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Glavas

dirt bike engine rebuilding

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So I've been looking at getting a dirt bike. Rebuilt bikes go for a mint, where as you can ones that haven't been rebuilt ( or not recently) for less.

 

Currently looking at either a 125CC 2 stroke or a 250CC 4 stroke.

 

Really just want to know what the cost is to rebuild a 125CC YZ125 engine. Complete rebuild.

 

Surely someone has paid to rebuild them :D

 

Alternatively, I could do it myself, but I've already got a car on the go, with another car coming soon and really can't find the spare time!

 

Cheers

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Rebuilding motorbikes is a very very basic thing, especially in the 125 2strokes which is pretty common for needing rebuild.

 

Piston & Ring kits are cheap, i would atleast try giving google a shot as you may be conifdent enough to DIY.

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and youtube..think there was a 250 basic topend rebuild..not the hardest thing to do..get a manual or join a specific forum post a will pay for rebuild thread if your slack and cashed up

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my mate got a yz125 for free, the bores only needed to be re-sleeved, cost him $350 all up to do, its a fun bike thats for sure. But its only good to learn on, it was my first time on the dirt with a motorbike and I was sitting on powerband, while just wearing a helmet. Im tempted to have a try on my mates 450cc yamaha :P

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I race motocross and have a 125 and 250 2 stroke

 

If your going to get anything as a fun bike get a 2 stroke, there fun and cheap. Four strokes are good for racing but cost a bucket load to fix, ( cost me a $1000 to do the top end on my old 250 fourstroke and like with cars there special tools and things.)

 

a top end on a 125 ( every 25 - 30 hours of flat out racing) costs roughly $350.

 

Motocross is a bit different to cars in that generally you only fix something when its broken, because it quick to fix and a broken part generally wont damage other parts ( on a 2 stroke anyway). So you wouldnt do a full rebuild on the engine, you would wait to something break or get low on compression and then pull apart the engine and replace anything worn. It did cost roughly $600 to pull apart the 125 and replace one of the gears that was slipping.

 

And dont listen to people who think they need a biker faster bike to go faster, dirt bikes are 70% rider 20% suspension and lucky to be 10% engine.

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I race motocross and have a 125 and 250 2 stroke

 

If your going to get anything as a fun bike get a 2 stroke, there fun and cheap. Four strokes are good for racing but cost a bucket load to fix, ( cost me a $1000 to do the top end on my old 250 fourstroke and like with cars there special tools and things.)

 

a top end on a 125 ( every 25 - 30 hours of flat out racing) costs roughly $350.

 

Motocross is a bit different to cars in that generally you only fix something when its broken, because it quick to fix and a broken part generally wont damage other parts ( on a 2 stroke anyway). So you wouldnt do a full rebuild on the engine, you would wait to something break or get low on compression and then pull apart the engine and replace anything worn. It did cost roughly $600 to pull apart the 125 and replace one of the gears that was slipping.

 

And dont listen to people who think they need a biker faster bike to go faster, dirt bikes are 70% rider 20% suspension and lucky to be 10% engine.

Thanks for the information :)

 

 

 

 

 

I'm an apprentice mechanic by trade, but i work 70 hour weeks, so it's hard to find the time to do it. The bike in question requires a replacement piston. I'm buying it more for a fun thing than anything else.

 

I really wanna get jumping, on the weekend I rode a WR450F, which is an amazingly fast bike but it's very heavy. I figured a 125 would be much lighter :D

 

Plus i'd have to tow the thing around too.

 

Cheers!

 

 

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Replacing the piston should be easy

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My brother managed to do this to his 125 on the weekend, make sure you rebuild it with a wiseco piston, this was a moto x or something along those lines and it only did 10 hours

 

But my brother and dad had stripped it down to here before my next practise session came up so only took about 20 minutes. It only takes them a little over an hour to do a piston and ring, but for your first time allow 2 hours.

 

125 is alot lighter than a 450, especially a wr450, it feels like your riding an angry bee lol

 

Although people love the power of the 450's they actually stop people getting faster, because there so heavy and touchee in the power you cant be aggressive, the 125 is so light and ya got to rev its tits off to get it to go, so ya not afraid of it and push it harder

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what about 250cc 2stroke, would thats cost/ take the same amount of time as the 125

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