The 2-stroke thread

I have a problem with excessive exhaust (bluish/white) smoke on my 03 YZ250. I have only owned this a month so I cant confirm what lies I may have been sold.
The bike is responsive and always starts first kick. Ocassionally (every 20 min or so it boggs down at high speed). I ride a fair bit of slow going trails.
Compression is good, recent top end.
Carb has recently been disassembled and cleaned to eliminate the possibility of clogged jets etc.
Carb has stock jets and air mixture screw is at reccomended 1 turn out.
Plug was cleaned (it had a lot of dry carbon on it).
Air filter is clean.
Fuel ratio is 50:1. A new fuel filter installed.
Oil brand is Stihl. I have some Castrol 2 stroke I have yet to try.
My thoughts:
1. the ratio should be at 30:1 as the manual states, not 50:1
2. the brand of oil is the cause, maybe try a more expensive brand? (smokeless)
The problem is not so much mine, as it is really more anyone who is following me, they are the ones getting smoked out!

 

Try some Mobil 1 racing 2T, or Yamalube at 30:1. Those two oils won't gum up your power valve like Castor based race oils do. It's not a big deal on a race bike that gets torn down once a week...or on older bikes without power valves. Stihl oil is for weedeaters.

 

Do you have a video of it once its warmed up how much youre smokin? its normal but you said excessive so im curious as to what that is when its warm. I run mine at 40:1 and it seems to work pretty good for me. Hardly any smoke and barely a drop of oil coming out the exhaust once ive rode it for a good amount of time. .

Also like username said, maybe try switching premix. I use bel ray but im sure most any motorcycle specific oil will work

 

I always ran Belray synthetic 2T oil. The bike smoked a bit when cold but cleared right up after that.

If switching oil doesn't help I'd look into crank seals.

 

My 2003 YZ 250. Fun for enduros and rocky stuff.
Next on the list is port and polish, fly wheel weight, rekluse clutch, and wr tranny gears. After that I'm hoping to move on to the ktm 300 xc

 

Save yourself the trouble and get the 300 now.

Nice yz though!

 

30:1 Yamalube and a NGK BR8EG did it. No smoke.
Must have been the Stihl oil and the NGK BR8YA.
Thanks,

 

X2. Three hundy FTW.

 

I'd really like to believe me! All about the Benjamins though. Sadly the heat and this drought has been taking a toll on my money tree. And truck needs parts too.

 

Really? I race a YZ250 with big bore kit (295) and put the WR gears in it (3-5) run a Gnarly pipe, Rekluse Z-start Pro. BTW with the rekluse Z-start you dont need flyweight due to the added weight already.
My bike is faster than a 300 hands down, a bit more peaky on the power but the rekluse mellows it out by clicking up a gear. I have ridden a bunch of KTM 300s and I thought I wanted one till I rode a few and realized my YZ is better IMO. the electric start is nice but the YZ is so damn easy to start it not necessary, plus I flat outrun KTM 300s all day.

Try Motul 800 oil, I mix mine at 48:1 and it works great. I bet it was your oil...that stuff isnt designed for dirtbikes.
30:1 is awful rich, thats a lot of extra money on oil. With a high end oil like Motul you dont need as much to do the same job.

 

Yep. 250 was faster, 300 is much more usable all around, especially on my stock SX gearing.

 

http://mxsponsor.com/public/sized/m/1000-1000/61207/GrumpysWCGP2014.jpg

Damnit cant post it as a pic, haha! From last weekends race at the Ranch, The West Coast Hare Scramble Championship, 1st in class again!

 

The rekluse and the extra rotating mass really calms it down, and yeah SX gearing is pretty short, probably has massive torque.

I guess it all comes down to personal preference, after borrowing a buddies 300 (6 days edition 2014) I couldnt wait to get back on my YZ! But OMG that KTM was purdy!! I think I almost blushed when it caught my eye!

I think for me at least the ergonomics of the Jap bikes fit me better. I feel so out of my element on a KTM for some reason. Most of my race team and riding buddies have KTM or Husky, I have 5 Japanese bikes, haha!

2004 Honda AF500 (01 motor, 04 250r frame)
2006 Yamaha YZ/WR 295 (race bike)
2005 CRF450r (dual sported)
2008 CRF450r (Havasu bike)
2013 KX450f (race bike) just got plated!!

And my wife rides an 06 CRF250x

 

So I will actually agree. I never felt totally comfy on the 250sx. If I ever pick up another bike it will be an aluminum frame yz250 and I'll just make a woods monster out of it. I just love the way yamahas and kawi's feel.

Only reason I recommended he get the 300 now is that it was his final plan, no point in sinking a bunch of money into his current bike he doesn't plan on keeping long.

 

Agreed the Katoom 300 is a VERY popular bike. And I had to do quite a bit to mine to make it what it is now....

 

Turn up qaulity to 720!

Havin fun in Johnson Valley yesterday.
Playin in the rocks..

https://www.youtube.com/watch?v=dtM4-z96VVU&feature=youtu.be

 

Looks like a great place to ride. I would love to go to Colorado or Arizona and ride the rocks on my Sherco

 

General question.
If I remove and replace a fuel line from tank to carb, should the line self prime? The carb bowl is full and the line will not fill with gas unless I squeeze it a bunch of times.
I would think that the pressure of the gas from the tank should coax the air up and into the tank. I was not a physics major.

I ask because the bike died from lack of fuel the other day. It was a clogged inline fuel filter. Or so my buddy says.
Thanks,

 

Yes gravity should send the fuel into the bowl, unless you have a bad fuel line.

 

anyone see pastrana on the rmzilla 500 at the straight rhythm ?!