4 new spark plugs but bike won't start
 

Hi,

Have been giving my bike a service and have just fitted 4 new spark plugs, but now the bike wont start. The battery is fine but the spark plugs are just not igniting. the bike started fine with the old plugs before i took them out, so im guessing iv possibley blown something when changing them? any help would be great thanks.

It's unlikely that you've "blown" anything. I'm going to assume that you set the plug gap properly before putting them in. 2 things that are common when changing plugs. 1 is that you get the plug wires attached to the wrong cylinder. Look closely at the plug wires, they've got numbers on them. That identifies the cylinder that they're supposed to go on. 2nd is that you don't get the plug boot seated all the way down onto the plug itself. It can be challenging to get them fully seated with the limited space you have to work in. Check these 2 things to see if they're the cause.

Hi thanks for the quick response, the gaps are correct and wires are the correct ones, and the plug boot is pushed all the way down too. Iv tried it with the old plugs and they're not starting the bike either now. Is there a fuse or anything else that could have blown? iv reconnected all the wires etc.

It could be your main fuse.

Not sure where it is exactly, I just know someone else was having starting problems the other day and that's what it was.

need more detail. is the bike turning over? do your lights come on? etc.

Basically I bought the bike a few days ago, took all the fairing etc off today to clean it and service (the bike ran fine and started first time everytime etc anyway when i bought it but thought id service it still). Changed the air filter and spark plugs then went to turn it on so could warm the oil up but it wouldnt start. When i press the ignition it sounds the same as if you started a bike with no spark plugs in, it turns over, but just wont ignite. Iv checked all the wires back to the fuse box, everything is fine, no fuses blown (inc. main fuse), petrol is getting to the spark plugs as can smell it on the plugs, all the lights come on the dash, the spark plugs all work (when tested on a diff bike), but they just dont ignite, if you start a bike with no plugs, its the same as that. I tried everything i can think of, even the original plugs wont start now so i must have done something to whatever creates the spark? i'm not a mechanic but i do all my own work on my bike but i just cant think what the problem might be. it started fine before i took it apart, but i have somehow either missed a connection somewhere (although iv retraced everything) or iv created a new problem, I.e damaging whatever creates the spark? can this happen?

Thankyou!

Only thing I can think of is that the ignition coils aren't being seated all the way over the plugs. They can be a real bugger to get on, especially if you're not coming at them from the top with the air box removed.

Lol, I bet your fairings are still off right?


In the nose cone there is a bank angle sensor, if this is not plugged in, the bike will do exactly what you just described.

Plug the headlight harness in and see if it starts.

double check the connectors to the coil by pulling on them. you have to really push some of them in or else they dont click and seat properly.

You DonnyBrago are a genius!! That's solved it, I can't believe it was something so trivial lol! I see you live in the UK, if you're anywhere near Birmingham i'll buy you a drink lol