DT125R ARCHIVE

polsta · DTR Senior Member

F**K F**K F**K whats happened ?

Seiki · Admin

ya piston has spat its rings m8 the engine is ceased time for a rebuild im afraid blankstare

Gixergav · DTR Senior Member

Sounds like engine seizure mate.Hope you haven't been ragging to much at 10000 rpm cos thats what happens.What two stroke oil do you use.Have you ever checked the settings on the oil pump.Was there enough coolant in it?Gearbox oil? Was mixture screw set at 1 1/2 turns out.How many miles on the bike and when was the piston last changed?
The solution is a rebore with fresh piston kit if your lucky.If its your bad day and its damaged the bottom end then its more hassle.Its fixable but how confident are you in rebuilding an engine.

polsta · DTR Senior Member

right, the last few days ive done everything on it, tyre pressure ,the oil was topped up, its a shell semi synthetic half decent one , topped the coolant up and ive just checked and tightened everything and the cables etc, a full maintinence on it basicly, rubbed down and re painted the exhaust, claned up the plug, gave the bike a full proper clean and polish, then put the exahust n brand new blue leather seat cover on , took it round my mates n did the chain

and i thought yes the bikes all sorted now basicly !!

took it out for a ride as it hasnt had a nice run out all week and ive been doing all this

although today it did seem to take a few kicks to start i

the bike was flying, didnt have the splutter i was on about the other day when it got to about 9.5

then that happened !!

, anyway ,ive just been out there having a look, tried clicking through the gears and moving it,and managed to unlock it somehow and free the kickstart

it will now kick , and i started it once, although it didnt sound healtly at all , sort of worked but sounded rickety funny clacky

by the looks of it its just the piston ?

i think maybe where i recently did the power valve n that new cdi and its been boosing , maybe for the 1st time ever ?? then thats finished off the pistion, also ive done maybe comming up for 2000 miles on it since i had it, and hed only done 400 in the year before i bought it

, can i just by a new piston ? or do i need the whole pistion and barrel kit and all that ?

any advice on what i probably need and what makes best or place to buy from etc and best way to go about things ??

as ive got every mot certificate and reciepts for everything ever spent and all work done, im just gonna have a look when it was last done

polsta · DTR Senior Member

would it be just a piston kit like this for £30 from wemoto ? would that be fine ?

or theres these on ebay would they be better or the same ?

http://cgi.ebay.co.uk/Yamaha-DT-125R-MITAKA-piston-kit-standard-size_W0QQitemZ280229198155QQcmdZViewItem?hash=item280229198155&_trkparms=72%3A985|39%3A1|66%3A2|65%3A12|240%3A1318&_trksid=p3286.c0.m14&timeout=1219012148318

also...is it easy for me to take my piston out n check/see the state of it all, and find out what size mine is etc ??

-- Edited by polsta at 23:33, 2008-08-17

polsta · DTR Senior Member

just looked through all the paperwork , the piston and small end bearings where done 2 years ago

so a fair while ago and ive done a lot of riding on it, and where i had the big one exhaust on it for the last couple of months, was revving quite hard

Gixergav · DTR Senior Member

Because the bike has been making more power a weak spot in the engine has failed due to the extra stress.It sounds as though it was time for a fresh piston.It has heat seized i think because you've managed to free it off.Don't run the engine anymore!

You will deffo need a rebore but it has no clever platings like a kawasaki so it should only cost 15-20 quid for this.The MITAKA pistons are very good quality and i have had very good results with these in yamahas.I used them in highly tuned bikes and they are very well engineered.DONT use cheapo pistons,say 35 quid and under cos they dont last and they have a habit of losing the piston ring pins at high rpm.Not good!

Your also going to need a full top end gasket set.Pattern parts are good quality so expect to pay around 20 quid for gaskets

When you take your piston out it will have a number stamped on the top if its been rebored before.Rebore sizes go up in 0.25 mm increments.So say you have a 0.75mm piston you are going to need a 1mm piston after the rebore.Thats to say if you haven't badly scored your barrel that it needs more than one rebore!

Most bike shops will undertake the work but they will send the barrel off to a specialist machinist to do the work.Tell them to order you a piston to match and gaskets and the whole thing isn't really a major issue.I'd budget around 80-100 quid all in.Thats if your prepared to do the work yourself.

Check the crank too.Make sure the con rod has no up and down play and that the side to side play in within the tolerance set in the manual.Also take the left plastic side casing off and try and pull the flywheel up and down.There should be no free play.If there is then its engine out and a complete strip to replace the crank bearings.

