2004 WR450F bringin' her back from the dead project

Update time; Oil System Upgrade

From my initial readings on this site along with various other online forums, I found out something... its been documented that essentially our motors will only fail for basically two reasons;

A: The connecting rod seizes itself (either the big end or small end), or

B: Piston to valve contact (usually attributed to timing issues within the motor associated with timing chain stretch.)

The oiling in these motors off-road are for lack of a better word... subpar with todays industry standards. Now, if you take the bike out of it's natural environment getting tossed around over jumps and bumps, and street legalize the machine running on smooth concrete/pavement, will only cause the problem to be amplified exponentially. The problem I'm referring to is the fact that the piston connecting rod is only lubricated by splash. Funny part is Yamaha's engineers came up with a solution for the motor, but only instituted the modification to 4 wheel vehicles and failed to carry over the modification to our 2 wheel brethren... why they did that, I'll never know.

To me anything inside a motor that isn't lubricated is only asking for trouble, especially if you're doing sustained higher RPM's. So, my research began to find out how to do the mod. First place I found was;


The object is, you remove the side case and send them the part. They intern perform the required machining and send the case along with some new shinny Yamaha parts back to you... at a cost of ~$200 USD + shipping.

Then I started looking at the prices of parts, and figured there must be a cheaper way. So, I found this post on YFZcentral which pretty much did an excellent explanation of completing the modification, found here;


Only problem there was I didn't have access to a milling machine, so I set out to do the modification with the tools I had at my disposal. What I ended up using was my Dremel tool (200 series rotary), with a High Speed Cutter tip (model #115), along with a Multipurpose Cutting Guide attachment (model #565). I then set out to slowly and carefully remove the top 3.5mm of parent material from the case.

Once I was finished, I moved into the drilling stage using a handheld drill using only NEW & SHARP cobalt bits (so if you've been out drilling concrete/steel/other projects with your existing drills... you might want to invest in some new bits). I moved incrementally from the existing hole cast into the case up to a final size made from a 21/64" drill bit. I just worked slowly, with a LOT of cutting oil, I cleaned the bore of the hole after each pass with the next size up drill bit. To get the right depth, I started by only drilling as deep as the cast hole in the case without going past, then I would install the nozzle (w/o oring) and take a look to see if it would sit flush with the recessed surface I milled with the Dremel. If there was a gap, I'd re-drill as necessary until it would sit flush.

Next, I moved to the oil feed hole. For that I used a 3/32" drill bit, and I drilled right in the centre of the bore I just created until I breached the other side into the oil galley.

So the part numbers you'll need to order to complete this mod;

1x 5D3-15155-00-00 Nozzle3 (~$ 20 USD)

1x 93210-05098-00 Oring (~$ 2 USD)

1x 5TG-15462-02-00 Gasket 3 (~$ 17 USD)

1x 5D3-13300-00-00 Oil Pump Assy (~$ 83 USD)

optional part

1x 5TA-13320-00-00 Pump Rotor (~$ 20 USD)

Here's a couple pictures from mine;





She isn't perfect, but in reality any upgrade to the oil system on these bikes is a improvement, which hopefully might slow or stop a ticking timebomb from ruining your day away from the house.

Edited by rs25

starters on older bikes cause catastrophic failure, breaks the case and puts metal in the gears, I bought one that went through that

RS25, Another excellent idea!! If I'm looking at this correctly, this squirter sits next to the oil filter cavity, correct? If so, how does the squirter get the oil to the crank? Just a stream aimed at the spinning crank? My WR is going down to Baja this winter and I think this would be an excellent up-grade for the extended slab riding we have to do from time to time. Maniac

Maniac.. actually you're pretty close, except the stream points in the opposite direction at the bottom side of the piston. By doing this, it'll lubricate the wrist pin, and as gravity takes over, allows the excess to saturate the big end of the connecting rod. Plus as an added bonus, it'll also provide cooling for the actual piston as the oil will take some of the temperature away. How it gains access to the piston/crank is thru the oval hole at the base of the jug pictured below.


From quad members who've done the mod, say that the squirter isn't affected by BB pistons/jugs, but if you're running a stroker crank, then the piston will make contact with squirter. So as a word of caution, if you do the mod do a full rotation with the crank by hand to make sure there's no contact.

