cuts out on steady throttle

8 replies to this topic
  • XR250_RIDER_14

Posted November 11, 2006 - 09:40 AM


Whenever I am at steady throttle my bike cuts out a little bit. Its really hard to do wheelies now. What could this be. COuld my hotstart be open? Whenecer I pull it in whill im on the gas it doesn't change anything. But when I let off it backfires and pops a little bit. I just got my jetting changed from a 165 main to 170 and 45 pilot I think. 1 bigger than stock.

  • flintlock28

Posted November 11, 2006 - 04:54 PM


Did you adjust the Fuel screw???

Sounds like you're lean. I'm guessing with the weather getting colder, you're running lean. try adjusting the Fuel screw out 1/4 turn at a time, and see if it makes a difference.

  • XR250_RIDER_14

Posted November 12, 2006 - 07:15 PM


the pilot jet is for idling. It cuts out on about 1/4 throttle. It sputters. When I gas it its fine.

  • Nova1194

Posted November 12, 2006 - 08:52 PM


Sounds like it is a little rich at part throttle, if it ran good before and then developed this problem, I would check for crud in the needle and seat or float height.
Popping on decel with the hot start out would be normal, the hot start is basicly a switched vacum leak so you can make it leaner so it will start when it is very hot or flooded after a crash.


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

Posted November 13, 2006 - 06:23 AM


My 07 did the same thing. I dropped from a 45 pilot to a 42 and it cleared it up quite a bit. I noticed that when I disconnected the TPS it went away completly. There was a running dialog w/ Eddie in the jetting forum trying to solve it a few weeks back.

The bike seems very sensetive to the fuel screw setting and it takes a bit to warm up the engine suffeciently to make adjustments. I have to take a lap or two at the track or around the block 2-3 times to get it warmed up enough that the adjustments are correct.

I still have a very very slight hesitation or rough spot if I just roll on the throttle on smooth terrain, don't seem to notice it in actual riding situations. I'm starting to think that that the spot is the ignition map switching from one map to another, due to the fact that if you dissconnect the TPS its gone completly.

Good luck

  • XR250_RIDER_14

Posted November 13, 2006 - 09:52 AM


Can I disconnect the TPS. Can the fuel screw solve the problem by leaning? It is scary doing a wheelie. It wheelies like a 250 two stroke! power surges and goes away

  • grayracer513

Posted November 13, 2006 - 11:11 AM


the pilot jet is for idling. It cuts out on about 1/4 throttle.

The pilot circuit influences overall mixture all the way through half throttle. At the very least, you should be able to determine which direction to go with the needle by tweaking the pilot screw one way or other and observing the effect it has on your problem area.

The slide cut away actually has the most effect on 1/4 throttle of any of the four jetting controls, but it's the most expensive to change and the least likely to need it. Look in the tuning section of the manual. There is a graph showing how pilot, slide, needle, and main jet overlap each other.

You might even find that switching to a needle with a different taper is the answer.

  • XR250_RIDER_14

Posted November 13, 2006 - 02:25 PM


Can I get away with adjusting the pilot screw?\

  • grayracer513

Posted November 13, 2006 - 02:36 PM


Maybe, but you won't know 'til you try.

Related Content


Chubby dad, looking at bikes , First trip to the orange/black forum ! by Slow_ride

Dirt Bike   Make / Model Specific   KTM   250-530 EXC/MXC/SXC/XC-W/XCR-W (4-Strokes)
  • Hot  28 replies

Help with 2000 yz426 by weekend woods racer

Dirt Bike   Make / Model Specific   Yamaha   YZ 400/426/450
  • Hot  36 replies

Michigan Motocross Tires by 288yz450

Dirt Bike   Dirt Bike Regional Discussion   North
  • 1 reply

First Hare scramble tips by dhend8

Dirt Bike   General Dirt Bike Forums   General Dirt Bike Discussion
  • Hot  33 replies

2016 YZ450 by CaptainKnobby

Dirt Bike   Dirt Bike Technical Forums   Suspension
  • Hot  59 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.