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Thread: Push most power out of 50cc barrel

  1. #16
    apriliaforum expert ToraTora's Avatar
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    Quote Originally Posted by Satanic View Post
    I don't have digital weighing scales.

    Engine mounts didn't fracture with the Airsal 80.

    Fractured within less than 300 miles using the MHR 80.

    Malossi's crank is more expensive than their cylinder kit.

    Airsal's pistons are probably lighter (speculation). Exhaust manifold on Airsal's aluminium kits is pathetic. Needs dremeling for correct fitment, unlike their iron range.
    How do you know that the time with the Airsal didn't weaken the mounts to the point that within another 300 miles they would fail? It's not something that you would necessarily see with the necked eye. Also, maybe the MHR was designed for the engines with the balancer. Again, I'm not very familiar with the Malossi product line. When I've looked at them at Treats they seemed nicely made.

    The thing here is that if your engine is vibrating a lot there's probably something that should be checked out, because they shouldn't vibrate as much as you are suggesting.

  2. #17
    apriliaforum Junkie Satanic's Avatar
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    Quote Originally Posted by ToraTora View Post
    How do you know that the time with the Airsal didn't weaken the mounts to the point that within another 300 miles they would fail? It's not something that you would necessarily see with the necked eye. Also, maybe the MHR was designed for the engines with the balancer.

    The thing here is that if your engine is vibrating a lot there's probably something that should be checked out, because they shouldn't vibrate as much as you are suggesting.
    Malossi's brochure lists their 80 kit for the RX / SX.

    Click image for larger version. 

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    Valenti sell Athena 80 kits for RME 50's http://store.valentiracing.it/index....y&path=182_186

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    Look at the reinforced bottom frame rail mount..

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    Thick chunk of sturdy metal (^)

  3. #18
    apriliaforum newb Kimmo kekki's Avatar
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    Malossi and Athena are quality products !
    These Airsal and all other cheap brand stuff are usually made of cast iron, and those are soft like cheese ...


    sent with OnePlus 5T

  4. #19
    apriliaforum prov-nov
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    Is jasil racing evolution crank any good?

  5. #20
    apriliaforum expert emX50's Avatar
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    Quote Originally Posted by Gvidas View Post
    Is jasil racing evolution crank any good?
    You are probably approaching this project from the wrong angle.
    The very first response by Rj got the perspective correct.

    That said, define 'power'. Do you ride between stop signs, and want acceleration, or do you ride freeways and need top speed ?
    These two ends of the spectrum may be better balanced by changing gearing.

    Remember that it is a SYSTEM, with all parts working together.

    So... standing on shoulders etc... and never one to use just a sentence when ten will do

    You need to think about your riding style.
    This is everything.

    So you want performance and fuel economy?

    That sounds like a noob statement, but the two can go hand in hand - so it's fine (within reason).
    By increasing the fuel burn efficiency, you will get more power per litre of fuel.
    ... only that, if you are taking advantage of that extra power (which you will), you will likely burn more fuel.

    Again, referring to Rj's advice... where do you need the economy?
    Is it around town?

    Then you'll need the stock pipe, to gain a broad power band.
    You can then keep the carb lean for town conditions.

    A larger atomiser diameter, a small idle jet, and push the taper further into the throttle range.
    If you are using a PHBN 17.5 you could go with an A7 on notch 4 or even 5 (with testing) - GA212 atomiser for 50cc will likely be fine.

    If PHBG I know both Xero and spudgun had/have their tapers hitting very late... around 40% throttle.

    The engine simply sucks what it needs through the atomiser... which has proved ideal for many people.
    So you gain a Jekyll & Hyde bike, that can function fine in stop start conditions, and yet when you hit the taper... boom... you fly.

    But with a stock pipe (de-restricted) there is no point in fitting a high compression crank.
    Such a crank is only valid, when the engine lives at very high RPM.
    The higher crankcase pressure increases the speed of the gas transfer to cope with the mind blowing requirements of an engine that lives in the 10k - 13k region.

    If you fit a high pressure crank into an engine that lives in the 6k to 10k region.... the additional pressure will simply push fuel down the pipe.
    If memory serves me right (I can't be arsed to confirm so don't quote me)... at 10k and 20mm bore, the airspeed is 24m/s so at 13k it is 32m/s
    You can see why additional pressure might be useful, to get all the gas in place, in time.

    So forget fuel economy

    My advice would be to take the project in stages.
    De-restrict everything, and fit a 17,5 carb, and a twin air filter (or similar) to help breathing.
    Then (repeating Rj again)... concentrate on the air path through the read valves.

