DT125R ARCHIVE

already whipped the whole top end off, head gasket was fine and coolant levels were fine, i did notice a rattle in the engine, sounded sort of like piston slap of something but my dad insisted it was normal

piston is badly marked/sort of melted just to the right of the arrow facing the exhaust port, will upload a picture tomorow if i remember

not sure on size but its not standard, its more than 2.5 tho as piston from my other barrel is loose fit, from what i can see there's metal from the piston stuck to bore but no scratches or scores

took about an hour pushing it home and got stopped by the police twice  apparently your not allowed to roll on the pavement at 10mph haha

 

heres a picture of the worst part, its the left side facing the exhaust port, the right side is scratched up too but not as bad. Checked rings and says '50' on them so this means its 5mm oversize?

ahh okay, so does that mean my other barrel is 0.25 oversize not 2.5? the engine had done 30k miles so i would have thought its more likely to be 2.5

Yeah man ,my bikes done 25,000 and is only on 0.50 ,I think they only go to about 2.00 ish before you get power valve damage !,,was you bike pretty standard when you got it ?

Oh oh oh just thought if all the damage is on one side it could mean the seal on that side of the lump has failed,it looks pretty white around that side of the exhaust port ,this would make sense of the marks and their position on the slug white would seem to indicate a lean mix on that side ,the dry side of the crank ,it's easy to put in and only a couple of quid to buy ....can we see a pic of the plug end???

Don't know what everyone else feels about this but looks lean dude ,air leak air leak lol,defo chec th dry side seal ,this piston was loose anyhow coz of da blowby?..Norfe ? Nev ? Trip ? Bradders? Mdk?etc etc

alright, does anyone know the tolerances ect needed for getting barrel rebored as i need to tell the guy tomorow when i take the barrel for him to look at

also there was a rattle which to me sounded like piston slap but i cant be certain

Epiphany !yours is a 3mb with 26mm , these have 56.40 standard piston size as apposed to the later 3bn which has 56.00'mmm this means a 0.50 piston from a later year would only be 0.10 over sized and would end up like this with the rattle aswel ,??? Did you get the piston for your year coz it matters ?? Let us all know man ,we'll help out

Ok kool ,I'll get you the exact tolerances for bore wear-in limits tomoz ,peace man I need zed'zzzzzzzzzz

flash is abit bright on camera so pictures make it all look worse, like the piston hasnt gone white just a light grey

how should i flush out bottom end and bearings NORFE?

EDIT: so i could just wash it out with petrol?

-- Edited by eG x LoGiKzZ on Tuesday 17th of July 2012 09:49:03 PM

yeah thats got well hot, lack of lube on that side or air leak, mix up some pre mix fuel and pull the oil line off and put ur finger on the inlet spigot, then hold the pump wide open with the pully and rev the bike see if it pumps oil

if thats ok id start looking ofor the left side crank seal leaking

like nev said to mucjh heat can wreck a head in warpage

and theres no need for a 500 mile break in on a piston

3 heat and cool cycles is fine ,never really run a bike in and never had a problem, 500 miles is just a manufactures thing on a brand new bike

aslong as u give it a nice gentle warm up it wuill be fine

i thought that it could have hit powervalve too but it doesnt touch although could hit after bike gets hot as i havent done any very long runs on it

will try that NORFE, bike does get warmer with the smaller dtr radiator on but not excessively hot... did the three heat cycles and and had been taking it easy, bike was at running temp and had been riding round town with a friend on his 50 for most of the day so obviously wasnt going flat out or redlining it

sending barrel to get rebored, new piston and some gaskets tomorow to hopefully get it all back by weekend or monday