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Thread: 2stroke vs 4stroke : Views by Destry Abbott

  1. #1
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    Default 2stroke vs 4stroke : Views by Destry Abbott

    Cool perspective from Destry Abbott. Looking forward to the full comparison article in August!

    http://www.dirtrider.com/features/video-kawasaki-kx500-2-stroke-vs-kx450f-4-stroke/

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    Quote Originally Posted by mevan123 View Post
    Cool perspective from Destry Abbott. Looking forward to the full comparison article in August!

    http://www.dirtrider.com/features/video-kawasaki-kx500-2-stroke-vs-kx450f-4-stroke/
    Most people say 2strokes are much lighter than 4strokes. For reference (all dry weights):
    2014 KTM 300 2T XC-W = 102.1kg
    2014 KTM 350 4T XCF-W = 107kg
    2014 KTM 500 4T XC-W = 111kg

    I.e. A 350 4T is 4.9kg heavier and a 500 4T is 8.9kg heavier. What's ignored is that modern, fuel injected 4T engines are far more fuel efficient (50~100% better) than equivalent power output 2T engines. As such, fitting a big tank on a 2T is usually essential if you want to do day rides in remote areas, or long distance offroad racing. Just look at the size of the KX500 tank in the video! Once the big tank on the 2T has been filled with fuel, any dry weight advantage becomes insignificant. The tank is also high on the bike making it very noticeable. Just something additional to think about when comparing...

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    Default 2stroke vs 4stroke : Views by Destry Abbott

    Very fair point. Unlikely 2 stroke offroad bikes win the points for fuel mileage (Including plug fouling). That said, a potential weight issue could come down to the type of riding. Plenty types of off-road riding to consider.

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    good point about fuel weights.

    pretty sure the 2014 350 EXC-F/XCF-W is 107kg wet but without fuel.


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    In my mind the big advantage of a KTM or similarly high end enduro 2 stroke would be:

    1) no shaken
    2) far less maintenance

    They also seem to be on the podium at the world class hard enduro races, so there's probably something else to them too that I'm leaving out.

    The downside would be crap road manners, at least going by what one owner says about his EXC 250 (now 300). The 350 EXC-F I rode was great on the road and Mark always seems to have a blast on his....

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    Quote Originally Posted by Twinrider View Post
    In my mind the big advantage of a KTM or similarly high end enduro 2 stroke would be:

    1) no shaken
    2) far less maintenance

    They also seem to be on the podium at the world class hard enduro races, so there's probably something else to them too that I'm leaving out.

    The downside would be crap road manners, at least going by what one owner says about his EXC 250 (now 300). The 350 EXC-F I rode was great on the road and Mark always seems to have a blast on his....
    The maintenance intervals of a 2stroke KTM are no better than a 4 stroke. However, it is easier and cheaper to do an engine overhaul on a 2stroke.

    A major PITA for performance 2strokes is you need to mix the 2stroke oil with the gas. This is OK if your riding out of a truck and have a mixing can, but isn't fun if you've got to fill up at a gasoline station.

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    Quote Originally Posted by Markw View Post
    The maintenance intervals of a 2stroke KTM are no better than a 4 stroke. However, it is easier and cheaper to do an engine overhaul on a 2stroke.

    A major PITA for performance 2strokes is you need to mix the 2stroke oil with the gas. This is OK if your riding out of a truck and have a mixing can, but isn't fun if you've got to fill up at a gasoline station.
    Wouldn't the elimination of valve clearance checks/adjustments/replacements make maintenance much easier? What is there to do besides change the transmission oil and ride?

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    Quote Originally Posted by Twinrider View Post
    Wouldn't the elimination of valve clearance checks/adjustments/replacements make maintenance much easier? What is there to do besides change the transmission oil and ride?
    Piston, rings and small end replacement. Clean out the power valve.

    The valve clearance check takes about 30mins and is very easy. Adjustments are not often required but also easy if you have a shim kit and micrometer.


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    dont have much experience with 2 strokes but my understanding is that the power is much more difficult to control. this is why some have opined that my 125cc 2 stroke will be more diffiuclt to handle than my 350 4 stroke. (havent gotten to try my 2 stroke yet!)

    if you are going to be touring a 2 stroke without an automatic mixer is a bit of a PITA. on our shikoku trip Gdogs 250 EXC 'broke down'. it turned out that he wasnt using a good technique for mixing the fuel and oil. the oil was going to the bottom and messing up the fuel system. we will see if he has figured out how to completely avoid this problem on his next multi-day tour...


