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  #1  
Old 4th June 2018, 03:51 PM
Mickysquint Mickysquint is offline
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37 posts since Apr 2017
Motorbike: FireBlade, X-max 125
Default What have i done????

Hi Guys

I may have really fecked up.

I have a work mule/winter hack Yamaha Xmax 125 that I needed to replace the starter motor replacing. So I replaced it, started fine the first time, but then went to try it one more time, starter motor makes noise but the bike wont start, after a bit of investigating I noticed the starter motor wasn't grounded properly. So I think I've fried something, My question is, what have I fried?
I've replaced the relay,
I've replaced the spark plug (just in case),
all fuses are in good condition,

My next plan is to get an ignition coil and possibly an ignition module and try them, after that I'm out of idea's.

Any help would be appreciated guys.
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  #2  
Old 4th June 2018, 04:07 PM
Gixxer's Avatar
Gixxer Gixxer is offline
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Biker.ie Member No. 19392
12,945 posts since Nov 2009
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Default Re: What have i done????

What do you mean by "the starter motor wasn't grounded properly"?
Did you leave the main earth lead loose/disconnected?
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  #3  
Old 4th June 2018, 04:11 PM
Mickysquint Mickysquint is offline
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Original Poster of This Thread Topic Starter
 
Biker.ie Member No. 37123
37 posts since Apr 2017
Motorbike: FireBlade, X-max 125
Default Re: What have i done????

Originally Posted by Gixxer
What do you mean by "the starter motor wasn't grounded properly"?
Did you leave the main earth lead loose/disconnected?
The ground cable cable from the starter motor came loose once I moved the bike after originally testing it, more so from stupidity on my part. So when I tried to start it again, the starter motor makes its whirling noise but there's no life after that.
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  #4  
Old 4th June 2018, 04:22 PM
sharpbikes's Avatar
sharpbikes sharpbikes is offline
bike broke
 
Biker.ie Member No. 30720 from Offaly
2,148 posts since Jan 2013
Motorbike: R1, zx7/9r, Uni-cycle
Modifications: inflatable doll underseat
Default Re: What have i done????

Originally Posted by Mickysquint
The ground cable cable from the starter motor came loose once I moved the bike after originally testing it, more so from stupidity on my part. So when I tried to start it again, the starter motor makes its whirling noise but there's no life after that.
sounds like the motor may not be engaging the gear in the engine and just spinning.
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  #5  
Old 4th June 2018, 04:42 PM
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Gixxer Gixxer is offline
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Default Re: What have i done????

Originally Posted by Mickysquint
The ground cable cable from the starter motor came loose once I moved the bike after originally testing it, more so from stupidity on my part. So when I tried to start it again, the starter motor makes its whirling noise but there's no life after that.
Is the engine actually turning over?
I haven't seen the wiring diagram so I can only guess, but If the engine is now turning over, and assuming there's a separate earth for the electronics... In the absence of its own earth, the starter motor will try to draw its current through other parts of the bike that are connected to earth, including the clutch cable (seen plenty melt doing this) and electrical cables that aren't designed to carry that current, and maybe through the electronics systems on the bike.
The whole of the wiring loom could be melted, as could any of the electronics.
It's not really something that can be diagnosed without having the bike at hand.
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  #6  
Old 4th June 2018, 08:49 PM
Mickysquint Mickysquint is offline
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Biker.ie Member No. 37123
37 posts since Apr 2017
Motorbike: FireBlade, X-max 125
Default Re: What have i done????

