My WR450F won’t idle without choke. (Gas?)

So, it’s all by ear, and my ear is no good (long time away from bikes plus a big hearing loss). But, to me it sounds like (very subjective, likely to be far off) it wants to idel at like 500RPM? And it sputters and spits unless under choke. With choke one, it idles VERY fast, like 2000 RPM? (again by ear, just a wild hair up the butt guess).

So, when I shut the choke off, it sputters along at at 500RPM(?) until it kills, bearly running because of the sputtering. It does it warm or cold. I thought, “bad gas” and have ran half a tank of 100 octane race gas (pump, not additive) through it, same thing. I dropped ¼ bottle of fuel injector cleaner in the ½ tank of 100 octane in (I don’t ride it often, it was 2 weeks later) and sloshed it around. 10 minutes in, good mix, flowing though, same thing.

Now, it run like I’m riding a badly tuned old 500cc 2 smoker… It bearly idles, kills often, but once it’s over (by ear?? 4000RPM?) it comes on so hard it’s like I’m bearly able to hang on.

I’m a TOTAL NOVICE rider, but big guy. And the way this bike is running scars me. It’s an 2004, and my wife’s TT-R125 had lacquer buildup like crazy when we bought hers (same time). $200 carb rebuild and cleaning and good gas, he bike runs like a champ. Now, why is mine a wild stallion that won’t idle? Did I buy the wrong bike and should have got a Honda XL650, or can I tame this beast that acts like a 1980’s two-smoker?

Someone at wok said 100 octane is TOO MUCH, and I need to put pump 91 octane in (altitude adjusted, just a little uphill of Tucson AZ in Vail for 95 octane in manual). He claims because 95 is recommended (test), 91 is good (pump) here and any more will be to slow burning and cause problems?

HELP? Clean the injectors and pay big $$? Change gas and ride it out? Timing needs tweaking (my guess)? HELP...

there is no timing adjustment on these engines.

It will idle the same regardless of octane rating.

I have a tacho on my 426 and it idles at 1650rpm no choke and just over 3000RPM on choke.

Will your bike idle on choke when it's hot? If so I'd say you have a manifold vacume leak somewhere. Check that the fuel screw hasn't fallen out. Also check that the hotstart is operating correctly.

Have you done anything to the carb?

It could be anything, don't worry you bought the right bike...

Tell us more about what jets are in the bike...


Need more information. :cry: What do you have for jetting? :cry: Once you have the jetting right, you have the idle adjustment knob right below the choke. You can adjust you idle there. You may want to invest in the JD Jetting kit that you can buy through the TT Store. It made a hugh difference on my '03 450.

Tom :cry:

I had the same issue on my 05 WR450. I just installed the JD kit and it runs great and idles great. Before, it felt like I had to keep the Choke on (even when warm) to keep it running (very lean).

Did you buy it new or used? If used , it prob'ly has a plugged pilot jet.....if it was from the same people you got the TTR, it definitely has a clogged pilot.

I have my 03 WR jetted 48PJ, DWR needle(04 wr) in mid pos., 162MJ, 70SJ. I ride Tucson and vicinity....Redington, Santa Ritas, Patagonia, etc.....

I will bet that your floats are not set right, this is the first thing that

I do when ever I buy a new Yamaha is take the carb off and set the

float to the right hight, in the last 3yrs I have bought 4 Yamahas

and they all have been off by 2 to 4mm, witch will cause what your

talking about.

Sounds like clogged jets. Pull your carb out and blow it out with carb cleaner or replace the jets all together. Should run like new.

I put about 1/2 a bottle of fuel injector cleaner through it, and it seems to have worked. I put about 40 miles on this morning, at extremely slow speeds trying to keep it at an idle as much as possible. It took me forever playing with the idle screw, because it was so out of wack from trying to get it to run right before.... But it seems ok now.

I always get a kick out of all the misconceptions with octane & their ratings. I am not trying to preach from a soap box. It's just that I have spent my career around all types of engines.

First off, your bike has a high compression at over 12.5:1. The minimum octane rating of fuel from Yamaha must be used simply to prevent detonation. This is possible if the fuel used is rated too low (93 or lower). However if a fuel is used that is much higher than what the manufacturer recommends than all that is truly effected is your wallet.

Realize that the octane rating is only the fuel's ability to resist spontaneous ignition when compressed. All pump gas contains virtually the same BTU content and is truly the same in the way of power production.

As for additives. Do not expect a "miracle in a bottle". The previous posts are pointing you in the right direction. When an engine will not idle there has to be something wrong with the fuel mixture. This can be from the installed jets and or the amount of air available. Such as a vacuum leak or dirty and/or clogged filter.

Take of the carb and look closely at the jet and needle size. Do the research for recommended sizes for this part of the country. Let us know what you come up with. I live in Marana and I need to do the same thing for my new 05WR450.

Good luck and keep us posted.

Be intrested in talking to you about that, but maybe over in > Where, When, & Who to Ride With > Southwest would be a better place...

Check out it's a new club in Tucson, more racing oriented, but we have lots of experience with the S. AZ trails + N.AZ and Mexico....

I have to work Saturday but probably will be riding Sunday.

Check out it's a new club in Tucson, more racing oriented, but we have lots of experience with the S. AZ trails + N.AZ and Mexico....

I have to work Saturday but probably will be riding Sunday.

I signed up for a login, they haven't got back to me. Would you want to put a note up there for me about this? which I also asked about at here but those seem to be just Phoenix guys.

if you have messed with the carb. you might need to either adjust the air/fuel mixture screw or get either a biger or smaller one depending what you have done to the carb.

02 WR426

re-jetted the carb. filed down the throttle stop. took off the lid to air box, 48 tooth sproket, took the core out of the spark arrester. bigger air/fuel mixture screw.

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