Messages

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General Two Stroke Talk / Re: YZ 250 EFI

« on: April 05, 2017, 08:05:04 AM »

Well, Flettner here has got a bit of light shone on him in the latest issue of VMX - Vintage Motocross & Dirt Bike Quarterly, issue #69.

It's on page 3, in the 'The Sweep Rider'. There's a couple of pictures of his handiwork, and, it even reveals his real name.......................

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General Two Stroke Talk / Re: TSM is back...

« on: February 07, 2017, 06:27:00 PM »

Good to see this back.

I didn't find out about this resurrection via Email, but by a Thread on Vital  on (my) Feb 8th - good on them there doing so.

I contributed money to the race effort here previously, so, if there is need of contributions to keep this running , let  me know. I'll not contribute megabucks, but am willing to help. Though, I see most websites as being a business, however big, or small. They've got to be, in this day and age.

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General Two Stroke Talk / YZ 250 EFI

« on: September 05, 2013, 08:04:27 AM »

There is quite some arguement that 2ts will go to more oversquare engines, especially with such techs as DFI, as the fuel component of the charge, will be less dependent on the 'whole engine' concept.

I disagree with the idea that a DFI two stroke would require an over-square engine configuration. Its still a two stroke, it still relies on crank case induction and exhaust scavenging, just like almost all other DFI two strokes (with boats being the exception).

However a DFI trapping valve two stroke would probably make good use of a short stroke as it does not need the long stroke for additional exhaust time area.

Disagree all you want young fellow.

As I wrote "There is quite some arguement that 2ts will go to more oversquare engines, especially with such techs as DFI". Therefore, there will be disagreements.

I don't believe there is a need for 2ts in Motorcycles to go that route - chasing revs to get HP, as naturally aspirated 4ts do. That's through my own, perhaps 'old timers' viewpoint, on what I want from a 2t.

2ts can keep relatively long strokes, whilst doing battle with 4ts.  Simple maths / time calculations show that 4ts "big bang advantage", so to speak, is gradually being negated by the revs they must go for, for power to compete against a 2t, at least for now. Though, Moto 3 rules (well, the max. bore rule of 81mm - shared with Moto 3 - is a somewhat of a 'control' in Moto GP) , are keeping a cap on revs.

But, as I wrote, there have been, and will remain to be, quite a varied opinion on what bore / stroke ratio is 'optimum'.

One Engineers "Optimum", will be anothers "Dud".

I gave the Evinrude dimensions as an example of what has been done, with a certain, pretty successful application of DFI  2 strokes.

I'll have to have a squizz at what the 2t Snowmobiles tend to use. It may be comparable to the
Outboards, as they may be more of a 'steady state' engine than a Motorcycle Engine ( but, I'd think, less so than an Outboard) would be. It, of course, may not be comparable, at all.

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General Two Stroke Talk / YZ 250 EFI

« on: September 02, 2013, 06:32:45 PM »

And then you get the various 2t Trials Bike Engines - most of which are quite oversquare.

Yet, they are Torque / soft(er) power oriented.

Optimal bore and stroke - it depends on a designers particular 'bent'. And each and every bloody one would argue furiously for their 'optimal' ratio.

Maico 250s, for a few decades, have had the 67 / 70 bore and stroke. My 320s had 76 x 70. When they had 72 stroke, and abandoned it, I have no idea. They may have 'pioneered' it, but they  sure didn't stick with it.

Maicos fabled 490 /500 engines, were never a square design - both being a slightly oversquare engine. I think the one '500' that I know of, with a 'square' engine, is the KX500, at 84 x 84. Though, I'd not be surprised to be informed of other '500s' that are square engines.

 Open Class 2t MXers, had such a surfiet of power and torque for their times, they were bouncing around with inumerable bore stroke ratios, when they were common.

4ts keep going for more and more revs, for getting their HP. So, more and more oversquare.

