Finished my 2002 to 2003 YZF conversion

[CBDaddy]

About $425 and 9 or 10 hours later, and I have finished my 02 to 03 tank/shrouds/subframe upgrade. I got the parts I needed used from a guy parting out his 2003 bike. The only tricky parts were welding on a small threaded lug so my pipe would bolt onto the subframe easily, and fabricating a drop bracket to securely fasten the tank to the existing frame mounts. In the end, both issues were pretty easy to solve. I had to cut/drill/tap a few small pieces and buy a 1/2 dozen M6 bolts from Sears hardware, but I am very happy with my results. Nothing is "rigged" and it all fit on very well. Check out My Garage for before and after pics. DeCal Works did my new number backgrounds for $70 (included in $425 total). The Bud Light graphics is my stock 2002 tank/seat setup, and the pic with the stock graphics is the 2003 version. I haven't ridden it yet, but I am excited to see if it feels any more narrow/light/nimble compared to the big stock tank.

2003 Parts list needed for conversion:

Tank with shrouds and gas cap

Seat

Subframe

Airbox

Airboot

Rear fender

Rear master cylinder

Side number plates

Also needed:

1/2" x 3/4" x 3/4" Aluminum lug tapped for M8 bolt (TIG weld to subframe)

2 M6 bolts and small plates for tank bracket

I'm going to have some 2002 parts for sale if anyone needs them!

[Doug.]

Very nice!

How hard was the install??

[wannabe_bubba_259]

I know this is just me I would never spend the $425 on the 2002 to 2003 conversion. I have an 01 YZF and my brother has an 03 YZF and I rode them back to back and I did notice a diffence but the difference was not worth $425. But everyone is different. But it does look pretty sweet.

[CamYZ125]

I think that looks very nice man! I prefer the 03-05 look over my '02... and I don't think $425 is bad at all! Definitely got a good deal on all those parts...

[CBDaddy]

The parts only cost around $350 - DeCal works hit me with an additional $70 for the number backgrounds, just because I am too hard headed to NOT have numbers on my bike. The conversion was very easy. I spent more time thinking than I did working. I could do it again in about 3 hours probably. You have to have a buddy that can TIG weld the pipe lug on for you, but the bracket for the tank was a snap, if you have ever drilled and tapped a hole before.

[Wideopen24_7]

That price isn't bad at all and you can still sell your stock parts. Are the new backgrounds silver?

[RiderX]

More impotantly does the bike feel any different?

[johnk408]

Why $70 for the backgrounds? And now you need to work on the 06 look

[CBDaddy]

DeCal works charges $59.95 + $8 for shipping and handling for the number backgrounds. I had them in 3-4 days though - very fast service. Yes - I went with silver backgrounds and blue numbers.

I haven't ridden the bike yet since I only finished it last night. It does feel noticeably narrower while sitting on it in the garage making BRRRAAAPPP noises and leaning forward and back though!

[CamYZ125]

What if you bought an '03-05 pipe? You wouldn't still have to weld a tab on, would ya?

[CBDaddy]

What if you bought an '03-05 pipe? You wouldn't still have to weld a tab on, would ya?

Probably not, but I already had a Dr. D complete system for my 2002 and a $.50 tab welded on is a lot cheaper than a newer exhaust system.

[Doug.]

Probably not, but I already had a Dr. D complete system for my 2002 and a $.50 tab welded on is a lot cheaper than a newer exhaust system.

And there is nothing wrong with that Dr. D, its an excellent system.

[CamYZ125]

No doubt... I was just toying with the idea of a conversion in my head, and thinking if I got an exhaust system too, that an '03 would probably work.

[CBDaddy]

I just got back from riding my converted 03 YZ250F. I wouldn't say the ergonomics are night and day different, but I was happy with the new feel, and the bike looks much newer now as well. I feel I got my money's worth and I am happy with the new overall feel of the lower profile tank/seat.

The only questionable issue of the day was the bike felt/sounded a little soft on the bottom end power (up to 1/2 throttle). Normally it is real crisp and sounds sharp when I nail the gas, but today it sounded a little more "booooyaaa" than the crisp "Braaaap" from before. At the same time I made the model year conversion, I of course switch air boots and air boxes, I used a new clean OEM air filter (had been using Twin Air), and I also switched to a new X-ring chain (from stock chain).

I think it could be from one, all, or none of the below options. What are your thoughts?

1. The new air boot/box shape makes the bike sound quieter, but it actually has the same power.

2. The new air boot/box is somehow more restrictive, robbing my bike of low-end power.

3. The combination of the new air boot/box and OEM filter are robbing my bike of low end power.

4. Since the new air boot is about 1/4" too long, it pushes in on the bulging part of the boot that connects to the airbox, and in turn disrupts the airflow enough to rob my bike of low end power.

5. The power is the same, I just need to re-jet my pilot and/or needle clip to dial in the airflow of the new air boot/box.

6. The new X-ring chain is robbing my bike of low-end power.

7. All of it is my head and the bike runs exactly the same as before the conversion.

Which do you think is the most likely cause?

[Satch0922]

you should have used the old/stock air boot with the new airbox. I did that on my 426/450 conversion and everything fit better....

But....I think it's all in your head ! LOL

Good job on the conversion.

[CBDaddy]

you should have used the old/stock air boot with the new airbox. I did that on my 426/450 conversion and everything fit better....

But....I think it's all in your head ! LOL

Good job on the conversion.

I looked at switching the air boots but it looks like the 02 boot mounts to the airbox differently than the 03. Is there a trick to it?

[RiderX]

It may be just a combination of the different airbox and a stock filter that's giving you the different throttle response. The 03 air box is supposed to be an improvement over the 02. With a little tuning you will probably get the power back. Try tweaking on the pilot screw and moving the needle clip.

[Satch0922]

I bought a brand new airbox from Yamaha. It had no holes where the airboot mounts to the box. I took my 426 airbox apart, aligned the 426 airboot and mounting ring on the new box, marked the holes and drilled them out. Then I assembled the 426 airboot and mounting ring on the new box. I used silicone sealant around the inside of the airbox where it contacts the airbox. Not that you NEED to do this to make it work, but it was just for saftey sake...(it's not a bad idea on the 98-02 bikes to take the stock airbox apart and seal the airboot anyway).

If you notice in this diagram, the 2001-2002 bikes had an airboot that you installed by putting the airboot in the airbox (from the inside out) and the the mounting ring goes on the outside and you them bolt it all together.

http://www.psndealer.com/fiche/images/YAMAHA/2001/Motorcycles/1038_intake.gif

on the 2003-2005 bikes the airboot goes in from the front and clamps from inside the box.

http://www.psndealer.com/fiche/images/YAMAHA/2003/Motorcycles/1175_intake.gif

The hole for the actual boot is the same size on both boxes. Therefore if you use the 01-02 boot with the 03-05 box all you need to do is drill the mounting screw holes in the new box, then assemble it the same way the 01-02 box/boot is assembled.

[Satch0922]

here is a picture of my bike right before I sold it. You can see the 03-05 airbox but the 01-02 airboot (see the mounting ring?)

[CBDaddy]

here is a picture of my bike right before I sold it. You can see the 03-05 airbox but the 01-02 airboot (see the mounting ring?)

Thanks man. I'm hip to your jive. I will swap boots so at least it fits better.