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Thread: ESE's works engine tuner

  1. #32551
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    27th October 2013 - 08:53
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    Quote Originally Posted by Michael Moore View Post
    peewee, did you peen the hole shut or give it a quick burst with a TIG welder to melt it shut?
    i welded it shut with tig then used dremel bits to grind and make it smooth. 1/16 " blue tungsten . 135 amps on the machine then use the peddle according to what you need for the part. 1/16 4043 rod, 1 or 2 small dabs is enough. about 15cfh on the gas i think. 140freq. 65 balance. preheated the pistons alittle in the oven. take caution near the edge of the piston so it doesnt blow off.

  2. #32552
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    peewee, you from the USA, what is their obsession with this RK tech wrinkly squish area head? How is it supposed to work? Looks like a real bad machining job, chewed out.

  3. #32553
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    Quote Originally Posted by AndreasL View Post
    Frits or anyone with interest, going through your (Ken)-pictures I found the suggested pipe for the Trabant. One can see that you have opted for a straight header section.
    This is in line with my own thoughts trying to not over scavenging my old (50cc moped designed in the 50-60:s) engine...
    As a general rule of thumb, should you suggest to start with a straight header and go from there with antic designs like this?
    A friend with the same type of engine have tried all types of pipes, the last one a modern thing from a scooter. Way to extreme I say and I think he confirmed it with “more revs...but terrible dip, with fuel reversing out the carb, just before a final rush of power”.
    He is at 190/131 duration so my take is that the “already too good pipe” even worsen the negative 2/3 of max hp-rpm dip and is even more pronounced by having optimal timings?
    You are right about about the exhaust timing, Andreas. 190° is just about ideal for a pipe, but the more effective a pipe is, the more it can, and will, mess up the torque curve below the power band.
    The transfer timing plays a role too: the higher the transfers, the bigger the risk of wrongly-timed exhaust return pulses entering them.

    You also have a point about overscavenging antique engines, but my main reason for giving that Trabbi pipe a straight header was much simpler: conical headers would have such a shallow angle that it would have been a lot of work to make them, for very limited returns, if any. And since it is not easy to fit two looong pipes in that little engine bay anyway, I tried to keep everything as makeable as possible, which included the possibility to bend the headers instead of building them from segments.
    Click image for larger version. 

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  4. #32554
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    Quote Originally Posted by ken seeber View Post
    Frits very generously gave me a library of pics... I say generously, as this collection is a product of many years of his association with, and just good old passion for, something we are all here for: the 2 stroke... the generosity was not to just me, but everyone here. Enjoy. https://drive.google.com/drive/folde...of?usp=sharing
    I collected those pics over a number of decades, initially for my personal use, so I never worried about copyrights. All pics marked with F©S were made by me and I hereby declare them copyright-free, but not all other pictures were, so you may want to give this a little thought before using them for publications.

  5. #32555
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    7th October 2015 - 07:49
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    Quote Originally Posted by Michael Moore View Post
    Ken and Frits, thanks for making that material available, I'm looking forward to viewing it.


    Does a typical modern 64-68mm 250 MX piston usually have enough material around the wrist pin to allow boring to take a 20mm pin instead of the common 18mm pin? I'd think that the strength concerns are at TDC when the pin is trying to pull down and out of the piston; BDC would have the pin forced into the body of the piston.

    I suspect they may start out with a fairly generic casting/forging, but I don't know if they get trimmed on the underside of the piston below the pin (to save weight) enough to not leave sufficient material. Would it be a good plan to offset the new bore upwards so it just cleans up the bottom of the original bore and so removes minimal metal below the pin?

    Any thoughts as to what is a good number for a safe minimum thickness below the pin for high RPM use?

    thanks,
    Michael
    Michael, usually, for two stroke cycles, under pin material thickness is strong enough to hold things, even with weakened area for bigger pin. But for the cast pistons, all kinds of vibrations and detonation can propagate small cracks at weakened area.
    Early Honda RS 500 triple pistons had 18mm piston pin and was prone to cracking around skirt, but later reduce to 16mm.

    With forged piston you can do what you want…. Once at testing with 125, at 12000rpm , engine suddenly lost power accompanied with some metal sound, but engine still spinning, so return safely to home, 2 km , in first gear at 5000 rpm.
    Take off the cylinder and cant believed. Short piston pin was hanging only on one side of piston eye as pin moves out because I forget to insert circlip. Results was that this forged piston pin eye ( 3.5 mm thick under pin ) was deformed and enlarged from 15 mm to 15.6mm, but not broken, after this 2 km riding. Cylinder left with typical rails on trans side.

