is working at incorporating my Power Range-concept in the next version of EngMod. I do not use EngMod myself (yet); I still use my own two-stroke simulation program, but I think EngMod is the best product of its kind on the market (my sim is not on the market).
Blowdown time.area is paramount; total exhaust time.area is utterly unimportant by comparison.

Very cool Frits, I'm looking forward to seeing the addition of your concept to EngMod. Have you by chance inquired with Neels if it would be possible to incorporate a vector summation of the port leading and trailing angles, positions, and axial angles? This is something I'm envious you have at your disposal in your sim and must be fairly useful for keeping track of what port geometries are working?

Without the vast amount of tuning experience like you, Jan, and Wobbly have and only having examples of smaller displacement configurations it is hard for me to determine if I have a realistic design for my larger engines. I will head your advice though and pay little attention to exhaust STA and focus on blowdown, transfer, and intake. Thanks for the info Frits.

That has been incorporated in the latest updates.

Institute of TwoStrokes a écrit:

That has been incorporated in the latest updates.

Can you confirm the latest update and where this info is presented? Thanks

Hi, I'm still a little in shock to find this forum with lots of information, I have days reading posts and I've just reached the middle !!! prior to contribute something, I would like to say that unfortunately my experience on the aprilia rsr125 was very negative, I had a model 91, I remember that property at the time of Eduard Giro. Its engine was very difficult to put Carburetion point to the point of not even start several days. So I decided to remove the 125 and pass 50cc, but I did not like the chassis to a bad driver like me, it was very difficult to drive, honda rs up useless as I can go faster, but in the races ended aprilia be sick. So soon I made a change by a 95 honda rs125

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WOW !

This gives me an idea....let's talk religion and ethnic properties.


I'll start things off...

Three guys posted onto a forum, a Harley-riding pope, a Donkey-riding hebrew, and a Mopar-motating gentile.....it was a dark & stormy night, suddenly a shot rang out, an ex-Aprilia racer didn't walk into a bar, but rather lowered the bar. Subsequently, he, along with shipping orders, was nailed to a pallet. The bill read : Destination Unknown.

The End.

I rec'd a PM from brokedown telling me what to post and what not to post.

Hey, First Amendment rules you little wannabe hotshot.

If anyone has anything else to say, spit it out for the whole class.

My above comment reflects the total surprise I had when reading the Aprilia criticism.

If the Boss feels my blurb of semi-satirical humor is unacceptable amongst grown men, or those who pose as adults, then please remove the post. No harm, No foul.

Anyone with at least a Jr. High education from a low ranking American school will recognize the intent of " dark and stormy night ".

If the intent is not understood, then google might work for ya'.

It's a joke. J-O-K-E

As for brokedown, his grammar, spelling, and sentence structure is D- work all the way.

With, or without emoticons, it's torturous to read.

I doubt the kid graduated from high school.

The bottom line here is if somebody wants to start anything beyond MYOB, just be prepared for what comes down the open pipe.

lol


He would NOT have passed where I attended, let alone made it through any college courses in America.


Now, let's get back to the malfunctioning race bike...

I'd say on a technical-based forum, information beyond claiming it didn't run for two days, would be in order.

Why didn't it run ?

What was done to solve the problem ?

Was there a mechanical issue ?

Perhaps an electrical problem ?

If it's pilot error, please explain.

I doubt anybody here has never made one small error.

You know, if a guy is going to race motorcycles, he'd better have a thick skin.

If he can't take a little ribbing, he won't last.

It's all in fun.

Comprende ?

One more thing...." dudes "....I am an American with a background over many decades relating to Harley-Davidsons. Such includes both 4T and 2T, street & competition.

If you don't like it, that's not my problem.

I have an excellent collection of nearly 200 machines which have been acquired over a lifetime.

No brag, just fact.

Others have similar, some better, others amazing !, but I meet few people who are not inspired by my assortment & work.

Just saying, so we understand each other a little better.

i told you to have some respect for the people that want to read and learn about 2t engines. i dont think this is the place for donkey harley davidson jokes. i didnt call you names or say anything derogatory about you . sorry to the moderators and all members for this nonsense

hello Ambike, these messages are my fault? I do not know the English, I translate with google, so excuse my language or confuse my answer and not directed towards me. It is terrible to find much information and have the difficulty that I have to understand, it is a great effort for me to communicate and understand what is said.

ktuner...you are OK.

