Yamaha YZF125 Won't start!

[Stu]

right

thought you was getting the sound when trying to start

so trying to bump start you only get the sound when you are running with the bike? and as soon as you start moving it?

that points to something on the final drive to me

as for the not starting try a new plug first of all

[Ricky]

right

thought you was getting the sound when trying to start

so trying to bump start you only get the sound when you are running with the bike? and as soon as you start moving it?

that points to something on the final drive to me

as for the not starting try a new plug first of all

 

Yeah while I'm running it starts to make the noise.

I'll get a new plug tomorrow but when I checked it had a massive purple spark :/

[Stu]

makes no odds if it looks a good spark it could still be not good enough

or another trick is to warm it up on a hob to burn any fuel off as the fuel can seep into the plug

[Ricky]

makes no odds if it looks a good spark it could still be not good enough

or another trick is to warm it up on a hob to burn any fuel off as the fuel can seep into the plug

 

I'll pick one up as soon as then, I've done the hob trick, numerous times still get a bright purple spark:/

You mentioned testing the chain before, how do I that?

[Tango]

If you listen to the vid it makes the same noise on the starter....but not as fast as the starter is spinning the engine slower.....I've got an external speaker hooked up to the laptop and the noise is definitely there on the starter.....

I don't think it's transmission......why would the bike fail to start because of a slack chain or worn sprockets?

I say bottom end because that's what it sounds like to me....but without seeing the bike it's all guess work.....it could be the piston hitting a dropped valve......hard to tell really.....

If it were my bike....I'd start with pulling the cylinder head off and checking all around there.....and if that showed nothing then I'd go about splitting the crankcases and checking the bottom end.....

Pull the spark plug out and shine a torch into the plug hole and slowly turn the engine and see if there's anything on the piston crown.....or anything floating around in there.......but I'd certainly not be turning the engine over quick as it can be doing more damage if there is a valve floating around in there.....

Good luck Ricky

[Stu]

bob the sound starts as soon as he pushes it with the clutch in so the engine won't be turning! ......... well thats how I'm reading it anyway

its not the sprockets it could be a shafted chain knocking or it could be a shafted output shaft

but like I say its hard to say by a vid as noise could be coming from anywhere and some things sound worse then they are

[Ricky]

If you listen to the vid it makes the same noise on the starter....but not as fast as the starter is spinning the engine slower.....I've got an external speaker hooked up to the laptop and the noise is definitely there on the starter.....

I don't think it's transmission......why would the bike fail to start because of a slack chain or worn sprockets?

I say bottom end because that's what it sounds like to me....but without seeing the bike it's all guess work.....it could be the piston hitting a dropped valve......hard to tell really.....

If it were my bike....I'd start with pulling the cylinder head off and checking all around there.....and if that showed nothing then I'd go about splitting the crankcases and checking the bottom end.....

Pull the spark plug out and shine a torch into the plug hole and slowly turn the engine and see if there's anything on the piston crown.....or anything floating around in there.......but I'd certainly not be turning the engine over quick as it can be doing more damage if there is a valve floating around in there.....

Good luck Ricky

 

Thanks a lot for the reply tango

I'll take the top end off and check around but I daren't go any further because I'm only asking for trouble.

What is a dropped valve by the way?

Stu I can't hear the knocking with the electric start but tango can :/ I think I'm going deaf in my old age:/ perhaps watch the video stu? It explains it a lot better than what I can type

[Tango]

But when he spins it on the starter it's definitely knocking then too.....only a bit slower.....

I'd like to think that it's something simple....but TBH partially seizing an engine is never going to end well......

I hope for Ricky's sake that I'm proved wrong.....

[Tango]

Just to clear any confusion Ricky.....when you're pushing the bike is it in gear with the clutch out.....or in neutral or with the clutch in?

[Stu]

that could just be the exaggerated sound of the single piston as video mic's pic everything up really loud

my car sounds shagged to others when I have been working on my car with it running and my head under the bonnet but it runs cock on phone and video mic's pic up the sound and make it sound worse

I'm not ruling it out Bob but without hearing it for myself in person I'm not going to guess

[Tango]

Yeah....it's kinda hard to diagnose a problem on a bike using Youtube video shot on a phone camera......

[Ricky]

Just to clear any confusion Ricky.....when you're pushing the bike is it in gear with the clutch out.....or in neutral or with the clutch in?

 

Yes it was in the second gear with clutch out, when I put the clutch in the noise stops.

One thing I didn't mention was it got power washed the day before, could that of done anything?

[Stu]

listen how rattly and ticky mine is on camera

http://www.youtube.com/watch?v=MQgFQ151BPM

[Stu]

Just to clear any confusion Ricky.....when you're pushing the bike is it in gear with the clutch out.....or in neutral or with the clutch in?

 

Yes it was in the second gear with clutch out, when I put the clutch in the noise stops.

 

ah well that changes everything!

[Ricky]

Sorry stu

[Tango]

Just to clear any confusion Ricky.....when you're pushing the bike is it in gear with the clutch out.....or in neutral or with the clutch in?

 

Yes it was in the second gear with clutch out, when I put the clutch in the noise stops.

One thing I didn't mention was it got power washed the day before, could that of done anything?

Power washing bikes is not a great idea mate.....too many exposed connectors to get filled with water.....and it can wash the grease out of bearings and linkages.....

I'm sorry to say that I don't think the power washing is your problem.....lack of oil was......

Try shining a torch into the plug hole and turn the engine slowly and see if you can see the piston crown.....and if there is any damage on it.......

[Stu]

after reading that it does it in gear clutch out I have to agree with Bob and that the lack of oil has probably killed it!

do as Bob says pull the plug shine a torch and look for damage

[Ricky]

I tried to get a good view of inside the spark plug hole but its in such an awkward position I couldn't get a clear view so I didn't get to see inside it unfortunately

[Tiggie]

looking at your first post you said that it happened after you overtook someone. So you would of been using higher revs and putting the engine under a greater load without adequate oil to protect its innards

I do think that something has blown inside, possibly a conecting rod as Tango mentioned. I do hope not though and you can get it back on its wheels again soon.

P.S. CHECK YOUR OIL MORE OFTEN!! I have a look at mine every time I fill up with petrol (approx 150 miles) as I do a lot of short journeys it seems to drink a little more .

[Fozzie]

Common failure with this bike!

Another member did the same with the same bike and got a bad rumble from the bottom end.

Solution? Buy a second hand engine.

This one could possibly be had for around £375 if you made an offer

http://www.ebay.co.uk/itm/2009-Yamaha-Y ... 2a2d6c6758

The engine is very simple by the way, tape everything up and write down what it is with lots of pictures, get the engine out, and start stripping it otherwise until you find the broken bit. I reckon the bottom end blew when it starved of oil.