The 2t design, is so interweaved within itself  - bore / stroke / crankcase volume / porting as making up the whole induction, and exhaust cycles, as to be incredibly varied in how it's done.

Someone coming out with "this is optimum", I just think of as one who has picked his 'favourite' - or, is subscribing to their particular worship of  a designer / brand / model.

There is quite some arguement that 2ts will go to more oversquare engines, especially with such techs as DFI, as the fuel component of the charge, will be less dependent on the 'whole engine' concept.

I think, for quite some time, the Evinrude E tech outboards have been based on a fairly oversquare ratio. It seems to be 96mm x 76mm for the V6s, and 91 x 66 with the V4s and inline engines. Of course, these engines are used in a much different context.

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General Two Stroke Talk / Honda AR PDI Two Strokes

« on: August 09, 2013, 02:24:03 PM »

It's an interesting design but the forced air induction make the bikes illegal to race. Although Honda have a way of getting thier own way nearly all of the time...

There's an American company Ecotrons that sell EFI fits for bikes and other small engines. They have a 2T kit which run two injectors in front of the throttle body. I look at them once a month or so and think....?

It is no more "forced air induction" than Any EFI / DFI set up out there, on most cars, trucks and bikes. There is pressurisation, through a variety of means,  of any Injector unit. The main air charge comes in through the reeds, into the cases. Though, the base drawing does make me think that it may have had an 'air purge' arrangement to it. The earlier EXPs, ran with carbs, and an engine that was very much based on the architecture of early 500s. Then, as can be seen in those pictures, it became something   quite unique. The CRM250ARs, ran with a carb. And you can find them in the various bike classifieds here in OZ, pretty easily.

It's conceivable that the entire fuel / air charge could be delivered purely by the injector unit on an ICE unit, but it's almost completely impractical, and truly complicated and expensive to do so on a bike. The sort of expensive, complicated and heavy, that so many people are scared of - and, in that case they'd be right. But, it's not something we really need to 'worry' about.

DFI / Whatever Clean Tech, that companies have,  is in road going 2ts future, simple as that. The date, now appears to be 2017 for us to see it, if that remains the Euro ?? standards introduction. I'd like to see it sooner, though.

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General Two Stroke Talk / YZ 250 EFI

« on: July 14, 2013, 10:20:00 AM »

I really see no risk in doing modern 2ts, that will pass legislation. Or ones that may not, such as just pre reed EFI, with regards to MXers. Most solutions are being sat on, and the placing of a 2t in an existing 4t chassis, can be done at minimal expense.

If you , Uniflow, can do a EFI 2t - that is far more sophisticated than just the placement of an 'electronic carburettor', which is so prevalent now, as to be of little expense, it's not much of an ask, for a major manufacturer to put such basic tech (I emphasize the 'electronic carb, that EFI basically is - not your impressive transfer port / case injection efforts) on a 2t.

  Frankly, I think the   Biggest Risk for manufacturers, is to not make a return, at least partially, to 2 Stroke production.

Rotary Debacle? With relation to bikes, Suzuki's RE5, Yamaha's never produced Rotary ( and their never produced, road going inline , pistoned Four cylinder 2t that the TZ 700 /750 were supposed to be 'race versions of, for the F750 class) Van Veen's OCR(?), Hercules / Sachs , Nortons  (great track record, for such  small operations, in both Race teams) Rotaries, were not debacle, just a branch of motorcycle engines, that was barely touched on. I know bugger all about the car market, but I don't recall lots of manufacturers, going for Rotaries, and losing their shirts over them?

 But, I may have easily missed such a 'debacle' - as I said, I'm not particularly car orientated. Two Wheels have always been my passion - 4 or more, transportation, is all.

It's funny, my little suburb against the mountain, seems to have a bit of a RE(?) 8 cult  going - I know of at least 9 of them being nearby  ......... I love how my  two V8 worshiping / Drag Racing brothers nearly foam at the mouth at the sound ( or even sight) of them! 

