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 Post subject: Ktm 400 exc 2009 won't idle!! And backfires. Help please
PostPosted: Fri Nov 18, 2016 8:05 pm 
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80 cc

Joined: Sun Aug 14, 2016 4:04 pm
Posts: 17
Hi everyone, bought my bike a few months ago and it ran like a dream. About a month ago I decided to have it fully serviced and get everything checked so I could start a fresh. I told my local garage that the only thing that I could say was out of place was that the bike wouldn't idle at low revs all the time. Just occasionally it would do this but it was the only minor things wrong. Anyway I got the bike back and straight away I had to adjust the fuel screw because it just wouldn't start, after this it seemed to run fine but every so often it would pop and bang from the exhaust but I just put this down to the carb being cleaned. Then I put my back out so I've been off the bike for a month so it's just been garaged up. The other day I jumped on it fired it up first time and let it run for 10 minutes before I set of on a small journey just to warm it through, about half a mile down the road it popped and farmed then glided to a embarrassing stop, after this it wouldn't fire/kick up! This resulted in me pushing the bloody thing up what felt like mount everest. Fast forward a week and this morning I had a spare hour so I fired the bike up and let it warm up while I got ready then set off out, after about half an hour I was on the road so I opened it up a bit as you do, then as soon as I started to ease off the throttle I could hear the popping and banging again and yep you've guessed it, it stopped and wouldn't fire up again! I've since been and fired it up but after a few minutes of running idle it cuts out and struggles to start, when it does its not long before it cuts out. I phoned the garage up and he said he thinks it's perhaps a faulty lead on the plug! I've no idea but it's doing my head in. So with cap in hand and no experience I shall throw this open to the board for your help! Thankyou all very much in advance.


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 Post subject: Re: Ktm 400 exc 2009 won't idle!! And backfires. Help please
PostPosted: Fri Nov 18, 2016 9:51 pm 
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650 cc Monster
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Joined: Fri Dec 07, 2012 2:22 pm
Posts: 2439
Location: Romiley
Greetings,

The fault could be something simple as a faulty plug cap and/or lead but then again it could be more serious.

KTM are very susceptible to loss of compression so I would have a technician check for compression loss. This involves applying compressed air through the spark plug hole with the engine locked at TDC. If compression loss is a factor then the loss of air will most probably be heard, felt, seen and/or smelt at one or more of the following;

the exhaust pipe - leaking past exhaust valve and seat
the carburettor - leaking past inlet valve and seat
crankcase oil filler - piston/rings/bore
bubbles in the coolant - head gasket

At the very least check the valve clearances.

If you are not confident or competent to under take this test then you will need a good garage, tell us where you live and perhaps somebody else could recommend a suitable company to you.

TTFN

Hugh.

Ps let us know how you get on or if you need further suggestions.

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Please note that I am not a National TRF Officer, any views expressed are my own and may not be in accordance with any official policy.


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 Post subject: Re: Ktm 400 exc 2009 won't idle!! And backfires. Help please
PostPosted: Fri Nov 18, 2016 10:54 pm 
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200 cc

Joined: Thu Oct 15, 2009 11:08 pm
Posts: 429
i think i would try replacing plug cap first as they are known to break down and cheap to replace,i had this problem once with bike cutting out and messing about only sussed it was the plug cap when at night i ran it up and saw a little spark jumping across to cylinder head


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 Post subject: Re: Ktm 400 exc 2009 won't idle!! And backfires. Help please
PostPosted: Fri Nov 18, 2016 10:56 pm 
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80 cc

