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Thread: ESE's works engine tuner

  1. #34096
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    Twin rotary valves, although these cases are for a uniflow project, they are able to be set up as a twin rotary valve. Crank can be 48 up to 58, so plenty of room to make it a 100cc bucket engine. Gearbox is 175 Kawasaki. Clutch is 250F. Bit of paint and a sand next.
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  2. #34097
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    14th April 2011 - 23:44
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    Quote Originally Posted by katinas View Post
    It would be really interesting.
    Other thing to worth to try, milled spark plug, that Frits and Jan advice to try, is very helpful.
    With this year Huqvarna TC 85 we ended at 31,53 hp with std spark plug.
    Then milled plug 31,1 hp
    Then retard ignition with woodruff key (approx 3mm retard at lobe) 32.06 hp 11876 rpm (from rear wheel with triangular 16 inch woody 1992 GP Dunlop front slick tire)
    Std plug with retarded ignition 31.45 hp and lower everywhere except at over 12500rpm.
    Looks like milled plug shortens the burning time, maybe due to the plug inserted deeper into the chamber, closer to piston and/or due to the more open ceramics.
    We tried this at Aprilia about 20 years ago. It gave about 0,7 HP more. The problem was that we could not possibly modify hundreds of plugs to satisfy all our customers. Asking the plug manufacturer to produce plugs that way would have meant to throw our advantage away...… So it was never done anymore.... Another interesting thing: a plug was returned to us after a race with the earth electrode completely broken off. But it had finished the race, so it was tried on the dyno: about 1HP more! Very nice, until after a couple of runs the ignition coil failed.... It might have worked with a better ignition coil.... Which we didn't have!

  3. #34098
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    Quote Originally Posted by Frits Overmars View Post
    Radiusing the bore edge, like Katinas and Wobbly suggest, works every time. A radius of 6% of the bore would be a good value.
    Attachment 346413 Attachment 346414

    As for the remainder of the transfer duct inner walls, it should be noted that the smallest radius will be decisive for flow detachment. It's no use making that radius big in some places when it reduces the radius in other places, so go for a the biggest constant radius that can be fitted in within the available space.
    Attachment 346415
    The Aprilia cylinders had a constant inner and outer radius in the transfer ducts. Doing this gave a really big improvement!. The narrowest point of the duct was the port itself, 12,25mm. Transfer timing remained the same for all 12 years of development. Maybe I should have tried a shorter timing, now I regret that I never did.... One of the biggest improvements came from making the port UNDERSIDE being made exactly as high as the piston in BDC! Many cylinders are wrong in this respect, the piston top causing severe disturbance to transfer flow, and detonation.... The most sensitive point in the cylinder proved to be the A-port front side, the nearest to the exhaust port. It's direction was machined to be very much angled away from the exhaust, as far as material thickness allowed. In this way it could be made wider, giving good improvements. Wall thickness was 1,5mm between water passage and duct.

  4. #34099
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    7th October 2015 - 07:49
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    Jan, it is very interesting, thank you for your words.
    Denso racing plugs side platinum electrode is pressed in, so it is possible to adjust gap or even can be easily pulled out. NGK side platinum electrode is solid with plug body.
    With Denso IA, two times ceramic falls down and every time when the engine goes very well.

  5. #34100
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    Quote Originally Posted by katinas View Post
    Jan, it is very interesting, thank you for your words.
    Denso racing plugs side platinum electrode is pressed in, so it is possible to adjust gap or even can be easily pulled out. NGK side platinum electrode is solid with plug body.
    With Denso IA, two times ceramic falls down and every time when the engine goes very well.
    We had the same problem, seems to be caused by plug overheating. We solved it by getting the cooling water closer to the plug. After that it never happened again.

  6. #34101
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    Quote Originally Posted by jamathi View Post
    Another interesting thing: a plug was returned to us after a race with the earth electrode completely broken off. But it had finished the race, so it was tried on the dyno: about 1HP more! Very nice, until after a couple of runs the ignition coil failed.... It might have worked with a better ignition coil.... Which we didn't have!
    Very interesting. With so big gap, maybe is some delay of spark moment, but faster burning because of more waiting electrons, accumulated on the electrode, burst during the same time interval. Just a guess

  7. #34102
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    A new project!

