WR450 power/gearing questions


12 replies to this topic
  • energydoc

Posted July 20, 2010 - 08:49 PM

#1

Just got an 03 WR450 with a revloc clutch, FMF Q, completely uncorked(supposedly), low miles, well maintained.
The off idle bog is small but noticeable, and the gap from first to second is too wide-the bike falls on its face under a heavy load.(14-50 gearing)
I have also owned modern 450 MXers, and miss the midrange punch.
This bike has none.
It does rev to the moon, and is an easy bike to go fast all day, just wondered if there were any suggestions to find that missing punch.
Could it be the revloc clutch, cam, jetting,? I have done everything else.
Thanks

  • CanadianWR450

Posted July 21, 2010 - 05:03 AM

#2

Make sure all the free mods are done, and it's jetted right for starters....
I have a 04 and with 14/50 gearing, and if it is truly uncorked, it should NOT be falling on it's face going from 1st to 2nd under load.......

- Grey Wire
- Snorkle on air box at minimum, and maybe go for the side cut out's if your willing.
- make sure your jetting is correct...I like JD ...others have thier own opinions.....

If all above is ok....could be your clutch.......

personally...I'm suspecting jetting.....

  • Dee Perry

Posted July 22, 2010 - 05:12 PM

#3

I also suspect jetting. My 426 was the same until I jetted properly. Both the 426 and my 450 will pull your arms off all the way through the gears.

  • energydoc

Posted July 22, 2010 - 08:26 PM

#4

Thanks for the info. you guys.
Obviously I'm too lean somewhere, right?
Pilot and the main feel right, what next?

  • CanadianWR450

Posted July 23, 2010 - 02:10 PM

#5

Thanks for the info. you guys.
Obviously I'm too lean somewhere, right?
Pilot and the main feel right, what next?


Not necessarily....you could be rich....
Lean = surging...rich = it's just kinda flat...like the back brake is dragging.....I like the term.."wallowing" for the engine when rich....lol.

You can be lean one place in the rev range, and rich in another as well.....

Step #1 - go to the stickies and find the jetting database and look for a good comparison to your bike/conditions.

I like the JD kit, because it takes the guess work out for most ppl as long as your not too heavily modded (follow the instructions exactly), and far as I'm concerned the support is outstanding. I went with a big bore, hotcams, and full FMF megabomb/Ti PowerCore combo...so my jetting changed from the "normal" JD instructions. Couple emails back and forth, and I was good to go.

You can jet perfect by yourself...with time, and patience...which I don't have...lol...so it's up to you on how much your time is worth.

  • jayh300

Posted July 23, 2010 - 02:54 PM

#6

Not necessarily....you could be rich....
Lean = surging...rich = it's just kinda flat...like the back brake is dragging.....I like the term.."wallowing" for the engine when rich....lol.

You can be lean one place in the rev range, and rich in another as well.....

Step #1 - go to the stickies and find the jetting database and look for a good comparison to your bike/conditions.

I like the JD kit, because it takes the guess work out for most ppl as long as your not too heavily modded (follow the instructions exactly), and far as I'm concerned the support is outstanding. I went with a big bore, hotcams, and full FMF megabomb/Ti PowerCore combo...so my jetting changed from the "normal" JD instructions. Couple emails back and forth, and I was good to go.

You can jet perfect by yourself...with time, and patience...which I don't have...lol...so it's up to you on how much your time is worth.



agree with that .... My friend bought an 04 wr450 about a year ago or so.. It was in the mountains and we are not, and it was in the low 30's when we picked it up.. I rode it and it ran ok, not great, but ok.. Figured we would rejet when we got home.. Pulled the carb, it had NO main jet in it... It ran really weird here.. Took a stab or two but we got it figured out.. It feels stronger than my 06 does btw..

My 06 i bought last year has a JD kit in it and it is spot on. I have never touched the fuel screw..

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  • JSanfilippo

Posted July 23, 2010 - 07:40 PM

#7

Pulled the carb, it had NO main jet in it... It ran really weird here.. Took a stab or two but we got it figured out.. It feels stronger than my 06 does btw..


It should, the '03 and '04 bikes had higher compression.

  • Leardriver

Posted July 24, 2010 - 06:57 AM

#8

Where do you live in Denver? I've got lots of jets and practice setting up those bikes to run great.
Bring lots of diet Mt Dew.

  • PBDBLUE

Posted July 24, 2010 - 07:04 AM

#9

It should, the '03 and '04 bikes had higher compression.


The compression is slightly higher (12.3 vs 12.5) but I suspect the biggest difference is in the cams. 05 and newer cams are designed for smoother delivery. None the less back to the op's question. Definitely sounds like the jetting is not correct. Once jetted properly if you still want more rip put in the YZ exhaust cam. My 04 with a YZ cam and Procircuit exhaust is as fast as any 450 I've ridden but it comes at a cost. The power delivery can be a handful in the technical stuff.

Edited by PBDBLUE, July 24, 2010 - 08:06 PM.


  • CanadianWR450

Posted July 24, 2010 - 07:38 PM

#10

"My 04 with a YZ cam and Procircuit exhaust is as fast as any 450 I've ridden but it comes at a cost. The power delivery can be a handful in the technical stuff."

Now there is a true statement.
Last year, my bike with Hotcams, and just the power core slip on with stock header and a 14/51 gearing combo was pretty nasty. Great in open fire roads and stuff...not in tight rooty or slick stuff.

As it was time for a cylinder, rings, and piston anyway, I went with a 480 kit, and a SS megabomb and a 14/48 combo.

Far as I'm concerned, it's perfect for me now. As crazy as it sounds...it tamed the bike down, made it far more user friendly, and easier to ride....all while gaining gobs of power, and bottom end torque.

I always liked the feel and power delivery of the old XR 600's, and if thats what you like....the combo I have is the way to go .. at least for me anyway...it's like a XR 600 on a crash diet, and steroids....lol

  • MaddogYZ

Posted July 25, 2010 - 11:20 AM

#11

I personally like 14/51, I was suprised one tooth would make a difference but it help close the big from 2-3 just enough to save a couple downshifts.

  • energydoc

Posted August 13, 2010 - 10:42 AM

#12

Howdy Leardriver,
Had some jetting questions for you about my wr450.
Thanks,
Glenn
Energydoc
Boulder
720-225-9181
cell 303-818-5203

  • wartsnuff

Posted August 13, 2010 - 10:56 AM

#13

Jetting all the way

my 08 WR450 uncorked is a monster... pulls you arms otta the socket.. its also forgiving power there is so much even if you torque out low low rpms it will not fall on its face.

I used the JD jetting kit... works great.. i am only 780 above sea level... so should have put the YZ jetting guide provided by JD, not the WR jettting provided....

I did however loose 15-20 km/h speed... but the bike is ultra fast. and its runs so much better starts better stay idliing.. never have to mess with the mixture screw.

anyhow good luck!

cheers
Warts




 
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