Carb Issues....

7 replies to this topic
  • 03ac

Posted January 18, 2010 - 05:27 PM


Bike-06 yz450
jets-170 main, 45 pilot, stock needle in 5 postiton, aftermarket fuel screw
Location- Virginia Beach, VA.

What I did- Completely took apart the carb and gave her a good clean and look through. Once i put it back together and on the bike, she started in about 10 kicks. Once it started it would shut off after about 10 seconds of idling. It did this 3 times. After the 3rd time it stayed idling. once idling i noticed the carb was leaking fuel, it was really hard to tell where it was coming from but it seem to be the accelerator pump but still a little uncertain. The thing that concerns me the most is the bike got extreamly hot really fast, like the bike was idling with the choke on for maybe 5min (and would not stay running with the choke off) and started to push out Radiator fluid from the overflow drain.

Does anybody have any help for me here or where to start as far as tuning. Another thing My aftermarket fuel screw that i have is weird to me or maybe its just me but. How far is that screw suppose to screw in? Does it go until you cant turn it anymore or until you start feeling a good amount of resistance? This is my first experience with going through the carb tearing it down and trying to tune the bike. So please guys go easy on me!

  • cwcarter

Posted January 18, 2010 - 10:57 PM


Have you got a manual if not get one from here -
Read the sticky's at the top of the page about carbs.

Make sure everything is put back together right, no missing orings and find the source of the leak . You won't be able to do any tuning until this is rectified.

The bike will over heat quickly without airflow, 5mins will do it.

You say it won't idle - did you install the slide plate flat side down, pilot screw 1-2.5 turns out.
The pilot [fuel screw] will screw in to a stop, don't force it . Did you get a good brass pilot screw or one of those nasty aluminium ones ?

And don't tamper with the tps.

  • got5steelman

Posted January 19, 2010 - 06:16 AM


Did you have the accelerator pump cover off? If so, there is a small oring that seats between the cover and the base of the float bowl. I had the same problem of a fuel leak after cleaning mine. The oring is small and can fall out easy without even knowing it was there, it will cause a fuel leak from the acc. pump cover. You can go to the TT store and go to OEM parts and fill in your bike info to view a parts breakdown of you bike. You may need #32 or #34 in the carburetor parts fisch. As far as the fuel screw goes, turn it in until you feel it seat or stop turning, do not force it past this point because you can break the tip off the screw, turn it out to 1 3/4 as a starting point. you will have to fine tune it from there.(Alot of the after market screws do not come with a new spring, oring and washer that go with the screw it is ok to use the old ones but make sure you reinstalled them with your fuel screw). Do this process first before starting the bike, the bike should only need the choke for 30 secs to a minute depending on the outside temp. I live in petersburg Va so I know it has been cold here for last couple weeks. Another thing you can do is set a fan in front of the bike to blow air through the radiators while it is idling, these bikes will overheat pretty quick if you are not riding it and getting air flowing across the radiators. Like cwcarter said, unplug the TPS from the the wire harness and leave it on the carb, the manuel will show you how to reset this if you took off the carb, you will need a volt meter and a lot of patience to reset the TPS if you took it off. it is a good idea to etch a mark on the TPS and carb body before you remove if you absolutley need to. There is also a Sticky thread on jetting in this forum to look at to see what other people are running. I have an 05 my jetting is #48 pilot, #168 main, stock needle 4th clip, #35 leak, fuel screw 1.5 to 2 turns out. I have after market exhaust and air filter. Hang in there. Alot off good info and help on this site.

  • Ga426owner

Posted January 19, 2010 - 06:31 AM


Please please tell me you did not disconnet the TPS sensor from the carb itself but you disconnected the TPS cable at the male/female connector. If you did remove the TPS from the carb it will need to be reset - a Royal PITA

other things to check
the Acell pump orings
Float - is it stuck
Hot start plunger - is it moving up and down properly or sticking
Did you reinstall the slide correctly

Visit the ThumperTalk Store for the lowest prices on motorcycle / ATV parts and accessories - Guaranteed
  • 03ac

Posted January 19, 2010 - 10:45 AM


Hey guys thanks alot for the responses, I have yet to get back in the garage and trouble shoot due to work. Just to let everyone know NO i did not remove the TPS plug from the carb, Only the male clip. I did install the slide correctly as per the Manual. Plan on pulling the accelorator pump today....Thanks again for all the inputs and anymore would be greatly apprciated

  • 03ac

Posted January 20, 2010 - 05:59 AM


Hey guys again thanks for the responses, but i have another questions. Does the 06 450 have a thermostat and if so where is it located? I check through the manul last night and had no joy. Like i stated earlyer in the begining of this post the bike got really hot in like 6min of idling. A guy on here suggested that my airfilter could be clogged but i had just cleaned it right before i had started the bike when it over heated so im thinking that thats not the reason. The bike was hot enough in that 6min that it was spuing coolant out of the over flow tube, So im thinking that if it has a thermostat that it could be stuck. Tell me what you guys think! Thanks again!

  • cwcarter

Posted January 20, 2010 - 06:21 AM


No thermostat. My ktm 450 and yz426 will vent coolant if left to idle for 5 mins. Its normal.

  • dirtdevil72

Posted January 20, 2010 - 08:32 AM


Just send it to zip ty racing, you wont regret it.

Related Content


Michigan Motocross Tires by 288yz450

Dirt Bike   Dirt Bike Regional Discussion   North
  • 1 reply

2016 YZ450 by CaptainKnobby

Dirt Bike   Dirt Bike Technical Forums   Suspension
  • Hot  59 replies

Yamaha YZ450F 2017 by Chris.GVS

Yamaha YZ450F 2017
  • - - - - -
  • 0 reviews

yz250x vs 450 4t comparisons (preferably desert riding) needed by JakeNorthrupYZ450F

Dirt Bike   Make / Model Specific   Yamaha   Yamaha 2-Stroke
  • 9 replies
WR Camshaft Swap Info - last post by jamesm113

WR Camshaft Swap Info

  • 0 replies

Join Our Community!

Even if you don't want to post, registered members get access to tools that make finding & following the good stuff easier.

If you enjoyed reading about "" here in the ThumperTalk archive, you'll LOVE our community. Come join ThumperTalk today!

The views and opinions expressed on this page are strictly those of the author, and have not been reviewed or approved by ThumperTalk.