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lastchild

LA Sleeve 400 kit for YZ450

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I see in the new Dirt Rider that LA Sleeve has a 400 kit for the YZ450's.

I did a search but found nothing.

Does anyone have this kit or have any thoughts on it?

Might be good for a bike that sees alot of woods riding, as mine does.

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I see in the new Dirt Rider that LA Sleeve has a 400 kit for the YZ450's.

I did a search but found nothing.

Does anyone have this kit or have any thoughts on it?

Might be good for a bike that sees alot of woods riding, as mine does.

Did you mean a 400cc kit for your 250...F....?

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So, obviously from the rampant sarcasm, no one has read the article.

It claimed it took some of the "heavy" feel(not my words) out of it.

It also said it made it pull like a 250 2-stroke...whatever.

I'm not advocating it, just wondering if anyone had any experience with it.

Anyway I called LA Sleeve myself and it's a new product that is just being released.

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Doesn't seem like a particularly good idea to me, frankly. For one thing, any time you run a ferrous sleeve in an aluminum cylinder, you have heat transfer issues come up at the joint of the two metals.

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I gotta say that is about the weirdest thing I've ever heard of. Nothing pulls better than a 450...and certainly not a 250 2T. I have both. And Gray is right...you want to avoid sleeving if at all possible.

Do you have a link to the article?

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So, obviously from the rampant sarcasm, no one has read the article.

I read it. But, there is no way I'd ever try it (even if I had a 450).

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A great idea for that 15 year old beginner rider kid that has to have a 450.....or the dad who has decided to learn to ride dirtbikes on a 450.....:bonk:

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what kind of issues do you run into when sleeving, and how severe are they? My buddy and I just saw that article in the Dirt Rider about the kit and thought that it would be perfect for us....weve been tossing the idea around of switching to 250Fs...cuz we arent really capable of just flat out pinning the 450s...but read the 400cc kit and now we're really thinking about it...

but how bad would it be?

gray?

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Just restrict the exhaust , rejet, and voila, you'll have turned your 450 into a 400 for a few bucks! Not to mention, it'll be super quiet!

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put a throttle stop on your bike... way cheaper and no need to tear your bike apart. and then when you feel comfortable enough to open it up, it's there.

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I read the article and it seems like a very interesting idea to me as well, not like all these pro riders who have been giving you a hard time who ride their 450's full throttle all the time and need all the power they can get their hands on. Sheer horsepower is a great feeling, especially in a drag race but on a motocross bike HP's doesn't always make you faster. I

I am sure gray will chime in on this one and it might be comparing apples to oranges but when they decreased the motor size in the gp superbike class this year everyone was turning faster lap times, the traction control probably had something to do with it to? No replacement for displacement huh? Not always the case.

I see in the new Dirt Rider that LA Sleeve has a 400 kit for the YZ450's.

I did a search but found nothing.

Does anyone have this kit or have any thoughts on it?

Might be good for a bike that sees alot of woods riding, as mine does.

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I voiced my opinion already (see post #6), but I'll elaborate. There's a basic problem that shows up anytime you use an iron or steel sleeve in an aluminum cylinder with heat transfer across the union of the two metals. Methods have improved, especially with regard to cylinders originally manufactured with a sleeve in them, but still, it's not ideal.

Then there's the expense. What are we trying to accomplish? Taming the beast? That makes sense for some people, but why such a costly approach? If I wanted to drop some power, I'd start with a WR exhaust cam, or one from a YFZ Quad engine for an even bigger drop. This alone would take you from about 46-47 hp on a stock '04 YZ to about 40 or 35, depending on which way you go. Then add the biggest flywheel weight you can find. You could do all of that for under $250, have no more than two hours down time, and change it back in two more hours anytime you want.

I'm not buying the reduced top heaviness thing right now, BTW.

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No replacement for displacement huh? Not always the case.

BS. Its always the case. :thumbsup:

I really don't see how a stock 450 has too much power. IMO, the stock 450 lacks the punch that the 426's have. I rode a bone stock 07 and was pretty disappointed with the power. The handling and suspension was awesome, but the power delivery was too slow for me.

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I voiced my opinion already (see post #6), but I'll elaborate. There's a basic problem that shows up anytime you use an iron or steel sleeve in an aluminum cylinder with heat transfer across the union of the two metals. Methods have improved, especially with regard to cylinders originally manufactured with a sleeve in them, but still, it's not ideal.

Then there's the expense. What are we trying to accomplish? Taming the beast? That makes sense for some people, but why such a costly approach? If I wanted to drop some power, I'd start with a WR exhaust cam, or one from a YFZ Quad engine for an even bigger drop. This alone would take you from about 46-47 hp on a stock '04 YZ to about 40 or 35, depending on which way you go. Then add the biggest flywheel weight you can find. You could do all of that for under $250, have no more than two hours down time, and change it back in two more hours anytime you want.

I'm not buying the reduced top heaviness thing right now, BTW.

Hmm..I never thought of the cams. and Im not really thinking about it for the "reduced top heaviness" I love the handling on this bike, its just I don't think Im at a point where I am wringing out the engine, and might be faster on something a little less potent, hence the thought of switching to a 250F...

thanks for your input everybody.

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Im at a point where I am wringing out the engine, and might be faster on something a little less potent, hence the thought of switching to a 250F...

If you're riding MX, you might be. Tighter tracks put the little thumper at a kind of advantage in that you almost never have too much power on tap, so you don't have to rhink about it or fight it.

I really don't see how a stock 450 has too much power. IMO, the stock 450 lacks the punch that the 426's have. I rode a bone stock 07 and was pretty disappointed with the power. The handling and suspension was awesome, but the power delivery was too slow for me.

If you run your 426, or early 450 side by side with an '06/7 on pavement, something surprising will happen. That soft feeling new bike will run right with you, and then probably start pulling ahead. The power delivery on the new bikes is a masterwork, IMO. Not as thrilling as it used to be, but still all there, and much more useful. A lot like the 250F is, just a whole lot more of it.

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I don't disagree that the new 450's have the same or more horse power as the 426. I just think the smooth delivery is too slow and boring for me. I'd love to have a new 450, but its going to need some motor work to make me happy. :thumbsup:

BTW, wouldn't a 03 YZ450 motor in a 2007 chassis be the perfect bike? (with an auto-clutch, of course) :thumbsup:

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