Joined: Sun Feb 12, 2012 2:17 pm
Posts: 34
Percy619 wrote:
Hi everyone, bought my bike a few months ago and it ran like a dream. About a month ago I decided to have it fully serviced and get everything checked so I could start a fresh. I told my local garage that the only thing that I could say was out of place was that the bike wouldn't idle at low revs all the time. Just occasionally it would do this but it was the only minor things wrong. Anyway I got the bike back and straight away I had to adjust the fuel screw because it just wouldn't start, after this it seemed to run fine but every so often it would pop and bang from the exhaust but I just put this down to the carb being cleaned. Then I put my back out so I've been off the bike for a month so it's just been garaged up. The other day I jumped on it fired it up first time and let it run for 10 minutes before I set of on a small journey just to warm it through, about half a mile down the road it popped and farmed then glided to a embarrassing stop, after this it wouldn't fire/kick up! This resulted in me pushing the bloody thing up what felt like mount everest. Fast forward a week and this morning I had a spare hour so I fired the bike up and let it warm up while I got ready then set off out, after about half an hour I was on the road so I opened it up a bit as you do, then as soon as I started to ease off the throttle I could hear the popping and banging again and yep you've guessed it, it stopped and wouldn't fire up again! I've since been and fired it up but after a few minutes of running idle it cuts out and struggles to start, when it does its not long before it cuts out. I phoned the garage up and he said he thinks it's perhaps a faulty lead on the plug! I've no idea but it's doing my head in. So with cap in hand and no experience I shall throw this open to the board for your help! Thankyou all very much in advance.


Hiya, I'm not familiar with KTM beyond helping a couple of trailriders with them broken down - start point is that you say the bike was running perfectly, and then with a slight problem which was only present at tickover (idle circuit on the carb) and wasn't present at any other throttle setting on the bike. There are normally a minimum of three circuits on a carb (some Italian bikes have four or five) and it's telling you something that its running on an open throttle on a different circuit but not running on the idle circuit with the throttle closed when the engine is hot.

And you say that the problem then was worse when the bike came back from the garage. If this is absolutely right then surely its the garages fault and for them to fix??????

So...my logic...the garage did something, altered something, disturbed something that is causing the problem. As you probably paid to have the work done my logic further says then it is up to the garage to fix it for you?

So why not take it back to the garage and explain it was fine (apart from low speed idle) when it came in and not now - could they help you get it back to where it was when you brought it in?

However - you say that you have been off the bike for a month and a week - well, the modern fuels are absolutely atrocious - even if you had highest rated octane unleaded it may have 5% or more ethanol and if you don't drain the fuel from the carb float bowl every time you put the bike away (tap off and run the bike till it dies) then you will leave sticky fuel residue in the carb. The idle circuit in most carbs I am familiar with have very small apertures and are easily gummed up by the residue in the fuel.

I run redex in every bike I have and have had superb results with it. Its basically posh paraffin but dissolves the fuel residue and cleans the internals.

So, one thing I would try is a double dose of redex in the tank. Then ride the bike.

Popping and banging is either unburnt fuel into a hot exhaust or an air leak. If the bike was running before then see above my first guess would be residue in the carb but you'll need to look at air leaks too.

Yes, problems with HT leads, plug caps and spark plugs could all be a problem but usually these are either heat related - they only become a problem when the part gets hot, or load problems and only get to be a problem when the bike is put under load which isn't in the idle circuit. Yours seems to be when hot, which is a suspect, but only on idle which seems odd. Could be HT lead, cap or plug, could be air leak, could be fuel.

However - one fundamental of tracing bike problems - only change one thing at a time. So do the easiest things first and try them. Do not change multiple things - you'll not know what the problem is and you may mask it:

1 - Give the bike back to the garage to fix - their responsibility save only for the month and week youve left it
2 - Clean carb, blow through airways if at all possible (and if not then a heavy dose of redex straight into the carb and fill the float bowl with it and leave it overnight to soak)
3 - Redex the fuel (double dose to start with) and I'd do this anyway with any and every bike
4 - Change spark plug _ I recommend an Iridium Plug for an electronic ignition system - try SparkPlugs.co.uk - they'll tell you what you need for the year and model of bike - I like Denso whenever possible and haven't been disappointed so far but each to their own. Make sure it is gapped properly
5 - Change HT cap - shouldn't be too expensive but fit an OEM part
6 - Change HT lead- ditto cap
7 - Battery - I'm assuming you have a good battery and it's been checked?

