Help with a YZ

[Mark MurphyMember]

i’m after some help with a YZ125.I’m trying yo get a mates son bike going for him. The bike was going but had blown the inner o ring on the cylinder head. I’ve changed that but still will not go. The spark seems a little weak, is there any way of checking the timing on these as it has a cdi unit so checking point gap cannot be done.
Hope someone can help as we are going riding over Easter.
Smurf19

[DeanMember]

check the basics first smurf.confirm it has compression and is getting fuel. Try changing the plug,check the plug cap and lead and also the coil readings if all that fails or shows that its ok you will need to go deeper into the magneto coils and timing.Usually the timing is not a concern. best of luck mate,keep us informed of your findings.

Ollie

[Mark MurphyMember]

Thanks mate,
Compression is fine as I put a new weisco about 6 months ago. Going to try a new plug tomorrow if that doesn’t work I’ll try the windings etc. It’s getting fuel but I may try putting a fresh batch in to see if that helps. The thing flies when it’s going so I hope I can get it up for him.

[Mick DMember]

My ears pricked up a bit when you mentioned fresh fuel. A new plug and fresh fuel can make all the difference on a YZ125 or any 2banger for that matter.

[Bruce CurtisMember]

I heavily suspect the low speed winding may be the culprit in this case, not the first YZ, and won’t be the last to suffer, or the CDI unit is too close to the coil and is interfering with the signal.

BC

[Mark MurphyMember]

put a new plug in and away she went for ahile then stoped. tried to kick it over again and it back fired on the kickstarter and jammed it into the side of the clutch cover. I’ve got the shits now so it can get stuffed until tomorrow night.
thanks for all the sugestions I’ll keep you informed when it gets going again
Smurf

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