View Poll Results: 2stroke or 4 stroke

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  • 2 stroke engine.

    43 75.44%
  • 4 stroke engine

    14 24.56%
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Thread: 4stroke vs 2stroke?

  1. #1
    apriliaforum expert chrism15's Avatar
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    Cool 4stroke vs 2stroke?

    what is better in your opinion - GENERALLY, i know 4stroke bikes have the reliablility advantage but 2stroke have that amazing power from lower cc...........
    what do you prefer
    Engine Always Screaming!

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  2. #2
    Honest always, feared often Micah / AF1 Racing's Avatar
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    Less moving parts...combined with modern electronics...emissions no longer an issue really...2T all the way. The sun will rise again on the 2T motor, reports of its death are greatly exaggerated.
    Diminished expectations is the key to happiness in life.

    Micah Shoemaker
    AF1 Racing
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  3. #3
    apriliaforum expert Mardoch's Avatar
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    4 for me. Reliability trumps the insanity in my book.
    2011 Dorsoduro 750 - Black

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  4. #4
    Honest always, feared often Micah / AF1 Racing's Avatar
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    In the near future reliability on 2T can well exceed 4T. Look only at total moving parts count for say a twin or even single cylinder engine. Reliability on 2T motors has been heavily tainted by the use of carburetors and case induction. Cyclic variability (difference in mixture between any sequential set of firing events) has been one of the worst problems. A little boost, no more case induction, below the base gasket injection and forced oiling change about EVERYTHING you have traditionally known about the 2T motor. If any of you hit the mega Bazillions jackpot last night let me know, a little angle investment and some sound engineering can bring about the resurrection of motor Christ.

    In the traditional sense yes, 2T motors are less reliable than traditional 4T motors. Newer high strung 4T motors however are no more reliable than 2t motors when pushed to the limits. You think WSBK motors are used all season long...nope. The more the OEM's make a $t behave like a 2t, the more they will indeed behave like a 2t. This is easily seen with modern dirt bikes, 15 hour valves, 30 hour cranks...sound familiar at all? If given displacement parity AND emissions parity there is NO reason a 2T motor cannot be both more powerful and more reliable than a 4T motor. Thermal management is well within reach now given advances in metallurgy and electronics.
    Diminished expectations is the key to happiness in life.

    Micah Shoemaker
    AF1 Racing
    699 W. San Antonio
    New Braunfels, TX 78130
    830-626-3966
    micah@af1racing.com

  5. #5
    apriliaforum expert TRexRacing's Avatar
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    My 1984 RZ350 has 39,549 miles on it. All but 1601 mine. It has never left me stranded or even been difficult to start. It ran 141 honest MPH with my fat ass on it. In 1984 I rode my first RZ from Columbia MD to Midlothian Texas. 3 days down and 36 hours coming back. 1449 miles on the odometer coming back.

    It's fairly heavily modified internally and in it's last incarnation got an average of 42 MPG. Should pick up a few MPH and MPG when I finish it up next month. Izzat reliable enough for a 28 year old 2 stroke? Who needs modern stuff? A well built old stroker is far better than the myth would have you believe.
    “Never quite ready.............it just becomes your turn.........." Jason Newsted

  6. #6
    Honest always, feared often Micah / AF1 Racing's Avatar
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    One of my old racing buddies still rides his dads 1970's gt750 Suzuki in a regular basis. 80k miles on clocks, never even had the motor open at all.
    Diminished expectations is the key to happiness in life.

    Micah Shoemaker
    AF1 Racing
    699 W. San Antonio
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  7. #7
    apriliaforum expert jrflanne's Avatar
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    My brother built a water buff dragbike for a guy. I'll see if he has some dyno numbers around.
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  8. #8
    Honest always, feared often Micah / AF1 Racing's Avatar
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    As mentioned needlessly by me on a regular basis, look seriously into the BRP and Evinrude 2T motors of recent vintage. www.rotax.com and www.evinrude.com. You have to dig a bit for technical data. Read every word Harold Bartoll has written on the subject, he was/is KTM's motor development guy. If REALLY reliable fully modern 2T aviation engines excite you look for the company that makes the recip motors for our insane fleet of drone aircraft our government so loves. They would give me zero tech details but I did get to examine the external portions of one of their motors at Lackland AFB a few years back. The irony was I knew FAR more about the engine than the A&P who was showing it to me...and he works on them!

    Ever wonder how a drone can fly non stop for days...fuel efficiency is a HUGE part of that equation. The non turbine drones are almost all 2T and not little cylinders either. With so little internal friction they can use more of their fuel payload for pushing the aircraft (I despise drones btw) through the air, even at VERY high altitudes. Until the turbine/hybrid revolution takes place, the 2T motor CAN be absolutely tops for both efficiency AND reliability.

    No, I have not been drinking...
    Diminished expectations is the key to happiness in life.

