Yz250 cylinder

Flit250
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Flit250
Edited Date/Time 9/1/2013 2:52pm
Hi there I ride a yamaha yz250 2008 model and it just recently popped.... I have had to buy a new barrel as it completely destroyed it, have any of you guys got any idea why this happens? I have done about 80 hours since the piston was changed and I had to split the engine to get all the pieces of cylinder and piston out so its got full new wisico crank and piston kit I'm also run this bike on a fmf goldseries fatty and fmf shorty power core 2 and I have been told this pipe set up burns bottom ends up getting to hot ect is this true...??? It's had regular oil changes every 2 rides filter cleaned every time all the right maintenance done so why dose this problem happen? Also can any recommend how much oil to put to 5ltrs I'm running mine on putoline mx5 and I've used it for years and using 150ml to 5ltr.
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Flit250
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Flit250 8/31/2013 2:27pm
8/31/2013 2:27pm


Ready for power valve to be reinstalled in to new cylinder.
Paw Paw 271
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Paw Paw 271 8/31/2013 4:02pm
8/31/2013 4:02pm
I would suggest that 80 hours is past the normal service time for that stock piston, but I would need to consult your service manual to be sure. Exceeding that limit will let the piston break due to piston slap.
pete24
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pete24 8/31/2013 4:11pm
8/31/2013 4:11pm
take that wiseco crank outta there and throw it in the trash oem crank or at least hot rods, that wiseco aint going to last 10 hrs, racing mx we do a top end on a 250 2stroke at 25-30 hrs you blew it up cuz you let it go to far
JT408
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JT408 8/31/2013 4:14pm
8/31/2013 4:14pm Edited Date/Time 8/31/2013 4:15pm
Bin the crank dude and 80hrs wow tempting fait.

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FGR01
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FGR01 8/31/2013 8:19pm
8/31/2013 8:19pm
Yeah, 80 hrs is too long for a stock cast aluminum piston. They are known to shatter when ran too long.

150ml oil in 5L of gas is a ratio of 33 to 1. Yamaha recommends 32:1 so you are good to go on oil amount.
Flit250
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Flit250 9/1/2013 2:24am
9/1/2013 2:24am
Thanks for your comments guys, are wisico really that bad? I thought wisico is a good make? The yam had hot rod a hot rod crank when it went and I was told theses where bad, looks like some one has been telling me a load of crap then.
Paw Paw 271
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Paw Paw 271 9/1/2013 5:37am
9/1/2013 5:37am
OEM cranks are the best, Hot Rods are second and Wesico are last. But with that said, all new cranks need to be checked before install to be sure they are running true and then installed correctly.
Flit250
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Flit250 9/1/2013 7:43am
9/1/2013 7:43am
Damm... I don't know if its best taking the new wiseco crank out then and installing it with oem parts what do think is best? Another question my top piece of the power valve has broken off but i have been told this is not a problem as it just stops the spring from popping out but even when you open the power valve fully its nowhere near popping out. What's your suggestions guys?
kijen
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kijen 9/1/2013 2:15pm
9/1/2013 2:15pm
Flit250 wrote:
Damm... I don't know if its best taking the new wiseco crank out then and installing it with oem parts what do think is best? Another...
Damm... I don't know if its best taking the new wiseco crank out then and installing it with oem parts what do think is best? Another question my top piece of the power valve has broken off but i have been told this is not a problem as it just stops the spring from popping out but even when you open the power valve fully its nowhere near popping out. What's your suggestions guys?
just a quick recommendation, go to thumpertalk.com, they have a very active YZ section, quite a few from your location too....

we run hot rods in both our YZ's, and weisco pistons...they are forged and won't shatter...mx 25/30 hours trail riding maybe 40....
lot oif guys run the powervalve with no problems when the tab breaks, just makes sure to get it out of of the PV assy so it does not jam anything...
Flit250
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Flit250 9/1/2013 2:39pm
9/1/2013 2:39pm
Flit250 wrote:
Damm... I don't know if its best taking the new wiseco crank out then and installing it with oem parts what do think is best? Another...
Damm... I don't know if its best taking the new wiseco crank out then and installing it with oem parts what do think is best? Another question my top piece of the power valve has broken off but i have been told this is not a problem as it just stops the spring from popping out but even when you open the power valve fully its nowhere near popping out. What's your suggestions guys?
kijen wrote:
just a quick recommendation, go to thumpertalk.com, they have a very active YZ section, quite a few from your location too.... we run hot rods in...
just a quick recommendation, go to thumpertalk.com, they have a very active YZ section, quite a few from your location too....

we run hot rods in both our YZ's, and weisco pistons...they are forged and won't shatter...mx 25/30 hours trail riding maybe 40....
lot oif guys run the powervalve with no problems when the tab breaks, just makes sure to get it out of of the PV assy so it does not jam anything...
Cheers kijen I will check it out, I have seen a lot of issues with power valve tabs braking off on mx forums but why does this happen if its under no stress what so ever why should it break...?
Flit250
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Flit250 9/1/2013 2:52pm
9/1/2013 2:52pm
The little beauty

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