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06-10 YZ 250/450F tank mod to fit a 99 YZ 250

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I know how to fab, and tinker so I want to know If the YZ 250/450F 06-10 tank will mount to a 99 YZ 250 frame with just making mounting brackets for tank positioning...how will the 99 seat line up, with the 250F tank and radiator shrouds?, do i need to switch the seat too?

I currently have modded an 06 YZ tank and shrouds on my 99....so I am hoping it can be done....as well will a 250F/450F sub frame mount up to the 99 frame w just some welding?

whats the best technique...if there is a link to this being done please lmk?

Edited by phantom1

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I have not seen it done as the frames look so different where the tank sets.

But, if you succeed it woudl be a very popular mod!

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I tried it.

Bought a 2006-2009 450/250F tank, and attempted to mount it on a 2006 YZ 2-stroke. (Though my '06 has an aluminum frame, the basic configuration is similar to your steel-framed '99.)

Very nearly impossible conversion.

#1 - The "F" tank has a bit of a "belly" that runs afoul of the YZ backbone. It forces the tank 'way too high up above the bike. The only way to fix it would be to start radically cutting away at the aluminum frame or mold a new underside for the tank.

#2 - The seat attachment button (that mounts on top of the tank) is in a different location, so you would need to buy an "F" seat.

But then you'll need an "F" subframe, because the rear seat mounts are also in a different location. Or you could modify the 2-stroke seat pan, but the whole affair would still be 2 inches too high because of #1.

#3 - There is no attachment provision for the forward tank mount in the 2-stroke frame. And the tank's mount is still 2 inches from the frame anyway, due to #1.

#4 - The backbone dampers (rubber pads) are completely different, because the two backbone designs are completely different. And you really need correct, stable rubber pads because the "F" tank only attaches at the front and rear, because...

#5 - There is no way to attach beneath the tank.

#6 - I think even the petcock location caused contact with the motor or carb or something.

I'm not trying to drive you away from your idea (cuz I'd LOVE to do it!), but sadly, the 2-strokes and '06-up 4-strokes are radically different under the bodywork.

Unless Clarke or IMS manufactures a special hybrid gastank, "F"-type tank and shrouds on a 2-stroke is just not going to happen.

http://www.thumpertalk.com/forum/showthread.php?t=793234&highlight=tank

Edited by CaptDan
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so i am wondering if you cut the tubing on the YZ frame where the tank mounts and then try to re-weld a custom fit to where a F tank needs to be if that would work? and then custom weld a F sub frame to fit the YZ to run the seat and fender.......would that work you think?

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Also from that thread...

The 4-stroke tank is too deep underneath.

You can see how the 4-stroke's frame is much "deeper" at the rear than the 2-stroke's frame (see arrows). The gas tank has a depression that nestles into that area. The 2-stroke frame is just not "deep" enough in that area to accept the 4-stroke tank.

frames.gif

When the lowest point of the F tank touches the 2-stroke's frame, the rest of the tank is propped-up 25mm too high. (Darn it!)

www.yamahapartsdepot.com

Its not the width of the tank thats the issue, its the fact that the whole underside of the tank is designed differently to fit into the differently designed frames. The 2 stroke frames are back bone style while the 4 stroke frames a back bone/bilateral beam sort of hybrid

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