Originally Posted by Gixxer
Is the engine actually turning over?
I haven't seen the wiring diagram so I can only guess, but If the engine is now turning over, and assuming there's a separate earth for the electronics... In the absence of its own earth, the starter motor will try to draw its current through other parts of the bike that are connected to earth, including the clutch cable (seen plenty melt doing this) and electrical cables that aren't designed to carry that current, and maybe through the electronics systems on the bike.
The whole of the wiring loom could be melted, as could any of the electronics.
It's not really something that can be diagnosed without having the bike at hand.
No, the engine doesn't turn over now, but was mechanically working fine apart from the starter motor issue. I turn the ignition on, everything turns on as normal, then when I press the engine start button, you can hear the starter motor but that's it, there's no other sound from the engine.
What you described is what I'm worried about. It's a great little bike for the work run, but it's not worth spending too much time or money on trying to sort it. Looks like its going to be stripped down and sold as spares.
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  #7  
Old 4th June 2018, 08:58 PM
DavyH DavyH is online now
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Default Re: What have i done????

Either the starter isn't bolted in correctly or the starter clutch is fucked, from what you're saying....
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  #8  
Old 5th June 2018, 09:31 AM
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Spoonman Spoonman is offline
Break it. Fix it. Repeat.
 
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Default Re: What have i done????

Could be as simple as the battery being low and not kicking the starter hard enough to engage the starter clutch.

If the starter is making a noise then it's spinning, and if it's spinning then that circuit at least, is grand. So first thing to check is the battery, then that starter clutch, and then work from there.

As to the earth strap being loose - unless the motor is mounted on rubber bushes, I wouldn't be concerned. If the starter return is from it's chassis then it'll couple to the motor, from there to the chassis, and from there through any other return wiring to the battery. Whilst this isn't ideal, it's a 125, it's not like you're drawing a huge amount of power to spin the thing up - if it was a big v-twin, then it would be a very different story and potentially close to what Gixxer outlined.

For now, charge the battery, then try again; then check the starter clutch. If it's neither of those, *then* you can start worrying about other bits.
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  #9  
Old 5th June 2018, 04:25 PM
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Gixxer Gixxer is offline
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Default Re: What have i done????

Originally Posted by Spoonman
As to the earth strap being loose - unless the motor is mounted on rubber bushes, I wouldn't be concerned. If the starter return is from it's chassis then it'll couple to the motor, from there to the chassis, and from there through any other return wiring to the battery. Whilst this isn't ideal, it's a 125, it's not like you're drawing a huge amount of power to spin the thing up - if it was a big v-twin, then it would be a very different story and potentially close to what Gixxer outlined.
It doesn't matter if the engine is rubber mounted or not. If the main earth lead is disconnected, then the current has to come from elsewhere. Inevitably it has to come through a wire from the battery negative that is nowhere near heavy enough to carry that current, but that's the least of the problems, as there are loads of smaller wires and connections to earth that will be used to route the power, and each and every one of those points will likely have hundreds of times the current running through it than it was designed for, and millions of times more in the case of electronics.

Here's a picture from the first bike I came to in the garage. It clearly shows the main earth lead, then the secondary earth, which is nowhere near heavy enough to run a starter motor, and that second earth wire will be much lighter on a 125.

Click the image to open in full size.




But that's purely academic if the starter isn't spinning the engine.
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  #10  
Old 11th June 2018, 02:57 PM
Spoonman's Avatar
Spoonman Spoonman is offline
Break it. Fix it. Repeat.
 
Biker.ie Member No. 1842 from Westmeath
3,828 posts since May 2005
Motorbike: '87 NC24; '98 TL1000S
Modifications: TLS: M4 system, PCII, K&N, GI-pro ATRE, c/f hugger
Default Re: What have i done????

As you say, all academic given the problem isn't likely related in any case, but I think we may have been coming at the the point from different interpretations of the phrase 'earth strap'.

In any starter I've seen where there's an earth strap (my interpretation being a strap to the chassis and not a direct return to the battery), there's also a heavy strap from the battery to the chassis to compliment it. Assuming this to be the case then that's why the nature of the engine mounts does matter as the return can take the path through the motor housing to the chassis as an alternative to the wires are you're suggesting.

If, on the other hand, by earth strap you are actually referring to a dedicated return line rather than a strap to the chassis then yes, I can see your point.
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