Stalling in 1st gear

I just purchased an new '08 YZ450f. I took it out for it's first run, and I've not experienced any problems with starting te bike hot or cold, and the bike seems to idle well.

However, I'm having problems with the bike stalling in 1st gear while holding the clutch lever in. The problem happened several times in a 1 hour period. The bike seems to stall everytime I break to slow down, down shift to first, and before I let the clutch lever out to engage the gears the bike stalls, unless I keep the engine reving very high.

This seems very odd, since there are several times when I need to come out of first gear without high revs. for example. Slowed the bike down to approach a small hill that I've not been down. Down shifted to first, got to the top of the hill, while I was still holding the clutch lever the bike stalls. Any ideas?

Start with the basics:

Adjust the pilot screw and idle speed:

Normally, when a YZ450 acts like that, it's because the idle is too low, and/or too rich. If you bought the bike used, the latter is quite possible, since a lot of riders will richen the idle excessively in an effort to eliminate all of the popping in the exhaust on deceleration. The popping is normal when not excessive, but some become obsessed with eradicating it, and end up with a bike that's too fat as a result. Tune the pilot so the bike runs right, and ignore the exhaust for now.

If you didn't get a manual, get one now:


I'll try adjustig the idle speed. Hopefully this will work. The bike is new, I bought it last Wednesday. I was assuming the idle speed was set correctly. I'll swing it by the dealer if the idle adjustment doesn't work.

The bike is new, ... I was assuming the idle speed was set correctly.
A practice you should plan to curtail in the future. :thumbsup:

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