blew top end!!!!

D

Dirt Addict

New member
my 1st ride on my new to me 2006 ec250. about 2 hours into it poof. engine shuts off while climbing a hill. after getting the bike turned around on the trail, i kick it over. no compression / wont fire up.
prior to riding it i checked the jetting. its supposed to have a ltr jet kit in it. 175mj, needle in 2nd pos. i think a 48pj.
temps were 75 -80 f. elev. - 4000' - 6500' asl. 40:1 motorex syn.
what happened?
it did seem rich off idle and lean up in the rpms....
so where do i get a top end kit from?
i will open it up this week to see what the damge is...
 
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Sounds like you've burned a hole in the piston. Usually this is caused by ignition timing being too far advanced or old/ stale gas( pre-ignition, not always the same as detonation). Detonation is usually caused by low octane, not bad enough to cause a meltdown, but sooner or later it would cause trouble. Pre-ignition can be caused by old gas, low octane + low/ no vapor pressure. It could also be caused by a hot spot on the head or piston. Think of a chisel mark instead of a smooth surface. If you have score or siezure marks on the side of the piston that would indicate jetting trouble. After you tear it down, let us know what you've found.
 
Damn, that sux. Please let us know what it looks like
once you get it torn down. I'd be curious too.
Depending on where in So. Cal. you live. There is a
real GasGas guru not too far away. Check with
Steve and MotoWest. If there is any confusion on
why your motor failed. He can diagnose it for you.
As always, GoFasters for your parts, but, Steve can
also get them for you. I have also have had great service
from Bob @ NorthTahoe motorsports.
Sorry for all the plugs in one post. These are just great
people to do business with. Good luck.
Jeff So. Cal.
 
ok i got it opened up. there is a 5mm hole in the piston. ughh. im looking for my camera to take pics now...... more to follow.
 
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oops i meant farenheit. fixed it.

well the cylinder looks good. still has the cross hatches, no scoring. the head got roughed up on an edge, i think i can smooth it out with some fine grain wet sanding.
 
well i just ordered a piston kit from gofasters. $200+ !!
dang gina. im used to 130. for my jap bikes.
oh well, im looking forward to getting this bike back on the trail...
thanks to everyone for the help. more ??'s to follow im sure.
 
That sounds rich to me.

Check the jetting thread stickied on the Carb forum.

Heck, I'm in Phx with 90F, 1200 MSL, with MJ=172 and PJ=42. I've been running it like that for nearly two years. Leaner in the summer and a tad (178/45) richer in the winter when it gets all the way down to 60F.

Plug looks Snickers brown.

I've just gotten the RB-Designs squish band mod so I might not go that rich in the summer.
 
definitely wasnt rich. plug was white. the previous owner told me it had a ltr jet kit. the needle was a ddk. he said he was having trouble with spooge and was trying to lean it out.
i put the oem needle 2nd clip, back in and went to a 180 mj. when i get the parts in i will work on fine tuning it.
 
I run LTR kit on my '00. 48 pilot (as recommended by Les) and 180 main (he sent a 175 but I like the 180 better). My kids bike is 46 pj and 180 also.
 
latest update: everything has been cleaned and looks good. i flushed the bottom end with kerosene and drained it out the plug on the bottom.
cylinder looks good. just waiting on topend kit from gofasters.
i'll update after its back together... thanks again.
 
Check your carb and reeds. If it went lean and holed
the piston. It must have done it for a reason. (air leak?)
It would really suck to have it fry another one.
Jeff
 
top end "kit" showed up today. i gotta say im disappointed with what comes with the gasgas setup. no pv gaskets, no o rings for the pipe, and only 1 base gasket :mad:
maybe im spoiled by the jap kits that come with everything for 75.00 less.
so tomorrow i'll try to fab gaskets for the pv covers or wait another week for them to show up.
on the bright side a local shop is becoming a gasgas dealer next week. i know the owner and he will go out of his way to stock parts.
 
Dirt Addict: How far are you away from the LAX airport?
I am pretty sure I have spare gaskets for a full top end
rebuild. At least the three standard size base gaskets and
several powervalve gaskets.
If you need them this weekend. You can order
replacements for mine later.
PM me if you want to stop by and pick them up.
Jeff
 
well i made some pv gaskets from sheet gasket. seems to work fine. test rode it around the 'hood and it works.
rejetted to a 180mj and oem needle. doesnt feel near as lean as it had been.
i may do a technical / hill climbing ride tomorrow and put it to the test :eek: .
thanks again for everyones input.
 
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