    Maybe, is it possible to find bigger small end bearing.

  6. #32556
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    7th October 2015 - 07:49
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    Quote Originally Posted by AndreasL View Post

    A friend with the same type of engine have tried all types of pipes, the last one a modern thing from a scooter. Way to extreme I say and I think he confirmed it with “more revs...but terrible dip, with fuel reversing out the carb, just before a final rush of power”.

    He is at 190/131 duration so my take is that the “already to good pipe” even worsen the negative 2/3 of max hp-rpm dip and is even more pronounced by having optimal timings?

    Once boy asked to help him prepare Yamaha Airox air cooled 100cc for scoot racing just two days before event. The only part that he bring , together with original scooter, was nice racing exhaust. After all usual work on engine was done until the evening, before next day race, he came to test and when return said that power just little bit better. After so much was changed, engine goes just marginally faster.
    There is no time left to play with ignition and all variator/transmission stuff , so I ask him bring back his old rusty original exhaust and he was even more embarrassed.
    After test riding he returns on one wheel, with a big smile. It was another engine.

  7. #32557
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    24th January 2014 - 08:12
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    Quote Originally Posted by OopsClunkThud View Post
    Question about tuning for longer engine life:

    I'm building a Lambretta engine for endurance road use and bucking the trend of trying to get as much displacement/power as possible. I need to be able to do 300 mile days for several days in a row. I know I'll have to give up power but I'm also thinking that the power itself is not the cause but the effect. I'll be sleeving an aftermarket cylinder back down to a stock 175cc but the sleeve also gives me the ability to set the port area, timings, and angles as
    This sounds like a question for me!
    The issue about Lambrettas is the super small transfer area since they got an asymetrical stud patern. Usualy, you get transferports worth for 80cc combined with exhaust area worth 150-300cc. The flow patern on the aftermarket cylinders are also not that nice & the cylinder is twisted somewhat 12° to the crankshaft & it is super hard to get a decent inlet, since the frame is limiting the inlet port.

    In short: Tuning a lambretta is trying to win a horse race on a donkey.


    If money is not an issue I would buy the killer case https://www.sip-scootershop.com/de/p...case+_22010190 combine it with a SIP crankshaft and use the simonini 230
    https://www.sip-scootershop.com/de/p...ini+2_78246200
    or simonini 270 cylinder
    https://www.sip-scootershop.com/de/p...ini+2_78246210
    This will give to best powerband with VS fuel consumption.

    There is an other case (CasaCase from Casa Lambretta) which is made for superwide crankshafts. I am currently working on one to get it flying (Rotary Inlet). See pictures here:
    https://www.facebook.com/Overrev.me/?ref=bookmarks#

    On the ignition I would suggest you use an Overrev Ignition (designed by me ) which you can get here https://1537118469.jimdofree.com/deu...-z%C3%BCndung/ If you want one, write me a pn

    Regards
    Tim

  8. #32558
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    17th September 2013 - 01:07
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    Quote Originally Posted by Frits Overmars View Post
    You are right about about the exhaust timing, Andreas. 190° is just about ideal for a pipe, but the more effective a pipe is, the more it can, and will, mess up the torque curve below the power band.
    The transfer timing plays a role too: the higher the transfers, the bigger the risk of wrongly-timed exhaust return pulses entering them.

    You also have a point about overscavenging antique engines, but my main reason for giving that Trabbi pipe a straight header was much simpler...
    Thank you for the answers. Good you mentioned the transfer timing as well. Perfectly logic, but I didn’t think about it.

    Every design is a compromise. In racing, the one with the best one often bets the ones doing something extreme (in one or a few areas).
    So sounds like a very wise decision to go for straight headers on the Trabbi. For several reasons.

    I have to see what the owner says and what is reasonable to try.
    But a comparison between, let’s say, a basic FOS-pipe with straight vs tapered header could be interesting. I have a feeling though that with the low level off tune we will see the same as you did. Small angles and differences in power. But who knows... The FOS is possibly “to much” as is. Test and see.

    Would love to have a way to predict or at least get some cues when things start to go south regarding overscavenging. But since EngMod is 1D that’s not possible Neels told me.

