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Will not idle KTM 50

The bike runs like a dream through top end and has grunt, I have cleaned carb, jets, bowls etc. The ****** just won't idle I am stumped could it be coil or reed valves. @

Posted by Gavin Crawford on


5 Related Answers


  • 9 Answers

SOURCE: 2005 yamaha yzf 250-unstable idle

I had the same problem, Turns out that my shims were finished, replace the chims and check clearences.

Posted on Mar 12, 2009



  • 3567 Answers

SOURCE: wont run...

Any water in the gas? Remove the water trap bowl at the bottom of the petcock, (gas valve). Any water or trash in the bowl? Drain a cup of gas from the tank. Any water or trash in the cup? Dump it, clean it and re-mount it, ( not all bikes have a water trap bowl ).

Get a fresh set of stock NGK spark plugs. Clean or replace the air filter. You seem to be pretty thorough in what you have done, but since plugs and filter weren't mentioned I had to ask.

Assuming you are getting air, gas and spark, and the timing is correct then it should run. Right? Not necessarily. Can the bike breathe? If pressure cant get out of the tailpipe the bike won't run. Mufflers can sometimes collapse internally. This restricts the flow of burned gasses. causing backpressure. If nothing goes out of the cylinder then nothing goes in.

Try removing the exhaust pipes. Now see if it will run. Get back to me because I would like to know what you find.

Posted on Mar 29, 2009



  • 3567 Answers

SOURCE: dead pw 50 and sad boy.

Many things could cause the problem. Let me see if I can help out.
You have spark, but is it enough spark? A weak battery can rob power from the coil so only a weak spark is present. Get a new stock NGK spark plug to eliminate the possibility of a problem plug.

It is good that you cleaned the carb because that would be my second target. Reset the air and idle screws. IMPORTANT > do not tighten these two screws down. Only screw these in until they LIGHTLY seat. Now turn each screw one and one half turns outward. Clean or replace the air filter and be sure the bolts are tight on the carb manifold. INSTALL AN IN-LINE FUEL FILTER. Let the float bowl fill then start the engine. Set the idle speed with the idle screw.

Remove the cylinder head. run the piston down to the bottom of the cylinder. look inside the cylinder. On th carb side (intake) you will see an intake port > a large hole that lets gas into the cylinder. Now look at the exhaust port. It is possible the exhaust port is pretty plugged up with carbon. The intake and exhaust ports should be approximately the same size. Are they? If not then remove the muffler and take a screw driver and plastic hammer and knock the carbon into the cylinder, thus enlarging the exhaust port to its' proper size and allowing the exhaust gases to escape. Vacuum the carbon out of the cylinder. De-carbon the piston top and the cylinder head.

Get back to me and tell me what you find. If more is needed we will go further.

Posted on Apr 12, 2009


  • 3567 Answers

SOURCE: 1981 gl1100 has 4 keihin carbs bike sat 7 years

648d54b.gifWhen removing the pilot jet screw, count the number of turns to remove. Put the screw back the same number of turns then unscrew 1/4 turn.
A “very helpful” rating on this answer? Thanks!

Posted on Jul 02, 2009

Fabrice Wolters

  • 331 Answers

SOURCE: i have a 1974 dt 250 same as an dt 360 the bike

Compression is too low!

Replace the piston rings.

Also check continuity from engine to frame till high-tension coil...
Check if breaker points aren't dirty ( clean out with fine sandpaper )
Check breakerpoint settings

Posted on Nov 01, 2009

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Related Questions:

1 Answer

Why doesn't my 2007 ktm 125 sx idle

Check inline fuel filter ( if you installed one) and the one on the top of the petcock in the tank. Then clean all of the carb and jets too. There is a special wire tool made by companies like k&l for cleaning inside of jets. Usefresh gas to and make sure the premix ratio is correct. Clean air filter while you are at it, and replace spark plug after checking the gap.

Jan 07, 2014 | 2007 KTM 125 SX

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Runs great with choke on but continues to die when choke is turned off. 2008 ktm 530 exc

Hey mate,

you definately have a problem with your fuel system, I would say you have had some dirty fuel thru your bike, the first thing i would check would be the fuel filter between your tank and the carby then if still does not run drain your carby bowl... after this if it still does not run you will need your fuel system/carb stripped down and flushed would recommend getting this done by a mechanic as there is alot of small parts involved...

Hope this helps

Dec 16, 2009 | 2008 KTM 530 EXC-R

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2008 ktm 250 sx.the bike starts and runs fine until about 3/4 throttle then missfires,i have changed the complete ignition sistem but the problem is still there can any one help.

Sounds like the main jet is clogged, or you have water in the bowl..
First try draining the bowl on the carb, drain into a glass so you can see if there is any water dirt etc... If there is water, it should be fine after that. If its the main jet you are going to have to remove the carb and clean it.

One other thing it may be. If it has a CV carb (constant velocity) the boot may be ripped on the slide causing it not to lift during acceleration.

Nov 06, 2009 | 2008 KTM 250 SX

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I have a 02 kx 85 when u ckoke the bike it runs choke off bike shuts off

The choke allows more fuel. I would guess that you have a plugged jet in the carburator. Remove it and go through it all to make sure all passageways are clear.

Aug 21, 2009 | 2001 KTM MXC 250

1 Answer


Hi I am vortash it may be you have a blocked idler jet you will find this is the jet in the bowl area .. just pass a thin strand of wire through it and clean the bowl out .. if that don't cure it check the carb manifold gasket it may be letting air in .. it may be that your cable is badly adjusted most bike carbs have the adjuster on the acelarator cable as it eneters the carb ..hope this helps regards Vortash

May 18, 2009 | 2002 Yamaha TT-R 125

2 Answers

Honda 2003 crf 230 bike idles fine with choke on,dies with choke off

You sound like you have a blocked idle jet in the carb. Honda trail bikes love new oil, clean air cleaners and clean fuel. After a while a build up of tannins and crusty residue will invade the carby bowl and usually migrate through the carb via the jets and the emulsion tube where the jet needle runs. The easiest way to fix your problem is to remove the carb and go through it. Clean all jets and check float height and generally get it back to scratch. You will have to re- adjust your idle and mixture settings after you have fited it back to the bike. If you are not Mechanicaly savi then I would suggest you take the bike in to your local honda dealer and get them to go through the carb for you.. It's not a big problem and is easlily fixed.

Hope this helps...


Apr 27, 2009 | 2003 Honda CRF 230 F

1 Answer

Time for a top end or jetting?

sounds like the idle jet is cloged and u need to clean out the carb jets

Dec 10, 2008 | 2008 KTM 250 XC

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