saloonstudios Posted August 12, 2009 Share Posted August 12, 2009 So after a carb and tank cleaning and a new battery I got my 1980 XS400G to start without a problem. The problem arose a few minutes of running when faint white smoke started coming out of where the exhaust pipes connect to the heads. Could this be the valve guides? I was told the bike had sat for around a year, so I put new oil in it before I started it up. I also changed the oil again and tried running the engine again and after a minute or two the smoke returned. The pipes also got pretty yellow at the first bend near the head. I may have had a little too much oil also- but that wouldn't be the primary cause of the smoke would it? I've drained the oil and I'm standing by on any other suggestions you guys may have on what to look for or if I should even open up the head- Thanks for your input- Link to comment Share on other sites More sharing options...
Moderator drewpy Posted August 12, 2009 Moderator Share Posted August 12, 2009 So after a carb and tank cleaning and a new battery I got my 1980 XS400G to start without a problem. The problem arose a few minutes of running when faint white smoke started coming out of where the exhaust pipes connect to the heads. Could this be the valve guides? I was told the bike had sat for around a year, so I put new oil in it before I started it up. I also changed the oil again and tried running the engine again and after a minute or two the smoke returned. The pipes also got pretty yellow at the first bend near the head. I may have had a little too much oil also- but that wouldn't be the primary cause of the smoke would it? I've drained the oil and I'm standing by on any other suggestions you guys may have on what to look for or if I should even open up the head- Thanks for your input- from the exhaust it could be flooding of the carb. mine did/still does that,(another job on the to do list) burnt oil is blue in colour. there realy should be a seal around the header as no smoke should be comming out there, so i would get new gaskets. Link to comment Share on other sites More sharing options...
saloonstudios Posted August 17, 2009 Author Share Posted August 17, 2009 If anything I would guess the mixture is a bit lean, so I'm hoping it's not carb flooding. (which as an aside, where is the idle mixture screw? ah, I'll find it) Just change the exhaust gaskets at the head? I was hoping I wouldn't need to take the engine off of the frame to check the valve guides, but I'm thinking I'm not going to have enough room if I leave the engine where it is. If I pop the head cover off, do I need to re-check the valve clearances? (I would just assume to check everything again anyway but since I've never done it I wanted to know what to look for) While I'm in there is there anything else I should replace or check as culprits for the smoke? It could just be that a little bit of white smoke is normal under these circumstances (assuming the exhaust gasket is all that needs to be changed) but I want to explore all possibilties. Thanks- Link to comment Share on other sites More sharing options...
Fahren Posted August 18, 2009 Share Posted August 18, 2009 I have the same problem...i know u get a little whie smoke in the morning due to condensation but whilst on a long run a friend said when i changed up he saw a puff of white smoke come out of the exhaust...said not to worry cos his fireblade does it sometimes...anyhow i copied this from another forum see below. It's normal for "white smoke" to appear out the exhaust in colder temps - there is a small amount of water present in gas that gets burned in the combustion process and is released as vapur, or white smoke, out the tailpipe. Other causes of white smoke are blown head gaskets on liquid cooled bikes - but as yours is air cooled, this obviously isn't the problem. Next time this happens, check the outlet of the muffler closely... if you see lots of water droplets coming out with the "smoke" then I'd suspect cheap too low octane of a fuel. Try a higher octane to see of the problem goes away. White smoke can also be caused by unburnt fuel. If a spark plug is erratic in operation (ie: misfiring) it can fail to ignite the fuel/air mixture in the cylinder under compression forces and shoot it out the exhaust valve as white smoke. One other cause is the engine running too lean. As your bike is fairly old, I'd check the condition of the carb rubber intake boots. If they are cracked, this can allow air to get sucked in and lean out the mixture, causing white smoke. Another clue to a lean engine is that it will run very hot and the headers/exhaust pipes will turn a deep blue. I think the bit in bold is prolly whats causing my bike to smoke occasionally.....especially after its sat for say 15 mins then i restart it...no moisture present... Link to comment Share on other sites More sharing options...
saloonstudios Posted August 19, 2009 Author Share Posted August 19, 2009 Okay- what should I use to seal the valve cover? Gasket sealer? Anything specific? Link to comment Share on other sites More sharing options...
Recommended Posts