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    Quote Originally Posted by haildamage View Post
    dont have much experience with 2 strokes but my understanding is that the power is much more difficult to control. this is why some have opined that my 125cc 2 stroke will be more diffiuclt to handle than my 350 4 stroke. (havent gotten to try my 2 stroke yet!)

    if you are going to be touring a 2 stroke without an automatic mixer is a bit of a PITA. on our shikoku trip Gdogs 250 EXC 'broke down'. it turned out that he wasnt using a good technique for mixing the fuel and oil. the oil was going to the bottom and messing up the fuel system. we will see if he has figured out how to completely avoid this problem on his next multi-day tour...
    2stroke power delivery (typically a surge when the power valve opens) is very different to 4strokes, more difficult to control and certainly more tiring to ride. However, due to this power delivery characteristic, they are a lot of fun to ride

    The 2stroke mixing technique I used when I didn't have access to full size mixing tank was to put the correct amount of oil into a small container (500ml pet bottle is OK) 2/3 fill it with gas, put the lid on it shake it up and then pour it into your tank. Then fill the tank up with gas. This ensures good mixing of the oil with the gas. Do not just pour oil into a full tank of gas as it will probably not mix well.

  11. #11

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    For the same capacity, a 2-stroke is usually considerably more powerful. Although I have a couple of larger capacity sports bikes, I choose 2-strokes for the smaller capacity machines. No Shaken, low annual tax costs and cheap Gibai Seiki's!
    Some 2-strokes have a seperate tank & pump for mixing 2-stroke oil.
    If I could only have one bike I'd choose a 4-stroke as they're more able to do long distances, but if you can have several there's nothing wrong with a good smoker. When it's finished, my modified little '88 model TDR250 should be making around 60 bhp.
    Try getting that out of a 250 4-stroke!

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    Default 2stroke vs 4stroke : Views by Destry Abbott

    Quote Originally Posted by Newera View Post
    When it's finished, my modified little '88 model TDR250 should be making around 60 bhp.
    Try getting that out of a 250 4-stroke!
    Excellent. God bless them very cool yamahas!

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    Default 2stroke vs 4stroke : Views by Destry Abbott

    Quote Originally Posted by haildamage View Post
    dont have much experience with 2 strokes but my understanding is that the power is much more difficult to control. this is why some have opined that my 125cc 2 stroke will be more diffiuclt to handle than my 350 4 stroke. (havent gotten to try my 2 stroke yet!...
    Cool! Is it a YZ? I'm sure you'll get a solid grin ear to ear the first day out squeezing the throttle on her!

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    Quote Originally Posted by mevan123 View Post
    Cool! Is it a YZ? I'm sure you'll get a solid grin ear to ear the first day out squeezing the throttle on her!
    nope, it seems the YZ 125 has a very loyal following!

    it is a 2004 KTM 125 EXC. it is a summer project. i am a bit too busy to get it fixed up and registered until August unfortunately. hopefully, i'll get a chance to flog it on the enduro track before then to find out what work it needs.


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    Default 2stroke vs 4stroke : Views by Destry Abbott

    Quote Originally Posted by haildamage View Post
    nope, it seems the YZ 125 has a very loyal following!

    it is a 2004 KTM 125 EXC. it is a summer project. i am a bit too busy to get it fixed up and registered until August unfortunately. hopefully, i'll get a chance to flog it on the enduro track before then to find out what work it needs.
    Awesome! Probably going to be a fun project. Curious to see the updates afterwards.

  16. #16

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    Never had a problem mixing oil/gas in my RMX250R tank. Add the oil and shake the bike. In less than 30s
    all was good. For the correct amount of oil, I found some small clear plastic bottles and marked them for the
    correct amount of oil for the full tank. Then if i added half a tank of gas i added half a small bottle of oil.
    Carried two of the small bottles with me and a liter of oil. Took about an extra minute on fuel stops. If you
    cannot afford a minute, suggest lift style change

    Rode the bike everywhere and never bothered me carrying the oil or mixing. As once the bike was moving it
    more than made up for the small inconvenience. Only problem i had was once filled it with regular instead of
    hi-oc and invented the smoke machine. Had to dump the fuel and refill with hi-oc and the world was good again.
    Apexmoto Inc - Dyno tuning, engine/chassis/suspension upgrades, repairs, shaken, tires & changing with balancing, graphics printing, stickers, media blasting, painting & powder coating.

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