2009 WR450R exaust and jetting

I've recently bought a 09 wr450r off my boss brand new only has 200k on it so it has barely been driven not even beat in yet. I had plans on getting an fmf powercore4 for it because my friend has a 09 klx450 with stock exaust and his motor overheats quite frequently. I'm afraid my bike will do the same which is why I want to put a new exaust on it.. Is this a good idea? also when I put the powercore4 on would it be mandatory to rejet my carb as well? Any bit of help with this topic will be greatly appreciated. Tell me any opinion u have.. Thanks.

Changing to an after market exhaust will not stop an engine from overheating.

Not letting the bike idle for long periods (minutes) and running proper coolant - will.

Your friend's bike is probably overheating because it is lean, not because he is running the stock exhaust. An FMF Powercore 4 is too loud for offroad. I stuck with my stock exhaust on my WR and it runs great. Spend your money on a JD Jet Kit. You won't be disappointed.

oh ok the reason why I was confused about my friends bike is because the mechanic told us if he switched to a different exaust the overheating would stop and sure enough he got a different exaust it didn't overhead as much.. whether the mechanic was up to something fishy I dont know. lol but I was also told that the stock wr's ran lean. so your saying you ride yours stock and everything is fine? Where can I take a look at this JD jet kit

A 450 would be diff than a 250 wouldn't it lol.. I think I might try the powercore4 I enjoy loud exausts

oh ok the reason why I was confused about my friends bike is because the mechanic told us if he switched to a different exaust the overheating would stop and sure enough he got a different exaust it didn't overhead as much.. whether the mechanic was up to something fishy I dont know. lol but I was also told that the stock wr's ran lean. so your saying you ride yours stock and everything is fine? Where can I take a look at this JD jet kit

No, the mechanics right. A more restrictive exhaust will get hotter than a free flowing one.

Well finally an answer that fits the events that occured.. So do you think it would be in my best interest to get a more opened flow exaust like the powercore4 for my new WR..? I'm just worried about the bike and its performance I want the best performance and most healthy for the bike.

Well finally an answer that fits the events that occured.. So do you think it would be in my best interest to get a more opened flow exaust like the powercore4 for my new WR..? I'm just worried about the bike and its performance I want the best performance and most healthy for the bike.

Well I run a Powercore4 Ti with powerbomb header on my 2fiddy. 175# main with a 40 pilot. When noise is an issue I put in the 'quiet insert'. That way you get the best of both worlds. :cheers: Here's a pic.....

7d960e39.jpg

Well finally an answer that fits the events that occured.. So do you think it would be in my best interest to get a more opened flow exaust like the powercore4 for my new WR..? I'm just worried about the bike and its performance I want the best performance and most healthy for the bike.

The difference is minor to the heat of your engine. The big thing is these bikes do not like to idle or go slow. Doesn't matter what you have for an exhaust, it will overheat if you go slow enough, the number the rads need to work is somewere around 8mph...

Rejet if the bike hasn't been, will help some, and it will run better. Cooling system can be improved with a Boyesen water pump or if you like to go extremely slow, a rad fan.

As far as a pipe, anything that's going to open it right up will be LOUD. And if you add a silent insert to said exhaust, you're back to square one, you're restricting it.

Don't sweat about your bike running a little hot, they were meant to, as long as you're not continually overheating....

And for what it's worth I've boiled mine over more times than you could ever keep track of. 450+ hrs of racing and riding and shes still running strong. No heat damage, just regular maintenance :cheers:

The powercore's are pretty loud. You ride MX or trail?

The stock header on the WR is very small. Might want to pick up an 07 YZ one to properly bring out the power of the slip on.

Jetting??

Any mods done to it?

Elevation, temps?

Many variables......

Best to go to the stickys and go through the jetting database.

I have a 07 WR450 and I found stock 08 YZ450 header and muffler on ebay in new condition for $100. The header on the YZ is ti and it is much larger in diameter as well for better flow. It is much louder, but not as loud as I thought it woulb be. Power gains were very good too, so I am pleased overall with the result...

Rich

Ive read in one of the Mags on the new WR's is that the stock muffler on the WR is so good that anyone who swaps it out for anything (if theyre not racing/making a living from riding) is an IDIOT! :thumbsup:

....it's that good.

Well I run a Powercore4 Ti with powerbomb header on my 2fiddy. 175# main with a 40 pilot. When noise is an issue I put in the 'quiet insert'. That way you get the best of both worlds. :thumbsup: Here's a pic.....

7d960e39.jpg

Your bike looks REALLY sweeeet man! :thumbsup:

How quiet is it with the insert?

Agreed, dgcars thats one of the nicest looking Dubya's I've seen. How is the phase 4 or has that bike ever been ridden? Mine looked like that for a week, then after a few TCCRA cross country events it looks like a used dirt bike... I should have my phase 4 kit in next week. What is your weight, spring rate setup as well?

Rich

Ive read in one of the Mags on the new WR's is that the stock muffler on the WR is so good that anyone who swaps it out for anything (if theyre not racing/making a living from riding) is an IDIOT! :thumbsup:

....it's that good.

my stock muffler had a tip on it the size of a dime..... good for quiet maybe, now it makes a good door stop...:thumbsup:

I guess there are lots of us idiots out here..

Your bike looks REALLY sweeeet man! :thumbsup:

How quiet is it with the insert?

Its as quiet as a Q4 I had on a 450.

Agreed, dgcars thats one of the nicest looking Dubya's I've seen. How is the phase 4 or has that bike ever been ridden? Mine looked like that for a week, then after a few TCCRA cross country events it looks like a used dirt bike... I should have my phase 4 kit in next week. What is your weight, spring rate setup as well?

Rich

Oh yeah, it gets ridden! Just like to keep 'em clean. The DaveJ kit was the best thing I ever done. He done an Enduro set up for me....I call it the KTM Killer!! 84kg. If you want the spec PM me your email. :thumbsup:

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