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  #1  
Old 12-28-2006, 12:17 PM
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Default 03 and maybe newer 03 CR250's how to:

email us for info.

Last edited by ProAMA725; 02-05-2011 at 11:17 AM. Reason: Tested and works great
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Old 12-28-2006, 12:54 PM
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Default Re: 03 and maybe newer 03 CR250's how to:

Cool. Good information for sure.

Wonder if a previous year boot would fit on it?
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Old 12-28-2006, 12:59 PM
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Default Re: 03 and maybe newer 03 CR250's how to:

Right on.
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Old 12-28-2006, 07:28 PM
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Default Re: 03 and maybe newer 03 CR250's how to:

Have you checked and adjusted the RC valve cables yet? It seems that this was a serious issue that contributed to the "wah, wah" effect on this engine. Any slack in them and the engine pulls like you are describing. There's also the Mikuni issue and that bike was jetted really rich at the OEM settings. I don't know how much of this the previous owner took care of, but it's a couple more things to look at.
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Old 12-29-2006, 02:55 PM
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Default Re: 03 and maybe newer 03 CR250's how to:

Quote:
Originally Posted by Woody_393 View Post
Wonder if a previous year boot would fit on it?
The ’02 cage/manifold will fit but it’s a step backwards IMHO. The ’03 design was better performance wise and helped to extend reed petal life.

Why didn’t you just take the stuffer (white block) out? FWIW, its size has a purpose and it’s not restricting air flow. None of these bikes suffer intake breathing problems unless your air filter is dirty.

There are gains to be had in the head; the squish clearance is overly large contributing to reduced potential power and increased octane requirements.

Changing the port timing to get an overal increase in power isn't too hard. By lowering the base 0.030" (0.75mm) and raising the exhaust port 0.060" (1.5mm) the bike will be a better overall performer. Be sure to relieve the squish 0.030" (or dial it in to your liking) to compensate for the removal of the base material.

I’ve posted the ‘how to’ for the 12mm adjustment for the exhaust valve that seems to give the best spread of power. A guy by the name of Henk Jager has the dyno sheets to prove it.

12mm Adjustment

There is enough play in the clearance holes of the exhaust manifold that if you just let it hang and tighten it up there will be a mis-match between the manifold and the port. Make sure that your exhaust manifold matches the exhaust port before tightening it down.

The stock 48 tooth rear sprocket doesn’t help thing either. A 50 tooth on the rear makes everything better (unless you’re riding desert) and helps close the gap between 2nd and 3rd.

The replated big bore cylinders have a lifespan of two or three seasons before failing. You might have better luck with a sleeve though…
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Old 12-29-2006, 04:21 PM
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Default Re: 03 and maybe newer 03 CR250's how to:

Anyone tell me why this shouldn't go to the KB?
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  #7  
Old 12-29-2006, 07:23 PM
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Default Re: 03 and maybe newer 03 CR250's how to:

Everything Faded said. Why? Cause i owned one. Welcome to the i just bought a 03CR and now i have to fix the motor thread.
I'm not being sarcastic i'm just tired of screwing with mine. By the way its for sale. I had head work done as well as ported the cylinder. Eric Gorr did the work, and it did run better. There are way to many issues with this motor to have to deal with in this day and age. Especially when there are so many choices out there.

I found a v force reed block helped
JD jetting or a different carb all together. An airstryker off of a 2000 CR will work nice. I opted for the JD kit it worked great.
You can try and bump up the compression a bit. The compression is low in these bikes to begin with.
Other than that just ride it and have fun.

The funny thing is that these motors were actually a generation behind the mid to late 90's motors that everyone is looking for.

With motocross bikes newer doesn't always mean better.
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Old 12-30-2006, 03:17 PM
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Default Re: 03 and maybe newer 03 CR250's how to:

Quote:
Originally Posted by sandflyz View Post
An airstryker off of a 2000 CR will work nice...
I prefer and would recommend the PWK Airstriker off of the 1999 model, the only difference is the needle which has a 'standard' profile and is a better starting point than the 2000 needle.


Quote:
Originally Posted by Florida 393 View Post
No KB for this one now, the originator can't handle a comment or a question.
Bill
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  #9  
Old 12-30-2006, 03:27 PM
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Usflag Re: 03 and maybe newer 03 CR250's how to:

Andrew,
if I could move just your replies I would, maybe someone that understands computers and the vBase software can do this. Or you could do a copy, paste and comment in the 2T KB and I will okay it "quick like a bunnyrabbit" (not you Hopper, settle down.)

Bill

Last edited by Florida 393; 12-30-2006 at 06:19 PM.
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  #10  
Old 12-30-2006, 05:10 PM
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Default Re: 03 and maybe newer 03 CR250's how to:

hmmm.. I didn't see that coming at all

Faded, we'll get it moved over regardless.
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