Mikey*DTR Posted July 1, 2008 Share Posted July 1, 2008 hi again! ok i really want to rebuild the top end of my yam dt125r but im slightly put off by the fact so far this bike has been a curse and something always happens with it . i have a few questions id be greatful if you could answer: 1. Ruff price of a rebore? 2.will yamaha sell over size pitsons/rings 3.ruffley how long will it take? 4.whats the worst that could happen lol 5. any tips or tricks that could save time or money? 6. before starting should i drain the cooling system from the waterpump? cheers all answers received will be a great help! Link to comment Share on other sites More sharing options...
Ryan09 Posted July 2, 2008 Share Posted July 2, 2008 hi again! ok i really want to rebuild the top end of my yam dt125r but im slightly put off by the fact so far this bike has been a curse and something always happens with it . i have a few questions id be greatful if you could answer: 1. Ruff price of a rebore? 2.will yamaha sell over size pitsons/rings 3.ruffley how long will it take? 4.whats the worst that could happen lol 5. any tips or tricks that could save time or money? 6. before starting should i drain the cooling system from the waterpump? cheers all answers received will be a great help! Rough price is about 120 - 150 quid yamaha... not sure bout over size parts, The worst that could happen hmmm put it like that anything might happen lol but its only a stroker so a straight off with old head on with new quite simple. Tips - dont rush or force anything and make sure you remember where all the nuts/bolts came from and keep your working area clean. Not sure about the pump but most people do disconnect the rad before doing engine rebuilds. hope that helped Link to comment Share on other sites More sharing options...
Mikey*DTR Posted July 2, 2008 Author Share Posted July 2, 2008 Rough price is about 120 - 150 quid yamaha... not sure bout over size parts, The worst that could happen hmmm put it like that anything might happen lol but its only a stroker so a straight off with old head on with new quite simple. Tips - dont rush or force anything and make sure you remember where all the nuts/bolts came from and keep your working area clean. Not sure about the pump but most people do disconnect the rad before doing engine rebuilds. hope that helped Cheers! Ryan09 thanks for the advice orite i didnt know yam do rebores thats good saves me hassle trying to find some where else to do it! other question i have is do i keep the powervalve in place as i dont really fantsy taking it out etc should i just disconnect the servo from the frame? thanks again im going to my local yamaha dealer after i get back from sunny spain Link to comment Share on other sites More sharing options...
mr benn Posted July 2, 2008 Share Posted July 2, 2008 the people that do the rebore will normally supply you with a piston kit, but get a small end bearing as well. I waited while mine was done - it took about 2 hours for 2 cylinders. you should remove the power valve to stop it getting full of swarf and debris. and drain the coolant at the pump before you start taking it all apart. you can get the bits from you Yam dealer but they'll be more expensive than your reborer. Just make sure you get a decent brand of piston - ART or Mitaka. I used a place in Waterloo or Crosby, Liverpool - just can't remember who it was! Link to comment Share on other sites More sharing options...
philnorth82 Posted July 3, 2008 Share Posted July 3, 2008 When do you know that you need a top end rebuild? What are the signs that you have no compression? I have recently bought a DTR that needs some attention and think that this may need doing. I was wanting to do this myself and want to know if there are any books/guides/videos out there to show me the process Thanks a lot!!! Link to comment Share on other sites More sharing options...
Mikey*DTR Posted July 3, 2008 Author Share Posted July 3, 2008 the people that do the rebore will normally supply you with a piston kit, but get a small end bearing as well. I waited while mine was done - it took about 2 hours for 2 cylinders. you should remove the power valve to stop it getting full of swarf and debris. and drain the coolant at the pump before you start taking it all apart. you can get the bits from you Yam dealer but they'll be more expensive than your reborer. Just make sure you get a decent brand of piston - ART or Mitaka. I used a place in Waterloo or Crosby, Liverpool - just can't remember who it was! great cheers mate im glad the rebore is quit a quick process theres me thinking il have to send if off for weeks! yer Yam are seriously ££££ where can i buy a art or mitaKA piston? cheers mate Link to comment Share on other sites More sharing options...
Mikey*DTR Posted July 3, 2008 Author Share Posted July 3, 2008 When do you know that you need a top end rebuild? What are the signs that you have no compression? I have recently bought a DTR that needs some attention and think that this may need doing. I was wanting to do this myself and want to know if there are any books/guides/videos out there to show me the process Thanks a lot!!! when you hear piston slap a light metalic noise when your bikes not under load rubbish running speed. you can find a guide in your haynes manual or type in top end rebuild on youtube theres none of dt's but there all pretty much the same. good luck Link to comment Share on other sites More sharing options...
Ryan09 Posted July 3, 2008 Share Posted July 3, 2008 Will you be doing this yourself or paying someone to do it??? Link to comment Share on other sites More sharing options...
Mikey*DTR Posted July 3, 2008 Author Share Posted July 3, 2008 Will you be doing this yourself or paying someone to do it??? what the rebore lol? il be rebuilding myself dont have machines or experence to rebore Link to comment Share on other sites More sharing options...
Ryan09 Posted July 3, 2008 Share Posted July 3, 2008 lol i ment the re build, always better to do it yourself in my eyes (if you know what your doing) plus i enjoy taking my bike apart lol and more money saving Link to comment Share on other sites More sharing options...
Gas up - Let's Go! Posted July 3, 2008 Share Posted July 3, 2008 Guys, Generally 125's are aimed at the 17+ learner market, if you are looking at a rebore, make sure it isn't going to push the CC capacity over the limit - when you're talking about a couple of thou out of the bore it won't make that much difference, but it's best to check. You can of course offset this by taking a skim of the head That said, I can't place the fuzz stripping your engine down to check You'd be best advised to get the same people who do the bore, to supply the rings and piston, that way any mismatches would be covered, especially as they will know how much they have taken off, as well the final diameter Link to comment Share on other sites More sharing options...
mr benn Posted July 3, 2008 Share Posted July 3, 2008 it will doubtless be 1st oversize ...... + 0.25mm Link to comment Share on other sites More sharing options...
Ryan09 Posted July 3, 2008 Share Posted July 3, 2008 To be honest that little bit of re bore wont do any difference in terms of power long as you dont bore it out to say a 150cc theres nothing to worry about. Link to comment Share on other sites More sharing options...
Mikey*DTR Posted July 11, 2008 Author Share Posted July 11, 2008 lol i ment the re build, always better to do it yourself in my eyes (if you know what your doing) plus i enjoy taking my bike apart lol and more money saving ohh yer il be rebuilding it myself i couldnt let some one else enjoy it could i? lol Link to comment Share on other sites More sharing options...
yoda Posted July 11, 2008 Share Posted July 11, 2008 How do you know that you need a rebore? I know how to tell and what to do. You might only need a new set of piston rings. Consult someone who knows. Link to comment Share on other sites More sharing options...
racerd Posted September 18, 2008 Share Posted September 18, 2008 when you get a rebore done if you go more than 0.50mm over size piston kit then you need to re profile the power valve spool also to find out when you need a rebore you have to measure the cylinder bore and measure the piston diameter and this will let you know the running clearance and if the running clearance is to much then time for a rebore and the same if the bore has scores in Link to comment Share on other sites More sharing options...
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