heylawnguy Posted April 10, 2009 Share Posted April 10, 2009 Hi everyone I am new to the forum. Looks like a great place to learn. I live in Vancouver BC Canada and I just bought a 1981 XS 400 Special II, this will be my first official motorcycle although I also own a 2003 yamaha BWS (zuma) 49cc scooter. I posted some questions about the motorcycle last week after I went to see it and one of the cylinders was dead. The previous owner took it to a shop where they determined that the spark plug wire was all corroded, so they replaced it and when I went back to see it again it was running nice and smooth with lots of exhuast comming out of the tailpipe. I decided to buy it. The next day I started playing around with the bike and I noticed that the exhuast pipe on the suspect side was still cold after running for a long time. I pulled the plug and it was covered in oil residue. I noticed a small puddle of oil had collected on the inner lip of the muffler so I cleaned it all up. I took the bike for a 15 min spin and when i got back I noticed that their was more oil in the muffler lip. I am assuming now that the cylinder not running strong is from oil getting in to the combustion chamber. My question is where is the oil possibly comming from? Is it a huge task and expense to rubuild these motors? When I drove the bike around it seemed to have lots of power and idled nice. Any help would be great. Thanks Link to comment Share on other sites More sharing options...
Moderator YamaHead Posted April 10, 2009 Moderator Share Posted April 10, 2009 to the forum Could be a head gasket that's gone south.......or your valve guides have seen better days......would be my 1st assumption. Either way, it sounds like a top-end refresh could do wonders.....not too difficult really.....as long as you're familiar with a wrench & have a decent manual.....it should be a reasonably affordable fix. Link to comment Share on other sites More sharing options...
GaSo Posted April 10, 2009 Share Posted April 10, 2009 mmm, if that side isn't firing, maybe oil is getting past the rings? Link to comment Share on other sites More sharing options...
Moderator drewpy Posted April 10, 2009 Moderator Share Posted April 10, 2009 if its not been run for a while, the oil control ring can gum up letting oil get past into the cylinder Link to comment Share on other sites More sharing options...
JimR Posted April 11, 2009 Share Posted April 11, 2009 Hi everyone I am new to the forum. Looks like a great place to learn. I live in Vancouver BC Canada and I just bought a 1981 XS 400 Special II, this will be my first official motorcycle although I also own a 2003 yamaha BWS (zuma) 49cc scooter. I posted some questions about the motorcycle last week after I went to see it and one of the cylinders was dead. The previous owner took it to a shop where they determined that the spark plug wire was all corroded, so they replaced it and when I went back to see it again it was running nice and smooth with lots of exhuast comming out of the tailpipe. I decided to buy it. The next day I started playing around with the bike and I noticed that the exhuast pipe on the suspect side was still cold after running for a long time. I pulled the plug and it was covered in oil residue. I noticed a small puddle of oil had collected on the inner lip of the muffler so I cleaned it all up. I took the bike for a 15 min spin and when i got back I noticed that their was more oil in the muffler lip. I am assuming now that the cylinder not running strong is from oil getting in to the combustion chamber. My question is where is the oil possibly comming from? Is it a huge task and expense to rubuild these motors? When I drove the bike around it seemed to have lots of power and idled nice. Any help would be great. Thanks Hi there, is the residue oil or a shed load of unburnt fuel ? To confim this do a dry compression test followed by a wet one this should give you a good idea to the state of the engine without having to strip it. If this turns out OK then look at the service items i.e. Dwell, timing,tappits & carbs. Regards Jim Link to comment Share on other sites More sharing options...
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