WR450 2007 top speed problems

[condor74]

Could it be that it is just louder now so you can hear the revs differently?  If the exhaust changes the flow characteristics of your exhaust, then you should rejet the bike.  I dont know that rejetting will fix your complaint but it will make you have a smoother running bike.  The bike doesnt really have a redline so to speak.  It has a rev limiter and I doubt you are in 5th on the rev limiter. 

[DunmireD001]

Change your sprockets. 14/52 is mx/trails gearing. Drop it to a 43 tooth in the rear. Then it will run 70 no problem

[Carlcox89]

condor74 yeah, it can be that... this fmf sound is totally different from the stock one.

I dont seem to hit the rev limiter, never went that far.

 

DunmireD001, i know that with 14/52 gearing it could easily reach at least 110kph so , that's all i'm asking for ?  (of course i wont travel at that speed for long distances!)

And i have my supermoto tires + 15/41 gearing for 'long' runs.

[splynter]

I just recently fitted a FMF slip on with the stock jetting and it ran fine, it did improve the bottom/mid but I didn't notice it losing it up top that much if none at all. It was still running a tad rich with the slip on. I rejet it on the weekend and it is running fine with more in the bottom/mid✊✊✊

I knew nothing on carbs but tackled it anyway with the help of YouTube and Internet. Hardest part is getting the bloody carb off the bike, fitting the jets is easy, UNDERSTANDING how the carb works and FINE TUNING it is the challenge.

[splynter]

Problem is it sounds louder so you think it's revving harder but isn't. Just hold it wide open in top and see what kmh you do?

[condor74]

I took my 2006 WR450 out today and made a top speed run because after reading this thread I got curious.  I had never bothered with top speed before on this bike and it is my only bike with a speedometer.  On a dirt road, I got up to 70.  I took it out on a strait deserted asphalt road and had it up to 85.  I backed out of it there, I think 90 was there if I wanted it but honestly I didnt think it would go this fast. 

[KennyMc]

Yeah, I had mine up to 92 with 13/49 before, dirt road on in Lucerne Valley, still had more if I wanted it.  82 with 12/49 street, Pioneertown (Landers).that didn't end well

[condor74]

The main problem I had at that speed was I wished I had more aerodynamic helmet lol. My bike is mostly stock save for the free mods and a desert tank. Stock exhaust with baffle removed.

[SteveThe Snakes]

I took my 2006 WR450 out today and made a top speed run because after reading this thread I got curious.  I had never bothered with top speed before on this bike and it is my only bike with a speedometer.  On a dirt road, I got up to 70.  I took it out on a strait deserted asphalt road and had it up to 85.  I backed out of it there, I think 90 was there if I wanted it but honestly I didnt think it would go this fast. 

 

 

Yeah, I had mine up to 92 with 13/49 before, dirt road on in Lucerne Valley, still had more if I wanted it.  82 with 12/49 street, Pioneertown (Landers).that didn't end well

 

Whoa boys 90 on a stocker and 92 is pretty fast for a dirt bike. A slight down hill maybe.

 

My built supermoto with street tires goes over 100 and at that speed the front wiggles all over the place. I can't even get down on the bars afraid of a tank slapper. Definitely could use a steering damper.

[condor74]

Whoa boys 90 on a stocker and 92 is pretty fast for a dirt bike. A slight down hill maybe.

 

My built supermoto with street tires goes over 100 and at that speed the front wiggles all over the place. I can't even get down on the bars afraid of a tank slapper. Definitely could use a steering damper.

The Front end felt pretty solid at those speeds but I was a bit worried about the stability.  That is why I didn't hang out at that speed for long. If I was planning to run sustained speeds like that, I would definitely go for a steering damper as well..  I was also impressed the the bike did not vibrate very much at those speeds.  Tires are not balanced on dirt bikes typically.. I know my KX250 starts to hop at anything over 45ish.  I just figured no balance and you have the single rim lock as a big weight in the rim.

[KennyMc]

I have a steering damper and this is with YZ hotcams (for the WR so as to retain the e-start) and a slight port job/bump in comp in the piston.  It's a wheelie machine