Snowys WR450F Project

Hey guys, just a quick Hello From me, I live in the innaloo area in perth. just bought this WR450f with a blown motor.

Plan is to get it going again and Get it on the street. This is the first engine re-build i have ever done, been working on cars and 4x4's and recently bikes for a number of years now, but never really did much with motors, thought this would be a good project to learn then!

so here's the Girl just before i took her off the trailer last night

and here's the rest of her.....

I dont know where the clutch plates are or the Carb, will have to ask PO if he still has them.

So to start off, one of the valves in the head got pretty messed up, looks like another vave got bent, the original cylinder cracked apparently due to the impeller failing they reckon. PO gave me a spare cylinder and its the right size for the piston, the original piston looks ok too, ill be waning a new gasket kit and new piston rings i think. i am thinking of just getting a whole new head, although they are costly, but so are individual valves and springs, not to mention the messed up valve guide id need to remove! cams, chain, bottom end seem alright, i assume the carb is ok, and i can always get more clutch plates if need be.

this seems like a fairly simple motor so shouldn't be too hard lol.

once the motor is going, ill go through all the rest to get it road legal then do the motard converting!

when i get back tonight i will get more in depth on the head for you guys, would be interested in some input of that.



Wooo Hooo looks like you have some fun ahead of you mate! Keep us updated.

- Shauny T

well quick look tonight after work at what we have.


so Cylinder bore looks good, 



piston and rings look ok, just need a clean. but looks like the piston has been dropped lol, maybe a quick sand will make it ok







The Head is where im gonna need people with experince to chime in, where the valve springs sit it looks like there is a collar, looks to be partially demolished... easy option is to get a new head ofcourse, but im looking to repair because why not. more pics







i am oncall over the weekend, so will be spending alot of time going through the service manual, looking to put the botom end back together, as PO pulled everything apart. YAY!


and as she sits Pic, because lets face it, we dont buy nuddie mags to read the articles!


That head looks easily repairable.  Send it off to a shop like Millenium tech (not sure what you have over there) and have them put in what it needs.  Likely they will recommend new valve seats, new guides, and at the end new valves.  If you can get a NEW head for less than $1000, it would be the way to go, otherwise repair what you have.


I wouldn't reuse that piston, especially since it's been dropped.  Buy a new one.


Check your crank for play very carefully, it looks like the piston was slapping the head quite a lot from looking at the head pic.  

Bit of an update, got into the bottom end tonight putting back together what was there. only missing one washer which i had a spare, idle gear cover missing, (will ask PO for that). need impeller, and piston and gasket kit.

Also, went to the machine shop today, asked what we could do, general consensus is that its way too much effort and expense as the valve bucket had destroyed the stem, would need to machine it out, new guide, bucket, spring, new intake valves, lotsa $$$$$!
So will look for another head.

also was missing most gaskets, so i have put the rest of the bottom end together, cleaning as i go, but not torque ing it all down, will do it proper when i get a gasket kit.

Oh, and put the race glass on the CBR yay!







Actually, maybe i will paint the crank case covers black, and get the shiny blue aluminium inspection hole covers.

Anyway, thats where im at now. will probably fix and mod the back indicators as one is broke. thats about all i cna do for now, need to just order parts and wait!


I know we're many miles apart but I've got New in the box cylinder head for that bike, sitting on my shelf.

Lots of other new factory Yamaha parts left over. I'm running an 09 WR now.

PM me if you want to strike a deal on the Head, piston& rings, Carb etc.

I'm unsure of overseas shipping practices, it may be worth your while


@stainless601 looks soo shiney!

I have found a local selling a 05 head off a yz that will fit. Cheers!

Problem I'm having now is that the starter gear cover has vanished from existance like most first dates! I noticed there is a 04' upgrade option but, I don't want to speed and extra ~200 to fix something that's not broken.

Any ideas?

hey guys, another update, got back from holiday not long ago, so getting back into the bike, So while i was away i trawled and poured over the forums seeing what common problems happen, not many, seems these motors are sensitive to valve clearances. well i have ordered the 2008 cbf crf? the upgraded diaphram and the updated spring for the Apump. Piston and gasket kit is on its way from the US, just bught a 05' head off a YZ with the cams and valves.


Cant wait for all the bits to show up and reassemble it!


