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The SINGLE most reliable 2 stroke dirt bike ever made?

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LOL. No such thing. They are a ton of fun. But they all require maintenance. I am constantly working on my KTM SX’s but wouldn’t trade them.

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Posted (edited)
12 hours ago, S.O.A.N.Z said:

Definitely not KTM  :D

Yz 125. Reed cage and pipe. 32:1 and keep oil and filter fresh. 

Edited by 777654321
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4 hours ago, nobade said:

1978 Yamaha GT80

yes I had a 68 Yamaha 360 Enduro registered when I was fifteen and I drove it for years on the street and in the dirt and never serviced it. It ran great when I sold it. it was four years old when I bought it and I bet the guy I got it from never touched it either.

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Posted (edited)

It sounds like OP is asking "what can I buy and not perform regular maintenance and have it last?" while also stating it will be ridden at the track.  There are no magic physics one manufacturer has to make parts wear less fast than everyone else.

Larger displacement in general will last a bit longer than a small displacement (ex 125 vs 250) since it generally runs at lower rpm and receives better lubrication.  But any modern bike you buy will require top ends per the recommended maintenance schedule, especially if you race.

Expect to do top ends every ~50 hours for heavy track riding unless you decide to forego it and then come ask us if your cylinder can be reused when it has drag marks through the plating after a catastrophic failure...

Trail only on a 300 2-stroke can last >100 hours between pistons but that is going past the recommended maintenance.

The exception may be an older 2 stroke like a KX200 or an old Yamaha.

Edited by mbrick
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Posted (edited)

1915660306_RobATKOct1991desert.jpg.9a6cb1a8c720c1eab3ca8d9556bb81cd.jpg

 

1991 ATK 406.  Never had the top end apart...even after seizing it solid running down the drag strip during a GP at Carlsbad.  Let it cool and finished the race. Cleaned the booger outta the main jet and it never stuck again.  

Now, you may have a problem replacing the pipe after you mash it flat.....

Edited by Sunny Socal
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My vote is for kdx200/220, or 90's and up cr500/kx500. The 500's are hard to beat on..they hit back!

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Posted (edited)
11 hours ago, Nicholas Sibley said:

Alright enough bullcrap. I'm gonna buy a two stroke because they are fun. I'm gonna ride it everywhere including the track. Performance aside, what is the single most reliable 2 stroke dirt bike EVER made? Is their any bike that I wont have to put a top end in every year? (Assuming I'm not an idiot who overrevvs it everywhere.)

1980 KD80 lol

This is the ACTUAL bike I grew up riding as a kid.  My cousin got it for christmas when I was 9 in 1980.  We rode this thing all day every day all summer every summer for 10 years.  It's never had a top end done, never had any seals replaced, heck it hadn't been started for 30 years and it started right up after I cleaned the corrosion out of the carb.  1980's 2 stroke oil still in the oil tank!

But I don't think its what you are looking for.

C3FE250B-62E8-4D86-A377-B867423B23A4.jpeg

Edited by Florida Gliderpilot
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Bigger engines last longer than smaller engines. get yourself a cr500 honda.  pistons will be a lot, lot less of an expense than tires will be.

as for long life, I had an xr250 for 15 years and wore out 1 clutch. that was all the engine needed. I did go through a lot of chains, sprockets, tires etc in 15 years. never had the head off and it was running stronger when I sold it than when I bought it.

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I have an old  KDX 250   1982 .  NEVER BEEN OPENED UP .. ALWAYS RUN  CASTROL TT OIL .  40:1    IT IS FOR SALE .....

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I have 6 Honda motorcycles ,  2 and 4 stroke ..   would not trade them for anything ...  50 cc  100 cc  125 cc 150 cc 250 cc  ,       750 cc street     ROCK SOLID ,    BEST BUY ...   PROBABLY HAVE HAD 15 IN MY LIFE ...

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5 hours ago, slowmoto said:

KE100. 25 year production run of proven reliability. Reliable=boring.

My friend had one growing up. You couldn't kill that bike. He probably put five or six hundred hours on that bike and did nothing. Same top end, sprocket and chain ,tires. I think he changed the transmission oil and cleaned the air filter once a year.

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Had a 2008 ktm 200xc owned for 8 years and had two seasons of harescrambles all original top end. Started first kick till the day I sold her

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Posted (edited)
55 minutes ago, Florida Gliderpilot said:

1980 KD80 lol

This is the ACTUAL bike I grew up riding as a kid.  My cousin got it for christmas when I was 9 in 1980.  We rode this thing all day every day all summer every summer for 10 years.  It's never had a top end done, never had any seals replaced, heck it hadn't been started for 30 years and it started right up after I cleaned the corrosion out of the carb.  1980's 2 stroke oil still in the oil tank!

