doh. 11 year old piston gives up the ghost.

stainlesscycle

stainlesscycle

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zipping along on some single track today for about half an hour and bike just stopped. i thought it was a holed piston - i've had one hole before and it seemed just like it.. pulled plug and it sure looked like it. half white/half black plug.

but i finally got it home, tore it apart, etc...(after a quick 3 hr trip to smith's powersports to pickup a new piston - in stock! thanks!)

and this is what i found. looks lean, but also looks like something else happened - any guesses??

my cylinder is gouged too. guess i gotta send it out. anyone have a decent 200 cylinder laying around??

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Yes....looks lean?? wrist pin looks dry? what does the head look like? Sparkplug in tact? What about the reeds? Are you missing any screws from your crank stuffers? Something rattled around in there!

Good Luck!

Rick
 
It's the piston ring giving up. on pic.3 you can see the end of the ring bend up, and there is a big piece of the ring missing.
I've seen this a lot of times, when you don't change the rings for too long the metal get's tired and finally give up, you can run with the same piston for a very long time if you just change the rings in time.
 
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Rick said:
Yes....looks lean?? wrist pin looks dry? what does the head look like? Sparkplug in tact? What about the reeds? Are you missing any screws from your crank stuffers? Something rattled around in there!

Good Luck!

Rick
Click to expand...

head looks surprisingly good. plug looked bad...

i think it was lean and the ring gave up. oh well. now i get to split 2 300 motors today, make one good one from the 2, pull the 200 motor, and jam the 300 motor in. then jet and tune. all by saturday night. fun.
 
stainlesscycle said:
yeah, it sure looks like ring died. i replaced rings last year.
Click to expand...

I'm new to gasgas, and I was wondering how often do you need to replace the piston And/or rings. On the mx bikes i owned before I changed rings for every 20-30 hours and the piston when it's out of spec. or looked bad.
Is it too often for the gasgas? when i bought my ec250 the counter said 48 hours, and i was thinking to do the top end soon, but the bike runs really good and don't seem to have lost comp. how often do you guy's do a top end?:confused:
 
in general, i change rings once a year also. when you're in there you can look at piston and see if it's still good. mine lasted a long long long time...


anyways, 2 motors split, 1 good motor made of the 2, now to pull old motor and put new motor in. 4 hours so far. not bad time wise...
 
How often you replace really depends on how you ride. If you are wringing the neck out of it, you want to do it more often. If you ride low in the rpm and occaisionally wind it up, then you can lengthen that out. I probably push it a little too far, but I rarely wring it out. I run 50:1 as recommend by GG and use good fuel.

For example, I used to road race a Honda RS250 grand prix bike. The manual called for new rings every 50 miles and pistons every 100 miles, a new crank (they were not rebuildable) every 250 miles. But that was a bike that ran between 12,000 and 15,000 rpm for extended periods of time. BTW, the HRC manual for the grand prix bikes is the best manual I have ever seen or used. Wished others would give you one like that.
 
stainlesscycle said:
in general, i change rings once a year also. when you're in there you can look at piston and see if it's still good. mine lasted a long long long time...


anyways, 2 motors split, 1 good motor made of the 2, now to pull old motor and put new motor in. 4 hours so far. not bad time wise...
Click to expand...

Wow that's fast.. did the 300 fit right in the 200 frame?

Thanks for the answers I think I'll give it some time before i do the top end on mine, the mx bikes used to get ringed the heck out off, but I like more the slow crawling things now.
 
i am putting the 300 into the 200 frame right now. taking a break for a second, the dang swingarm/linkage/rear mount is always a battle to line up. hardest part of the whole bike to deal with. also one of my linkage bearings is toast. i'm assuming there's a crossover - gotta look it up in a bit.
 
dang. filled radiator and had a leak at the base gasket. had to tear it back apart and redo it. that's enough for me today. it's all together i'm outta amsoil, so no starting it till tomorrow. that's a logn long day, but now i know i can completely tear down/split cases/rebuild motor/reinstall in about 10 hours.

i jetted it this way, hope it's close. i only have about 6 hours tomorrow to get it running/tune it.
38mm pwk
#7 slide
45 pilot
178 main
ddk needle #3

with
messico pipe, 9oz fww, 2k2, ec200 cdi. 13/52 gearing.

should be interesting. will only get a few minutes to ride it today before i go 2 hours on it. gotta learn to stay up a gear - since i'm switching from a revvy 200 to a torquey 300..
 
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