I was " ONLY JOKING " with you.

Good luck with your race bike & racing !

brokedown is not qualified to * talk down * to me.

OK, all is good.

Drive Safe, & have a nice day.

ok! excuse me but do not quite understand the Texan humor, maybe I have not seen enough episodes of gas monkey garage! (it's a joke, Spanish humor)

Paul Olesen a écrit:

Institute of TwoStrokes a écrit:

That has been incorporated in the latest updates.

Can you confirm the latest update and where this info is presented? Thanks

Go to

Transfer
Passage Layout
Display

RSW 125 is now a scavenging option as well

Institute of TwoStrokes a écrit:

Paul Olesen a écrit:

Institute of TwoStrokes a écrit:

That has been incorporated in the latest updates.

Can you confirm the latest update and where this info is presented? Thanks

Go to

Transfer
        Passage Layout
                           Display

RSW 125 is now a scavenging option as well

Perhaps you have a later version I missed? I'm on 5.6.2. I've been working a lot with "passage layouts" but I only get a schematic of what it will look like. No summation of all the vectors.

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more images of my bike. I had it 15 years ago, I remember that was the year 91.

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Paul Olesen a écrit:

Institute of TwoStrokes a écrit:

Paul Olesen a écrit:

Institute of TwoStrokes a écrit:

That has been incorporated in the latest updates.

Can you confirm the latest update and where this info is presented? Thanks

Go to

Transfer
        Passage Layout
                           Display

RSW 125 is now a scavenging option as well

Perhaps you have a later version I missed? I'm on 5.6.2. I've been working a lot with "passage layouts" but I only get a schematic of what it will look like. No summation of all the vectors.

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That's what I see as well wemust have a different definition of vector summation

ktuningteam a écrit:

more images of my bike. I had it 15 years ago, I remember that was the year 91.

Well I for one am interested in your RSR125. There is less information on these models than for the RSW/RSA !

Thanks for sharing, and I hope you enjoy finishing the last half of the forum thread. These is a lot of gold contained in there !

CTS is a period quickshift circa 93???

Bob van der Zijden a écrit:

However  IGNITECH is programmable and very cheap indeed but what can one expect from cheap stuff ? The ratio quality vs price isn't  that bad after all !

What you can expect? Getting a good working ignition system. Just because it is cheap, doesn't mean it is crap.
We won a lot of races with Ignitech stuff. Can't be that bad.
Please name a better ignition-system for the same price.

Bob van der Zijden a écrit:

When talking fe about ignition systemsI am rather disappointed on  the level of knowledge and vision regarding the subjects ignition  and injection on this forum. Therefore it  would be very wise  to do ones homework properly before grabbing the digital pencil...

Then try it like it Jan and Frits: Don't tell, what is all wrong. Tell how it is made right.
Or do you just mean: Buying Motec-stuff from you is the one and only way to do it right?

Ian Harrison a écrit:

As far as I'm concerned 135mJ is more than adequate for your application and perhaps  a bit "over the top".

I've tried just about every programmable ignition box/system on the market. We currently have about 85mJ with the system we use and the best results that we have ever achieved from a 250 single cylinder 2-stroke race engine.

Hi Ian,

do you measured the spark energy? Or is it just the producers promise?
And which ignition system do you prefer?

As Energy is P=U*I*t, there are three ways to modify the spark energy: The voltage, the current, the spark time.
So spark energy isn't just spark energy.
And modifiy voltage and current can produce trouble.
On the one hand the components getting more expensive and handling the EMC is a science on its one.
On the other hand: It really can end in live danger.

The most of us know, how it feels when the ignition try to "ignite" our hand instead of the plug.
And now try to imagine, what happens with a higher spark energy.

I'm working on an analog cdi (digital follows, but I'm just doying my homework ), raising the spark energy works fine, but the improvement in poweroutput is minimal (at my engine - maybe other engines benefit better).
The main part in improvement is the right ignition curve (but this is not easy at an analog cdi - you allways have to make compromises).
PS: My test engine isn't a high-power 2stroke, because ignition development on such expensive engines isn't good for my wallet.

