Question about 2002 KTM SX 125

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Choking up my ktm starts fine with lots of compression but dosen't seem to run very well it's like the choke is always on.. my fuel mixtures are good.. so can anyone help

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Try lowering your oil/petrol mix ie 100ml oil-4.5l petrol (if premix), if not change spark plug to hotter grade (whatever plug number is go down a number)

Posted on Feb 21, 2009

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Why doesn't it idle unless choke is on?

Maybe you are running too lean. When the choke is on it reduces (chokes) the air being drawn in meaning higher fuel to air mixture (richer because of more fuel and less air). Turn the choke off and more air is drawn in and the fuel to air mixture is reduced. There should be a mixture screw where you can alter the mixture to the required setting for normal running.

Feb 16, 2016 | 2004 KTM SX 450 racing

1 Answer

I installed new carb. on my tecumseh 5hp. snow king and it wont start. I have spark and gas is flowing out of carb.

This can be very frustrating and tough on the back and arm.
Always confirm the the fuel tank valve is open and the stop/run switch is in run position

It takes three things to run:
  1. Compression. This is the resistance that you feel as you crank the engine. Some engines have compression release to assist getting the rotation started. You should be able to feel the compression stroke as you rotate, Remove the plug and you can easily tell the deference. If it had, last time used, been running and starting with no problem I would assume that the compression is OK. Gauges are available to check. at lease 120 PSI
  2. Spark. It is near impossible to lose the spark timing on these. It can only be magnitude and presence. If in doubt about the condition of spark plug replace. I usually lay the plug on top of the head with wire attached and observe for the spark. No spark no start.
  3. Confirm that the throttle is in the wide open position. It is possible during the repair the spring or rod has closed the throttle air valve. Air/fuel mixture is always hard to trouble shoot. I use open choke and starter fluid to conform that compression and spark are working. After that I will choke on a cold motor and pull listening for the first fire. At the first fire I would usually half choke and pull to first run. Full choke for many pulls will only flood engine!! If no joy then I would allow engine to vent and go back to start fluid. If it will run on start fluid than either carburetor is messed up or quality of fuel is bad.
If after several tries and fuel is certain to be good remove plug and check for gas. It is possible that the new carb float valve or mixture adjustment screws are messed up.

Jan 10, 2016 | Tecumseh Garden

1 Answer

KTM SX50 wont run without choke

carb is running tooo lean, remove carb and strip down, removing all internal jets, check float height setting and note number of turns mixture screw is set at.......completely clean internals in a large can of carb cleaner- available at wall mart- has a basket inside the metal container so you will not loose small parts while the carb is soaking in the mixture...leave for a day, the crean all parts and blow out with high pressure compressed air. and re-assemble, and refit.....please note, never use ethanol fuel in your motorcycle, I only use classic gas in all my vehicles...less problems

Dec 27, 2013 | 2009 KTM 50 SX

1 Answer

Lt1050 black smoke after 15 minutes

The black smoke and black spark plugs indicate that the engine is running very rich (ie too much fuel). This could be caused by the choke not opening fully after the engine starts and the fuel mixture is too rich OR the fuel mixture setting is opened too far.
Check the choke lever, make sure the choke is fully open when the choke is in the running position.
When the engine is running with the throttle is in the 3/4 rev position then adjust the fuel mixture to get the highest RPM.

Apr 19, 2012 | Cub Cadet Garden

1 Answer

My son's KTM 50 senior pro doesn't start. has petrol vapour coming out of the pipe.

The engine is running too rich. The carburator needs tuning to get the fuel mixture correct or the choke may be stuck in a partially closed position.

Feb 11, 2012 | 2006 KTM 50 Senior Adventurer

1 Answer

Hi, my ford 2000 gas wont run without choke. Was fine this morning, now wont run, any ideas? It seems to be getting fuel to carb, but it has some weird fuel pump beside a sediment bowl, could this be a...

If it won't run without choke, then it's not getting enough fuel. You probably either have a clogged jet in the carb, or you have an air leak somewhere that's allowing air to dilute the air/fuel mixture.

Unless a gasket suddenly died, fell apart, and left a gaping hole, a sudden failure like that is probably a clogged jet.

I'd clean out the bowl on the carb and hose the jets out really good with carb cleaner. If you have it, hit the jets up with some compressed air, too. While you're in there, make sure the float isn't sticking and the fuel flow is good.

Dec 31, 2010 | Ford Garden

1 Answer

Bike only starts with choke on and wont idle .by the way its a ktm 250 xc 2006.air filter is clean and has new plug . wondering about needle adjustments?

If your bike ran good previously - and nothing has been changed that would require rejetting or a needle adjustment, I would look for problems elsewhere. Such as:
Has the bike been stored for more than a few months at a time? If so, the carburetor jets could be plugged with fuel varnish. Only being able to start with the choke applied - and an inability to idle are both classic symptoms of this. Remove and disassemble the carburetor. Clean it and the jets out with carb cleaner and compressed air, then reassemble. Also make sure the fuel in the tank is fresh and that the fuel strainer (usually with the fuel petcock) is clean.
There are three ingredients required for combustion: fuel, compression, and a spark (at the right time). So long as you've got each of these - it has got to run.

Feb 21, 2010 | 2008 KTM 250 XC

1 Answer

Mcculloch 3516 chain saw, does not always start.

It must have spark, fuel and compression to run. Your task is to figure out which is missing.
Sometimes electrical components quit operating once beyond a certain temperature. Does it always start cold and become tempermental when warm?
IMO most hard start problems on a chainsaw with a good fuel delivery system are flooded.
Start Procedure
  1. Ignition on/off to on
  2. Set compression release – optional step even if saw is equipped with a compression release
  3. Pull (close) choke, set fast idle (done when choke closed on some saws); pull starter and listen for an attempt to start. once heard (usually two pulls; no more than 4)
  4. Set compression release – optional step even if saw is equipped with a compression release
  5. Push (open) choke pull starter until it starts. (usually first pull)
  1. Ignition on/off to on
  2. Set compression release – optional step even if saw is equipped with a compression release
  3. Pull (close) choke, set fast idle (done when choke closed on some saws) - Don’t pull with choke closed.
  4. Push (open) choke, pull starter until it starts. (usually first pull)
The 3516 is a MTD McCulloch (Chinese). These saws are in a class by themselves. Good Luck

Nov 15, 2009 | McCulloch Garden

2 Answers

Runs ok with choke almost closd

With the choke almost closed your using the vacumn of the intake maniflod to **** more fuel. This means that your engine is running too lean with the choke open. Why? Possibilities are, Fuel pump output to low, Check by disconnecting the fuel line at the carb (this takes two people) hold the end in a tin can, crank the engine. if fuel flow is good then pump isn't the problem if it's just a trickle replace the pump and the filter and you should be good to go. Other possibilities are clogged fuel lines. On an '86 I'd replace them unless they are stainless in which case I'd just blow them out with compressed air. Pinched fuel line, look for crushed areas or kinks, clogged fuel filter, should be an in-line filter near the carb on an '86. Other than that your carb might be set up wrong or in need of a good cleaning ang rebuild. I'd start by inspecting the furl lines and flow and go from there. Sounds like a fun ride! Good luck with it!

May 12, 2009 | 1986 Chevrolet Corvette

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