DT125R ARCHIVE

sebamax2 · Guru

RE: now a non runner

madrevs · DTR Senior Member

Might be the better way it just strange how it still rode 5 miles home

MDK · DTR Legend

barrel may be fine just the rings that have worn down and with metal expanding or shrinking will or would seem ok hot rings cooled down head ..

not gona know till you take topend off fact is its not running and no sign of it starting so it has to be done .
I know if cash is short this is worrying just in case you take it off and all is fine then turns out to be something else but better safe than sorry something went wrong so you need to find out what now rather than later .

MDK · DTR Legend

madrevs wrote:
Might be the better way it just strange how it still rode 5 miles home

you lucky then lol . I have had many bikes that start great ride fine then die miles away from home bloody kills pushing the fckers home wilst trying to hide your face in shame with all the bike hateimng car drivers having a lol as they drive past .

sebamax2 · Guru

hey i had my aprilia mx die on me when a circlip from he piston jumped out and scored the **** out of the piston and barrel. but still took me down the road untill it died completly :) but yes your best bet is to go ahead and pop the barrel off. need some instructions let us know we will guide you

madrevs · DTR Senior Member

Ok thankyou will be stripping it down soon hopefulpy it will only be the top end thats gone.

madrevs · DTR Senior Member

Have managed to have a look up exhaust port amd everything seems to look ok although I coupdnt really see alot however I did have a look ovrr again and have noticed that the spark from the spark plug is a orange colour and a friend has told me a strong spark is meant to be blue.is this right and what could cause this.would it be the magneto or does that just charge the battery

NEV · Guru

Could be a dodgy coil/HT lead that, bout £12-£15 for a new one

madrevs · DTR Senior Member

Well the lead does look pretty okd and did get a bit of a shock while holding the cap through the insulation not enough to hurt just a bit of a tingle

madrevs · DTR Senior Member

Will take back previous post had another look up exhaust with a bright torch this time and this is what I found hopefully it hasnt damaged the cylinder too much have ordered a replacement coil anyway as old one is rough

yamahayz125 · DTR Senior Member

defo need a rebore if you drove 5 mile that ring would of caused rapid wear to the exhaust port done it myself a few times

madrevs · DTR Senior Member

Am gonna see if I get time to whip it off tomorrow but am expecting the worst with the barrel.my main worry is whats happened to the pieces of metal that have broke off.a bottom end rebuild is way out of my budget at the minute

yamahayz125 · DTR Senior Member

noting would of got past that 2nd ring bud all of it would of went out the exhaust port but you could just flush the bottom end out

madrevs · DTR Senior Member

Didnt think of it like that how would I go about flushing the crank out though

madrevs · DTR Senior Member

And if the ring goes like that is it just one of those things or is there a underlying problem.dont want to rebuild it and same thing happens 100 miles down the road

yamahayz125 · DTR Senior Member

use paraffin to fush out the bottem end heres a link of another member on here doing it http://dt125r.activeboard.com/t51316720/slobs-dt-125-x-2005-restoration-project-pic-heavy/?page=2&sort=oldestFirst as for your piston it could of been many a things best bet is to strip it down and take pictures so some 1 can have a good look and let you know

madrevs · DTR Senior Member

Thankyou will do

madrevs · DTR Senior Member

Top end of bike is now stripped out the ring has damaged the exhaust port quite badly.
is there anyway of getting this repaired
also is there meant to be any side to side play on the conrod as theres movement on this one.
thanks

dread123 · Moderator

its up and down play you dont want in the crank pal. always going to have side play :p rebore for the barrel and new piston kit is whats needed as well as flushing bottom end..likely that bits gone out through exhaust thn anything :p

easy job anyways to get back on road-also making sure you have ground the powervalve back when rebored so that doesnt hit the valve and do same damage

yamahayz125 · DTR Senior Member

+1 on what dread said but you might have to get a new barrel depends on how much damage the ring has caused to the exhuast port as for the power valve you have 2 options do what dread said or just lock it open then you dnt have to mod the power valve at all

madrevs · DTR Senior Member

looks like the metal part of the ring must of caught the valve on the way out of exhaust.few questions though
what do you think caused it to go
how do I tell the size of the blown piston
does the valve always need to be modified
whats the bike like with the valve locked open and will it be ok to do the running in with the valve locked open
And does anyone know the rough price of a rebore if the barrels still useable

madrevs · DTR Senior Member

dread123 · Moderator

rebore £15-30 then piston kit £22.50-£70 -no need to worry about piston size-who ever rebores should be providing the correct piston kit for it.

depending on current piston size, the powervalve may not have been modified before hence it hitting valve now?

with valve disconnected and fully open you lose a little bottom end kick but get one hell of a rush after 6-7000rpm.

dread123 · Moderator

plus need a genuine or athena head gasket not those cheap nasty ones that are all over ebay :p

madrevs · DTR Senior Member

Thanks for the info will go for the athena top end gasket kit I think.with the piston is it worth spending the extra on the wossener forged or are the mitaka pistons just as good.what sort of place will I need to take the barrell for a rebore as wasbthinking a engineering place but they wont sell the pistons kit.also will the damage to the exhaust port in the picture effect the running when its rebuilt or should I get a replacement cylinder

madrevs · DTR Senior Member

Also if the valve was catching the piston would it not of gone along time ago and will the powervalve need replacing now its damaged

yamahayz125 · DTR Senior Member

I cant tell from the pictures but the exhaust port doesn't look to bad and should go away with a rebore done it plenty of times dnt worry about that as for the power valve if its damaged ad just buy a second hand 1 their cheap enuff I might have 1 for sale if I still have it as for a piston ask the place what does the rebores what they sell I like wossner but that's just me

madrevs · DTR Senior Member

Would I need to take the barrell to a motorbike garage though or somewhere like a metal engineering company.one other thing the head bolts and the bottom barrel bolts a few where impossible to get to with a wratchet so had to use a spanner.do these need to be torqued ehen putting back together as cant see how I can get a torque wrench on them.the most awkward one seems to be at the front

yamahayz125 · DTR Senior Member

yea you will have to take the barrel m8 so the engineer can have a good look and see if he can rebore it depending on the damage but he will let you know their and then m8

MDK · DTR Legend

MDK wrote:
maybe take exhaust of if possible have a look at piston and rings

first post bleh get this feeling I was talking to a wall ?