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