Question for you all, l sent my son is cylinder off to have it re-plated.about a weak ago..l called today and they wo not be able to get to it for another 10 days..(backed up) but'' they have a 134 cylinder there ready to go for only 20 bucks more after core rebate..sounds good to me...Question is> what do you think the HP gain will be...The yz 125 stock has 33 hp....

l think that for the money it`s a great by and the extra hp and cc`s sounds lie it`ll hall after. l woul do i

im voting u do it cuz its a great buy and you will end up with better HP

l personally own 2 yz series bikes yz-426 & my son has a yz 125 there already bored out for full HP so u wont see a huge gain if u where to get a 450 4 stroke & bore the cylinder then that is when u get into the big HP, but either way ur wasting Your money & ur time yz-125 they go like snot already why would u want it faster ., the best upgrades would be better fuel & better oil get a light weight crankcase & tranny this will give u allot more torque & a big difference . but for getting it re plated why not just buy all new?????? & a 134 would suck in that bike!