So i pulled apart the carb to clean it too, and the air side of things was a little dirty, but the whole carb is pretty much clean as a whistle, so i have given it a quick clean with some carb cleaner. will wait till the gasket kit comes, not sure if there are any o rings in it for the carb, otherwise i will just reuse the current ones as they ain't bad. Jets are all clear too so thats good












And here is the new (Old) Head.



Compareing the heads, i realise that my one has alot of blowback on the intake side, im pretty sure that the PO has done something and got the timing chain wrong.


will hopefull not have to wait too long for more parts! :-D

My adjustable pilot screw arrived! Yay bling haha


Edited by Snowynonuts

I have a 2003 model and I'm doing the 2004 starter mod.  I was able to pick up parts off ebay for around $60 total.

I'm getting the bits off a 07, the part numbers are different but they look the same. Will see I guess!

You guys gotta also remember I live in Australia, so to get any decent bits it costs 2-3x what you guys in the US would pay! I bought the crf08 updated diaphragm and the better spring and cost me over $150 shipped!!!!

Also a bit of an update coming. I have been lazy with photos and updating so will take a few tonight and share :-)

i have a massive update to do. soon

My adjustable pilot screw arrived! Yay bling haha





Alloy fuel screws have a taper, unlike the stock brass screw, making fine adjustments much harder.

Alloy fuel screws have been known to break off inside the carb.......not a rareity either.

Cheers, well bike ain't running g yet so it ain't a problem. Also, was unaware of the R&D screw before I bought the alloy one. But will hold off as the R&D screw will cost just shy of $80 !

well, its been a rough few months, Mum passed away after fighting cancer for 2 years, not 6 weeks later my Grandad passed from brain cancer. been in NZ spending time with family.


So, after all that, im back in perth now, and back working on the bike, i pulled it all apart to see why the starter or kick wouldnt work, and well. the picture shows why!




I decided a whole new crank was cheaper, so i got a crank with a straight rod from an 06' it all goes together, everything on the right side bolts up, but turns out, the flywheel and oneway bearing are different! so i had to get new ones of those too! AND THEn upon tightening everything together i accidentally sheared off one of the bolts in the clutch boss!!!!  :banghead:



I mannaged to get the whole clutch assembly off the same guy i got the crank from, so mix and match and now i have good clutch plates too!


new fule line and filter to monitor fuel.


here is how she stands now



all together now and the kick works, starter is shagged. and wont start!  :foul:

send halp.


at this point, took spark plug out to test, i get spark when kicking over, and a mist of fuel is spit out when kicking. it backfired once. and im just not sure at tis point.

Also, when i turn the bike on, ignition on, no lights come up on the speedo, the two fuses on the relay by the battery are good, and tested the stator, seems to be just JUST in spec. switches seem to all be ok.

any insight would be greatly appreciated! please note this is my first engine rebuild so im totally open to any suggestions.


Anyway, hopefully i can get it started soon and work on the rest of the bike!





What's your jetting?

If you have spark, and it backfired... it may not be jetted right.

What are you doing when you start it?

Some people go ham on bikes, twisting throttle and basically flooding it, and wonder why it's so hard to start.


I'm about 1000 ft above sea level, my bike will start easily with the button, and first kick, no choke, no twisting the throttle, open exhaust, 45 pilot, airbox mod too.

Do you have the engine timed right? Didn't try to advance the exhaust cam for YZ spec yet?

I am about 50ft above sea level. I has a yz head and cams. New cam chain and the cams are set per service manual with the flywheel at TDC, timed from between the I on the flywheel lined up at the inspection hole. Valves aren't hitting.

I am kicking it over with the choke out on the carb. No throttle.

Also as was suggested on another thread, I shaved 1mm off the start pin on the exhaust cam.


Also as was suggested on another thread, I shaved 1mm off the start pin on the exhaust cam.


Huh...?  You did what?    What's the reason behind this?     I hadn't hear of this mod for this bike.   Where is that thread?


I always assumed that the reason why the KTM's are so easy to kick over is because of that start pin on the exhaust cam

Huh...?  You did what?    What's the reason behind this?     I hadn't hear of this mod for this bike.   Where is that thread?


I always assumed that the reason why the KTM's are so easy to kick over is because of that start pin on the exhaust cam


He put a YZ cam in the WR, and that grinding is needed because of the ex valve stays open too long otherwise.


All modern motors have an 'autodecompression' system.

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