scootergangbang

[ In an effort to verify my own findings (and experience) I obtained what a current Japanese manufacturer uses as an ignition curve on a 125cc two stroke engine. See attachment.

Yes, I most certainly have strobed them all. I spent quite a bit of effort making templates for the cases to measure the degrees. I admit it's not the most scientific, but it certainly is better than I have had access to before. I had 2 coils sent from a from home, that originally where on Yamaha and a Suzuki 50cc "twist and go" style scooters. I could not find any information on what the factory claimed these ignitions curves where (Even calling shops in the UK, they didn't have a clue what I was talking about) Both these where identical at 14 Degrees I also got 2 brand new items from "elsewhere" that made no claims whatsoever regarding ignition curves, but strobed up at 20 Deg. and 22 Deg One I got from a local scootermatic shop (origin unknown) and it was 7 Deg. I have looked (vis the net) for suppliers of "performance" coils, but I have been unable to find any manufacturer who claims anything. The interesting thing is there was no perceivable difference between the 7 deg and 14 degree coils, but the 20 deg coil has proved (on every occasion) to provide significantly more "over-rev" Granted, as you point out, cylinder head and exhaust design are "significant" factors in such results (To be truly accurate I really need to test a variety of engine setups), but (so far) I am finding that, like on most Japanese two strokes, (high revving ones) more than the current 7 degrees retard seems to be advantageous. Again, it's not very scientific, but (from my experience) it seems that the smaller engines benefit slightly more from this.

Hmmm, ok I don't work for my previous employers now, and don't have ready access do a dyno as before, and subsequently testing is all done on the road. Previously, I to, had found there where no perceivable gains in deviating from what seemed the "tried and true" setting of 17 Deg Admittedly, all the previous tests had been done with standard "PK" style ignitions. While attempting to find an "absolute value" for "retarding" ignition systems (just using road testing, primarily on a slight incline) it has become apparent that there are tangible gains with larger amounts of retard. At first I suspected this was simply because of the lighter flywheels such systems provide, but "blind" tests of different coils (providing different amounts of retard) indicated that there was "real" gains when the engine had more retard than the standard 7 degrees most systems provide.

I have spent the last few months playing around with different retarding ignitions on Small Frames (of varying manufacturers), and I also have found large variations in the static point (up to 10 degrees sometimes) certainly I would never take the settings for granted. I'm curious too see if anyone has experimented with coils providing different amounts of retard. Depending on the manufacturer they seem to vary from 7 degrees to 12 degrees. I'm quite familiar with the concept (as to why it's required), but I have been testing different coils (using various Japanese "scooter matic" coils) and experimenting with larger amounts of retard that the current systems available. Has anyone else experimented in such a way? Just from my experience with 125 and 250 GP bikes even at the sort of RPM a tuned Vespa is operated at such engines require alot more retard than the current ignitions provide. My (semi scientific) testing seems to confirm this.

What sort of cylinder head are you running with that engine?

I don't. There was interest in the new cylinder, and for that reason I thought it prudent to write a little. I am only stating facts. The exhaust is a very good one, not EXACTLY what the new Cylinder was developed with (but reasonably close). I have seen 3 PS gains on Plug and play Quattrini cylinders (compared to other exhausts), and 2 PS on well set up Mallossi's. They are quite noisy, but certainly a good "sports" expansion chamber.

My translation needs updating eigenentwicklung (Deutsch) self development (english)

Yes, quite right, however Chris, the exhaust is not your design. To claim it as such is untrue.

Hmmm, O.K, with-out trying to turn this into a German lesson, I have had it translated, it would appear that he claims the Exhaust is his creation, (correct me if I am wrong). If that is the case, it also is an untrue statement.