    Thank you Jan, Frits and Katinas for answering my question about the transfer tunnel. Right now I don't see much I can do about the outer tunnel wall radius, but I can reshape the inner wall beginning radius after I radius the bore edge. I will try the other mods as I go along.

  8. #34103
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    That's definitely an option, keeping air pump and going with a carb.

    I also made a post asking for thoughts on porting an air only cylinder that is of typical 2 stroke configuration.

    In a sir/fuel cylinder we're trying to fill bore as much as possible, but keep fuel away from exhaust port.

    In an air only cylinder is it still an advantage to have a Schnuerle style transfers? Should the transfer roof angle just be really steep in an air only cylinder?

    Quote Originally Posted by ceci View Post
    Hi Ken. Excuse me for the nonsense that I am going to suggest, but I am beginning to wonder if we have not gone in the wrong direction regarding the anti-pollution solution.
    The denial of the manufacturers to the use of an auxiliary piston pump (attempt to keep the 2S as simple) to carry out a load stratification (solution to the short-circuit effect) led the researchers to choose the lines of research in which the crankcase only can have clean air, this research line begins with "Multi-Layer Stratified Scavenging (MULS)" by Blair G. P, until the rest of the investigations both with auxiliary compressor (pre-pneumatic injection system) and without it.
    And why not twirl he omelette "a typical Spanish saying", instead of using the air from the compressor to create the mixture of air and fuel, we use it to create a wall as a solution to the short circuit



    In case you do not end the problems of the fuel pressure regulator and decide to change to the use of a carburetor (something very common "if you look in the Aprilia forum there are many cases").
    Why not try something different, keep the air injection system (create the "avoid short circuit" wall) together with a carburettor supply

  9. #34104
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    Quote Originally Posted by jonny quest View Post
    On a Ditech SR50 the fuel is injected through the head as piston closes exhaust port.

    It still has a standard looking cylinder with case reed.

    I'd like to get more performance out of cylinder, but transfers are just moving air.

    I'd like to hear some of your ideas on how to increase performance with the cylinder porting
    Hi, we never play with DiTech, but maybe modifications similar like with the carb. Or even more attention on things that prevent losses air to exhaust, as the air is less inertial than mix and it is even harder to hold high density air streams in the compact shape, coming from the transfers. And less resistance for reverse flow. And no cooling effects for transfers. But less drag on pumping. Interesting about DiTech injection rpm limit. Maybe all works must be done for mid rpm.

    I remember funny DiTec repair, fifteen years ago. Accidentally, two Ditec Rs50 had to be repaired at the same time. One does not have a spark and the spray system does not work, other with air leakage from crankcase pump. I swapped cdi from other and everything worked. I wanted to call the client to order a new cdi, but before that decide to connected the old cdi again and everything worked. It was the fastest repair.

  10. #34105
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    I forgot to reply to you F5 Dave - the volume of mixture in the transfer duct total is in excess of that getting into the cylinder , so in reality there is no flow from the
    case ,thru the duct and out the port at BDC.
    Thus in many cases the duct volume may be too big , and maybe this is a downside due simply to inertia effect.
    Some are too small , and the energy needed to try and move mixture from the far end of the duct is too great - again a down side on power.

    I will try the milled spark plug idea on a KZ2 as soon as I can , we have a tech rule about no plug body intrusion into the combustion space past the end of the head threads.
    But with the nose sticking out 3mm , and the body flush , this puts the ionizing spark gap way closer to the middle of the chamber - and its legal as.
    Will post dyno graph as soon as its done.
    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.

  11. #34106
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    This is interesting, the long-dreamed-of "Free Piston" engine at last appears to work.
    This iteration of it appears to make no attempt to drive wheels, but uses the motion of the rods to produce electricity, which obviously can then drive wheels or whatever.

    https://www.aquariusengines.com/technology/

  12. #34107
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    Quote Originally Posted by wobbly View Post
    I forgot to reply to you F5 Dave - the volume of mixture in the transfer duct total is in excess of that getting into the cylinder , so in reality there is no flow from the
    case ,thru the duct and out the port at BDC.
    Thus in many cases the duct volume may be too big , and maybe this is a downside due simply to inertia effect.
    Some are too small , and the energy needed to try and move mixture from the far end of the duct is too great - again a down side on power.

