DT125R ARCHIVE

Sgt-syphilis · Guru

RE: Dt wont start after top end rebuild...

Sgt-syphilis · Guru

I put the zaust behind the plate so you can see when it fires....it seems to me like no compression, i wasnt there when it was checked, but was told its all good...?

NORFE · DTR Trusted Engine Builder

is it constantly turning the engine over as the starter is spinning sounds way fast that starter like its not spinning the engine....and only catchin now and again then doing the odd fireing

???take the magnito case off and press the starter see if the magnito is spinning when ur pressing the button

if not the starter clutch is shagged

Sgt-syphilis · Guru

da faq is the magnito case?

does same thing when bumping if that makes a diff...?

what do you thing re compression...about to go out an dbuy my own comp tester...worth it? or just get one at weekend?

Sgt-syphilis · Guru

and yeash it does turn the engine...i tired turning it over with head off and it was turning engine over fine, and sparking...?

any ideas

NORFE · DTR Trusted Engine Builder

Sgt-syphilis wrote:
da faq is the magnito case?

does same thing when bumping if that makes a diff...?

what do you thing re compression...about to go out an dbuy my own comp tester...worth it? or just get one at weekend?

the caseing that covers the magnito u tit ha

biggrin

Sgt-syphilis · Guru

ffs...just went to fúcking shítty wánkfest Halfrauds to buy a comp tester...the thing is the biggest comp tester in the fking universe. mix that with the smallest working space between a head and a frame and you get a totally useless tester. rather plssed off tbh. magnito is fine...

everything else was working perfectly till the rings went. i dont understand why its so hard.

the starter is turning the crank. The plug is sparking at the right time. The plug is wet with petrol. ive been told comp is fine...even with my own testing (just jammin the fooker in ther) it still managed to reach 50psi and it was leaking at the tester connection like a bástard.

What am i doing??!?!?!

NORFE · DTR Trusted Engine Builder

just coz the plugs sparking out side dont mean it is inside, have u tried a new plug or different plug mate?

Sgt-syphilis · Guru

It is a brand new plug, and i tried my old one in it too, same thing. I find it very odd that the bike only fires evry so often...soesnt sound like a conventional fire either!

Calum122 · Guru

My DT did this.

Went months everyday trying to figure out what the fúck was going on.

In the end I decided to put it on eBay.

It was on eBay an hour. Had loads of interest. And it got me thinking. If these mugs on here are snapping it up then it must be an easy fix.

Went downstairs. Just chopped all the wires. Went from CDI to battery to engine. No Stand switch, no kill switch. Just the basics

An voilÃ it work! So any chance that the stand switch has broken? This will start the engine but then cut it? Neutral switch. Same thing. Uhh fault to earth?

NORFE · DTR Trusted Engine Builder

ghost in the machine aghhhhhhhhh its wank i no been here many times

if it was me this is what id do

strip it down as far as u did when u rebuilt it wever just top end off with bottom end in frame

check and inspect all components in the top end

while top end is off with some more room check every single wire connection above and around the frame,clean them and give them a lil pull mek sure there in the plugs proply...

ull be suprised how many times people have just snagged a wire taking somets off and broke a connection giving wank conductivity to a circuit giving similar problem

strip clean the carb

dont put any more oil in when u rebuild the top end sounds like uv plenty in alredy ha

rebuild bit by bit

then hopefully u will find the problem

all it needs is comp & fuel & ignition

dont get dishartened its in front of ur eyes some where its just finding it

and its sumets u must of dun as it ran b4 u did it if u get me

biggrin

Calum122 · Guru

+1 On NORFE.

Just take your time. Don't get disheartened keep at it.

You can do it mate.

Sgt-syphilis · Guru

ill try looking at wires etc...

have already re-striped it and rebuilt it again, tripple checking everything as i go...(didnt add any more oil ;) lol )
have also already stripped and cleaned carb...

maybe when the rings went it took something else out with it?

Yeah i know exactly what you mean...it has to be something related to the rings failing and me re building it !

Sgt-syphilis · Guru

Other thing im worried about is the alarm (which has an immobilser), might have failed or gone wrong when the battery died. Talking of which...do you think its worth replacing the battery? i personaly think its fine...it sounds like its turning the bike ok right??

MDK · DTR Legend

been there also mate and I know it fcking realy pisses you off ..I have a short fuse and if a hammer is close have and would smash the fck out of a bike..then cry in a corner later ..its best just to walk away and leave it for a couple of days .. it,s at night laid in bed ideas pop in to ur head and you think ill try that tomorrow lol.

seem.s we have all gone over all the standard stuff but still no start . if you was local to me mate I would be happy to sit in yard a day with you put my dtr at the side and swap and change every part till we found the problem all the way down to the fly wheel and pickups . but im way up here in sheffield .

is none of you lads local maybe you could meet up on bikes all pop round and have a group go at it.....

only just noticed the alarm thing have you tried takeing it off ?

take it you have tried another carb ?