Hope this helps - and as Hugh says - don't be afraid to come back and ask more.

Stuart


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 Post subject: Re: Ktm 400 exc 2009 won't idle!! And backfires. Help please
PostPosted: Sat Nov 19, 2016 1:50 am 
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650 cc Monster

Joined: Sun Nov 11, 2012 7:31 pm
Posts: 3512
Valves....when they get warm they get tight ,easy to check,But they will need smaller shims,unless they are on their arse...fingers crossed.See valve shimming a KTM on the interwebs....experienced this on a few bikes.Fine when cold,but go to shit when hot.ps Don't buy any Redex....your mileage may vary....


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 Post subject: Re: Ktm 400 exc 2009 won't idle!! And backfires. Help please
PostPosted: Sat Nov 19, 2016 6:02 am 
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125cc
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Joined: Thu Apr 16, 2009 4:45 pm
Posts: 146
Location: South Yorkshire / Derbyshire
All what everyone else has said to check, do you know if the carb was ultrasonic cleaned by garage ?
if so its possible the tiny wee hard to adjust brass air fuel mixture would have been turned all the way in for cleaning,
check your manual for settings should be in the range from all the way in to backed out to one and a half turns to one and three quarters , while your at it remove the air fuel mixture screw completely and check the assembly of the components ,starting at the bottom it should be screw .spring. washer "o" ring , sometimes the "o" ring gets damaged .
I hope you find the fault .

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 Post subject: Re: Ktm 400 exc 2009 won't idle!! And backfires. Help please
PostPosted: Sat Nov 19, 2016 8:47 am 
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125cc

Joined: Tue Oct 23, 2012 2:16 pm
Posts: 144
It seems to stop after a similar amount of time. I would check the petrol tank breather is clear. Just to rule it out.


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 Post subject: Re: Ktm 400 exc 2009 won't idle!! And backfires. Help please
PostPosted: Sat Nov 19, 2016 9:57 am 
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80 cc

Joined: Sun Aug 14, 2016 4:04 pm
Posts: 17
Thanks for all the advice, I'm off for a few days so I'll have a good look at it. Anyone recommend any good YouTube video or websites that are for the, shall we say non mechanically minded. Cheers everyone


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 Post subject: Re: Ktm 400 exc 2009 won't idle!! And backfires. Help please
PostPosted: Sat Nov 19, 2016 10:29 am 
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650 cc Monster
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Joined: Fri Dec 07, 2012 2:22 pm
Posts: 2439
Location: Romiley
Greetings,

I note that you have called yourself "shall we say non mechanically minded", if this is the case then I have to ask should you really be fiddling with carburettor parts, etc, :?: :?:

Carburettors are expensive items, relatively delicate parts and easily damaged so I would advise you not to play around with it.

Similarly valve clearance checks and re-shimming can be tricky if there is nobody there to guide you :idea:

As described I can not see it being a problem with the tank breathing but to check you simply run the engine without the fuel cap in place, if the engine stops then you know that the cap is not the cause of the problem.

I note that your 'name' is a black colour which indicates that you may not have joined yet, if not then join up and check out your local Group, they will be best to advise you of a trusted technician in your area or somebody with greater experience might offer to take a look and guide you on the practicalities.

TTFN

Hugh.

_________________
Please note that I am not a National TRF Officer, any views expressed are my own and may not be in accordance with any official policy.


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 Post subject: Re: Ktm 400 exc 2009 won't idle!! And backfires. Help please
PostPosted: Sat Nov 19, 2016 10:56 am 
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80 cc

Joined: Sun Aug 14, 2016 4:04 pm
Posts: 17
Cheers Hugh. I totally agree with you, I can check plugs and wot not but I'm afraid it's a trip to the garage for the carb/jets etc. It's just if it's a simple fix then I'd sooner sort it myself other than pay big bucks for a simple thing. I've just been out this morning and the bike just keeps turning itself over and not firing up! I'm going to check the plugs and perhaps have a look at the fuel and air intake screw to see if it'll fire up. Thanks again.


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