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ride4funRGL

Help needed on 2003 Yamaha WR450FR Performance Upgrades

11 posts in this topic

I have a 2003 Yamaha WR450FR and would like to upgrade the performance. I would like to eliminate the bog/delay when I snap the throttle and want to make it rip like a YZ 450F. My previous bike was a 1995 WR 250 two stroke and I miss the quick power. The WR450FR bike has the air box boot removal, grey wire clip, YZ throttle stop, GYTR exhaust tip, power now insert (air box side), and a Boysen quick shot accelerator pump cover.

I would like to make the mods in steps for cost reasons.

First, adjustment of the carb for the bog. Any suggestions?

Second, YZ exhaust cam or new pipe with matching jetting? Which would give me the performance I am looking for?

Third, New pipe or cam (depends on step two). Any suggestions for a pipe? Is a powerbomb worth the added cost?

Thanks for any suggestions.

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I have a 2003 Yamaha WR450FR and would like to upgrade the performance. I would like to eliminate the bog/delay when I snap the throttle and want to make it rip like a YZ 450F. My previous bike was a 1995 WR 250 two stroke and I miss the quick power. The WR450FR bike has the air box boot removal, grey wire clip, YZ throttle stop, GYTR exhaust tip, power now insert (air box side), and a Boysen quick shot accelerator pump cover.

I would like to make the mods in steps for cost reasons.

First, adjustment of the carb for the bog. Any suggestions?

Second, YZ exhaust cam or new pipe with matching jetting? Which would give me the performance I am looking for?

Third, New pipe or cam (depends on step two). Any suggestions for a pipe? Is a powerbomb worth the added cost?

Thanks for any suggestions.

Why do you want to do all these mods? The bog will not go away completely.. And can you utilize all the power? This will be to much for you!! This bike is 20 lbs heavier than a YZ so it will not perform like one.. This is a great bike as I have an 03 too... Dont worry about the cams just do the air screw,jetting looks like everthing else is covered.. This bike will rip with your small girly frame..

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For the bog, time the AP and try a #40 or 50 leak jet. Maybe try Redbeards AP mod, but you'll need a #70 or 80 leak jet for that. Get the rest of your jetting down also. Check the jetting sticky for a good starting point.

2nd, I would get a YZ pipe. It's way cheaper than aftermarket and provides decent performance.

3rd, I would stay away from the YZ cams. They are geared for top end performance and will hurt the low end grunt that make the WR such a good trail bike.

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Thanks for the input. I don't understand "Check the jetting sticky for a good starting point.". Can you elaborate?

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I have the YZ exhaust cam in my 06WR450 and it is the single biggest improvement you can make for the entire powerband. Some that obviously haven't tried it think otherwise. It is a little harder starting when cold but that's no biggy. The gains far outway that issue and once run, mine starts easy with e-start the rest of the day.

Don't mess with muffler tips as the stock can is so plugged up, at least get a slipon like the FMF titanium powercore. The FMF powerbomb isn't worth the money. The stock header puts out more low end.

For the bog I have a zero leak jet and did the BK mod with about a .2 sec squirt. My bike runs as good as you can make it run. It has instantaneous throttle response and feels as snappy as my old yz250 2 smoke but has so much more power.

My mods are for making the bike run as good as it can so take it for what its worth.....about 2 cents.

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Thanks for the input. I don't understand "Check the jetting sticky for a good starting point.". Can you elaborate?
Sorry. It's sort of changed names.

Look HERE for the jetting database. It's normally found in the Performance Index sticky at the top of the WR forum. Indy put together a chart that is a great starting point. I found that my 03 likes slightly leaner jetting than his chart, but it's real close.

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Get yourself a yz450F pipe, i put one on my '03 WR and it rocks. I was going to say to stud up a set of tires with the money you'll save, but then i checked where you live. A little too warm for studs.

Cheers

Chris.

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What is the BK mod?

Do a "Search this Forum" for BK Mod. You will get all the information you'll need.

Cheers.

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This thread is over the top!:confused::crazy::lol:

All of you should read this: http://www.thumpertalk.com/forum/showthread.php?t=444630

And then you should read this: http://www.thumpertalk.com/forum/showthread.php?t=440372

A lot of people all smarter than you and me put a lot of time and effort into this body of work. They did this because thay are passonate about dirt bikes. and they want to share their experience with dirt bike community out of the kindness of their heart. Their experience is vast! Since they took the time to share with you do them the courtesy of at least reading it. You will become smarter as a result.

One more thing, You could easily tune the low speed "bog" out of you bike if you only had a clue what you were talking about.

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