But I don't think its what you are looking for.

C3FE250B-62E8-4D86-A377-B867423B23A4.jpeg

All those old rotary valve engines last forever it seems. Just this winter i brought a couple back to life for a guy. they sat for years.  A G5 and a F7

Edited by Motox367
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8 hours ago, Zomby woof said:

Italian huskies go forever and are the easiest bikes I've ever owned to work on - when you rarely have to do it.

While people are completely rebuilding their YZ125's at 60 hrs, big bore 125 Huskies are getting 200 hrs to a top end

IF you find it, take a Husqvarna WR 360.
In the USA it should be called "WXE".

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Definitely nothing made by Japanese. Most reliable bike I ever had was a 1975 Husqvarna CR125.

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Definitely nothing made by Japanese. Most reliable bike I ever had was a 1975 Husqvarna CR125.
I can't say the same. I had an air cooled 84 atc250r. Bought it in 1998, previous owner owned it since 1985. That family was awful to it. Premix was 10w30, outboard, dollar store 2 stroke, gear oil, whatever was oily they could get their hands on.

Most of the time, it was ridden on the road 3 miles wide open to fill up with gas at the gas station, then 3 miles wide open back. For years. No maintenance, just beat it.

I cleaned the jetting up when I added a pipe and reeds. Was doing a burnout when the original piston finally let go. Bored .020, and rode it for years until I stupidly sold it.

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12 hours ago, S.O.A.N.Z said:

Definitely not KTM  :D

I gotta disagree, I have a 2000 KTM 125 EXC that went 7 years on the original piston until I swamped it. It was daily driven and even highway driven but rpm was generally kept low and run at 40:1 oil. 

image.png.04f3f35004c90fa2f2d740006523a44f.png

And highway legal: 

image.png.f8ae7c89659111c6e931edb76e9bd1af.png

I also have a 2003 and a 2002 KTM 380 and 300 that still have the original pistons in them. They get less running than the 125, and in tight eastern woods don't typically get run very long at full throttle. Most bikes my son has had needed a piston a year or more. He runs them hard and sees that as the cost of doing business. We ride together but he is generally a gear or 2 lower and moves more gravel than I do. 

image.png.ee718e3a9f20a1ae1174eea0ad413874.png

This Yamaha ate 2 pistons a year but dang! He was fun to watch! 

We also ran mid-1980s DT200 bikes for years as loaner bikes to bikeless friends:

image.png.ae2bf2248bd7721db033095cf2da1b68.png

These are oil injected engines which run great at mid-range and really pump the oil when on the pipe. 

Currently I am street riding a 1990 DT200R, very similar to the 1992 WR200: 

image.png.6cde5df49ea5e0224f2b5644830d0cf2.png

I am riding this because the KTM 125 is to loud and too wild for city streets. This is a quieter and more civilized bike that Jonny Law likes better. 

I bought this bike with low compression and worn out bore and rings. It gets lots of oil, what happened? Poor seals and filter letting dirt in to wear. 

If you want a 2 stroke that lasts forever you must do these things:

  • First of all start with something good. A reliable well built bike designed for longevity. 
  • Give it plenty of oil. 32:1 is what I run on iron bores and 40:1 on nikasil. Run the injection pump if it came with one. 
  • Chose nikasil if you can. Lasts FOREVER if you keep it oiled and clean and don't destroy a bearing or piston skirt. 
  • Keep an oiled and well sealed air filter, ideally OEM or better quality. Grease the edges for better seal. 
  • Keep the RPM moderate. Get on the pipe every so often but don't live at max revs. 
  • Jet it right. Keep the carb clean and don't burn it up with jetting or mods that lean it out. 

That is it. That is how I got thousands of miles and hundreds of hours out of the same 125 cast piston. That is why a PW50 lasts forever. No secret. 

image.png.781e9310bbc7337d7249b73d50220ada.png

Oh yeah, another of my favourite little 2 strokes. This beauty came to me with no compression and no air filter. Cost less than $50 and 30 minutes to rectify both. My kids ran this for years without ever replacing another ring (original piston). I kinda liked riding around on it too. I think I looked like some sorta circus act on it but dang it was fun. 

Good air filter, enough oil, moderate RPMs, don't burn it up. Will last forever. 

Edited by sbest
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3 minutes ago, sbest said:

I gotta disagree, I have a 2000 KTM 125 EXC that went 7 years on the original piston until I swamped it. It was daily driven and even highway driven but rpm was generally kept low and run at 40:1 oil.

1 KTM out of how many were built - congratulations on finding a rare one  :banana:

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