WR450 ?'s....about vibration and low rpm "hit"

11 replies to this topic
  • edwardsp

Posted January 04, 2004 - 05:29 PM


Well, it's been about 4 months, the new has finally worn off my 2003 WR450(about 300 miles, about 100 e-starts and no failures - dealer did service bulletin) and I have two things that I sure would like to improve on my bike. A lot of you guys are obviously pretty good at bike improvements. I could sure use some of your input here.

I have made no modifications to the carburetor jetting, but I have shortened the throttle stop screw, removed the air intake silencer(actually, I don't think I removed all of the airbox restriction that most people do.), and sometimes use the GYT-R exhaust insert.

1. There is a lot of vibration, particularly in the handlebars. It's especially noticeable on dirt roads, even at low speeds. I compared the feel of smaller bikes(XR100, XR200, TTR125) and they are very smooth. Is the vibration normal for big bore fourstrokes like this?

2. When i try to run at very low RPMs just off idle, the motor is a little held back, but with a very small amount of throttle eased on, there is a quick "hit", making it difficult to find a sweet spot for "putt-ing" when I want to. It makes me jerk backward and forward(enough to be tiring, but not exaggerated enough to be comical) :D as the engine speed crosses the "hit" point. The higher this bike is revved, the better it runs. It breathes fire from half throttle on. I know this is a competition bike, so maybe it insists on staying above near idle rpms. Is this just how it will be? :) Thanks for any help.

  • HighPlainsWR

Posted January 04, 2004 - 06:10 PM


edwardsp. Bet you've got the stock steel handlebars ? Go to a thick-wall aluminum Renthal, or comparable handlebar, and get some thick squishy grips. Once on my 98WR400, I filled the aluminum bar with silicon sealant to absorb vibration. It helped, but that single piston thumping with an imbalanced crank always made itself noticed. On the off idle "hit", it's still a detuned YZ race bike. On technical trails that's a handfull. What I did on the 02WR426 and now the 03WR450 is install a Revloc clutch with steel clutch plates. Now I shortshift going in to technical and low speed "thump-and-slip" through the rough stuff. Sounds like you've got an imbalance between eliminating the vibration by keeping it in the midrange and experiencing that "two-smoke" hit when you whack the throttle. Can't have it both ways on this bike ?!?!?!? :)

  • Oouthere

Posted January 04, 2004 - 08:15 PM


I think I know what you are talking about on the off idle hit. I installed the JD kit using the blue needle and 170 main jet. I put the idle mixture adjust at about 1 7/8 turns and the needle pin at the next to the leanest setting. This seemed to make the no-power idle condition go away and help smooth-out the off idle hit. I can now start the machine and idle through mud without her wanting to bog as where earlier she didn't want to run even out of gear.

My only other mods are the throttle screw and and no exhaust insert.

We just got back from a 25 mile trail ride and it was the first time she really got to stretch her legs. She stands-up at about 1/2 throttle in third but has to be snatched in fourth. I'm still getting used to the bike and really enjoy being able to wheelie through puddles and not have any squirming, the TTR225 just couldn't do it...

I've about 110 miles on my bike in a little over two weeks and like the bike more everytime she hits the dirt.


  • wjc2003

Posted January 04, 2004 - 08:29 PM


Yeah,mine does the same thing.It doesn't like to putt.So I go in a higher gear and use the clutch or live with the hit in a lower gear.This bike does not want to go slow,it likes to move at a brisk pace.It sure aint no trials bike!

  • edwardsp

Posted January 05, 2004 - 07:08 AM


Thank you guys for your input. Anyone else? It sounds like unless I spend more money :) I'm going to have to live with the vibration and most of the low rpm "hit". I really like my bike, but for the type of riding I do, I sometimes think I'd have been better suited with an XR400. The main reason I chose the WR450 over it is the better suspension for when I ride(not too aggressively) at local practice tracks with my son. Anyway, the money's spent now, so I'm a Yamaha guy.

  • Oouthere

Posted January 05, 2004 - 08:39 AM



You may find someone willing to do an even trade. I suggest doing a test ride on a DRZ400 if you pursue that path. The bike feels just like a big TTR125 except it's taller and has lots more linear power. No hit of any kind that I noticed.


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  • rekless

Posted January 05, 2004 - 06:51 PM


I think that you just need to get your jetting squared away. This bike is jetted terribly from the factory and I can "putt" around on mine all day long.....that's what I love about this bike. Fix the jetting and you'll be much happier. This bike will cruise slow as good as any XR....order the James Dean kit...you wont be disappointed, I promise!! rekless :) :D

  • fishwar

Posted January 09, 2004 - 02:40 PM


I just purchased a 04 WR450F. I do a lot of technical single track, lots of big rocks, logs, tight woods, etc. I have noticed the hit and the bike is hard to keep in the low RPM range. I think my bike is geared to high. The first thing I am going to try is going down one tooth on the counter sprocket and up three on the rear sprocket. This should put me in the sweeter PRM range where the bikes likes to run. I use a lot of slow 2nd gear. What a awesome bike! :)

  • edwardsp

Posted January 09, 2004 - 02:51 PM


I have already dropped my 14T on front to a 13T. I can tell it's slower, but the "hit" is at least as present as before. I don't think that is the solution for the "hit". I'm going to tinker with my fuel screw this weekend if I can make a custom screwdriver to fit up in there. I'll let you know if that makes any difference.

Yeah, these are awesome bikes.

  • Indy_WR450

Posted January 10, 2004 - 10:34 AM


Put a YZ450 exhaust cam in it and the hit will be gone. It is a WR trait to get good bottom end power. You will also get faster mid range and top end rev out of the engine. :) :D

  • wrkaholic

Posted January 10, 2004 - 12:10 PM



My son just went from an XR100 to a YZ250F. He also complained about the vibration. We went to renthal bars with pro-grip gel grips and he says it is much better now. We consider the problem solved. However, there is no doubt that the bigger 4 strokes vibrate more than the "trail bikes".

As for the "hit", I agree with others that have commented. First dial in your jetting. Then if you want, try YZ timing. I loved my WR426 when I went to YZ timing. On my bike, I can putt all day long. I do not think there is anything specific to these bikes that does not allow them to putt around. I ride mostly in 2nd and 3rd gear with stock sprockets. The throttle is touchy in the slow stuff because the bike has a lot of torque, but, you get used to it. With such a big piston and high compression, the bike jumps when you twist the throttle. To me this is an attraction, not a problem. The more you ride, the more you will love it. You just have to get used to being more precise with the throttle. Getting your jetting right will definitely help this learning process.

IMO, do not give up. You will end up loving this bike!! An XR400 does not hold a candle to your bike! They will be lining up from miles around to trade you. Personally, I do not think an XR400 does anything better than a WR. Woods, desert, tight trails, etc..., I think a WR does it better than an XR400. The XR400 has a fan following and they produce alot of rhetoric because they love their XR400s. Personally, I believe if you gave those same people a WR and they took the time to get used to it and dial it in, they would think of their old XR400 as an "inferior" bike. :)

  • Alabama_Rider

Posted January 14, 2004 - 11:41 PM


Hey Ed, I ride with alot with XR400's and they are an excellent bike in the tight woods, like where you and I ride. Take note that most riders on this site ride out west and ride in open country. They don't understand what tight southern pine forest are like. One "hit" at the wrong time and its into a pine tree. I am still trying to get rid of the "hit" and will be turning the accelerator pump way out next. :)


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