Bike won't start / ktm 450 / carb

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Patt959
125cc Novice
Posts: 17
Joined: Sun Dec 06, 2015 10:34 pm

Bike won't start / ktm 450 / carb

Postby Patt959 » Sun Jan 15, 2017 10:45 am

Hi, I have a 58 KTM 450 EXC. I went away for a few months last year and when I returned my bike wouldn't start. The tank and carb were full of very stale fuel.

Since then I have drained the old fuel and replaced it with new. Still wouldn't start.

Next thing I did was drain the float bowl of the carb.

Next thing I noticed was when I tightened the drain screw on the carb it would start leaking once I turned the fuel on which I think was a problem with the float needle - if I tapped the carb it would - I'm guessing - raise the float up properly and activated the needle which stopped the overflow leaking out.

Anyway I took the carb off, dismantled it, cleaned it and put it back. To my joy it started momentarily. When I tried to start it again, to my utter frustration it wouldn't.

I realise there may be a problem with the float needle but ding think that's why it's not starting.

Any ideas of where to look now?

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blackflyer
125cc L Plates
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Joined: Sat Dec 29, 2012 6:17 pm
Location: godalming

Re: Bike won't start / ktm 450 / carb

Postby blackflyer » Sun Jan 15, 2017 11:06 am

sounds like your on the right path with the carb.
Possibly sucked up a bit of sediment and blocked the jet. I would start by stripping carb down and blowing jet's out.
Steve
My theory of the motor car.
They have too many wheel's, get in our way, and all end up in the same place.

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newsh
350cc Veteran
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Joined: Sat Dec 08, 2012 11:31 pm

Re: Bike won't start / ktm 450 / carb

Postby newsh » Sun Jan 15, 2017 11:45 am

Also make sure your carb breathers are not blocked with mud, it's a good tip to route the top 2 of these into the air box

Patt959
125cc Novice
Posts: 17
Joined: Sun Dec 06, 2015 10:34 pm

Re: Bike won't start / ktm 450 / carb

Postby Patt959 » Sun Jan 15, 2017 1:40 pm

I completely cleaned the carb and all jets yesterday. All breather tubes are also clear and have 2 routed up to the seat.

Latest update: when I put the carb back on yesterday I had forgotten to put the fuel jet back so took the carb off again and put the fuel jet back and turned it 3 3/4 turns back to its original position which I made a note of when I first took the carb apart.

This morning the bike started again but again it conked out 15-20 secs later.

Something is stopping the engine for running and then stopping it from starting again.

Any ideas?

My feeling is it's something to with the float needle or float level.... might it need a new fuel inlet needle?

http://www.thumpertalk.com/topic/347305 ... read-here/

Mine is a 4 stroke

Maybe one of the jets has become blocked again as you suggest....?

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newsh
350cc Veteran
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Joined: Sat Dec 08, 2012 11:31 pm

Re: Bike won't start / ktm 450 / carb

Postby newsh » Sun Jan 15, 2017 4:00 pm

Run the fuel pipe from the tank into a bottle and check you have good flow of fuel. If not remove the fuel tap and clean.
If fuel supply is good, connect fuel to carb with float bowl removed and a dish under. You should be able to switch the flow of fuel on and off by raising and lowering the float. You'll be able to see if the float needle sticks in its seat too.

If it's a blocked jet you should be able to twist the throttle a few times to use the accelerator pump to squirt some fuel in and get it to start and run for a few seconds.

Patt959
125cc Novice
Posts: 17
Joined: Sun Dec 06, 2015 10:34 pm

Re: Bike won't start / ktm 450 / carb

Postby Patt959 » Sun Jan 15, 2017 10:45 pm

Ok great thanks for the advice. Will have a go in the next week and let you know how I get on. Cheers


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