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XR250L jetting

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May 12, 2001
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#1
My Neighbor has an Xr 250l, he has stripped all street equipment off, and now wants his 250 to keep up with my KLX300.

We have pulled the baffle, cut out the backfire screen, removed the snorkel, and now the jetting is too lean. I know very little about his carb. I was wondering how i go about jetting his bike a little richer. I would appreciate any input anyone has to offer. his bike is a 1994 xr250L

Thanks
 
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Aug 22, 2000
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#3
He'll need to go up probably one size on the pilot jet and one size on the main.

Hopefully the pilot is replaceable on this model. Some of the XL's have non-removeable pilot jets.

The down side is the bike may still not run right. The engine is designed to work with the backpressure provided by the stock pipe and stock muffler combination.

His best bet would be to spend a few $$ and buy an aftermarket exhaust if there's anything available. It needs to be a complete system. Just the muffler won't really help.

Check with Thumper Racing, White Brothers or Supertrapp.

Any of these systems will give him about a 15% gain over stock horsepower after jetting changes. If the above don't make anything, even the dreaded Cobra system is an improvement with this bike.

BTW, he's still not gonna keep up with the KLX - only the modern '97 and later XR 250 could hope to do that - but you probably already knew that, didn't you :p
 

G. Gearloose

Pigment of ur imagination
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#4
Did he already dump the sprockets??
Those come geared really tall.
 
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#5
Carb, and sprokets

He is thinking about buying a pumper carb from stroker, is a bit pricey, but they will pre jet it and it should make a hell of an improvement. Anyone think that is a good idea, he is gonna buy some sprokets now, so by the time he can afford the 350$ carb, bike will be ready, or should he just buy a carb from an XR250R?

If so, anyone got one?


Yeah i knew he would never catch my KLX, but the boy can dream right?
 
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#6
He is thinking about buying a pumper carb from stroker, is a bit pricey, but they will pre jet it and it should make a hell of an improvement.
Don't waste this great carb on an XL.

If he really wants to mod the thing, get an XR, then go to town.

The XL is really a tank compared to the XR, and all the componentry is cheaper (brakes, forks, shock, etc). There's really no good reason to spend any aftermarket $$ on the XL - if he wants street legal, the XR is easily kitted with a Baja Designs kit.

I'd recommend doing the free, or cheap modifications available and leave it at that.

If you can get an XR carb, you'd better get the airbox too. They are usually different (also, it depends on the year of the XL and the XR - there have been MANY changes to the XR).
 
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#7
Exactly

These were my thoughts too, but he really likes the bike, i don't know why, it is in mint condition and he payed very lil for it, i suppose that would be his reason for just not up and buying a new machine. Oh well you can't tell him what to do.

Thanks for the replies though
 
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#8
Understood. Many people I know have "guilded the pig" because they didn't know how much better other bike options may be.

He'll be held back from spending much aftermarket $$ on the XL simply because there's not as much stuff out there for them.

You're a good friend to help him out with this!
 
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#9
hehehe

well now i am back on my own accord,

i rode the ole xr today, mind you, it is an XR, it just has lights, and an emmisions carb on it, bolt for bolt the machines are the same, except for a few differences, the tranny has the first same ratios as the XR250r. But i really think if we could find him an XR250R carb, the bike would truly come alive, but i can't do anything with this emmisions carb, nothing is adjustable and it really is making the bike out to be worse then it is.

the bike is perfect for him otherwise, my belief is just find a carb, then let him out grow the bike, and then get a new machine.


Any ideas on how and or where to get a carb ffrom a 94 XR250R, the air boxes are the same, and so our the mounts, so i believe..........
 
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Aug 22, 2000
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#10
I believe with the 1994 XR-L model, you will be able to use the manifold and carb from an XR 1986 - 1995. Check it out here:

www.yamahaoftroy.com

Look on their OEM fiche guides (I couldn't access them this evening, but normally they're working). Check part numbers for each - if the numbers are the same, then bingo!
 
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#12
those dorks! I can't believe they have the Z50, and not the XR line. Weird!

I'll look it up for you tomorrow if you don't have anyone else that'll do it for you. We have all the fiche at work.