I know running a fresh motor in for 500 miles is a ballache but just grit your teeth and do it right.If it isn't run in correctly then the piston,rings and bore will not wear and 'polish' themselves in correctly.Result: The top end will blow again or at best you can be down on power as much as 20%

polsta · DTR Senior Member

nice one mate, think ive got all that !

been busy all day so not had a chance to get at it , but im on it in the morning , i rang a local place today, who said get the top end apart and take the barrel and piston in and theyl tell me what the crack is , which is handy , a rebore is £15 they said , if they can match or better the lowest ebay or web price for a mitaka and order me one in il go with them ,if not il gett hem to send the barrel of and tell me what size il need and order one in

ive got some mates who can help out with the putting it all in anyway, as i wouldnt feel confident doing all that myself incase i dont do it right !

il post up as soon as i have got it all off and had a look at it tomorrow

, like you say it was last done a fair while and miles ago anyway and i think the extra power in the last week or so has finished it off, thats probably whay i had a couple of probs with it anyway coz the piston was on its last legs !

look forward to getting it done and all good to go, 500 miles aint so bad, il just have to wizz round a lot localy taking it easy n clock up the miles, what revs do i keep it under then etc ?

hopefully after its done and run it it will be flying and all be good for a long while

thanks mate, appriciatwe you taking the time to help !

thinking about it...what gaskets do i need for the top end ? there are some gaskets in my spares that the fella i got the bike off gave me, but ive never looked at them

polsta · DTR Senior Member

right ive got it all off , the piston hadnt blown, was worn and needed renewing anyway, but i took the head to a local palce he said its not too bad, could do witha rebore and a new piston kit but thats not whats done it

he told me to get home and hold the con rod bit and see if theres any play...and there is , it moves round smoothly with no noise , but had a cm or so of play in it up n down

...rang him up, he said its hard to tell without getting it all apart to see the expent of it all n see if the webs something are worn or ok, and could be £400 odd to sort it all

im ****ing gutted n not sure what to do

((((

Gixergav · DTR Senior Member

You have got to take the engine out i'm afraid and its got to have the crankcases split to get the crank out.This is a total engine rebuild.It does have the advantage that you can replace all the bearings and seals and if done correctly you will have a 'brand new' engine.The crank will need to be put in a press to get the big end bearing changed so is again a specialist job but most bike shops will undertake the work.
Or you could get another second hand engine and use that.The trouble is unless you can see/hear it running you could be buying a dog.Getting one from a reputable breaker will minimise the risk but at greater cost.
If you can undertake the rebuild yourself then your gonna be looking at another 200 quid for the crank work,all new bearings and seals.
Personally i would shop around for a couple of days on ebay and around breakers to see what complete engines are available at what price.Like i said i would budget around 300 quid for parts and services to completey rebuild yours if you do the work yourself.You should find a cracking engine for less than that.Also most breakers will give a 28 day warranty on engines.After that you can sell the useable parts from your old engine ( clutch,oil pump,casings etc to recoup some cash.
The choice is yours!

polsta · DTR Senior Member

im totaly gutted mate, i aint got the wonga to get all that done really on the downside , £400 is a lot of cash , on the upside a nice new engine would be lush , he said its £120 odd in vat id be paying

i cant do that work myself, as ive not got a clue, i wasnt even gonna put the top end all back together and in myself

only other option is if i can get someone to help even maybe with cheap on the side cash in hand labour, one mate ive just spoke to who i thought could,said its a big job thats gotta be done perfectly, and he wouldnt even do that himself on his own bike

im sick as a pig

a second hand engine is probably the way i have to go...if i can find one for reasonable cash ?

i really dont know what to do, cash is a problem, im totaly gutted

im gutted coz my bikes realy clean and lush condition, even all the engine is all spotless, a full rebuild would be nice, but £400 is a f**ker !!

polsta · DTR Senior Member

no engines on ebay ? anyone know any breakers where i could possibly find one or any other possible sources ???