As the revised Cylinder arrived from being produced Vietnam (plug and play), so to speak, with a franz exhaust, it produced the following results. (see attachment) Quality of finish is quite good (in my opinion) After some further work (testing of which was not available on the original prototype (due to liner design complications) as well as the new exhaust, power is typically 23 PS and 19 NM (no graph of that I am sorry) Its not much work to make over 25PS......(and still no "squish" heads are used.) It would have been interesting to use a head design concentrating on MSV......., as well as an ignition that had some retard......... it's all academic now I suppose!

You're full of shit Chris. I ported your cylinder for you.

Its just ascreen shot saved on to my mp3 player, then posted here. I assure you. If thats what it shows, so be it. I changed nothing.

I see, I havn't really the desire to develop a cylander that competes with the Falc, far more intelligent and experianced people than me have said it is better than they could make. I have now had a reasonably good look at one "in the flesh" (so to speak), and could never speak negatively of it's finish etc. To show my lack of product research, I have never heard of the m1l , but will (slowly) read what is posted on this forum. (It may take some time.) I take your point (reguarding the finish & performance vs price comment), noting that the, I guess you could say "competition" is similar in performance, yet the fact that it is a plated Aluminium cylander, would suggest it is quite superior. I appreciate your advise on the cylinder head choice, and I have simply re-machined (and o-ringed) a Polini head (as that was the best available to me), no leaking (to date) I guess my "lack of development" in that area would have been motivated by condition of several "tuned" engines (built by other people) that I have seen in my tenure here, that have simply detonated them selves to death. We do have a lathe, but unfortunatly, it is only good for sharpening pencils. You advise on operating a dyno is noted, and assure you that all runs are as consistant (as can be), and I do multiple runs before making alterations. Reguards

Thank-you again for your comments. I concur that a "Dyno is simply a tool", and must be treated as such. I had overlooked checking such things as the accuracy of the correction factor, as past experiance shown that I had no need to query it. Point taken though, the way I took it, was that I was "fudging" the factor to obtain the figures I wanted. It seems very easy to misconstrue postings (again, I have no experiance in internet forums of any kind) I assure you that I have more runs (I do not post them all), with even higher figures, as I make changes daily, and I see a few do have the incorrect correction factor. If anyone knows A) why this happens, and B) how to avoid it, please feel free to tell me (if you feel so inclined) In any event, I have attached a run from last night, and you will notice all correction factors are correct. Though I am sure it was colder than 7 deg!!!!! I do read all that you write, and agree with the things you point out. Please be aware that I have VERY limited resources here, and to change the combustion chamber shape (as well as the 12 other heads we have) is, at best, a mamoth task. On a slightly different tangent, after speaking to Tom and Wolfi this morning, (and asking for some more resources $$$$$$$), the response was that while there is still alot of potential that could be released, the figures are what they wanted, and as the production is still a simple process (as it does not involve a complete new casting, only a different liner), then we can now head towards producing a 20hp aluminium cylander (almost) "plug and play". Be that as it may, I still have another cylander (125cc) I am working on, and, for my own benifit, will develop that to the best of my abilities, as after a conversation with a guy from this forum last night,(which was very much appreciated, as many things both reguarding small frames, and the politics surrounding this, and a few other topics was explained to me) I would enjoy seeing (and competing) in some of the endurance races they have here in Germany. Before this conversation (based only on the experiances I have here in Ingolstadt), I would never have believed a 22hp cast iron cylander could be raced full throttle round a F1 curcuit......my thoughts on that matter have been completly changed, and look forward to seeing this for myself (not from pit wall though, rather from the seat of a competing bike), and all going well that could well happen. What is an S&S pipe, I am sure you don't mean the famous twin cylander tuning company in America? Or am I again missing something here?

Firsly, thanks for the info, I will read it in time. But, too call the Dyno into question? For you, my friend, I will now go down that cold, unheated workshop, reassemble the bike, and do a run for you. Such is my dedication!

Well, that's ok, but lets keep it on the frindly side aye? I am new to Forum postings of anykind, and yea, enough said! But Please do not think I am cheating the Dyno........ We have no Dyno room, we have an unheated workshop (faster slave, faster), and the degrees at the moment are between 14 and 8 deg! I assure you of this 100% I have nothing to gain by artificially bolstering the curves.

