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new to me 03. smokes, need help..

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I traded my old 92 CR500 for a 03 WR450F a few weeks ago.

It's my first 4 stroke and maybe my last!

When I made the deal it ran OK and didnt smoke but it never got up to temp.

The carb is jetted as followed:



air jet-70

starter jet-65

leak jet-70

Needle- Y357

4th clip down from top.

1 1/2 turns out on air screw.

I've read that a smaller leak jet is better. I understand that 70 is big.

What the hell needle is the Y357??? can't find it anywhere.

Should I try to find a OBDWR-4??(stock)

My TPS passed all the multi meter checks.

All 5 valves are within spec but they are right on the TIGHT end of spec.

It starts OK. runs great with the choke on. runs OK when off choke and warmed up.

Has a bit of bog when off idle but I figure that is the 70 leak jet.

I think I have the AP set correctly. I just did what the manual said to do. When I pick up the slide it shoots a decent stream. It doesn't hit the backside of the slide or anything.

If you half lazy run thru the gears it runs great, but when you put a good load on it (working it up a hill) it pings and makes a terrible sound in the mid to upper RPM range.

At a standstill in nutrual I can rev it right up and it will sound fine but as the RPM's come down I get white smoke coming out the pipe. :foul:

Brand new spark plug is very black and pretty ugly after 10 minites.

peering in the intake and exhaust of the head shows nothing obviously bad.

I'm still running the gas that came with it when I got it. Have no idea what it is.

Could old low octane gas with incorrect jetting(needle and leak jet) cause the smoke and noise I was hearing under load?

I would like to get the correct needle, smaller leak jet and fresh 93 octane, see how it runs before tearing the head apart to see whats going on.

Wheres the best place to get a complete jet kit with the correct needle and smaller selections of leak jets?

BTW, I have already replaced the starter clutch assembly with the 04 model.

Grey wire disconnected and shorter throttle stop screw.

Stock exhaust.

Edited by adam500

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White smoke (actually light blue) is burning oil

You probably have worn out valve guides. 

The motor is old enough where you should expect this.

You can do a leak down test to confirm, but a 11 year old motor is going to need some attention.

Time for top end and a head job; then it will last another 10 years.

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Yea I figured.

Well the carb still needs to be sorted out reguardless.

Can anyone identify the Y357 needle I have? Is it out of a YZ or what? Should I put a stock one back in there?

Who makes a good jet kit?

Where can I get an assortment of leak jets?

Who should I send the head off to? I have always liked Eric Gorr at Forward Motion for my 2 stroke stuff. Anyone here sent a head there?


Why would leaky valve seals make that terrible noise I hear when the engine is under load?

I'm not saying my engine isn't burning oil but I still think I have a jetting and detonation problem.

I've dumped out the old gas but I dont want to try it again until I get the correct needle and leak jet in there.

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Four strokes rarely detonate. 

You jetting is not so lean as to casue detonation

You have to not think like a two stroke when it comes to four stroke motors

The Needle you refer to is an unknown, and probably a 'dynojet' needle, which are notoriously poorly made.


If you were to search just a little, or read the FAQ's, all your questions would be answered.

We have been dialing in these bikes for 11 years now.



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Well after looking around it seems like I should pick up that ACP upgrade, smaller leak jet and a JD jet kit.

I would like to put the carb back together with the correct parts and fresh gas and see what she does.

If it makes that awful noise again under load then I guess I'll have to pull the head off.

This is why I've stuck with 2 strokes for 10 years... :foul:

Edited by adam500

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Ever ride a 500?

I just rode the wheels off my AF today.

My buddy has a 05 CRF450. After riding his bike for a day I decided I really wanted a four stroke. Thats what made me get the WR. I just wanted the electric start after years of kicking my 500's over. My buddys CRF was just so much easier to ride all day long.

So easy a kid could ride it.....literally.

Edited by adam500

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