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hi my 01 yz 250f idles weak(i've posted many threads, just want to know what this it)

if i try to turn up the idles, all my bike does is when i rev it, it takes a little while for the revs to return to normal

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sounds like your pilot circuit is out of adjustment, probably to rich. Try adjusting your fuel screw if you dont see an improvement, you may want to clean your carb. Another thing to check is your spark plug you could have a fouled up plug.

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well while in the process of "checking my valves"(my feeler gauges where too wide)

i pulled out the spark plug and it was(i don't know how its possible) but it was the tan colour that's its supposed to be

today i'am going to have a big play with the fuel screw, swap back to OEM screws and my aftermarket ones and see what happens

bike doesn't like the hotstart button anymore its likes to start without it

its been unusually hot lately in oz

is there anything like a easy manual thatll teach me all about jetting and how to clean a carb

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There was a great write up on how to jet a new fcr let me look around for it. I will pm you with it if i find it.

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that link is awesome

has everthing from jetting to valve adjustment

thanks

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Fuel Screw/Pilot Jet

Fuel screw settings in the 'book' are recommended starting points. Every bike is different, as is the temp and altitude. Set the screw according to this method. Do it with the bike fully heated up.

Gently turn the screw all the way in. Now back it out two turns. Start the bike and fully warm it up, go for a 10 minute ride. Set the idle to speed to 1,500~1,800 RPM as best you can (I know, without a tach this is tough, just set it to were it idles relatively smoothly). Once warmed, slow the idle to the lowest possible speed.

*** When turning the fuel screw, keep an accurate 'count' of the amount you are turning it and record it in case you have to reset it for some reason. Makes life easier when you can just set it from notes Vs. going through the procedure again.***

Turn the screw in until the idle becomes rough or the bike stalls.

if it stalled, open the screw about 1/4 more turn. Restart it and slowly screw it in till you can just perceive a change.

If the screw can be turned all the way in and the bike still idles perfectly and does not stall, then you need to go down a size in pilot jet.

Now very slowly, open the fuel screw till the idle is smooth. Blip the throttle, let the bike return to an idle, wait say ten seconds. Confirm it is the same smooth idle.

If the screw has to be opened more than 3 turns to get a smooth idle, you need to go up a size in pilot jet.

If you find it does not stall with the larger jet but has to be open more than three turns with the smaller pilot jet, put the larger one in and set the fuel screw at 1/2 turn.

If the idle speed increased, adjust the idle speed knob to return the bike to a real slow idle speed. You must then re-visit the fuel screw. Keep doing this till the fuel screw is opened just enough to provide a nice steady idle at the lowest possible RPM. Once this is done, increase the idle speed to the normal one for your bike, typically about 1,800 rpm, but go by the spec in your manual.

FCR-Tuning Guide

Basic Carb Theory

Jetting for Altitude and Weather

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