i cant believe it really

Gixergav · DTR Senior Member

Try these http
://cgi.ebay.co.uk/DT125-DT-125-DTR-125-DT-125R-DT125R-GOOD-RUNNING-ENGINE_W0QQitemZ170242041949QQcmdZViewItem?hash=item170242041949&_trkparms=72%3A12%7C39%3A1%7C66%3A2%7C65%3A12%7C240%3A1318&_trksid=p3286.c0.m14

http://cgi.ebay.co.uk/yamaha-dtr125-dtr-125-dt125r-complete-engine_W0QQitemZ200240752757QQcmdZViewItem?hash=item200240752757&_trkparms=72%3A12%7C39%3A1%7C66%3A2%7C65%3A12%7C240%3A1318&_trksid=p3286.c0.m14

http://cgi.ebay.co.uk/2003-YAMAHA-DTR125-DTR-125-Good-Running-Engine_W0QQitemZ190239269000QQcmdZViewItem?hash=item190239269000&_trkparms=72%3A12%7C39%3A1%7C66%3A2%7C65%3A12%7C240%3A1318&_trksid=p3286.c0.m14

http://cgi.ebay.co.uk/2004-YAMAHA-DTR125-DTR-125-Good-Running-Engine_W0QQitemZ190239269118QQcmdZViewItem?hash=item190239269118&_trkparms=72%3A12%7C39%3A1%7C66%3A2%7C65%3A12%7C240%3A1318&_trksid=p3286.c0.m14

http://cgi.ebay.co.uk/1997-YAMAHA-DTR125-DTR-125-Engine-Motor_W0QQitemZ200241368366QQcmdZViewItem?hash=item200241368366&_trkparms=72%3A12%7C39%3A1%7C66%3A2%7C65%3A12%7C240%3A1318&_trksid=p3286.c0.m14

polsta · DTR Senior Member

a lot of money still

, and no guarntee it wont go wrong in a few months, my engine was sweet when i got the bike, cosmeticly still looks better than all of them

with postage they are £300-380 anyway , is it really worth spending £300 on an engine that could blow up in a few months, or top end ? you have no idea when the piston was last done etc, and how it was rode

if your gonna pay £300 for an engine that you dont know and has only been road tested and said to be ok, your better off paying the extra to do a full rebuild on mine and know its brand new and solid for a couple of years ?

£150 or sommin it could possibly be worth a gamble, not £300

im gutted

polsta · DTR Senior Member

even this the cheapest at £270 delivered...looks a bit f**ked, and is from a stolen recovered bike...probably been ragged to death ,imagine if i spent £270 on that rather than £400 odd to sort mine,and that blew up in a few months or less , id be sick

Gixergav · DTR Senior Member

I agree.Try to find a breakers that has one and is prepared to offer a warranty.I would fully rebuild the motor you have but the problem is that you can't do it yourself so your gonna get shafted on labour charges.If you can do it yourself you also have the satisfaction that the engine is spot on and that someone who doesn't really care has built it.Shop around on the internet for engine rebuild services.A yamaha 2 stroke specialist will be cheaper than a main dealer for instance.

And dont worry about it.I also have blown plenty of engines especially at the track but they are always (usually!)fixable.A good bit of advice would be to buy a shagged engine dirt cheap and use it to practice stripping and rebuilding.It doesn't matter if you get it wrong first time.Confidence comes from experience and i had to start somewhere.

polsta · DTR Senior Member

yeah thanks mate , ideally i want to get mine fully rebuilt, so then i know whats what and that its good to go and will be a nice engine

what i was thinking...would it be wise or unwise, if i gotta re build the bottom and top end and get the barrel re bored and a new piston....if i got it bored out to a 175 and put a 175 piston kit in ?

would that make it unreliable and harsh on the bottom end ?

was speaking to a mate tonight, who has a gixer funnily enough, and has always dabled with bikes n cars, he said it wouldnt be wise to do on an old bottom end, but if your rebuilding the whole engine that would probably be ok but to seek a professional oppinion, what do you reckon ? would it be viable and have the same reliability as if i just re done it as a 125 and last as long or not ?

, he also said, hes never re built a bottom end on a 125, but hes done all sorts with big cosworth engines when he had a cossie n that, and can do most other stuff, and thinks he might be able to do it,so hes gonna come round hopefully tomorrow n have a look, but hes not sure about the gear box etc , would i have to do that too or not or can that be avoided touching when doing a bottom end ?

what i need to do is get it apart n have a good look at exactly the damage and what needs doing and price up all parts needed , theres another mate i thought of earlier who might be able to help, him and his dad are bike crazy and had them donkeys years ,il see whta they have to say !

cheer mate !

darkangel · DTR Respected Member

If there is a few mm's of side to side play on the conrod thats fine, but if there is any up or down then the bottom end definately needs a rebuild.
You cant bore the standard barrel out to a 175, its too small. you need to buy a big bore kit and stick it on, it would likely lessen the life of the bottom end but not by much.