Ok, am interesting thing has occurred here! Sometimes what is written in books (or on the internet) can not be taken as gospel "Dubious at best" does not mean "impossable", and thankyou for not out right dissmissing it! I have indeed run a GPS cylander with .68 squish (this is equall to the lowest squish I have ever run), and YES, the piston touched the head (surprise, surprise), but, no, the engine did not detonate. I gained torque, but obviously the engine would not rev over 7500 rpm (if you are intetested, I can show you the curve some other time) 4 Years ago I ran a UCCR of 18;1, while using ELF Super high octane (I can't remeber all the edetails of this fuel, other than 40L cost me around $800, and the fuel was oxegenated. The Australian rep for ELF told me I could run over 20:1 UCCR with no detonation. Ok, the race went well, and I had more torgue than ever before, however, the air pressure dropped (rain was about to come) and my DET counter went MENTAL. I finished (after dropping 3 places in the final laps in the last 4 laps (of a 25 lap endurance race) and the power went off BIG time. I finished after dropping 3 places in the final laps, pulled the head, and, well, you know the rest! Also, on another tangent, the moisture level of fuel also has an effect on detonation, all the more reason to play safe on a road bike. Would you agree? The bike that springs to mind for the 2 cylinder 2 stroke example would be an 89,90, or early 91 (ie, "reverse cylander") Yamaha TZR250 road bike (not to be confused with the TZ250R race bike) THe measured squish is 2.2mm This bike was also a nightmare, and would detonate with out any visable cause. The solution was too richen the main jet (and lose alot of power in the process)

oh, and also to reply to your squish/cr question- in a two stroke engine, compression ratio selection will have a large impact on the generated squish velocity

I'm not sure that I have modified my statement, rather clarified it, but, lets see anyway aye! Hey, 30hp is good for you! Maybe with some wime, when I finish the devlopment of the prototype (with the limitations I have reguading rideability, etc) How says this cylinder will only be available here ( Nz only has 91 octane for example) Lord only knows what they have in Vietnam! Do gernman petrol stations advertise the MON, or RON? But, lets not argue semantics please! I think I stated that the 1.7 mm squish engine was a development engine (which incidently has been sold to a customer, who is very happy), as we now use 1.33, with very satisfactory results. 2.2mm is common in performance water cooled twin cylinder strokes (which incidently all use power valves, and electronically controlled power jets), as well as digital ignition timing. This is done purely for reliability, yet, these machines, easily put out 30hp (per cylander), in standard form (emmissions gear fitted etc) Yes, squish increases will primarily affect low rpm power, but, for example, what happens if the air density increases dramatically? Get hold of a Det counter (under plug models are the easiest, and getting quite cheap actually), run the highest squish you can, on a hot day, in the middle of summer. Using the same set up, do the same on a foggy, misty day. What does you det counter read? more than 3 dets per 2 KM? Uh, oh.........

Very insightful words. Firstly, I am not Vietnamese. I am from New Zealand, my grandparents are from Ireland, and have infact never been to Vietnam. I agree with alot of what you are saying, (other than the poorly chosen words reguading my ethnicity) BUt thank you for your input. Please, no-one refer to me as being Vietnamese, I am, and have always been a Kiwi! Thanks!

