Athena 144 problems

Hi, I just bought a 2006 yz 125 that has a 144 athena kit on it, the guy i bought it from said he installed the cyl. then hit hard times and had to sell so he never rode it. i have about 2 hrs on it and so the "J" ground on the spark plug has broke off twice. The first time it crunched the top of the piston and pinched the ring, i was able to clean the piston top, and clean the ring land reinstall and all seemed well, I thought it was a freak thing, today I noticed after each practice session the plug was a bit loose, at the end of the day the plug broke again, this time the piston seized slightly. Whats the problem ? anybody have the original instalation instructions incase this guy missed something

Your fuel, jetting, and timing settings are not adequate for the compression/squish.

Run better fuel, less timing, or richer jet - or a combo of all and the issue will go away.

Also - you may have used the thinner base gasket supplied. If using OE base gaskets a quick "fix" is to run 2 stacked base gaskets.

It will hurt the already poor bottom on that kit - but if will keep the plugs from loosing the electrode.

I am using premium fuel, 410 main jet and the timing is stock, I never checked the squish but there is no way that the electrode could have broke off from mechanical contact,its not getting mashed since the center electrode is unhurt, its like the ground on the plug is just falling off, BTW the plug is a good colour if anything it is slightly rich

...squish as in to much turbulence/energy introduced at high rpm.

410 main on that kit from my experience is way too lean for that - especially on pump gas.

I am using premium fuel, 410 main jet and the timing is stock, I never checked the squish but there is no way that the electrode could have broke off from mechanical contact,its not getting mashed since the center electrode is unhurt, its like the ground on the plug is just falling off, BTW the plug is a good colour if anything it is slightly rich

I think detonation will make the tip come off on spark plugs. think that is what harrperf is getting at.used to be the detonation would take out the o ring now that they have fixed detonation is around long enough to do this.

My theory anyhow, I could be wrong.

ok, so please bring me up to speed for reassembly. can I use stock Yamaha base gaskets, piston pin bearing, clips ? what is the recomended sparkplug ? how much squish should I have ? What main jet would you recomend ? I have read on here that some people are jetting down on main , pilot and needle clip.

also do I go for the bank loan and get the Athena piston ( mine is the "A" piston which only Yamaha lists the A & B piston, most places only list 1 piston size ) or is there a Wiesco piston that I could use ? can I reuse my old headgasket, I have the 1 piece head and the head gasket is laminated steel .

Thanks

I just saw this thread about a guy that thought he had his piston in backwards, plug ground was broke off and plug color was same as mine, piston top and cyl head looked the same also, people were suggesting detonation, is that possible ? i was thinking that these marks were from the wire breaking and getting banged around in the cylinder, i have to be honest , if I back off the throttle then wack it there is a hesitation, I don't think it was there before I went down 1 size on the pilot and 1 leaner on the clip but in mid range it would blubber,

I had a kit on my 08 ran same jetting that i ran with stock cylinder. used stock base gasket and got 1.1mm squish but still confirmed it was 1.1mm every time i took it apart. I used priemem gas mixed at 32:1 never had an issue until i tried to lean it out on main by 3 sizes from 390 to 360 just for the heck of it as I had piston wash so bad that the piston always looked new. head oring lasted 1/2 lap9detonation took it out). detonation is a issue mostly if your fuel is bad or your squish is to small.

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