06 WR450 rough idle after AIS removal?

This being my first offroad motorcycle I don't know exactly what to expect from this bike.

Prior to uncorking my idle would vary from regular idle to high rev and back. Alot like an air leak. The dealer said that it was caused by running so lean (and being at 3000 feet). They rejetted the idle jet to a 50 and that seemed to fix the varying idle. Does this make sense to you?

I then uncorked the bike doing the much discussed basic mods and removal of the AIS.

The idle isn't actually horrible but it dips to the point of almost stalling. The idle speed seems correct (500rpm or so). What is causing the dips? Any ideas?

Before I get flamed....I did try to search several times but each time the search feature was disabled due to traffic.

Thanks for considering these issues!

Scott

Prior to uncorking my idle would vary from regular idle to high rev and back. Alot like an air leak. The dealer said that it was caused by running so lean (and being at 3000 feet). They rejetted the idle jet to a 50 and that seemed to fix the varying idle. Does this make sense to you?

I then uncorked the bike doing the much discussed basic mods and removal of the AIS.

The idle isn't actually horrible but it dips to the point of almost stalling. The idle speed seems correct (500rpm or so). What is causing the dips? Any ideas?

Thanks for considering these issues!

Scott

My bike did the same until I did the mods..

Scott, did you replace the fuel screw with an adjustable one? The #50 pilot sounds a bit rich - for most conditions up to 4000ft and 20c (68f) the #48 pilot should be OK [from memory]. This, with the fuel screw, will allow you to fine tune the idle (and low speed) mixture (see jetting sticky) - about 1.5 to 2.0 turns out from fully in should be OK for starters.

The WR is best set up with a high idle, I doubt if the bike would idle at 500rpm, 1200 is about the minimum and its best, as recommended by Yamaha, at between 1700-1900rpm - sounds high I know but as per manual and solves heaps of "off -idle" throttle hick-ups...

Other than the above, I would check for leaks from the AIS plugs and exhaust and check for semi-blocked filter??

My .02 worth

:thumbsup:

Thanks for the response. FYI - I meant to write 1500rpm. With the 48 pilot I get wildy fluctuating idle. Only the 50 seemed to calm the bike down.

I have yet to order the ZIP-TY adjustable fuel screw but will add that on the next go around.

I will check your suggestions again.

Thanks - SC

After uncorking, you would usually need a richer mixture. So, if the 50 was the ticket before uncorking, a larger pilot jet would usually be in order. But, 50 is already pretty rich.

I'd think that a #50 is rich at 3000 ft. But what are the temps?

Mine acted similar until I did the ZipTy screw. Try adjusting the screw that is in now. You'll need to pull the plug out of the screw hole anyhow. Just use a cut off screwdriver, for grip add a few wraps of electrical tape for grip.

The temps I have been riding in are upper 40s to 60F. I fear that there may be another problem being masked by the 50 jet. Do you think going from a 48 to a 50 is that big a difference?

The dealer told me that Yamaha service told them that they are seeing some problems with the 06 WR450s running too lean even after the AIS removal and uncorking thus the need to increase the jetting to a 50.

Being so new to this I really don't have a clue if what they are saying is even remotely true.

The temps I have been riding in are upper 40s to 60F. I fear that there may be another problem being masked by the 50 jet. Do you think going from a 48 to a 50 is that big a difference?

The dealer told me that Yamaha service told them that they are seeing some problems with the 06 WR450s running too lean even after the AIS removal and uncorking thus the need to increase the jetting to a 50.

Being so new to this I really don't have a clue if what they are saying is even remotely true.

No, not a big difference between 40-50 but like has been said, #50 is a tad high.

Try to adjust the existing fuel screw as suggested before. FIRST, screw it gently all the way in (should be no more than two turns). Then back it out, the further the richer [check jetting sticky for fine tuning pilot circuit]. NO more than 2.5 to 3 otherwise it may fall out.

Q? Did you have the throttle slide out of the carb? If so, check you inserted it back the right way up - the symptoms reflect this as a possible cause to your problem.

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