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Piston Burn-Down Problems, please help

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Piston Burn-Down Problems, please help

Postby mountain---max » February 14th, 2006, 1:49 pm

Could you guys give me some opinions on why this burn down Hapened? It's from my 1980 SRX440 modded to the nuts. It burned down both Exhaust sides only,My plugs read fine, nice tan, my egt's were about 1100 degrees, running 110 Octane Race fuel with Dominator Race Oil, Coolant Temp well in the green. Timing is also advanced as per SRX Snow Race Yamaha Manual. Oh, yeah they were New Wiseco Pistons that were coated at Swain Tech with ceramic on top and anti friction race coating on sides. I had good cylinder clearances and ring end gap. I Only got aobut 6 runs down the 660ft track (@75MPH) then i lost power as compression dropped and this is what I found.[img]http://www.totallyamaha.net/forums/attachment.php?attachmentid=10832&stc=1&thumb=1[/img]
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Piston Burn-Down Problems, please help

Postby cosmic muffin » February 14th, 2006, 3:30 pm

Here we go again!Try this web site for piston failure!
http://www.mztech.fsnet.co.uk/workshop/wrk_piston.html
By the way wild home page.
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Piston Burn-Down Problems, please help

Postby mountain---max » February 14th, 2006, 3:40 pm

What do you mean here we go again? this a common thing?? it's new to me, Normally riding Yamaha's don't need work like this, i know this is a little monstor though. thanks for the Hpage shout......and the link
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Piston Burn-Down Problems, please help

Postby Warroadthunder » February 17th, 2006, 7:46 am

what main jet r u running in it?????
could be a tad lean when u were running down the track!
good luck
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Piston Burn-Down Problems, please help

Postby mountain---max » February 17th, 2006, 10:30 am

runnint 410 mains, and i ran her down the track, hit the kill switch and jammed up the brake, checked the plugs, perfecly brown
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Piston Burn-Down Problems, please help

Postby mountain---max » February 17th, 2006, 2:43 pm

IM running 410 main jets, plugs looked good after each race. nice and tan color
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Piston Burn-Down Problems, please help

Postby h2onsnow » February 18th, 2006, 3:43 pm

Looks like the friction coating went belly up, those two hot spots indicate thin application of coating!! Ive seen similar, makes sense being on the exhaust side!!
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Piston Burn-Down Problems, please help

Postby mountain---max » February 19th, 2006, 1:37 am

I just got new pistons, however i don't have time to get these coated, any suggestions on keeping this from repeating?
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Piston Burn-Down Problems, please help

Postby cosmic muffin » February 19th, 2006, 1:24 pm

Make sure to check ring gap top,middle,bottom of cyl.Gap is different on different alloy pistons???
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Piston Burn-Down Problems, please help

Postby mountain---max » February 19th, 2006, 1:40 pm

Yes, I just noticed that i get 12 thous on one cylinder right through, the other i get 12 on top and 10-11 near the middle, any idea what it should be on a 1980 SRX440
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