Fuel screw adjustment for '09 450


8 replies to this topic
  • win2ksrv

Posted March 20, 2010 - 08:31 PM

#1

Well I went out and bought a left-over new 450 and did a little riding today. :thumbsup:

I had an '07 that I sold last summer and am happy to be getting back on a bike.

It ran fine, but it seemed the idle was high. After it got warm it seemed like the idle was high like the hot start was pulled all the time. I checked hot start adjustment and it didn't seem like it was stuck; the cable moved freely.

When I got back home I played with the fuel screw a bit, but it seemed to still be idling high. Where is the idle speed adjustment on these things?

Could the cool temps be contributing to my problem?

Will the Zip Ty FMS01 fit this bike? The Zip Ty site lists up to '08 YZ450s but I don't see the 2009. I thought they were all the same.

Am I safe following this article for the setup of this carb? http://www.thumperfa.../jetting.htm#PJ

Thanks!

  • grayracer513

Posted March 20, 2010 - 08:55 PM

#2

The idle speed is the large, bright finish screw on the bracket in this image:

Posted Image

The article you mention is suitable for use with the '09, and the ZT fuel screw you listed will fit (use the OEM spring, not the one it comes with)

  • grayracer513

Posted March 20, 2010 - 08:56 PM

#3

The idle speed is the large, bright finish screw on the bracket in this image:

Posted Image

The article you mention is suitable for use with the '09, and the ZT fuel screw you listed will fit (use the OEM spring, not the one it comes with)

Need a manual?

http://www.yamahaown...ook.com.au/?r=0

  • win2ksrv

Posted March 20, 2010 - 09:31 PM

#4

Thanks Gray.

Would the cool air have contributed to the idle problem?

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  • grayracer513

Posted March 21, 2010 - 08:59 AM

#5

Low temps increase air density, making the bike run leaner, yes, but normally it's not a huge difference.

  • win2ksrv

Posted March 21, 2010 - 06:25 PM

#6

I think I got it figured out. The idle was cranked up and I backed it off. That took care of the strange idling and the bike pushing me through corners.

I then played with the fuel screw. It seemed to run the best with the screw out 2 1/2 turns. I tried 1 1/2, 1 3/4, 2, 2 1/2, and 3. Below 2 turns it stumbled a little bit at a fast idle and just off idle, and 3 didn't seem any better than 2 1/2.

Each time I adjusted it, I ran it at a fast idle and listened for popping, and I took it out for a ride to check for hesitation and popping. Is that the correct way to check for proper adjustment?

I believe the article I mentioned above stated that it is good practice to adjust the fuel screw every time your ride. The Zip Ty should make that a heck of a lot easier.

  • tek_01

Posted March 21, 2010 - 07:10 PM

#7

Merge racing (http://www.mergeracing.com/) also sell an adjustable fuel screw that is solid brass. I think i have read the brass ones are better than the aluminium ones but i cant recall exactly why this was... or it could have been just a particular brand of alluminium ones were not good, either way i have the merge one and am happy with it

  • grayracer513

Posted March 21, 2010 - 07:37 PM

#8

The red screw in the picture is the Zip-Ty in my bike. It works perfectly well. The only trouble I've had with them is the springs they came with when I bought them. That's why I said to use the original.

  • Goobz_MX718

Posted March 23, 2010 - 06:33 PM

#9

Is this true, i thought this only helped with idle, not really it's responsiveness once the throttle is opened





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