polsta · DTR Senior Member

ok mate cheers, there is up n down play on it

so its a bottom end re build

im just trying to see if i can source someone to help me with the labour for free

pj`s have quoted me £215 for ...the crank rebuild and a new conrod all done n ready, a rebore n new mikita piston kit, all the gaskets,seals,brearings etc so its all ready to go

then i get someone to take the engine apart...send the bits off,get them back then re build it

, found 1 local mechanic bloke whos quoted me £150 to do that, or about £350 all in if he sorted the work n parts too

theres a crankshaft with conrod all good nick on ebay for £35 inc delivery,thought about maybe buying that, but is it worth doing that over getting mine re built ?

£200 is more than i cna do at the moment really, but thats looking like the only option,if i can sort out someone to help me with labour

on the upside...the engine will be like new after its all done and will last , providing the gearbox etc is all good,which i think it is

Seiki · Admin

where abouts in the country are you m8 i may be able to get someone who can help you

polsta · DTR Senior Member

in in hampshire in the portsmouth area !

Seiki · Admin

[spoiler]i run 2 bike sites myself
http://ukstreetfighters.noonhost.com/
http://ratfightersmcc.noonhost.com/

weve got lads all over the country so i will ask if we got a mechanic anywhere near you who can help out
no promises but i will try for ya biggrin

polsta · DTR Senior Member

ok mate cheers , nice one

AAAthreat · DTR Senior Member

I hope you get your bike fixed mate and you don't have to pay a fortune to get it back together.

polsta · DTR Senior Member

ive got 2 mates who can help me out with labour, tomorrow were gonna get the bottom end out and take it to my mates garage and open it up n see exactly whats what and then get the best price for parts

think i need...

mika piston kit

full gasket set

con rod kit (if i have to put a new one on ?)

main and other bearings

seals (anyone know excalty what il need ?)

a rebore of the barrel

the crankshaft re built

, then a full rebuild of the engine !!

im gutted really, but at least im saving on labour,il learn a lot about engines along the way and know my bike inside an out ,and it will be a luch engine once done and will last a long time and hopefully be faster than it ever has once run in !

AAAthreat · DTR Senior Member

Good man looking on the positive plus you will have a nearly new bike when its done :) and when you go to sell you can say it has had a full engine rebuild.

Gixergav · DTR Senior Member

Once you've done one engine rebuild you won't sweat over doing another one.I know that a cheap crank from ebay sounds tempting but dont bother.Put all new parts in the motor while its in bits.Theres gonna be nothing worse than the crank going again 3 months after you've rebuilt it.
The gearbox will be exposed when you split the cases but it should all stay attached to the casing and not come loose.Theres no need to take it out unless your replacing the bearings they run on.Definite bearings to replace are the two main bearings the crankshaft runs on and the oil seals that sit behind them.

mika piston kit

full gasket set

con rod kit (if i have to put a new one on ?)

main and other bearings

seals (anyone know excalty what il need ?)

a rebore of the barrel

the crankshaft re built

, then a full rebuild of the engine !!

That list has covered everything you need.You should be ok to commence.If theres any troubles let us know and i'll help

And yes you can bore a dt barrel out to 175.This involves a lot of machining and a new liner to be pressed into the barrel.However the water jacket becomes thin and only a couple of rebores are available so its best not to use it for the road.Dt crank and clutch are strong and can handle the extra power.I had a RD125LC bored to 175 using a skirted DT175MX piston.It gives a much stronger,broader powerband but can take a lot of time to sort the jetting and exhaust flow right.This was a well trick motor and it made a genuine 118mph.

polsta · DTR Senior Member

nice one mate cheers

hopefully gonna get it out this arvo and see what the damage is, il take some pics up and post

found a place today thats local that can do the rebore and crank without sending it off, so that saves a bit in time and postage costs, and heard they are good too and been recomended, so thats a bonus

any idea of the cheapest/best place to buy the parts from ?

when it comes to the seals....what do i need exactly ? as ive not got a clue ?

, i think il give the 175 a miss then , as i want to use on the road, a lot !!

Gixergav · DTR Senior Member

Use genuine Yamaha bearings and seals.You will need crank bearings and crank oil seals.Please use the genuine stuff.I know they are more expensive but this is a job you dont want to do often.Your local bike shop should be able to order them for you.

polsta · DTR Senior Member

ok mate, any idea of what price im looking at for the lot ?

-- Edited by polsta at 15:16, 2008-08-22