    Micah Shoemaker
    AF1 Racing
    699 W. San Antonio
    New Braunfels, TX 78130
    830-626-3966
    micah@af1racing.com

  9. #9
    apriliaforum expert cantcode86's Avatar
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    Their is a little more hope out there. It may be for offroad but it's showing hope that there are companies how haven't given up on the two stroke. Evinrude proved it can work. Hopefully the right companies jump on board and see it's worth doing. I've been wanting a 2t for the street forever, just haven't had the right deal at the right time. I have been eyeing up the 70's GT750. They seem to be not quite as scarce.

    http://twostrokemotocross.com/2011/1...ure-of-enduro/

  10. #10
    Honest always, feared often Micah / AF1 Racing's Avatar
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    Ossa or Osa, not sure since I see precious few tris bike has two NEW 2T models, nothing using an under the base gasket style of injection. Semi direct or port (literally into the flowing air stream of a transfer or boost port) solves most of stratification of charge problem which has plagued everyone from Bimota with V-Due to Aprilia/Piaggio with the pursuer and ditech motors. No fuel is allowed escape from the exhaust port due extremely precise injection event timing. The only downside is hat you need an injector capable of delivering its full payload in a VERY short period of time AFTER the opening of T1-2 and Boost port but only very slightly after. This does not allow the physical time required for short circuiting of the charge out the exhaust port while allowing just enough time for atomization to near completetion and with 2T motors chamber turbulence is so violent that more or less homogenous charge combustion is possible even in a fairly large volume chamber. This is LIGHT YEARS ahead of the early Ficht or Orbital/Synerject systems. Once you commit to high pressure oiling and plain bearing rods and crank, and cylinders sealed off from the case and what was previously "crankcase compression to force charge into cylinder" and replace that with a small roots type blower you have the very essence of what it takes to make my dream of a modern clean 2T motor possible. No, the next generation will only slightly resemble what we know of as a 2T motor BUT there is huge progress to be made.

    Before discounting all this as fancy new age shit that will never happen do a little reading on the roots of name "blower", pun intended. Also read up a lot on Detroit Diesel and their history. My ideas are far from original. Like I said earlier the 2T will eventually rise again from the ashes. The cycle repeats but it always goes back to the simplest way of spinning an output shaft short of a gas turbine.
    Diminished expectations is the key to happiness in life.

    Micah Shoemaker
    AF1 Racing
    699 W. San Antonio
    New Braunfels, TX 78130
    830-626-3966
    micah@af1racing.com

  11. #11
    apriliaforum expert The Commissar's Avatar
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    I think the bad rap two strokes get is from offroad. Frankly, the more I hear, 4 strokes are the finicky bastards of offroad with scheduled maintenance being scary expensive. While a 2t mx'er gets by with a 300 dollar complete rebuild.

    the 2t street bikes i come across have retarded amounts of miles on them, it makes me wonder really. Could not-quite-racing but high performance racing 2t be just as reliable as a comparable 4t? I think it could.

  12. #12
    apriliaforum expert aceyx's Avatar
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    Quote Originally Posted by Micah / AF1 Racing View Post
    If any of you hit the mega Bazillions jackpot last night let me know, a little angle investment and some sound engineering can bring about the resurrection of motor Christ.
    Just make sure you save twice your R&D budget for lobbying.

  13. #13
    apriliaforum Junkie oluckymana's Avatar
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    ...even though I voted a preference for 4 strokes I have only just rediscovered 2 strokes.....modern injected ones have it all over the older carbed models...
    ....let's have another drink....

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  14. #14
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    Quote Originally Posted by Micah / AF1 Racing View Post
    As mentioned needlessly by me on a regular basis, look seriously into the BRP and Evinrude 2T motors of recent vintage. www.rotax.com and www.evinrude.com. You have to dig a bit for technical data. Read every word Harold Bartoll has written on the subject, he was/is KTM's motor development guy. If REALLY reliable fully modern 2T aviation engines excite you look for the company that makes the recip motors for our insane fleet of drone aircraft our government so loves. They would give me zero tech details but I did get to examine the external portions of one of their motors at Lackland AFB a few years back. The irony was I knew FAR more about the engine than the A&P who was showing it to me...and he works on them!

    Ever wonder how a drone can fly non stop for days...fuel efficiency is a HUGE part of that equation. The non turbine drones are almost all 2T and not little cylinders either. With so little internal friction they can use more of their fuel payload for pushing the aircraft (I despise drones btw) through the air, even at VERY high altitudes. Until the turbine/hybrid revolution takes place, the 2T motor CAN be absolutely tops for both efficiency AND reliability.

    No, I have not been drinking...
    I was pushing an 18 foot Hi-Liner with a stock 1956 Evinrude Big Twin it was still going stong when I sold it at 30 years of age. Imagine an 18 foot boat with about 8 feet of beam and 3 feet of freeboard that would only use 12 gallons of gas on a full day out on the water fishing and trolling.

    The miniscule amount of oil residue it gave off helped keep the mosquito population down so we were not so relient on pesticides. Imagine no more 5 O-clock Charlies in their choppers spraying malethion on us.

  15. #15
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    THANK YOU MICAH!!! People need to hear the truth from a well respected source! Bottom line is a 2T can make the same power at half the displacement & less than half the weight of a 4T. Not to mention it's far simpler & less expensive. All this CRT crap in moto gp stems from sky high costs of the 4T's. Yes... my race bike is a TZ250

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