Question about 2008 Yamaha yZ250F

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Yz250f is idleing high then when it kicks down it quits where should I start

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Most commonly with high idle it suggests lean pilot circuit either by to small pilot jet or more common is dirty or gummed pilot circuit from fuel. out of list of possible reasons checking this area would be the simplest. valve clearances would also be worth a look as you got carbi off you are half way there to be able to pop the valve cover off and confirm clearances in spec ( roughly 0.004-0.005 intake and 0.008- 0.009 exhaust side is what you would expect for clearance) but double check you manual or ring yamaha to confirm clearance gags for your model.
there are several other options to check but these two would have to be priority

Posted on May 20, 2011


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High idle at start up 2200rpm then slowly drops but always seems high have to ride brakes to stop

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Nov 30, 2015 | 2004 Lincoln Aviator

1 Answer

Won't kick start

Hi, Anonymous for this scenario you will need your service/owners manual if you can't find the first and best tool you ever bought for your Yamaha, despair not, for a mere $0 you can download another one. For more information about your issue and valuable "FREE" downloads that you will need please click on the links below. Good luck and have a nice day.
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Apr 02, 2014 | 2003 Yamaha YZ 250

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My yz250f is taking too many kicks to start it

Hi, Randall and the usual suspects are:
1. Enrichner system plugged, not properly functioning or improperly operated.
2. Fuel overflow.
3. Restricted fuel supply.
4. Gas cap and or fuel tank not venting properly.
5. Plugged slow jet or passages.
6. Inlet system air leak.
For more information about your issue and valuable "FREE" downloads that you will need please click on the links below. Good luck and have a nice day.
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Apr 25, 2012 | Yamaha YZ 250 F Motorcycles

1 Answer

I have an 04 yz250f, runs like absolute ****. it takes quite a few kicks before ever starting and once started, things get very interesting. When i hit the throttle it backfires quite a bit and stumbles,...

I found this artical relating to your bike.. Sounds like you may need a new timing chain. Fits your symtoms.
Thumper Racing. The company warned that the cam chain may be a weak point. Thumper recommends changing the cam chain twice a year and the valves once a year for a YZ250F that is ridden hard. The cam chain is less than $20 and is extremely easy to change any time you are checking valve clearance...."
They have a step by step instruction here also..

Jul 20, 2011 | 2004 Yamaha YZ 250 F

1 Answer

I have a 04 yz250f that over heats at idle ?

All of the yzf,wrf models WILL overheat at idle.They need air to be going through the radiator at all times.What this means is if you are going to be stopped,for anything but a very short time,turn the motor off.Even after a short time the header pipes may start to glow.These motors are quite high performance and they need the air flow.Hope this helps

Jan 06, 2010 | 2004 Yamaha YZ 250 F

2 Answers

My Yamaha yz250F 07 starts first kick but back

I see: you changed the plug because it was backfiring.

Does it back fire when you let OFF the throttle after revving it, or does it back fire while being revved?

If it does it when you let off then Ollie's suggeston might do it. If that doesn't do it then check for dirt in your pilot jet.

If it back fires when revved up high could be dirt in your main jet.

Oct 31, 2009 | 2004 Yamaha YZ 250 F

2 Answers

Yz450f that quit running

Yes, it does have an automatic decompression mechanism. It is a centrifugally operated mechanism and it is EXTREMELY unlikely that is causing your problems.
The two highest probabilities are:
1. Fouled spark plug. Forget what it looks like, put a BRAND NEW plug in. It is the cheapest form of diagnosis you can do. These bikes are terrible about fouling spark plugs and a fouled plug produces the exact symptoms you described.
2. Inspect your valve clearance. Tight valves will also make the bike hard/impossible to start with the kick starter. In some cases, it can be push started, but still won't kick. With tight valves, the bike, although hard starting, will run pretty good, for awhile. Eventually it will burn the valves and quit running though.
If your bike isn't kick starting fairly easily, something is wrong and needs to be addressed. The only other issue is making sure the idle speed is set per the service manual. These bikes have a fairly high idle, some as high as 1700 rpms. If it is set too low, it makes them hard to start too.

Sep 11, 2009 | 2004 Yamaha YZ 450 F

1 Answer

My 02 yz250f has a very erratic idle. When slowing down it stays in a very high idle until it eventually dies down itself or i use the kill switch to bring it back to idle. Jetting is all perfect, ignition...

what you need to do is turn the screw on the right side of the engine with a flat head with the bike running it is suppose to bring the idle up or down... if not then take it to a mechanic before your engine blows. I to have had that before but it is simple to fix

Sep 06, 2009 | 2003 Yamaha YZ 250 F

2 Answers

Bike idles, but with a little throttle it jumps to high rev and wont come back down to idle

You need to oil your cables first....They make a gadget to help you do clamps around the end of the cable, and you spray oil into a provided hole for a spray nozzle tube...Then see if the cables are unstuck by turning the throttle grip back and forth for awhile....start it and see if that helped....if not you may need to replace the cable(s)...I doubt that the slide in the carb is hanging up...or valve.If this doesn't work notify me.

May 10, 2009 | 2003 Yamaha YZ 250

1 Answer

YZ250F kick starter is backing out of gearbox

Go to the site below and download a free factory service manual.

Kick starter starts at page 175. I am certain this will help.

Please rate this solution. Thanks!

May 02, 2009 | 2004 Yamaha YZ 250 F

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