ESE's works engine tuner

[seattle smitty]

Smitty, all the Japanese manufacturers make 85cc motoX bikes with oversize pistons available up to +2mm, some of the cylinders are Cast iron bores some Nicasil, our rules prevent us from using them in Buckets, The 85 cc engines are around 22hp

What I probably have to do is find a forum for the dads who set up these little bikes for their kids to race, in hopes that they can lead me to an engine-builder or two who specialize in this sub-specialty. My guess is that all these engines have pretty mild port timing from the factory, and probably smaller ports than I'd want for all-out horsepower. My hope would be to have some experienced tuner who has "seen it all" give an opinion as to which cylinder has the biggest, best shaped ports to start with, port timing being fairly easy to alter, but port shape/aiming/etc. being not so easy, especially in those tiny bores. Since Frits has already suggested KTM, I'd check that out first.

Currently (unless something has come along that I haven't heard of yet), the 175cc twin-opposed production racing outboards from GRM and VRP are derived from their other classes of engines, with the result that they are quite over-square. I got accustomed to square and long-stroke, long-rod engines long ago, and over the years watched the fashions change back and forth, but would prefer a somewhat long-stroke 175 (as you can see from my asking about 45 to 48mm bore cylinders). The engines built by those two Italian companies are very well-made and up-to-date, and a great improvement over anything we outboarders have ever had available to us, and we are very grateful to Mr. Rossi and Mr. Verona. (EDIT)(My info was out of date, as I've learned that at least one of the Italian makers has a "square" 175cc twin. Nevertheless, I'd still rather come up with something unique).

The trouble is, they are good enough that nearly all of the PRO racers nowdays just use the engines as they come from the factories, whereas the mark of alky outboard racing used to be that you had to do a lot of your own beefing up and hopping up (or get someone to do it for you). The idea of "checkbook boatracing" doesn't appeal to me at all. To me, there's an important distinction to be made between "racers" and mere "drivers." That distinction is ultimately the long hours a racer spends in his home shop, measuring and calculating and grinding and welding and turning and milling and wrenching, when the "mere drivers" are out on a golf course, or whatever it is that that sort of person does. I guess I just don't relate well to men who never get dirt under their fingernails.

So "turn-key" racing has no appeal to me whatever, and I like a site like this because I can see that many of you feel this way as well. For myself, I want to see if I can build something that nobody else in the pits has ever seen or thought of, and if it will keep up with or beat the un-modified new factory motors, so much the better.

[seattle smitty]

Did I miss something here, were you also doing engine development at Aprilia, Frits??

[peewee]

theres some ktm mx forums that have sections discussing the 65 and 85 engines but i wouldnt bother asking any technical questions. most of those members barely know how to change clutch plates, let alone how to properly modify the cylinder

[Frits Overmars]

Did I miss something here, were you also doing engine development at Aprilia, Frits??

Jan Thiel did all the hard work at Aprilia. Until he retired, I performed thermodynamic and gasdynamic calculations for him, and I also tried to think along with him about various two-stroke developments. I've explained it a bit more extensively in that Pit-Lane link I posted the other day:
http://www.pit-lane.biz/t117p246-gp1...-part-1-locked

If you start reading there, even if you only read the english texts, you'll be occupied for the rest of the year. So Merry Christmas and a Happy New Year .

[Frits Overmars]

... My guess is that all these engines have pretty mild port timing from the factory, and probably smaller ports than I'd want for all-out horsepower.... Since Frits has already suggested KTM, I'd check that out first.

The KTM 85SX already has decent transfers; all you need to do is set their timing at 130°, widen the auxiliary exhaust ports and raise them from their standard 174° to 188°. The central exhaust port already is 194°.

[TZ350]

do any of you guys have experience with these things that go inside the carb bore, either before or after the slide ? is it just rubbish with a splash of snake oil ? The Quad-Flow Torque Wing has vertical and horizontal air flow stabilizers which increase air flow.

Hi Peewee, there seems to be as many people who rush to rubbish a new idea without critical thought as embrace it, either way its a "Faith Based" assumption, if their opinion is not based on measured fact.

Humans have two great attributes, Faith and the ability to make Intuitive leaps.

And to make consistent advances, after the intuitive leap the objective needs to be measured empirically, and the real (sometimes difficult) trick can be in devising procedures to measure something in a way that reflects its intended improvement, ie its no good measuring a device that improves quarter to mid throttle response at WOT on a dyno.

In my efforts to find better ways of flowing air through a 24mm carb I found various flow straighteners helped a lot.



The best that was tested for outright bulk flow was this 24mm venturi insert pressed into the back of a 38mm carb. I think it worked by the body of the carb straightening up the air column before it entered the 24mm venturi.

I also found that air flow into the engine actually had to be a problem before I could improve it. As extra flow on the bench did not necessarily mean extra power on the dyno if something else in the system was really the bottleneck.

I inadvertently demonstrated strengthening the strongest link in the chain did not make the chain any stronger.

I had to find the weakest link and that is harder than you think. Because it might not be as obvious (or interesting to fix) as insufficient blowdown STA but as simple as poor fuel atomisation or any one of the 101 other seemingly little things.

In the quest for improved performance I think everything is worth a look, I would love to test those flow straighteners.

[richban]

I took the bike out for a test yesterday at a MotoTT track day in group one. A great day out and loads of track time.

I made a new plastic mount for the EGT but its still getting interference form somewhere. I will go over the wiring and insulate the lot and also make sure it does not pass to close to plugs etc.

So, new heads with proper squish and power valves all working. Oh and a real 15 degrees advance at peak. Woohoo it just keeps getting better. I am going to lower the shift light rpm as I think its just dropping out of the happy place at 11700 I will pull it down to 11500.

