engine cutting out (not the valve clearance)

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dunny29er

dunny29er

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hey guys went riding on the weekend with my dhz running better then ever anyway let my friend have ago and a big stick flung up and hit him and he said it also hit the the left side of the the bike (the carby side) anyway went to go start it and took ages to start and got going but if i let it idle it cut out straight away didnt splutter and i have checked the vavle clearance and idle screw and now its taking yonks to start and then dieing it i let it idle runs fin when u have some throttle so could anyone tell me anything that might help its a dhz dpro 140 with a 26mm oko flateside carby thanks guys also changed the spark plug and still oh and there isn't as much compression
 
have you gone over all the electrics to make sure one of the plugs didnt get knocked about and is loosely sitting together?

it doesnt sound like an air leak but check the rubber carby adapter for any tears

did you do your valves on TDC and not valve overlap?

check if there is a bent valve which will require taking the head off
 
pbk said:
have you gone over all the electrics to make sure one of the plugs didnt get knocked about and is loosely sitting together?

it doesnt sound like an air leak but check the rubber carby adapter for any tears

did you do your valves on TDC and not valve overlap?

check if there is a bent valve which will require taking the head off
Click to expand...

how do i check if a valve is bent i have taken off the head before so i know how to do that
 
your going to know if its bent :)

or

fill one port up at a time with petrol and see if it leaks out into the combustion chamber, also make sure its at TDC when you do this
 
take the head

take the manifold off

now that you have your head in your hands :p ..........(couldnt help it)

where the manifold bolts to the head, that hole is inlet port just put like a cap full of petrol down it when the cam is at TDC and both valves are shut

do the same to the exhaust port which is the hole on the otherside of the head
 
where you running it with an air filter or a clean air filter?? How long had it been since you cleaned it?
 
i clean it every ride and oil it oh and i did the port thing petrol leaks at just a tiny tiny tiny bit if i left it for half an hour it would all drain out i cant see light through it but the exhaust port i can see light through it open a like half a mm what do i do now???
 
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well if you have some money pull it out and replace it, BUT IF YOUR BROKE AND THE BIKE IS NOT THE BEST BIKE IN THE WORLD AND YOUR NOT GONNA RACE IT AND ETC ETC,THE valve stems on these are very weak and bend very easy right at the base of the shaft, find a socket the size of the valve place it on the face of the valve with it still in the head and tap the socket until the valve seats flush,now before you guys all say bodgie prick i did say BUT IF YOUR BROKE AND THE BIKE IS NOT THE BEST BIKE IN THE WORLD AND YOUR NOT GONNA RACE IT AND ETC ETC,please note i have done this over many years a couple of times with no negative consequenses
 
if your valve is bent then it would or at least had more valve clearance than usual..

so if you checked and adjusted the valve clearance, did you notice that one had more clearance than usual.
 
if your valve is bent then it would or at least had more valve clearance than usual..

so if you checked and adjusted the valve clearance, did you notice that one had more clearance than usual.
Click to expand...

yer the exhaust vavle was just a tiny bit looser but isnt it supposed to be more clearance because the top is 0.003 and the exhaust it 0.004

well if you have some money pull it out and replace it, BUT IF YOUR BROKE AND THE BIKE IS NOT THE BEST BIKE IN THE WORLD AND YOUR NOT GONNA RACE IT AND ETC ETC,THE valve stems on these are very weak and bend very easy right at the base of the shaft, find a socket the size of the valve place it on the face of the valve with it still in the head and tap the socket until the valve seats flush,now before you guys all say bodgie prick i did say BUT IF YOUR BROKE AND THE BIKE IS NOT THE BEST BIKE IN THE WORLD AND YOUR NOT GONNA RACE IT AND ETC ETC,please note i have done this over many years a couple of times with no negative consequenses
Click to expand...
not sure i understand do u have any pics or a post or something on this
 
well im not totally convinced you need a valve yet..

did you make sure the head is on TDC and has valve clearance when doing the leak test?

the gap you see thru the exhaust valve!! do you see the gap all the way around or only on one side?

now here's the bit that gets me, we fog the absolute pi$$ of out a zonger 140 every weekend and have never had a drama like this ever.. (included valve bouncing it all the time)

also going by the small amount your saying the valve is bent means the engine would run fine.. my engine has a bent valve (or 2) and it runs absolutely fine, idles fine, revs fine.

i think more diagnosis is needed, ot take the head to someone that can check it..
also carbon build up can hold a valve open while not running (when running it quickly blows thru and allows the valve to seat).

clunky64 said:
well if you have some money pull it out and replace it, BUT IF YOUR BROKE AND THE BIKE IS NOT THE BEST BIKE IN THE WORLD AND YOUR NOT GONNA RACE IT AND ETC ETC,THE valve stems on these are very weak and bend very easy right at the base of the shaft, find a socket the size of the valve place it on the face of the valve with it still in the head and tap the socket until the valve seats flush,now before you guys all say bodgie prick i did say BUT IF YOUR BROKE AND THE BIKE IS NOT THE BEST BIKE IN THE WORLD AND YOUR NOT GONNA RACE IT AND ETC ETC,please note i have done this over many years a couple of times with no negative consequenses
Click to expand...

i find nothing wrong with this method if the bent valve is only minor..
i have also done this many times in the past, and was also shown how to do this by a pro engine rebuilder.. tho my method is done in a lathe.

the bent valve/s in mine will get the same treatment but i will reface the valves afterwards..
 
no im not that much of a noob tho it does feel like that tho anyway just checked it again and yes the exhaust is bent only 1 side of it (this is on the exhaust, the inlet it fine) how do i bend it back could u explain it in full detail coz im noob and if it isnt that what else could it be
 
i think youve gone to fast and to quick in saying its a bent valve i put money on it being a bit of carbon clean the valve if the head is off then put it back togeather then start at the begining
you posted that a stick hit the carby side to me this is the place to start
(1) have you upped the idle and then checked that it does run correctly at different rev ranges
(2) have you checked for hairline cracks in the manifold or carbie
(3 made sure ya mate didnt do somthing he doesnt want to admit to like changed the mixes thinking he was upping the idle
 
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