Sgt-syphilis · Guru

havent tried another carb no....dont have one spare!

yea a few spanners have been thrown!

im really at a los now...i hope its something really stupid and obvious...like i put the piston from a lawnmower in. meh i dunno...cant get my head round it!

why would the carb just break...?

MDK · DTR Legend

it can some time the simmpleist thing

you ahve done all the standard checks

you have a spark and starter is working so electris and earth are ok

compression and pistons sound fine ect

think the next thing I would check is the carb althou fuel is getting throu and the plug is wet it could have some stupid yet overlookd problem ... with all the turning of brass screws ect things become worn miss shaped or set wrong ?

also not worked on re that much . have they got any wires to carbs like some scoots ect like a auto choke ?

everything else seems to be working as I say above and it seems to be the only thing left as no matter wht you do if the fuel to air mix are wrong its will never start ..

not saying go out and buy one but would be great to try a carb of a good working bike to see if that works ?

MDK · DTR Legend

NORFE wrote:
rings in the pipe wunt effect owt apart from the risk of getting sucked bak in the chamber and causing more damage
it a wierd on this one, my gues is electrical fault some where in or around the engine

not sure it ,s electrics as he states he has a good spark ? if was bad earths - faulty stater coils - ect he wouldnt have a spark I would think .

he seems to have everything you need to start -spark-compression-fuel-air . but my guess would be something is going wrong carb side fuel to air mix or fuel and 2 stroke mix maybe

thats maybe a point we have over looked the pre mix -- maybe make up a temp fuel tank with correct fuel-2st oil mix and attach to carb ?

as I said above would defo try another carb and check reeds maybe sticky or fcked ?

this user has a carb ect not sure how close you two are maybe he would drive or ride over to you to test them out then if ok you buy or drop him £20 for his trouble ? http://dt125r.activeboard.com/t49425997/breaking-dtr-125-all-parts/

-- Edited by MDK on Friday 8th of June 2012 01:01:22 PM

GADGET · Guru

When u did the top end did you have it bored + new piston or did you just replace the rings? Did you use a yammy head gasket? How bad wer the rings and did you check there was no rings in the exhaust as could be partly blocked? What size piston did you put in it if u did replace it? Sorry for so many Qs but this one has got me thinking

NORFE · DTR Trusted Engine Builder

rings in the pipe wunt effect owt apart from the risk of getting sucked bak in the chamber and causing more damage

it a wierd on this one, my gues is electrical fault some where in or around the engine

fused420 · DTR Senior Member

Have you tryed putting a drop of petrol directly into the engine, through the spark plug hole?

Sgt-syphilis · Guru

yup....still wont go

Do you need to bleed the oil pump...? maybe its fuel to air mix? the bleed screw on the carb is fooked so cant check it.

Any other ideas...? its just stupid now...

Sgt-syphilis · Guru

Yeah i just replaced rings, no over bore - standard size piston.

The rings were pretty bad and cracked a bit of the top of the piston off..

GADGET · Guru

Low compression it is then ? Was the piston you took out standard size then? If it was the original piston it will say prox inside the old piston,,,If not it will have a size stamp on the top of the piston under all the carbon buildup,,, Did you even have the barrel checked?

Sgt-syphilis · Guru

was orig piston and rings...so the dealer told me, and there is no reciepts or info re a rubuild and milage all checks out...but the it isnt a pro x piston.. its an ART which i believe is also stock yammy piston...?

I wanted to get the barrel measured and taken to next bore, but few people said dont bother - just put originals in....

I really enjoy wasting my own time..

Seanyftw · Guru

checked the HT lead cap? Sounds like a similar problem to my bike to be honest. turns over but no spark at all.

GADGET · Guru

Did the ring brake the top of the piston off?by the exhaust port? If so its hit on the way back down and probs fcked the barrel,,,,or if the barrel has got away with it somehow ,then the pieces could have split your crank seals,,,this would explain the oily mess your finding in the top end,sorry to say it bud but u gotta start again ,get it checked first tho as you may have fragments in The crank area,,if you can get some good pics of the barrel on here(espesialy the exhaust port area) We can get a better idea of its condition,also did you find all the pieces of ring? Good luck buddy ,we're here to help

MDK · DTR Legend

Seanyftw wrote:
checked the HT lead cap? Sounds like a similar problem to my bike to be honest. turns over but no spark at all.

he has a spark ?

with the new info above about the old rings was damaged and piston ect . then just bunging some new rings in .. I would also say there lie.s the problem maybe .. but also you say compression is fine so fck knows ..

still stick with my try another carb idea

GADGET · Guru

You could try looking behind the stator to see if u have oily stuff coming out of the dry side of the crank,,,,if not drain some of your oil and see if it smells petroly/has metal fragments in it as this could mean other crank seal,,but we need to see the damage first,,,don't get disheartened tho coz u would have been down on power anyway,,new bore and piston will have perfect compression when run in and you could see a gain in power over what your used to

MDK · DTR Legend

any updates ? is it going yet ?