05 Yz-125

My son mx races a 05 yz-125 we bought the bike with only about 5 hours on it froma friend . He had already installed vforce reeds.pc pipe and a 50 tooth rear sprocket.

We plan to race the bike again next season. I have been searching the site to get some setup tips.

We have already had Total Control redo the suspension

Engine wise : he dented the pc pipe so we installed the factory pipe back on he says the bike picked up bottom , lost alittle mid, but was more rideable. From what I have read on hear, the factory pipe seems the hot ticket with a aftermarket silencer? Correct??

I am afraid of the 144, is that logical. I have not found a post yet with any really real world results?? The athena kit looks really promising, but will it be an advantage for a novice/intermediate rider??

Race gas: we have been using 1 gallon of the sunoco 110 leaded race fuel with 4 gallons of 93 pump . Is this a waste ? All the fuel talk i found on this site goes alittle deeper than I care to follow! The bike is stock bore, does have weisco piston (which btw my son claims made the bike rev slower?)


I have heard many people raving about the athena 144 kit saying it gives a big change in low end. I do not have one so I cant say myself. I also agree that the silencer makes more of a difference than the pipe, i use the pc 304 shorty. You were right to have the first mod be suspension because suspension is clearly the the most important thing to be fast. As for the gas, I would save the money for the 110 octane and just buy 5 gallons of the 93 pump gas. I dont know about the weisco pistons making it rev slower.

You dont need an aftermarket silencer, but a pipe will help. The 144 kits are worth every penny. The bike will absolutely fly, be more rideable, and completely rip ass. With the kit, youll need to do top ends often and use race gas, so plan on spending much money. Suspension is number one in priority if it's stock, and if you're leaving it a 125cc theres absolutely no need for anything other than 93 octane, unless wasting money makes you feel good.

Oh by the way, a wiseco piston will not make the bike rev slower, but using race gas will make the bike rev slower.

thanks for the replys guys.

SO, you have to use race gas with the ATHENA? What would U guess the rebuilds at? 10hrs? 20? Would that be a ring or ring and piston. I have read that the 144 doesnt rev ect. ect. ect. I wish someone that has one and has mx raced it would chime in with their comments!

I had been thinking about the athena, but they are not legal in schoolboy class,plus we average about 6-8 hrs ride time a week(we have our own private track and access to several others) I would hate to have to rebuild every couple weeks! I could get over the schoolboy thing, but i dont a bike that is a nitemare! Thanks guys

Yeah, that is a real pain. The top end (piston and rings) will need to be replaced every 10 hours. So thats averaging you like $100 extra dollars a week on top of race gas, which is like $7 a gallon. The 144 is a real blast though, it doesnt rev as high but doesnt need to. If you are on a low... i mean Normal budget, i would stick with stock cyclinder, or maybe get another cylinder on ebay and have one cyclinder with the 144 kit and one stock cylinder, because that would be just awesome.

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