Quite good fun chasing the big bikes.

[TZ350]

EGT its still getting interference form somewhere. I will go over the wiring and insulate the lot and also make sure it does not pass to close to plugs etc.

Great Vid Rich.

If your picking up AC or Radio frequency interference try shunting it to earth with a small capacitor.

[richban]

Great Vid Rich.

If your picking up AC or Radio frequency interference try shunting it to earth with a small capacitor.

Sounds worth a try for sure. When I take it of the bike on the dyno and hold it in my hand it is as smooth as silk and dose not go over 1100F.

[peewee]

Hi Peewee, there seems to be as many people who rush to rubbish a new idea without critical thought as embrace it, either way its a "Faith Based" assumption, if their opinion is not based on measured fact.

Humans have two great attributes, Faith and the ability to make Intuitive leaps.

And to make consistent advances, after the intuitive leap the objective needs to be measured empirically, and the real (sometimes difficult) trick can be in devising procedures to measure something in a way that reflects its intended improvement, ie its no good measuring a device that improves quarter to mid throttle response at WOT on a dyno.

In my efforts to find better ways of flowing air through a 24mm carb I found various flow straighteners helped a lot.

The best that was tested for outright bulk flow was this 24mm venturi insert pressed into the back of a 38mm carb. I think it worked by the body of the carb straightening up the air column before it entered the 24mm venturi.

I also found that air flow into the engine actually had to be a problem before I could improve it. As extra flow on the bench did not necessarily mean extra power on the dyno if something else in the system was really the bottleneck.

I inadvertently demonstrated strengthening the strongest link in the chain did not make the chain any stronger.

I had to find the weakest link and that is harder than you think. Because it might not be as obvious (or interesting to fix) as insufficient blowdown STA but as simple as poor fuel atomisation or 101 other seemingly little things.

In the quest for improved performance I think everything is worth a look, I would love to test those flow straighteners.

i agree. everything is worth a look. i didnt see any talk or photos of any winged gadgets around here so i figured maybe you guys had already found them to be useless. $100 is alot of money for a $2 piece of laser cut stainless steel but if it does what it claims then maybe there is a free lunch after all

[husaberg]

The wings and the blades etc yes they might even have positive effect...... but is the effect they have on say drivability the result of poor factory jetting etc......... I know not the answer but if the F1 and moto gp and gp bikes don't have them I do wonder why.
I also get suspicious of gains that are not backed up by dyno charts.
I posted a few pics ages ago asking if anyone knew of them or had tested them I go no answers then.
I think the ones I asked were power blade and power wings.

[seattle smitty]

Jan Thiel did all the hard work at Aprilia. Until he retired, I performed thermodynamic and gasdynamic calculations for him, and I also tried to think along with him about various two-stroke developments. I've explained it a bit more extensively in that Pit-Lane link I posted the other day:
http://www.pit-lane.biz/t117p246-gp1...-part-1-locked

If you start reading there, even if you only read the english texts, you'll be occupied for the rest of the year. So Merry Christmas and a Happy New Year .

Good heavens, Frits, you are handing me my engine on a silver platter! I'd never have asked you for actual port timing, just general questions, figuring it's my place to cut-and-try. Very much appreciated, understanding that it has taken you many years to be able to state such figures with confidence. I'm still shaking my head at your generosity; Merry Christmas indeed!! One way or another, I'll supply photos of the build.

After I asked about your Aprilia connection, I did go to the first link to Pit Lane and read for a while (the English). Thanks for that lead. I also looked up a couple of your countrymen who have continuing Aprilia parts projects. I'm finding that, coming from outboard racing, and that decades ago, my awareness of what's happening in the wider world of 2-strokes has been a lot more restricted and insular than i'd guessed. I knew that GP roadracing was a big deal in Europe, but in my searching (the subject was fuels in this case) I have come on to little in-crowds of guys building custom-chassied, fuel-burning, drag-racing ATVs (quads) and others drag-racing equally wild snowmobiles.

You being a thermodynamics man, I've got some questions I'm dying to ask on that subject, but as I said, I don't want to become a pest here so I'll save that for down the road.

Thanks again!

(EDIT) Two old but serviceable hydroplanes are to be delivered to me in two days. The best boats in our sort of boatracing have been coming from Europe, but in the last couple of years, some American builders have started producing their versions. One of these builders is Mike Schmidt, whom I see has posted to this thread. Mike, along with his sons, is among the very top outboard racers today, many times a winner and national champion in the 250 and 350cc classes. He is an engineer and a very good guy, and if ever my own personal old-age racing program justifies the expense I'll be ordering one of his new-tech hydros.

[TZ350]

... i didnt see any talk or photos of any winged gadgets around here so i figured maybe you guys had already found them to be useless.

The wings and the blades etc yes they might even have positive effect...... but is the effect they have on say drivability the result of poor factory jetting etc......... I know not the answer but if the F1 and moto gp and gp bikes don't have them I do wonder why.

Possibly different riding conditions, and bike setups like you say. The wings might suit Trail and MX more than outright RR with its all or nothing WOT conditions.

[husaberg]

Possibly different riding conditions, and bike setups like you say. The wings might suit Trail and MX more than outright RR with its all or nothing WOT conditions.

I trolled the net found this no idea what it says or means as it bloody blurry as well.

[alfiestewart78]

why not just get a really big aircooled head off say a MZ250 weld up the combustion chamber and machine one that suits your engine. i think you are really going to struggle with the fan thing . I was looking at a fan at work today that would probably do the job but it was 1.1KW 3 phase. Think how big the fan at the dyno is and thats just for short runs.