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98 Yz 250 cylinder on 96 Yz 250...

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I think I posted this before but I cant find my original thread anywhere...:busted:

So heres the deal, as most Yz fanatics know the 96 had a massive midrange but absolutely no bottom end and signs off extremely early up top, in an attempt to make the monster motor that the Kx had durring that era and failed miserably. Yamaha fixed the problem in 98 with the updated cylinder and PV. So I got to thinking and my cure to the weak 96 motor was to install as many parts from the 98 motor as possible to make this thing run on the track like its capable of and the cylinder is at the top the list.

Ive been looking for a decent 1998 Yz 250 cylinder for my 96 Yz 250 for quite some time, and I finally found one and pulled the trigger on it. I think I can make it work. The cylinders look identical and use the same piston/ crank, so Im not too worried too much about fitment yet BUT they have different part #s obviously so Im curious as to what the differences are. I already have the 98 black box installed on the bike.

My question for now is what things do I need to check when I install the new cylinder?

A little info about the cylinder and what I have to work with:

It came as a bare replated cylinder but I did order the piston that they fit to the bore... I have no PV, no linkage, no head to match this cylinder from the 98. I need to know if there are any differences between these parts so I know what I can put on my list of needed parts to purchase and what I can plan on trying to swap over. Just judging by looking at it Im thinking the head will swap over, possibly along with the linkage. The part Im really worried about is the PV (again diff part numbers (96 PV # 4SR-1131A-00-00)(98 PV # 4XL-1131A-10-00)). Are there any differences and does anyone know where I could find these items. Been watching ebay for quite some time to no avail. The first snow of the season fell yesterday so I figure its time to tear into this thing.

Also wondering what I would have to do to get the intake to work? Will the carb and boot work? Obviously I will have to source a Reed Valve assembly for it but that part is easy.

Hopefully someone can help me out with this project as Im a pretty good mechanic when it comes to taking something apart and putting it back together or replacing/ repairing things, but I dont know too much about "retro fitting". Any info at all would help me out a TON!!!

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The change from 96 to 98, on the cylinder, was significant. Lots of changes, btu damn little performance difference. It may be expensive to switch over.

The exhaust port changed. I think you can modify your pipe to fit, but it wont drop right on.

The big change was on the intake side. The 98 uses the reed valve and block thats still in service today. The 96 wont drop in the 98 cylinder. You'll need a 98 (or newer) reed block, intake boot, gaskets, and a few more bolts.

You can only use the intake manifold from the 97, 98 and possibly the 99. Nothign newer will work as they will hold the carb at an odd angle.

I think the powervalve slips right in, but some of the dimensions changed. Not a sin size dimensions, btu shape dimensions for improved performance.

When all is said and done, you'll have spent a lot and ended up with little to show for it since power will be almost identical. The 98 black box is where the better snap came from. Also, a sa cheap experiment, make a flat plate to replace the left powervalve cover.

You would get a much better value sending your 96 cylinder and head to eric gorr. Also, you need to match your powervalve to the exhaust port. Try the plate and powervalve matching first, actually, since you'll only be out time.

Plus, even if you do all of these mods, you still need a Noleen pipe to make it work right. Without that, yor're screwed.

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Plus, even if you do all of these mods, you still need a Noleen pipe to make it work right. Without that, yor're screwed.

That my friend was supposed to be my little secret... its already hanging in the garage (got it from a member here)!:busted: :busted: Ive had it since I bought the bike.

Thats mostly the reason I want the 97/98 cylinder. Pipe wont fit my 96 cylinder. Since I now have the 98 cylinder I was hoping to make it work so I could use the Noleen! The Noleen in combo with the 98 black box and upgraded PV I should have a decent bike from what I understand. Just being able to run the Noleen will make it worth while! The money isnt really a factor either. I put a little extra aside just for this project!

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