  9. #32559
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    17th September 2013 - 01:07
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    Quote Originally Posted by katinas View Post
    ...so I ask him bring back his old rusty original exhaust and he was even more embarrassed.
    After test riding he returns on one wheel, with a big smile. It was another engine.
    Thank you katinas.

    A very good example that it’s physics that makes speed.
    Not glossy ads and big names. (Exceptions exist) Without harmony in the design, one is lost though.

  10. #32560
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    27th October 2013 - 08:53
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    Quote Originally Posted by Flettner View Post
    peewee, you from the USA, what is their obsession with this RK tech wrinkly squish area head? How is it supposed to work? Looks like a real bad machining job, chewed out.
    i have no answer but if it works so good then how could the rest of the world be so stupid to not have figured it out as well. the way i look at it, how good something is, kind of depends what your comparing it against. we should all pitch in a few dollars to buy one then have wobbly test it against a known good design. also remember that usa doesnt follow common reasoning . they would just as soon take a good plated cyl and bore it out to accept a iron sleeve
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  11. #32561
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    19th October 2014 - 17:49
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    Quote Originally Posted by katinas View Post
    Maybe, is it possible to find bigger small end bearing.
    I have a 66mm Wiseco forged 2T piston here with 20mm pin, the thickness under the pin (bottom of bore to the outer forged surface) is 4.5mm. I presume they'd probably adjust the machining for different size pins to give a similar thickness from the forged surface. To get a 68mm piston "off the shelf" it would need to be an 18mm pin. Unfortunately the rod small end bore doesn't match the OD of any of the 18mm ID bearings that I find listed at Wiseco, ProX, etc. But since with a 68mm stroke that gives 232.6 cc instead of 250 there's a lot of appeal in ignoring the small loss of displacement for having a piston that doesn't need to be modified (and potentially messed up in the process). If done it will be a "hey it runs, it is a winner!" project, not a "crap, it is down .0005 hp on the competition, what a waste of time" project.

    cheers,
    Michael

  12. #32562
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    forgot to mention what needle and drill bit i used. 1.95mm drill bit. needle is 1.98mm diam 9.71mm long. part# 0405222613 from ktm trans. ive got a few spare bearing if anyone needs some needles

  13. #32563
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    Did some last minute dyno work last week before winning the final round and NZ ProKart KZ title.
    Not the latest cylinder design, but a prototype for the new R1 I needed to run in pistons for so outright power is down about 1.5 Hp.
    First test is a stock , thin 0.8mm ring piston , with a 4* conical dome.
    Next was a change to a new design with angled squish only then a flat top , with new insert to suit that brings the plug down
    4mm closer to the piston face.
    Last test was the " fluid diode " in the boost port - 3mm around 3 sides.
    Picking up 1/2 a Hp in an afternoon with no failed ideas was a bit of a surprise.
    Comparing this new settup with NT software , using live track data , and the latest cylinder showed closer to 0.8HP and resulted
    in a qualifying time 0.3 secs under the lap record.
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    Ive got a thing thats unique and new.To prove it I'll have the last laugh on you.Cause instead of one head I got two.And you know two heads are better than one.

  14. #32564
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    2nd March 2013 - 15:04
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    Quote Originally Posted by peewee View Post
    good job mate. I thought of trying that horizontal pin method but I have no experience with it and lm sure I would of buggered it somehow . instead I felt less nervous making a vertical hole to fit a needle bearing then closing the hole, since ive done it before on another pistons.
    Peewee, did you block the old pinholes? Wouldn't want to reduce the gas pressure behind the rings by leakage.

  15. #32565
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    Quote Originally Posted by lodgernz View Post
    Peewee, did you block the old pinholes? Wouldn't want to reduce the gas pressure behind the rings by leakage.
    some pages back it seems i showed what i did. tried drilling the old pin flush with the back of the ring groove but the pin is just to hard for that small of drill bit and causes deflection of the bit. thought about trying a very small carbide end mill bit to make the pin flush with the back of the groove. that idea likely would of worked but the end mill bit was atleast 7-10 days out from getting to my house. on hand i had some mini dremel cutting disks that fit nice in the ring groove so i carefully grinded the pins flush with the back of the groove. i didnt drill out the pin and make a hole into the piston onderside. if i ever relocate pins again, ill probly try the small carbide end mill just for fun. hek i may even try it on a old piston just to see if it works as well as i think

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