    When you've got it running nice, and your money saved... or at least spent wisely
    ... you can move ahead from an informed position.
    You'll better know what you want to achieve.

    74cc would be the next typical step.
    74cc seems to provide the extra grunt and acceleration that makes the bike like a full blown motorbike.
    At least, that's what I have found.

    Good luck!

  6. #21
    apriliaforum Junkie Satanic's Avatar
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    Quote Originally Posted by emX50 View Post
    keep the carb lean for town conditions.

  7. #22
    apriliaforum expert emX50's Avatar
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    "keep the carb lean for town conditions."

    Yes... exactly that

    The Aprilia manual specifically warns about the risk of the engine choking up in such conditions.

  8. #23
    apriliaforum Junkie Satanic's Avatar
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    Quote Originally Posted by emX50 View Post
    The Aprilia manual specifically warns about the risk of the engine choking up in such conditions.
    What kind of risk?

    Aromatic smoke clouds?

  9. #24
    apriliaforum expert emX50's Avatar
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    Quote Originally Posted by Satanic View Post
    What kind of risk?

    Aromatic smoke clouds?
    Just had a look.
    They warn of contaminating the the cat, and the exhaust.
    However that also means engine choking and plug fouling.

  10. #25
    apriliaforum Junkie Satanic's Avatar
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    Quote Originally Posted by emX50 View Post
    Just had a look.
    They warn of contaminating the the cat, and the exhaust.


    Quote Originally Posted by emX50 View Post
    However that also means engine choking and plug fouling.
    Brainwashed hearsay.

  11. #26
    Honest always, feared often Micah / AF1 Racing's Avatar
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    16.4 bhp was the most power to tire I ever pushed from a 50cc gasoline AM6, at 15,300rpm if memory is serving. Pistons were good for almost three hours lol
    Diminished expectations is the key to happiness in life.

    Micah Shoemaker
    AF1 Racing
    9900 IH35N
    Austin, TX 78753
    micah@af1racing.com
    @ShoemakerMicah
    @AF1Racingaustin

  12. #27
    apriliaforum expert emX50's Avatar
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    Quote Originally Posted by Satanic View Post
    Brainwashed hearsay.
    What lunacy is this?
    The manual is there to download for anyone to see.

    This is a technical forum, yet you reduce it to little more than a troll fest.
    It kills any serious discussion.

    Infantile one line comments... usually with a gif, typical to adolescent females on Facebook.
    Have you never wondered why you get banned so often?

    Sorry micah... I know that you were turning the thread serious... but for fucks sake.
    This 'think of a response... anything will do' MO is like a cancer.

    There is no wonder that I get PM's telling me the forum has lost its way.
    The information just gets garbled.

    Anyway... it looks like I'll be making an announcement about garbled information (very shortly).

    If it happens (there are still two days left), it won't be my fault.
    My gut feeling, is that the response that I'm waiting for, isn't going to come.
    A period of 'folly rectification' lies ahead.

    I guess it must come to this.

    Oh yes... and for anybody listening... I'm up for it... the strategy is prepared... 48hrs and counting... then no more forks in the path

  13. #28
    apriliaforum expert ToraTora's Avatar
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    Quote Originally Posted by Micah / AF1 Racing View Post
    Pistons were good for almost three hours lol
    Less than three? Was this the turboed land speed record engine that you built?

  14. #29
    apriliaforum prov-nov
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    I decided to just make good power out of my bike without looking too much at fuel economy, so far I put Jasil Top Racing Competition crank, skf c3 bearings (Stage6 bearing and crank seals kit), Airsal sport 80cc.
    On airsal cylinder I didn't adjust the squish, I just put both paper gaskets under the cylinder, is that a mistake?
    Also what carb and pipe should I use for this setup?
    I mainly ride in freeways, looking to increase in both speed and acceleration.

  15. #30
    Honest always, feared often Micah / AF1 Racing's Avatar
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    If this is supposed to be a legit question involving stock barrel parts I'll happily share best specs I ever came up with. I'm not sure why you say my answer was too serious?

    No no and yes. This was one of the two identical motors (other than head volume) built for that turbo methanol land speed bike. The turbo methanol motor made closer to 25 bhp.
    Diminished expectations is the key to happiness in life.

    Micah Shoemaker
    AF1 Racing
    9900 IH35N
    Austin, TX 78753
    micah@af1racing.com
    @ShoemakerMicah
    @AF1Racingaustin

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