throttle stop????

The AIS mod only saves you a little weight and complexity. There is no power/performance change.

The ACV, well, if you want, do it, I did it to mine but then I reverted back to operational. It really only makes adjusting the fuel screw easier on some bikes.

Neither one truly affects jetting or performance, only convenience

Agreed!

I recommend doing the mods for the above reasons.

ok i think ill do the ACV mod now because i already have the carb off the bike and ill wait on the AIS and see how things go. Thank you guys for your help :banghead:

Certainly easier to do the ACV mod with the carb sitting sideways on a white towel on a bench Vs. on the bike.

While you have the carb off the bike, check the AP squirt timing. Now is the time.

AIS=Air Injection system

Before you pull the muffler and get all loud, get a James Dean jet kit, remove the snorkle, do the throttle stop, grey wire (if it exists) first, then decide, "is the bike too slow for you?"

+1. but would also add the adjustable fuel screw, which doesn't come with the JD kit.

I am from canada and got a 08 wr450 whats is the grey wire do thats so important that every one cuts? ive read all about it on here but what does it control? and does the canadian 08 model have it?

Your Canadian bike will need the grey wire cut.

awesome thanks to every one for their replys. im just getting used to htis web site so thanks again to every one. one more quick Q...what does AIS stand for? air intake system?

Air Induction System

Remove it, but don't throw it away. Keep the components together in a box.

You may have to install it back.

so because i have a ride comin up this weekend i only did the throttle stop and removed the grey wire from the plug...I am very happy with the results im able to do wheelies in 4th gear and lovin the full throttle....

thank you for every ones help and input.

i just got a 2003 wr450f and want to do the throttle stop mod.will i have to change jetting or anything?also im looking at the 250 throttle mod but like the other guy said do i cut off the same amount?would a yamaha dealer do it?that may be easier

i just got a 2003 wr450f and want to do the throttle stop mod.will i have to change jetting or anything?also im looking at the 250 throttle mod but like the other guy said do i cut off the same amount?would a yamaha dealer do it?that may be easier

You don't need to rejet for the throttle stop mod. It's the same on the 450F as the 250F. If you don't want to cut the throttle stop yourself, your dealer may have a YZ throttle stop you can buy, the GYTR AIS removal kit comes with one, and I'll bet your dealer (or neighbor) could cut it for you if it came down to that. :crazy:

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