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General Two Stroke Talk / YZ 250 EFI

« on: July 14, 2013, 08:57:41 AM »

.

I still have a bit of , faith in Yamaha - they at least have kept producing, and supplying to most world markets, 2t MXers. I live in hope, that the company that put reed valves and good porting into their production 2ts, of all types, over 40 years ago, then the single shock, and so many other things - including having the balls to mass produce 4ts that were not Foo Foo bikes, will be the first Japanese manufacturer to give us a modern 2t.

You may be right. My local Yamaha dealer told me the other day that Yamaha was bringing out a EFI YZ250 for 2015.
Who knows if it an internet rumor or not. Would be nice to see it happen.

Just give thought to the sort of sales Yamaha would get from such a bike. Just for a moment, cogitate on it........

They've made serious profits on the current alloy framed 125s and 250s, with the prices they've charged. They've 'milked' them for all they're worth, for many years now. If they didn't "go the gouge" on  'EFI / DFI / whatever the bloody things turn out to be', New 2ts, They'd sell a Lot of bikes. And that's what you'd think they'd want, in these straightened times for bike sales.

Hmmm, I wonder if they'd apply the reverse cylinder idea to such a "dream bike"? It would be logical, with their 4t MXers having gone that way. I, personally, think it's a very good set up (too many Drongos have equated JS's record on the reverse 450 as it being his "problem" - well, I guess the RMZ is a "POS", too?), that would enable so many benefits to 2ts. Tiny little Ossa, showed a great template for future 2ts. Just getting the pipe out of most harms way, would be a great thing.

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General Two Stroke Talk / YZ 250 EFI

« on: July 14, 2013, 08:11:27 AM »

The Japs are a very proud people and will not admit that maybe they got it wrong.
Jumping on the green band wagon was very easy for them to do and now the hole they have dug is rather large.

You're not wrong there, on both points.

I still have a bit of , faith in Yamaha - they at least have kept producing, and supplying to most world markets, 2t MXers. I live in hope, that the company that put reed valves and good porting into their production 2ts, of all types, over 40 years ago, then the single shock, and so many other things - including having the balls to mass produce 4ts that were not Foo Foo bikes, will be the first Japanese manufacturer to give us a modern 2t.

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General Two Stroke Talk / YZ 250 EFI

« on: July 13, 2013, 03:53:32 PM »

Imagine what Yamaha or Honda could accomplish if they threw their engineering department and half a billion dollars at it! Honda made good two strokes, whether they admit it or not.

The thing is, 1/2 a billion is not needed. Not even 1/2 a million would be needed for development. As I feel it's just sitting there, gathering dust, in quite a few company archives. Of course, you've then got tooling up / manufacture costs, but strict development costs, from right now .....

Yamaha have their DFI sorted in their Outboards - it, as it stands, may, or may not be suitable for bike use. Honda, you can guarrantee, have every damned aspect of 2ts sorted - and probably from a lot longer than decade and a half ago. Just their AR tech, could have been applied to real performance applications , and not just the Asian (and later, at a tiny scale, Australian ) trail bike / dual sport market. AR, with an electronic carb (EFI) - since it's got so cheap it's now on Postie Bikes (saw the new ones the other day - Wot, they are Green and White, not Racing Red?      It's just not right, I telz Yuz  ) -  would probably pass "whatever" these bloody Euro 3 specs are, whenever (2017) they bloody well 'have' to be met ...........

No, Honda = All Four Strokes, All The Time. Therefore, Honda, can well and truly, go **** themselves. 

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General Two Stroke Talk / yz 325

« on: June 26, 2013, 10:48:43 AM »

The PV is interesting.

Just a mod for easy changing of spring pre-load / perhaps spring weight, and a damper / adjustment of the air pressure related to the std PV, Or a different power valve entirely? I'm not that familiar with the 'look' of a std YZ 250 Cylinder, to instantly know of any differences with this ESR cylinder casting.

