Question about 2004 Yamaha YZ 450 F

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Carbi problems i have a yz450f 2004 with a after market exuast had a little flat spot i tiltetd the carbi a took out main jet it was a 180 it was clean so i put it back in then tryed 2 start bike took ages 2 start then when it did flames were coming out of the exuast then it wouldnt idle a did not run properly cant get it 2 run like it was took it 2 a mechanic a he cant find the problem either all i did was take the main jet a put it back in what should i do ps the bike was running good before i touched it

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  • jasonzucc Oct 02, 2009

    thanks mate i will give it a try



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Try adjusting the air/fuel mixture screw in the carb, clean the air filters and then check. Also clean the spark plugs.

Posted on Oct 02, 2009


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Related Questions:

1 Answer

How do I clean a carby

You can first try some carb cleaner. Remove the air cleaner from the carby, and the fuel inlet tube. Soak the innards or the carby in carb cleaner, and try to full the fuel bowl as well, via the inlet or the vent tube.

If the main jet and idle jet are gummed up the carby will need to be disassembled, at least partially. There are overhaul kits you can buy with new gaskets. Go very slowly as there are springs and little steel balls in a carby, and these have to be replaced correctly.

You can also get recon carbys for most models.

Jan 02, 2015 | Toys

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1989 chevy hesitates when giving it alittle gas and almost dies but dosent

It appears that you have what is known as a flat spot in the carby ( I assume you have one). It occurs as the butterfly is opened and there is a transition period from idle to increased rpm's in the jets . To over come this there is an accelerator pump that provides a squirt of fuel to provide the correct air/fuel ratio until the main jets cut in. If you have a Holley it is in the form of a diaphragm inside a nut in the immulsion block. IN other carbies it is a plunger . If you have EFI then have the codes read to find which sensor is failing

Mar 05, 2014 | Cars & Trucks

1 Answer

Hello i have a 1987 honda shadow when i down shift the moter back firers my freinds tell me it has aftermarket exuast pipes on it. so do i have to change jets in the carb. The spark plugs are tan to white...

If there are aftermarket exhaust pipes on your bike, the carburetor should have been rejetted at the same time. It does sound like a lean issue, especially where your spark plugs are tan/white. It's not going to hurt anything to be a little lean, just have an annoying backfire. The only time you should have to worry is if your plugs have no color but white and it backfires while riding, not only downshifting. If you are concerned about the backfiring, I would suggest changing jets, especially the pilot jet. The pilot jet is where you are getting your backfire from. When you let off the throttle and downshift, the main jet circuit is closed and fuel is pulled through the pilot circuit. The pilot circuit cannot provide as much fuel as the main circuit, especially when the motor pulls higher rpms on downshift. This will cause a lean backfire. I know it has been several months since you posted this and you may have this corrected already, but I just stumbled upon your question. Hope this helps, Daniel.

Apr 16, 2011 | 1987 Honda VT 1100 C Shadow

1 Answer

Flat spot off idle when cold.would like to know carb settings.i live at about 400m

hi,sounds like the bike is running a little to lean,it will take some mucking around but it is worth doing,buy yorself a set of main jets in steps of if your bike has a 100 main,then go get them at 105,110,115,120,125 etc,and just keep swapping them out untill your flat spot disappears,the other option is lifting the needle valve in the carb slide it will achieve the same sort of result but you wont have the adjustment,,most bikes are set at the factory to an average atmosphere and that obviously changes with altitude,it shouldnt take much to get it right...cheers

Mar 29, 2010 | 2004 Husqvarna TE 250

3 Answers

Bike seems to skip or feels like it wants to stall but when i keep throtle open at high speed seems to run a little better

sounds like your idle/intermediate carby jet has a blockage, take the four base screws out , remove carby bowl , there will be a main jet in the centre, then a smaller one in front of that, usually a small flat head screwdriver. take jet out, blow it out with compressed air and look through the jet to make sure it is clear. if air doesn't unblock it try a piece of very fine wire. hopefully that will fix your problem.

Jul 17, 2009 | 2005 Harley Davidson FLHTC - FLHTCI...

3 Answers

Yz450 f stalls when you hit gas hard

it sounds like your main jet needs to be rejetted and tuned in it is sending to much gas and stalling out the bike

May 27, 2009 | 2004 Yamaha YZ 450 F

1 Answer

I just put on an R and D powerbowl and i have a problem

Remove the slide and then move the jet needle clip one notch lower. Try two notches if one doesn't do it.

Please rate this solution. Thanks Robbutterfie!

Apr 16, 2009 | 2006 Husaberg FE 450 e

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