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ahaywood93

yamaha dt 125 strip down and engine rebuild

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ive removed the engine and have taken all i can at the moment the clutch and some primary parts are removed going to use my local shops air wrench to remove the transmission side and fly wheel as mine wrench is broke (knowing the shop owners a plus) im installing a new crank, ebc race clutch kit and the athena 170cc kit i will upload pics of stages so anyone else wanting to split there engine has a rough idea im just going by memory on here never had a dt engine open before looks simple enough though. im quite surprised the inside of the engine looks as if its new!

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this is what i emptied out of my exhaust not a nice sight

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nice con rod there must of been pretty old...

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casing looks new you wouldnt believe its a 2004 engine

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removing the clutch was really easy you need a 8mm for the springs then the front plate just pops off with a flat head and you remove the clutch inner plates just by pulling them out, i used a clutch/flywheel holder tool to hold the clutch in place while i got a wrench on the bolt you can just use a air wrench or electric, be careful as there will be some sneaky washers there!

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with the clutch removed i took apart what i could i will be taking the other cogs off tomorrow and splitting the engine new crank should be installed wednesday (thursday latest)

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few compartments i removed in my storage box the kick start drive, springs, part of the gear selector, front sprocket, clutch leaver part, and flywheel and clutch bolts + few other little things.

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engine so far

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frame without engine or forks (there at the shop getting new seals and oil) cost £30

i removed my 2 stroke tank and other things just for cleaning purposes they had so much old oil over them

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i will be adding more pics tomorrow or the day after

my athena 170 kit has came and looks great

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just waiting on the crank and bearings now

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thanks im just waiting for the bearings now then i can put my crank in then ill fit the 170 kit its all coming together nicely now ive been pushbiking it 45 mins every day to work so i cant wait to back on road haha

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Looking good there!!

Wish I had the time to sort mine, its at work in the yard given up the ghost unfortunately and my baby girl is not verywell so baby takes priority.

Ken

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If you think your 9 year old engine looks clean.inside, you wanna check the 35 year old castings on my DT! Unbelievable when you compare it to an old English bike! Keep up the good work!

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Thanks just waiting for my bearings to come and it can all go back together cant wait to ride it with the 170 kit on been a week off road so far

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nice project...any other problems encountered along the way? got me a spare engine i'm gonna attempt to rebuild. i have the bearings,seal,gaskets,conrod kit-rebored barrel and piston kit- think i need to get motivated lol

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thanks, not really these engines are so easy to work with and are engineered so well i ordered last week bearings, ebc racing clutch kit, oem clutch cable, athena 170cc top end, a crank from a 2008 dt 125 ( looks nearly new), complete engine gasket set and oil seals, oils and a few other little bits should beable to rebuild tuesday as im working tomorrow when the parts should come.

one thing though the pivot bolt that holds the swing arm and engine in is the worst part of the hole process i recommend a heat gun/ blow torch and hitting it with the hammer a lot, my one was proper stuck in there but i think this happens on loads of bikes as my mates yz125 had the same problem

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The reaon why swing arm piviot bolts are so hard to get out is cause nobody services them untill they need to remove the eng,when it should be part of a yearly service. I can push mine out without fuss. And this to your yearly service and you will never have a problem again.

Not so sure about putting a 170 on a used crank alot of $$$ to find out the crank is weak,good luck I realy hope all works out for you and will keep watching.

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yeah im guessing the person who had the bike before me didn't like servicing it ive ordered some grease so next time it will be easy :) and do you recon i should send it athena to replace the conrod and bearing (still would be 50% cheaper than a oem crank shaft)

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well as the rod and bearing is the weak part of the crank might be worth it,What I would be woried about is the fact that the crank has been shipped and possibly droped/thrown about and not 100% true, considering the way to true a crank is to hit it with a hammer and squeeze it with a clamp or force it open with a wedge. I would want a trued and welded crank. Eyons ago I twisted a crank just by drag racing the bike ever since I have every crank welded and never had that happen again

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I have no Idea what welders charge your way,but you want someone who knows there way around a tig welder to do it.Maybe athena offer that service. trick is to weld it without taking it out of true the heat from welding it can send the whole thing out of wack.

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top end kit fully assembled and ready to be fitted crank is ready to go in as well my bearings was dispatched last week so ill be expecting them today and i will be fitting them tomorrow just a few pics for a update and pics of my pv to show if it is correctly set up at the start position, i was wondering should i put the air restrictor back on to run the engine in or would it need the amount of air to compensate for the 170 top end.

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I want to know what the Athena goes like.

Would it give enough hp to go up a tooth on the front sprocket and still be able to pull in 6th...

Coming on well up to now

Ken

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Ken the same kit on a tdr125 was able to sit with me and blackhat250 at over 90.

Private road of course....

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