I'd love to know.

At that price, it puts it at the level of a 300 KTM OEM kit . Seems quite a deal, to me, especially as it retains a power valve, when many big bore kits have, previously, done away with PVs. Steel liner / plated liner - either has it's merits / demerits.

I dearly like to have an adjustable power valve on my 500 - and I intend, one day to fit one to it. My experience with pressure actuated PVs, on my Maicos, years ago, was great, especially after I made an alloy top plate, with pre-load adjustment and tried out various springs. The only problems I had, was with the diaphragms, when I went a bit too far with things. Simple, easy to make PVs. On the CR, I probably would have to raise the cradle tops / go to double down tubes on the frame, which is a simple thing to do. Though, I have given thought to using, say, 2 KTM 65 PVs, to widen the exhaust port, or give it adjustable outer 'eyebrows'. It's a way off, though.

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General Two Stroke Talk / YZ 250 EFI

« on: June 26, 2013, 09:28:26 AM »

 Yes, too many say things are impossible.

It's just curiosity - I'm not having a go at you for being secretive - though you'd have Every right to be so. You've enough on your hands, and have shown an enormous amount of your work.

When I see the injectors into the rearward of the transfers (3? - I don't know the configuration. of the YZ barrel, just thinking of the most common transfer set up) I think of the shrouding that it might create if the transfer splitters are there still (goodness only knows) as std, or if a long extension of the injector is used to get the charge point out of the one transfer, into the crank / lower case area, thence it doing the 'usual' routing of the charge. Then thinking perhaps, you are locating the main charge in the rear transfers,  using that shrouding, to have the forward transfers predominantly as an 'air' charge to block the fuel charge from exiting the exhaust, like a version of AST.

Yep, my imagination can go wild.................

Cripes, you're brave if you are going to try to run with no premix (re oil metering), although I think you are doing the oil metering to the mains / big end (little end?) Then using a Very Lean premix to lubricate the piston /rings / barrel (little end?)?

Just rapt at your efforts, fascinated by what you're doing, yourself. Not getting others to do things for you, and just doing a Cad Drawing and dimensions. A Doer, as I said.

Geez I Hate praising Kiwis, they're a 'Orrible mob of bastards................... somethings gone 'wrong' with me, I'm finding that funny little comedienne, Cal Wilson, quite attractive, nowadays............ I'll be deported soon, for being too tolerant / fond of Un Zudders. 

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General Two Stroke Talk / YZ 250 EFI

« on: June 24, 2013, 11:02:55 AM »

Just Brilliant!

I'd very much like to see the injector set up, from inside.

Looking at it positioned in the first transfer 'ducts', one could think it's just injecting into that, but, of course, you could have it with a long feeder deeper into the cases, or going to the boost ports, or,  well, anybloodywhere.

 And, of course, you have every right to keep it to yourself.

At first, I imediately thought of the Bimota 500 debacle, with transfer port injectors. But, that was 15 / 16? years ago, rushed into production, and I'd say Any software / hardware has gone through more than few generations of development.

I know you've got a lot on with this, and you're doing a brilliant job ( Bloody Kiwis    ), but have you, are you giving thought to a third injector, in an 'in manifold' position? Or, in a "in side of barrel", projecting up to the combustion chamber, as in the Athena and the secondary Ossa Injectors. Ossa have said that to get the power they want for the Enduro / MX version of their rearward sloper, they are going to at least 3 injectors.

As I said, this is brilliant stuff, it's fantastic to see a 'Do-er', doing.

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General Two Stroke Talk / Donate to the race team!!

« on: June 12, 2013, 12:23:30 PM »

I just put in $100. It may help to pay for a little bit of fuel.

Come on people, it's time to put your money where your mouth is, and financially support the effort put in by Charles and the people helping him.

I wish I could give more, and I'll try to contribute further in the next few months.

