HEADS UP!!!

Site upgrade in progress... Core site functions are working, but some non-critical features/functions will be temporarily unavailable while we work to restore them over the next couple of weeks.

Please post any bugs you encounter, but before you do, check to see if it's already listed.

Thanks for your patience while we work to improve the community.

Sign in to follow this  
Followers 0
Regalman

Top speed, the rev limiter and jetting

9 posts in this topic

I've got a couple of hundred miles on my 2008 WR450 so I decided to open it up this weekend. Its stock other than free mods. (OEM AIS kit, grey wire cut, and exhaust noodle removed)

It hit 88 mph on the stock speedo on flat road. It didn't seem to hit the rev limiter. Does that sounds about right? Were is the rev limiter with stock gearing in relation to MPH. I'm guessing I must have been close. [heck, I'm just assuming there is a limiter, never hit it in any gear.]

Is this normal or do I have the jetting off a touch?

How close is the speedo to being accurate?

Share this post


Link to post
Share on other sites

Sounds low. You have about 45 Hp, should be about 95. Might want to do a main jet checking/adjusting

Share this post


Link to post
Share on other sites

Just to cover all bases, you do have the throttle stop removed, correct? I don't know what the top speed is with it in/out:excuseme:

Share this post


Link to post
Share on other sites

Yes, I used the new stop that came in the AIS kit.

William, think I should maybe wedge the airbox open and see if I gain anything?

Riding in the woods the jetting seemed spectacular, it never bogs or anything coming off the bottom... but this is the first time I ever open it up and expored the top end.

Share this post


Link to post
Share on other sites

You know,,,,,, what oil are you running?

Inside joke - Not another oil thread trolling!!!

worf.gif

Share this post


Link to post
Share on other sites
Yes, I used the new stop that came in the AIS kit.

William, think I should maybe wedge the airbox open and see if I gain anything?

Riding in the woods the jetting seemed spectacular, it never bogs or anything coming off the bottom... but this is the first time I ever open it up and expored the top end.

Did you remove the snorkle and the rectangluar plastic part? I assume you did.

Go up one size in main and retest. Keep going up until until speed drops off. If speed drops off the first time you go up, then you are rich and need to go down.

In a perfect world, there will be one main that gives you max top speed. Next larger or smaller slows you down. If you find there is a range of three jets that alll give you the same top speed, go with the middle one. If just two jets do it for you, then go with the richer of the two for cool weather and the leaner one in the heat of summer.

Share this post


Link to post
Share on other sites

Nope, super easy on a Yamaha. Fuel tap off. Gently open the drain screw on the bottom of the float bowl. Put a jar under the hoses near the swing arm, drain the carb bowl. Place a rag on the engine cases below the carb, remove the cap on the float bowl (17mm). Main jet is right there. Just be gentle.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!


Register a new account

Sign in

Already have an account? Sign in here.


Sign In Now
Sign in to follow this  
Followers 0