engine keeps cutting out

[metalskin]

well, its finally happened... my bike stopped running and i've barley put 200k on it.

i have no idea why though. it was running ok, but had issues (see other threads- rust in bore + bottom end vibration)

it just cut out like i'd flicked the switch to off. its happened a couple of times today, and i have to leave the bike for 5min
and limp it another 500m.. i really cant think what it is.. im thinking its the new fuel filter, because the carby is fine,
and the fuel tap is fine. when i go to start it after that 5min, i cant give it throttle without it wanting to die, so i have to roll
it as i let the clutch out then work the throttle till its about 3k rpm.

i cant think what would stop it running. any ideas? all i can come up with is the fuel filter and possibly overheating, but
if it was overheating i figured it wouldnt still coast along like it does when it cuts out, it would just lock up..

                                                                                                                                cheers, Metalskin.

[vandy010]

how flogged is the bore?
a mate had an old YZ that was totally flogged and its symptoms sound similar to what your describing.
it'd "go for a few minutes, die, we'd let it cool then go again" it never locked up.

[metalskin]

how flogged is the bore?
a mate had an old YZ that was totally flogged and its symptoms sound similar to what your describing.
it'd "go for a few minutes, die, we'd let it cool then go again" it never locked up.

the bore is not bad but it has a tiny bit of pitting (see rust in bore thread- but i cleaned it up about 100k's ago..)
, i've had less compression on other bikes and they have ran fine. is there anything in the gearbox that would cause it?
only asking as i just gave it an oil change, and there was a couple of tiny bits (like 0.1 - 0.3mm or so) of metal, cant figure
out what it is, im hoping its nothing...
it doesnt even need to sit 5min, its probably more like 30sec, and then u gotta work the throttle to get going or it will stall.

its definatly not compression related. also, when it happened the 2nd time i was doing about 6k rpm, and it started to blow
a heap of smoke (didnt lose any power tho) about 50 meters before it cut out.
could it be a crank seal, and the spark plug possibly oiling up bad and needs to sit for a sec to dry out? im confused with this one,
i've had 4 strokes with exactly the same symptoms and in both cases my rings were shattered from overheating (due to lack of oil)

its getting VERY bad very quick.. i mean very quick. i think im officialy off the road         any help appreciated. metalskin.

[Viper79]

Sounds very much like a crankshaft seal on the gearbox side to me!  Once it warms up the seal fails and its digesting your gearbox oil.

[metalskin]

Sounds very much like a crankshaft seal on the gearbox side to me!  Once it warms up the seal fails and its digesting your gearbox oil.

among other things, i think that is the most likely problem with the amount of smoke its blowing once its warm.
checked the spark plug and its pretty dry, if anything looks like its running rich and lean at the same time..

if i put the choke on, it will kick over straight away, and run for the same several hundred meters,,

                                                                                       cheers, metalskin

[DR]

just out of curiosity, how much oil did you put in the engine when you replaced it as overfilling can cause woes.

Possible causes not mentioned..

kinked or squashed fuel line not allowing enough flow
the in-tank fuel tap strainer and filter could be blocked
vent pipe on the side of the carb body blocked or kinked
carb needle and seat stuck due to foreign matter

check these to eliminate fuel starvation. Undo the drain plug and check the fuel flow and also see what is actually in the plug cause if it's full of crap you'll have issues. Not sure with the DT's but many mikuni carbs have the mainjet suck fuel from within this particular item, if not flowing sufficiently give the fuel bowl some light taps with the handle of a screwdriver or such may shake the shit lose sometimes without having to removing the carb (not too hard and don't use a hammer ) no backfiring or missing more or less says the ignition is still good so I'm inclined to think it's a fuel problem
 

[metalskin]

just out of curiosity, how much oil did you put in the engine when you replaced it as overfilling can cause woes.

Possible causes not mentioned..

kinked or squashed fuel line not allowing enough flow
the in-tank fuel tap strainer and filter could be blocked
vent pipe on the side of the carb body blocked or kinked
carb needle and seat stuck due to foreign matter

check these to eliminate fuel starvation. Undo the drain plug and check the fuel flow and also see what is actually in the plug cause if it's full of crap you'll have issues. Not sure with the DT's but many mikuni carbs have the mainjet suck fuel from within this particular item, if not flowing sufficiently give the fuel bowl some light taps with the handle of a screwdriver or such may shake the shit lose sometimes without having to removing the carb (not too hard and don't use a hammer ) no backfiring or missing more or less says the ignition is still good so I'm inclined to think it's a fuel problem
 

oil is to spec... ran till hot, drained it... added 630ml.. perfect level.. carby seems to be getting fuel, but not heaps..
have checked when the bike cuts out if their is fuel still in carb and there is. will take the carby off again, just to check.

[rocketfrog]

check fuel tank breather tube for mud wasp nest, this problem was giving me the shits with an IT 175. I kept removing the fuel cap to check fuel level and it would run again miraculously then stop 500m down the track.

[metalskin]

when checking the oil level,  i should unscrew the cap and just sit it? there is about 1cm of thread.

im pretty sure thats the way to check it..  or am i supposed to screw it in? if thats the case its overfull.  cheers, metalskin.