A real powerful cdi costs more than an Ignitech. If you want to race cheap you will always be a backmarker. I dont see what my name has to do with MOTEC. I dont sell it but can  tell you that it's real serious stuff only for real serious people and not for back markers. Tada & ciao for now...

thats the attitude that will help none of us ;-)

if you are as educated as you act on ignitions, please go ahead and name some system which are superior to an ignitech (in your opinion).

There's always another guy who's better, smarter, and faster.

Today, if one is connected into the right " circuits ", one can be a loser and still collect many millions.

When it comes to money, the central banking fraudsters have all of us in a race to the bottom.

So.....Gotta be smart....risking life & limb for worthless fiat coupons is a joke.

That junk can ruled WORTHLESS tomorrow.

Kings trump pawns.

Fiat monetary units printed from thin air, or more often electronically created via another ZERO entered, is The Game.

Play on Suckers !

Ha Ha. Schmucks create " their horsepower " from NOTHING.

Their hands do NOT get dirty.

That's our job, aka, " Pay up punk ! "

Don't you amigos understand that simple equation ?


Oh, back to SPORT....

Yep, sport is GOOD GAME & FUN.

Perfectly executed engineering always costs LOTS of money.

Duh ! Tell me something new. lol

" How fast do you want to go ? "

Or, how fast do you NEED to go ?

And what makes a Motec better than an Ignitec?
Because its expensive, because its inside an extruded aluminum case that is anodized?
If its better, say why, I'm interested to know what makes something better, so I can take ideas to implement in my home brew ignition, that for now, costs 20€ in components and has H bridge driver to directly control a power valve..

There is not that much you can do in a two stroke ignition..
There is a pick-up, a high voltage winding or a dc-dc converter that uses 12v(or more) to generate something around 350-400v, yes, you can throw in inputs for quick-shifters, buttons for choosing maps on the fly, outputs for shift-lights and power valves.
But the basic thing, is a pulse that is filtered and goes to a micro-controller, the pulse is used to count rpm and for absolute positioning reference, after that, its software, and there is only two ways, it either work, or it doesn't.

You can throw expensive components, but there is no magic in using them, from my tests only one thing really matters, the quality of the output cap, and even then, a cheap(1 to 2€) ceramic does the work very, very well, two of them in parallel lower the ESR to ridiculous levels.

Motec doen't produce ignition systems, it sells some cdi systems that are as far as I know aremanufactured by M&W from Sydney. If someone wants a real good cdi have a go with an M&W system.
You can use higher cr's an MUCH richer mixtures that create more internal cooling which subsequently lowers the piston crown temperature and increases thermal reliability a lot. For your information here some figures of a 4 stroke test : with inductive ignition max torque with 32 degrees advance and a Lambda value of around 0.85.
With an M&W cdi the same torque with only 27 degrees advance. To demonstrate the M&W's potential we went to Lambda 0.63 !!!!! ( air fuel ratio of around 9.3 !!! ) and the exhaust temperature went down by 200 degrees C... . and asolutely NO misfiring at all. Only to demonstrate the enormous amount of current thru the plug. Torque loss with that setting was only 3 percent. As the piston crown in ANY piston combustion engine is the most vulnerable part lowering its temperature while increasing the cr is should be the dream of any serious thermodynamicist. By the way I have NO connection with or interest in M&W. I only want to inform the flock without serious knowledge on ignition systems that most of them in the dwarf engine dream world aren't worth the money  of  serious engine specialists. I'd like to finish with an odd question : do you happen to know what a dwarf is ? That's a frigid midget wit a rigid digit...
Tada for now.

Here's an interesting read I found.

Looks like M&W brings out plenty of spark ( and fire ) !

Indeed it DOES ! lol

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a question about timings :
I've been experimenting with a Honda Sky for MX-moped races. first made a "realy powerful" 13000 rpm engine with 195/130° timings, but clutch/vario suffered too much from stop-and-go causing it to engage sooner and sooner untill it dropped outside the powerband rendering it useless.
also realised that with fixed gearing (not able to change it) looking for power in higher revs is useless.

so the engine (39x41.4) would need to run about 8.500-9000 max, what timings would be ideal ? I'd like to make 2 versions : one with a peaky powerfull engine and one with a wide spread powerband that pull's all through the rev range.

peaky : somewhere 170-180/120-130° with 5cc heads
wide spread : keep original timings 160/107 and just widen the ports as much as possible, 4cc heads ?