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Thread: Thoughts on a 2-stroke

  1. #1
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    Central Valley, CA
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    Default Thoughts on a 2-stroke

    Hi there, just found Expedition Portal the other day and this site is great, Me and my family (Wife and 4 kids) love exploring and take every chance we can to get out. That being said, I was just given a old 79' Yamaha YZ-400-F, it's a 2-stroke dirt bike. With a price of free I couldn't turn it away, and adventure biking has always been something I have been interested in but not really something you can do as a family of six. It needs quite a bit of work to get it running and usable. At a minimum I am going to clean it up, get it running and sell it, but I got to thinking about turning it into something I could take by itself or load it on the back of our suburban for some extra range when we go to the mountains. Obviously a 2-stroke is going to be more involved in taking on long distant trips, fuel is just going to take a few more steps, but is this is big deal, or am I overthinking it? Second, this bike is more of a dirt bike, and while I really like the idea of fixing up a vintage bike, am I just getting myself off on the wrong foot trying to use a bike like this? Thanks!

  2. #2
    Join Date
    Aug 2008
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    Pasadena, CA
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    Put a little work into the bike and give it a try on your next trip to the mountains.

    Assuming is runs well and is mechanically sound, mixing fuel is easy and not a hassle.

    My guess is that the biggest potential problem you'll have is that the YZ400 is a purpose built motocross bike. It has a big motor by two stroke standards and probably has a power curve that looks like the Eiffel tower. Not any easygoing bike that likes cruising on trails and exploring. But great if you want a big hit when the power comes on.

    Good luck

    R
    2006 Sportsmobile EB51 4x4, 6.0psd.

    2005 Jeep Wrangler LJ with some mods.

    2015 JKUR: AEV 2.5", Cooper ST-MAXX 255/80/17, AEV tire carrier, KC LEDs, Frontrunner cargo slide and interior shelf.

    2001 Honda xr400 dual sport.

  3. #3
    Join Date
    Sep 2015
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    Central Valley, CA
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    That's what I have heard and read. I have ridden street bikes for the last year or so, but my off-road time is pretty limited so I think there will be a learning curve. A power band like that doesn't seem like it would be great for climbing technical trails either.

  4. #4
    haven is offline Expedition Portal Moderator Expedition Leader
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    Check to make sure your exhaust has a spark arrestor. They are required these days, and may not have been back in the 1970s. We don't need any more wild lands burned up this year.

  5. #5
    Join Date
    Jan 2009
    Location
    Elgin, IL (Chicago burb)
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    Don't know where you live, but some places make it rather hard to get a plate for a bike that was never meant for the street.

    Getting fuel/oil isn't a big deal as most gas stations still sell two stroke oil, and older two strokes run better on the cheap oil. I use the cheap gallon bottle stuff from Wally World when at home and whatever is available when I travel. My farthest trip on my KE100 to date was from Chicago to the Deals Gap (NW N Carolina).

    If you can find a heavier flywheel for it, that would help to smooth out the band and make it better on the trails.
    Aaron

    2005 Astro (Gandalf) - AWD, 4.3L, 3.42, 140k+ miles
    1997 Astro (Grumpy - $250 Rally Van) - AWD, 4.3L, 3.42, LSD, 2" lift, 31" tires, 335k+ orig engine, $30 eBay fuel pump
    2016 Patriot (MaK - Her Jeep) Painfully stock
    1980 KE100 (Bessie) - 100cc of fury

  6. #6
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    Sep 2015
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    @haven That is a good point I hadn't considered. I'll have to check that out and if it doesn't add one. I am in the Central Valley of California so we have had our fair share of wildland fires in the sierras above us. Pretty nasty actually because all the smoke comes down off the mountains and just hangs out in the valley.


    Quote Originally Posted by ihatemybike View Post
    Don't know where you live, but some places make it rather hard to get a plate for a bike that was never meant for the street.

    Getting fuel/oil isn't a big deal as most gas stations still sell two stroke oil, and older two strokes run better on the cheap oil. I use the cheap gallon bottle stuff from Wally World when at home and whatever is available when I travel. My farthest trip on my KE100 to date was from Chicago to the Deals Gap (NW N Carolina).

    If you can find a heavier flywheel for it, that would help to smooth out the band and make it better on the trails.
    Being in CA I have heard it's not a huge deal to get the bike road legal, but I haven't done it yet so I don't actually know. So is the flywheel being heavier just slow down how fast the engine can rev up?

  7. #7
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    Arizona
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    Back in the good ole days I had a couple of 2 stroke bikes. One was a street legal Kawasaki 350 with a compression release, the other was an old YZ that would kick back if it wasn't started correctly. Both were great fun off road, the Kaw was ok for getting to the off road trails.

    Those old thumpers were fun!
    IMAGINE ALL THE PEOPLE LIVING LIFE IN PEACE
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  8. #8
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    From what I've heard California is one of the hardest, YMMV.

    Flywheel will slow the change in rev up and down.
    Aaron

    2005 Astro (Gandalf) - AWD, 4.3L, 3.42, 140k+ miles
    1997 Astro (Grumpy - $250 Rally Van) - AWD, 4.3L, 3.42, LSD, 2" lift, 31" tires, 335k+ orig engine, $30 eBay fuel pump
    2016 Patriot (MaK - Her Jeep) Painfully stock
    1980 KE100 (Bessie) - 100cc of fury

  9. #9
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    Buy a KTM 300.. Call it a day
    -Tyler
    -SLO
    -Two wheeled things

    2004 E-350 V10 Motovan
    2002 Dodge Cummins 4x4

  10. #10
    Join Date
    Sep 2015
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    Central Valley, CA
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    I'll get it running and re-evaluate from there. It is looking like it will be enough work just to get it running, and this thing was never meant to be a road bike. Looking forward to it as a project though, I like old stuff.

    Sent from my SAMSUNG-SM-G900A using Tapatalk
    Transportation:
    1996 Chevy Suburban 1500 4x4
    1976 Ford Mustang Cobra II
    1979 Yamaha YZ400F
    My legs and a backpack for all those hard to get to places

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