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Zx7r white smoke and cutting out


Guest Legatron
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hiya, sorry , this is a potential re port as its covered in my projects thread but could do with as much help as possible.


I ve started the bike for the first time a week or so and somethings not right. It struggles to start even on full choke and once it has started any touch of the throttle causes it to stall.


Once it has warmed up and settled a little it idles ok but if i rev it at all i get whitish smoke with the odd backfire. with white smoke i'm concerned about head gasket but the coolant looks as it should.


could it be carbs need sorting? the smoke isn't constant it like it gets to a certain level and chucks out a gob full of it.


i am concerned...help!


p.s. the bike has recently had oil and filter change, plugs but not a fuel filter. the tank was drained when i bought the bike. I have touched the carbs yet as i have NO experience with them at all. ( dark art as far as im concerned!)

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posted on tother thread :thumb:


but you have answered a few questions


get them carbs apart they are piece of piss to do :)


you NEED good fitting screwdrivers though for the float bowls or even better screwdriver bits for a ratchet so you can get pressure on them

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white smoke I believe is water vapor. Two things with this:

One - all vehicle get white smoke on start up in the cold weather. Its condensation etc evaporating as everything warms up.

Two - after a few minutes it should stop. If it doesn't, have a close look at the exhaust (from the side). There should be an inch or so gap between the exhaust and smoke. This is infact water droplets being created in the air behind the exhaust and is not coming from the exhaust itself.


Black smoke is smoke rather than vapor. It can be cause by a bad air/fuel mixture

Blue smoke is oil being burned - then you are in for a headache.


My bandit use to throw out a load of white smoke when I revved it shortly after I started it up.


Try going for a ride of ten minutes or so, then see if the symptoms are the same. I think a few of them (possibly even the backfiring) could be caused by the bike not being warm enough. - thats just going off the issues I had from riding the bandit hard when it was cold (which was pretty much every day on the way to work. I used to get a lovely backfire under a particular bridge)

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I've heard that excessive white smoke can be valves. do you get a loud tick tick from the engine - could be that the valves need adjustment.

 


You heard wrong

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Yeah.....kinda sounds like head gasket. What's the oil like in the sump?.....any sign of it emulsifying?

Maybe worth doing a compression check to see if it is the head gasket..... :wink:

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Thanks all, bloody hope its not valves, although i dont think a clearance check has been done on this bike - its history isn't exactly extensive!


I'm going to whip the carbs off and give them a thorough dowsing in cleaner. i'll see if that helps.


I only changed the oil about 30 miles ago and what came out was fine - old and black but not sludgy like a HG fail would suggest.


I was told that bike has the exhaust from a zx9 on it (although it seems like a generic scorpion end can) and its been suggested it may be running lean as a result. I think some TLC with a mechanic could be worth wonders.


i'll try and video the startup and get a link on here. that should help.

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Just a thought, is the bike stored in a cold damp place? if so, you will get a lot of vapour out of the zorts on start up in the cold weather though this should disappear once the motor has warmed up.

You could be running it on choke for too long l'm thinking. My old zx10 with its manual choke was finicky at the best of time when cold. It would take full choke to fire it up but as soon as it fired l needed to blip the throttle and get on half choke to get it to warm up, running it on full choke it would just run splutter and die. Have a look at your plugs, the colour of these should tell you the state of the engine. Top tip! Look for the silly things before you tear down the motor . Best of luck

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Thanks Chris,


problem is i cant blip the throttle until its warm because the motor dies.


but yes, its in the garage and as everywhere else its pretty cold in there at the moment. And there is defo condensation because, i used to get a lot water vapour condensing and dripping out of a poor seal on the exhaust can. i have since sealed this. so theres only one way for it to go lol

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Thanks Chris,


problem is i cant blip the throttle until its warm because the motor dies.


but yes, its in the garage and as everywhere else its pretty cold in there at the moment. And there is defo condensation because, i used to get a lot water vapour condensing and dripping out of a poor seal on the exhaust can. i have since sealed this. so theres only one way for it to go lol

ZX10 was the same mate, was very finicky to start as said. Full choke gets it started then slowly drop the choke to half way and start to blip it till it gets warm.

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I've heard that excessive white smoke can be valves. do you get a loud tick tick from the engine - could be that the valves need adjustment.

 


You heard wrong

 

lol - cheers. i was on internet forums, so i guess that's how a myth perpetuates (one muppet passing it on!)


in other news - ignore me.

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I've heard that excessive white smoke can be valves. do you get a loud tick tick from the engine - could be that the valves need adjustment.

 


You heard wrong

 

lol - cheers. i was on internet forums, so i guess that's how a myth perpetuates (one muppet passing it on!)


in other news - ignore me.

 


your not too far off though


excessive blue smoke ie burning oil on start up for a few minutes can be valve stem oil seals :)


but valve adjustment doesnt make it smoke like that :)

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ok, i've checked a few things this evening.


I've taken the plugs out and they all look ok apart from plug 1 which has a bit of oil on the end, not a lot, but some is worse than none. the others were ok but maybe a little dark considering they've only done about 10 miles. no pics im afraid as my hands were too grubby lol


This is the left hand cylinder, do you think its bad or as simple as oil overfill and this is the side that leans on the side stand?


I've recorded a video of startup which is currently uploading so will sort that shortly.


The oil cap did have some white snotty stuff inside ( see the pic) , now i know it could be gasket BUT the bike has barely moved apart form starting up a few times, could this be condensation?


IMG_20131203_184710.jpg

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sorry missed the plug bit


that could just be fouled up a bit you really need to take it for a good ride and then pull the plugs it need to get up in the revs before you check the colour


at worse it could be the rings have gone or valve stem oil seal


is it white smoke or does it have a blue hint to it? if a blue hint your burning oil

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I will put money on that been condensation

 

aaah but how much? lol


well if you think that's condensation i'll cling on to that :)


any thoughts on the plug?

:stupid: me too! If that motor has only been fired up a couple of times then it's probably not been up to full operating temperature. The plugs will be showing a rich mixture from the choke being in operation. Is the bike legal can you take it out for a spin? I suggest you do if possible before you tare it down and find nothing wrong!

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OK.....from the vid I'm not sure you have too much to worry about......looks like a bit of condensation coming out the can.......and the misfire is just a bit of popping coz the engine is cold....sounds worse because of the can.......and a lot of carbed bikes don't like any throttle on choke until they've warmed up a bit...... :wink:

I'd get the bike out for a run when you can....and see what it runs like after it's been properly warmed up..... 8-)

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it needs a good run mate

 

sounds like a good excuse to me :)


then hopefully i'm worrying about nothing , it is a 16y/o bike after all.


thing is, im not familiar with the bike - there are lots of bits and bobs missing or not quite right. i got it cheap as a project I'm trying to get to know the bike as best i can by working on it and replacing/refreshing what needs to be without braking the bank. You can check the thread of how that's going HERE


cheers guys.

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