    . . .
    Ok thanks, gee ill have to measure that. I've seen some enormous cavity transfers. These in comparison are small so to measure volume and compare with something less pedestrian should give me a ratio vs cc of engine.

    So why would bore to duct radius help so much? As the plug of gas is blown then sucked into the cylinder it needs to be replaced i guess with least resistance.
    I've been told. Dreaming`s free.
    Think I'll go, back to sleep.
    Everybody listen, voices in my head
    Everybody listen, do yours say, what mine says?

  13. #34108
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    Quote Originally Posted by wobbly View Post
    I forgot to reply to you F5 Dave - the volume of mixture in the transfer duct total is in excess of that getting into the cylinder , so in reality there is no flow from the
    case ,thru the duct and out the port at BDC.
    Thus in many cases the duct volume may be too big , and maybe this is a downside due simply to inertia effect.
    Some are too small , and the energy needed to try and move mixture from the far end of the duct is too great - again a down side on power.

    I will try the milled spark plug idea on a KZ2 as soon as I can , we have a tech rule about no plug body intrusion into the combustion space past the end of the head threads.
    But with the nose sticking out 3mm , and the body flush , this puts the ionizing spark gap way closer to the middle of the chamber - and its legal as.
    Will post dyno graph as soon as its done.
    Quote Originally Posted by F5 Dave View Post
    Ok thanks, gee ill have to measure that. I've seen some enormous cavity transfers. These in comparison are small so to measure volume and compare with something less pedestrian should give me a ratio vs cc of engine.

    So why would bore to duct radius help so much? As the plug of gas is blown then sucked into the cylinder it needs to be replaced i guess with least resistance.
    Frits or Jan gave a very elegant answer on the dutch site to that question

    i cant find it and clearly lack the wisdom to paraphrase it either but he gave a rule of thumb or an indication of the size for transfer volume vs cylinders

    Jan said this though
    One thing I am sure about is: always give priority to flow over crankcase volume!
    Quote Originally Posted by Katman View Post
    I reminder distinctly .




    Kinky is using a feather. Perverted is using the whole chicken

  14. #34109
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    Quote Originally Posted by wobbly View Post
    I will try the milled spark plug idea on a KZ2 as soon as I can , we have a tech rule about no plug body intrusion into the combustion space past the end of the head threads.
    But with the nose sticking out 3mm , and the body flush , this puts the ionizing spark gap way closer to the middle of the chamber - and its legal as.
    Milling the spark plug puts the spark gap closer to the middle of the camber. It also promotes access of the mixture to the gap between the electrodes, helping it to replace the burned gases with stuff that still wants to burn. And it cools the plug.
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    Speaking of tech rules: the above rule seems so simple; what could possibly go wrong? Well, I would claim that the mass electrode is part of the plug body, so this simple rule simply renders all present-day spark plugs illegal .

  15. #34110
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    Quote Originally Posted by katinas View Post
    Interesting about DiTech injection rpm limit.
    If they are doing all their injecting after the exhaust is closed then they have very little time to get the fuel in there before the compression pressure becomes greater than the injectors fuel supply pressure. Even if they had enormous injector pressure they still have very little time because the distance between exhaust closing and ignition would only be 60-70 crankshaft degrees at most.

    A fuel injector takes time to open and start flowing fuel and then there has to be some time left for all the injected fuel to evaporate. All this severely limits the rpm possible with direct injection. Vertically downwards B transfer port injection overcomes a lot of those time limits because it can inject for 360 crank degrees but eventually it hits its own time ceiling.

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ID:	346434 B port injection. (not so time and RPM limited)

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ID:	346433 The father of B port injection.

    The modified Yamaha YZ250 cylinder above was running well before KTM's EFI bike. In fact KTM went down several wrong roads before copying this YZ250.


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