jandyb Posted May 11, 2009 Report Share Posted May 11, 2009 Hi As some of You have noticed I have opened my motor this winter and changed crank bearings and seals. After reassembling it started OK but are now burning gear oil (I guess). Actually quite white smoke are coming out of the exhaust. A lot of it... This evening I have taken the motor out of the frame again. What do you think I have to look for while disassembling? Or maybe even: Can there be any other reason for the smoke than burning oil? Thanks -Jan Quote Link to comment Share on other sites More sharing options...
jse Posted May 11, 2009 Report Share Posted May 11, 2009 HiAs some of You have noticed I have opened my motor this winter and changed crank bearings and seals. After reassembling it started OK but are now burning gear oil (I guess). Actually quite white smoke are coming out of the exhaust. A lot of it... This evening I have taken the motor out of the frame again. What do you think I have to look for while disassembling? Or maybe even: Can there be any other reason for the smoke than burning oil? Thanks -Jan Jan, When working with cars, the "code" for smoke is, white=coolant, blue=oil and black=over-rich fuel mixture. I find bikes to be a little more difficult and sometimes it's a little hard to really tell what the smoke color is, so we look for other things such as, if the coolant level goes down or if the transmission level goes down. If the transmission fluid level was dropping, it probably is the right side crank seal leaking. If the coolant level was dropping, it most likely is the inside head o-ring leaking. These are probably the first things to check for a start. Jon Quote Link to comment Share on other sites More sharing options...
jandyb Posted May 12, 2009 Author Report Share Posted May 12, 2009 Da Quote Link to comment Share on other sites More sharing options...
lowbrow Posted May 12, 2009 Report Share Posted May 12, 2009 I finally got my 300 back together again today after changing the crank bearings and seals. It started very nicely at the 5 th kick, but it soon became way too hot. The fan went on after about 30 seconds and after a minute even the rear muffler was burning hot. In light of what you said above the answer to your latest question is 100% certain! Quote Link to comment Share on other sites More sharing options...
jse Posted May 12, 2009 Report Share Posted May 12, 2009 Da Quote Link to comment Share on other sites More sharing options...
jandyb Posted May 12, 2009 Author Report Share Posted May 12, 2009 In light of what you said above the answer to your latest question is 100% certain! That could be right, but i think that was because I had forgot to tighten the flywheel and the flywheel was "off position". A second thought the heat could have dam Quote Link to comment Share on other sites More sharing options...
jandyb Posted May 14, 2009 Author Report Share Posted May 14, 2009 Latest news: Yesterday I took the cylinder head off. I didnt find any streaks there but I found some water pearls on the top of the piston. Then assuming that the smoke was because burning coolant I put the bike together again, and of course used new O-rings between cylinder and head. (The grease trick did the job perfectly. Impossible without it I think..). Now hoping that the new O-rings would solve the problem and that there wasnt any cracks in cylinder/head. Well... got it together and started at second kick. And smoke was again filling the air around me and anything else.. Fearing te worst case that the cylinder was cracked I now emptyed the coolant and started again without coolant. Luckily (?) it still smoked heavy, so the conclusion now is that the smoke comes from burning gear oil. So... back to the beginning. Starting dissassembly for the third time after work today... When - if ever - this is fixed I will grant myself a long day in the woods riding my bike and then celebrate... -Jan Quote Link to comment Share on other sites More sharing options...
jse Posted May 14, 2009 Report Share Posted May 14, 2009 Latest news:Yesterday I took the cylinder head off. I didnt find any streaks there but I found some water pearls on the top of the piston. Then assuming that the smoke was because burning coolant I put the bike together again, and of course used new O-rings between cylinder and head. (The grease trick did the job perfectly. Impossible without it I think..). Now hoping that the new O-rings would solve the problem and that there wasnt any cracks in cylinder/head. Well... got it together and started at second kick. And smoke was again filling the air around me and anything else.. Fearing te worst case that the cylinder was cracked I now emptyed the coolant and started again without coolant. Luckily (?) it still smoked heavy, so the conclusion now is that the smoke comes from burning gear oil. So... back to the beginning. Starting dissassembly for the third time after work today... When - if ever - this is fixed I will grant myself a long day in the woods riding my bike and then celebrate... -Jan Darn, I was hoping it was an easy fix. Looks like one or both of the inner seals is leaking. Unlike most two-strokes, you can suck trans oil from either side on a Pro as the crank mains are lubed by the trans fluid. In rare instances, an ill fitting case gasket will also allow trans fluid to enter the crank area, so carefully check all the case sealing surfaces to be sure there isn't a burr that keeps the case halfs from coming together completely. The area that seals on the cases is often only about 4mm wide. Good luck! Jon Quote Link to comment Share on other sites More sharing options...
jandyb Posted May 14, 2009 Author Report Share Posted May 14, 2009 Darn, I was hoping it was an easy fix. Looks like one or both of the inner seals is leaking. Unlike most two-strokes, you can suck trans oil from either side on a Pro as the crank mains are lubed by the trans fluid. In rare instances, an ill fitting case gasket will also allow trans fluid to enter the crank area, so carefully check all the case sealing surfaces to be sure there isn't a burr that keeps the case halfs from coming together completely. The area that seals on the cases is often only about 4mm wide.Good luck! Jon Thanks I need it. The motor is out of the frame again now. Only need a flywheel puller to get the flywheel off. There is one about 30km from here.. Any other easy way to get the flywheel off? Thinking abot buying a puller every time, but again everytime I am hoping to be the last time needing one.. :-) -Jan Quote Link to comment Share on other sites More sharing options...
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