Some help on leaning out my YZ250 please?

[Braap257]

Okay. So I know my bike is running too rich. And I Know it may need to be jetted. But I don't really know where to start? How do I go about leaning the carby out???

[G-MONEY]

Search the site there was a long descussion on this subject. It ended up with spanky"s guide to jetting your bike. Coop must have the link some place.

[Coop]

Search the site there was a long descussion on this subject. It ended up with spanky"s guide to jetting your bike. Coop must have the link some place.

 

[ford832]

Some would disagree with one aspect of that write up-but it's close enough

[Braap257]

Some would disagree with one aspect of that write up-but it's close enough

Everyone seems to have their own twist on this matter...

[evo550]

Braap,
Jetting is really an individual thing, by that I mean it depends on your climate, track conditions, engine mods, pipe/silencer set up.
I had a 04 yz250 for the 04/05 season and the only jetting changes where to go up 1 size on the main and drop the needle a clip or 2.
If your bike is standard, start by raising the needle clip (dropping the needle) a clip at a a time and perhaps one down on the main.

[Braap257]

Well the conditions around here tend to be pretty warm.. and its usually pretty humid "It's Florida" I'm gunna attempt to jet the bike soon. But I may try adjusting the air screw 1st. If i can find it lol.

[Hondacrrider]

This all sounds like a major headache, I think I will get my bike professionally jetted.

[ford832]

It's actually easy to do and once you've done it once you'll have it down.Besides,if you get someone else to do it you'll still have the drag it back to them whenever you ride in a different temp or elevation-and let them guess at what condition you might be riding in.

[Hondacrrider]

It's actually easy to do and once you've done it once you'll have it down.Besides,if you get someone else to do it you'll still have the drag it back to them whenever you ride in a different temp or elevation-and let them guess at what condition you might be riding in.

True, but no mechanic who wants to make money is going to show me how to jet my carburetor, my dad is is principal, he has no idea how to work with a carburetor, and the guys I ride with all run the stock jetting(as do I, because I have no idea of how to do it), so essentially, I can either wait until my grade 12 year to take mechanics(2 years from now) or send my carburetor to be jetted by a professional. I want to do it myself, but there are so many variable with engines, even two strokes, so, it is always good to have someone who knows what they are doing to help you through the process your first time.

[Friar-Tuck]

  You are right, it does help to have someone else there the first time to help out.  But that's not always gonna be an option.
It may take some diligence reading a service manual, and it may be boring.  One day the light will come on and you'll say what the heck was so hard about that!
   But just like anything else in life you are only gonna get out of it what you put into it.!!

Start Here: http://members.cox.net/bostonbrothersracing/General%20Boston%20Brothers%20Stuff/tuning/2stroke%20tuning.pdf

http://www.amazon.com/Motocross-Off-Road-Performance-Handbook-Motorbooks/dp/0760319758/ref=ntt_at_ep_dpi_1

http://www.amazon.com/Motocross-Off-Road-Motorcycle-Motorbooks-Workshop/dp/0760335966/ref=pd_sim_b_6

http://www.angelfire.com/zine2/boostajetski/carburetor_tuning.html

  Tuck\o/

  Jetting search TSM :  http://twostrokemotocross.com/forum/index.php?action=search2
You Tube Jetting search:  http://www.youtube.com/results?search_query=jetting+a+two+stroke&aq=f

[MyckMcClung]

where is it rich? top. Mid, or bottom? if it's on the top drop a main jet size
in the middle, lower the clip on the needle, bottom drop a pilot size.
Duh,

[MyckMcClung]

you might also have a leaky crank seal if you're oil fouling, look into that as well.