OK, The important thing to remember here, is that I do not hink that the Falc is a COPY of the Honda cylinder, it just uses technolgy learned from their cylinder/and exhaust. The picture I first sent (of the section of the exhaust) is a prime example this was designed by honda, and has a 1HP effect on the output if you remove the protrusion (as myself and many other people did when it first came out, (thinking that it was a manufacturing fault). I have seen this same section on the Falc exhaust. Honda deveolped it, and now almost everyone uses it, Derbi, Yamaha,Harkpro,Arrow, almost everyone. To be honest I don't even know if Honda invented it, it might have been some polish guy in his garage for all I know, but the fact remains, Honda where the first to implement it (to my knowledge) Now, in reguards to the cylinder comparisions I mentioned, the RS125R (which is a gp race bike, not a road bike) was based on the MT125R, which is how honda learned their development skills with "high port "Big Bang" two strokes (sorry, I don't know the German terms for these "buzz words", and is a CCI (crank case induction) cylander, so the port timings cannot be compared, but it is the development lessons that they discovered which enable us all to learn from. Basically, what I am saying is that if you gave a Vespa frame engine to the HRC department, they would start with something thay already know works, adapt it, improve it, and make it! Also, no one here has re-invented the wheel! Do you notice from the pictures that the inlet port shape of the Falc is the same as the 80's Yamaha, and the transfer boosts are the same as the old KTM picture? It's a good example of the fact that Mr Falc ( I guess that is his name) is a DEVELOPER, he has not changed the laws of physics, he, from what I have seen has a wealth of experiance with two stroke DEVELOPMENT (more than me) I am not trying to call his product to questuion, and indeed , from what I see his cylinder is "the standard" of competition cylinders for smallframes. The GPS cylinder is a road going cylinder, it has no welding on the cases, and the transfers are only matched to the cylinder. My instructions for this where clear! This cylinder has the design brief of a cylinder that will work well with any of the current ROAD exhaust systems available today (eg Hammerzombi,Franz,pm,), with the customer choosing the size of Carb that they want, and not have to change the ignition timing, squish, Copression ratio other than the first time they fit the cylinder. As close to "PLUG and play" as possable! In short- a cylinder you can ride evry day, do the occasional quarter mile, perhaps a scooter race or two, then home! Ok, not an every day occurance, but you get the idea! I am trying to record as much data as possable (something I learned from racing), so than, with the values I know work while still being reliable as well as having competitive power. Hench 1.3mm squish, opposed to .9 Yes, that would enable me to make more power, but experiance tells me than if using "pump fuel" this will make the bike "peaky" on a trailing throttle..... not a nice bike too ride slowly aye?

Ok, It is too hard for me too reply in German, but with time, I can read the majority of your comments (it lust takes a while!)\ Firstly, I would like to say that nothing insulting was intended by calling it Geman Nerd forum, and was simply "tongue and cheek", and not meant to insult anyone. A bit of Kiwi humour gone awry I surmise! To anyone that has taken offence, I appologise wholeheartedly, and will refrain from doing so in the future. I guess it is a lesson for all, not to let this get personal aye? I for one will refrain from personal attacks. I was asked to provide proof that the Falc cylander (for exampe) is simply a development, adapted improved version of other companies work, I provide you with the following examples. Pic 1, shows a Yamaha inlet port, from the mid 80's Pic 2 shows a Falc inlet port (sorry, this is the best I can find) You will notice Startling similarities the shape of the port (with no bridge!) next, Pic 3 shows a KTM inlet, with Boost ports above the main inlet port (which have absolutly NOTHING to do with the Patent referred too previoulsy!), as well as direct transfer boost ports! Now, the final pic, is the UNMODIFIED, as "out of the box prototype cylinder" (note spelling!) note the inlet only "Boost ports" (which in the current cylinder I have changed the angle), no Transfer "Boost ports" (yet) , and bridged inlet, with basic window shape. In the 22hp cylinder, this shape has not been altered at all, and is the same as this picture. The exhaust port we currently use, is, however very different to this (or the falc), and I will include this development in the latest cylinder design (which by the way, starts on Monday afternoon!)

Yes, the current mock up is 125cc, with enough room for rebore(s) Obviously there is a huge shortfall in the service life of the current cylinder!

Oh, so the German Scooter Nerds are ganging up on the poor Kiwi! Oh well, I can hack it! I believe you have a Falk system? If so, do you recognise the highlighted section here?

Consider it done!