Edited by rs25

That is brilliant that you applied that from the quad to the bike motor. Ive known they do that to the quads but I never put them together.I guess quads are good for something

Honestly I think that is a great idea. How many threads are on TT about smoked WRs and YZs that had catastrophic failure from a crank failure?

Why wouldnt Yamaha do that to the bikes too? Yes quad motors get abused much more than bike motors but it wouldnt have taken much from the factory to do this to the bikes too.

Is there a visible difference between the oil pump you just bought and the one on your bike?

Next thing you know you are going to be running a helmet mohawk like a quad rider too!

without pulling out a micrometer to measure passageways, I couldn't see any overly obvious differences between the two pumps. The casting has changed a little but I'm not sure if it has anything to do with a higher flow rate. Only time will tell how well it works.

I do know one thing, with both rotors getting changed out, the oil pump really moves a lot of oil even with just rotating the unit by hand.

Nah, definitely no helmet mohawks for me. I'll stick to my Halo'ish Master Chief, Icon Variant bucket.

Edited by rs25

Thanks RS! I was hoping you'd throw a couple pics out there to show me where the oil squirt is aimed! As you've mentioned before, you had hoped that documenting all of these mods on ThumperTalk would inspire people to do the same on there machines. Well, it's working! This is a mod I will definately be doing!!! Thank you sir!!!


NP Maniac, glad you're getting some insparation from the thread.

Hmmm. Think I'll be doing this soon. Maybe order a mowhawk or just make my own with neon zip-ties..

haha, sounds good.. make sure you post a picture :banghead:

I cant believe that every Yamaha owner isnt flipping over this mod. All the threads on TT about running oil coolers , added oil capacity and WR long term reliablity. RS digging up the oil mod from the quads and bringing it to light for the WR and YZ , I would think is a bullseye.

I have been humbled. Quads are really good for something

Even without using a 07+ oil pump but using just the squirter adds a significant amount of oil to where its needed most

Thanks RS25 for posting this mod

Edited by MaxPower

Thanks for posting this RS! However, I thought all you need to do to upgrade the 03-06 wr's oil system to satisfactory was install a new 07+ WR450 clutch cover that has the piston cooling jet unit inside?

Yes, you could do it that way. I believe the only p/n difference between the WR vs YFZ pump is the first three numbers, which I beleive is just a general vehicle descriptor. For me, my pump was done, so I had to replace it.

Will this work with a 2002 WR426 or is the problem just with the 450s' starting in 2003?

Edited by jcbikes

Depends on your case design. Honestly the mod would be beneficial to any WR/YZF/YFZ Engine as long as it doesn't come factory

Well today I changed out the exhaust camshaft in favour of a new one from a 2006 YZ450f, also while I was there I changed out the timing chain for a Wiseco unit. Wow, does the motor ever develop a LOT more compression when you rotate it by hand. I'm hoping the starter can handle the extra load, if not, I'll just continue to use the kicker. This bike is gonna be fun.. I can't wait. :banghead:

Yesterday I picked up some new street oriented riding gear as most of my current equipment was designed for off-road application... This is what I picked up;


Are those Kevlar jeans? If so, definately a worthwhile investment!!

(don't ask me how i know!)


Yeppers they're Icon Victory kevlar jeans. Obviously I still plan on using some armour underneath for any rides. I've got a Dainese pressure suit, various nylon armoured jackets, and some armoured shorts and knee pads from roller derby.

Quick update. She runs :thumbsup: I got her out of the basement today and finished the assembly outside in the beautiful sunshine. Thankfully after a short run I've only got couple minor problems to fix so far. :banghead:

-I lost both seat bolts somewhere on my ride (I guess I forgot to tighten them)

-Cold starting this thing is a bitch (appeared to flood easily)

-Jetting is off, almost appears to be rich everywhere

-Valve cover gasket leak at the 2 half circles.

But, I can deal with that. Hopefully that's all that pops up in the next bit.


Will this work with a 2002 WR426 or is the problem just with the 450s' starting in 2003?

The cases are different between the 450 and 426.The oval shaped hole that the squirter passes through in the center case is just a round hole on the 426.Im guessing that if you could determine where the added oil squirter would go through into the crank area i would think you could drill a hole and make it work

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