Pull your fingers out, open your wallet, and do a bit more than just write about how great Two Strokes are.

Or are most of you just blowing smoke up each others arses?

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General Two Stroke Talk / KTM Fuel Injection.

« on: June 08, 2013, 09:42:45 AM »

That they have said for the last few years that they would not introduce DFI / EFI / whatever they have ready now (well ready for the last few years), has been common knowledge for years now. That, is nothing new, at all.

The cost / complexity and difficulty of service, sound like a load of horse **** to me. Unless they have developed a ridiculous system and /or are paying someone like Orbital crazy licensing fees. Pumps etc mentioned, hints that they've done a high pressure , in head system, such as Orbitals, that others have used.

High pressure, in head DFI - not really the best solution for a 2t. There are other ways to do it, that are simpler, and cheaper.

Pierer made note of BMW / Huskies interesting 2t tech they had in his main interview with Alan Cathcart, as being of main interest to him with Huskies future - I was surprised it was part of the purchase, but it must have been.

Perhaps they are going back to the drawing board, and they have had their eyes opened by seeing and acquiring something much better / simpler / cheaper than they had developed. It wouldn't be the first time that a company and it's engineers, became so self involved, that they stuffed up right royally.

If a tiny, re-start up company like Ossa can do a superbly working   EFI - I've ridden the bike, and it' 'carburates' superbly, and starts easily, the drongos that are having problems with respect to starting, just aren't doing it the way the bike requires - a much bigger company such as KTM should do better, with whatever they have developed. Perhaps they haven't. Classic

 Sauer may just be protecting sales of 4ts. They've sunk multi millions into so many 4t engine designs, that, whilst they can still sell every ancient 2t they produce with Big Profit margins, why bother putting out new 2ts? So, BS a fair amount about the "costs" of a new 2t.

I'd really hoped that BM / Husky would thoroughly gazump KTM with regards to 2ts - well, it certainly won't happen now, with KTM getting their hands on Husky. Lets hope that some other company(s)  'c o c k s  their leg' on KTM, and not just teeny tiny Ossa.

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General Two Stroke Talk / Courtney Duncan WMX at Hangtown Qualifies 1st on a YZ 125

« on: May 24, 2013, 09:59:32 AM »

A short vid from Hangtown that shows more of her:



Lets hope that the other women now step up, and try to match her - JP and others have been either cruising for a few years, or they have reached their personal best. Tara Geiger and a couple of others, were in Spain for the Enduro X, but she / they would not come close to Courtney.

I do hope she is not ignored for being less than a 'glamour girl' - I've long thought, that besides the stagnant level of WMX talent in the US, Ashley Fiolek got a lot more attention and backing because many males would think she was 'cute'. JP , I think, suffers from the 'non glamour girl' syndrome, I believe. I don't give a flying f*** about that sort of thing in the athletes I admire ( though I like a good perv like most blokes), and I've never been more impressed by AF's genuinely great accomplishments by her being being deaf.

  Stusmoke - you're an OZ bloke, aren't you? And you haven't heard of Josh Coppins? If you follow MX - well, at least a tiny bit of the GPs and OZ MX, you would have heard of him. Hey, I'm the first bloke to put my hand up and say I don't very closely follow OZ MX / MXers, until they get to hell out of here, to go for other, bigger things, but if you are an Aussie - or one of those 'orrible Kiwis', his name has been thrown around for years. Strewth, I think even the mainly inward looking Americans, may have heard of him............

As for your comment :   "My concern is though, the extraordinary amount of ammunition this will give to the AMA and by extension the big four to say that DD is fair."   I too. share this same concern.

She'll have to race back here in the Antipodes, the be allowed to race a 250 2t, against 250 4ts - though, I think Loretta Lynn's allows equivalency? - She'll be on a 250F though, if she goes to a 250 - it's how it goes. Though, I'd love to be wrong on that.