So this is kind of a story, with a few questions in it. I have a 93 kx250 that I've had for about 6 years, only paid $1500 back then. Its been a good bike overall. i ride occasionally, about 6-12 times a year. I've done hardly any maitenence, other than cleaning the air filter, changing the crank oil, and fixing anything that breaks. That's pretty much it. Yeah, I know theres probably lots of things, like fork oil changes, or rebuilds, carb rejetting, etc that should be done, but I'm the type of guy that as long as something is working good enough for me I don't want to take the time or money to fix it unless it breaks.
Its partly just because I don't have alot money to spare, but its also because at this point, the bike is old enough that mechanical things are breaking. (brake caliper, kickstart, kickstart spline, various bolts, etc). I'm thinking about upgrading to a newer bike, like around an '02 '03 yz250, since I've heard the yz's are very reliable, and I've been seeing a bunch like that for about $1400-$2000.
In any case, my bike right now is running good enough for me, might not be its best but its got plenty of power, only thing is it has seemed to be smoking way more than it should. I mean I know two strokes smoke alot, but I don't remember mine making nearly this much in the past, it smokes up the whole trail. I can't let my girlfriend ride behind me or she'll get a headache. I can't figure out why its smoking so much though, I only mix the oil at 40:1 (guy i bought it from recommended that), and it doesn't seem to be burning crank case oil, since the crank case oil level is fine and I haven't added any in there in probably 10-20 hours of riding. So a big part of my question is why is my bike smoking sooo much?
I had asked a guy at the bike shop, and he said its probably built up oil in the exhaust expansion chamber, and silencer from all the years, he said to clean it out and repack. So I took it all off, and heard something rattling in the exhaust, turns out its an exhaust valve, looks like its been in there a very long time. So I ended up deciding to take my top end apart. I've never done a job like this before, but since i'm unemployed at the moment, I have time to mess with it. the exhaust valve is part 12005B on an exploded view, and the price is about $40 even online which I find rediculous. As far as I can tell it doesn't even seem important, all it seems to do that I can tell, is when the other exhaust valve its connected to slides open (making the hole of the exhaust port about a centimeter taller), it sort of flaps shut over the other one. But it doesn't seem like it actually opens or closes anything, seems like the most it does is smoothes out some turbulence that would go over the other valve. So I'm really leaning towards just leaving it out, since I don't want to spend $40 on such a tiny part, that just might break again. And the bike has enough power, so is it a good idea to just leave it out?
Now the other part of my question is if I might want to consider any rebuild? I don't know how much a rebuild costs, or how much is involved, but since I've got the top end off, would it be something I'd want to do? If its something I can do without a whole lot of time (since the engine is already apart) and only costs $50 or something for little parts like new rings or whatever it takes, I'd do it.
I had tried doing a compression test before I took it apart, but I just found out I think I did it wrong. I've been hearing now that your supposed to have the throttle open, I didn't, I had it shut. I kicked it over about 5 times without using all my strength and got about 130. I didn't use nearly all my kicking strength because I didn't have my mx boot on, and after once getting a major major gash on my leg from kickstarting in regular shoes, I now only kick start in boots. I figured that if its reading 130 without even kicking it my hardest it must be good. So is this reading completely inaccurate? Should I think about just bolting the cylinder back on with those 4 bolts and leave everything else disconnected and give it a few more kicks? (I'm guessing with the carb off, it would be about the same as full throttle?
Anyways, long winded story, hopefully you can answer the various questions in there. Really the just of it is I'd like it to hopefully smoke less, since it seems excessive. And I'd be willing to put a small amount of money into the engine, like $100 or less total (including that valve), if it would do me much good, but in all reality I'm happy enough with the performance not to want to spend any more than that.
Thanks.
Its partly just because I don't have alot money to spare, but its also because at this point, the bike is old enough that mechanical things are breaking. (brake caliper, kickstart, kickstart spline, various bolts, etc). I'm thinking about upgrading to a newer bike, like around an '02 '03 yz250, since I've heard the yz's are very reliable, and I've been seeing a bunch like that for about $1400-$2000.
In any case, my bike right now is running good enough for me, might not be its best but its got plenty of power, only thing is it has seemed to be smoking way more than it should. I mean I know two strokes smoke alot, but I don't remember mine making nearly this much in the past, it smokes up the whole trail. I can't let my girlfriend ride behind me or she'll get a headache. I can't figure out why its smoking so much though, I only mix the oil at 40:1 (guy i bought it from recommended that), and it doesn't seem to be burning crank case oil, since the crank case oil level is fine and I haven't added any in there in probably 10-20 hours of riding. So a big part of my question is why is my bike smoking sooo much?
I had asked a guy at the bike shop, and he said its probably built up oil in the exhaust expansion chamber, and silencer from all the years, he said to clean it out and repack. So I took it all off, and heard something rattling in the exhaust, turns out its an exhaust valve, looks like its been in there a very long time. So I ended up deciding to take my top end apart. I've never done a job like this before, but since i'm unemployed at the moment, I have time to mess with it. the exhaust valve is part 12005B on an exploded view, and the price is about $40 even online which I find rediculous. As far as I can tell it doesn't even seem important, all it seems to do that I can tell, is when the other exhaust valve its connected to slides open (making the hole of the exhaust port about a centimeter taller), it sort of flaps shut over the other one. But it doesn't seem like it actually opens or closes anything, seems like the most it does is smoothes out some turbulence that would go over the other valve. So I'm really leaning towards just leaving it out, since I don't want to spend $40 on such a tiny part, that just might break again. And the bike has enough power, so is it a good idea to just leave it out?
Now the other part of my question is if I might want to consider any rebuild? I don't know how much a rebuild costs, or how much is involved, but since I've got the top end off, would it be something I'd want to do? If its something I can do without a whole lot of time (since the engine is already apart) and only costs $50 or something for little parts like new rings or whatever it takes, I'd do it.
I had tried doing a compression test before I took it apart, but I just found out I think I did it wrong. I've been hearing now that your supposed to have the throttle open, I didn't, I had it shut. I kicked it over about 5 times without using all my strength and got about 130. I didn't use nearly all my kicking strength because I didn't have my mx boot on, and after once getting a major major gash on my leg from kickstarting in regular shoes, I now only kick start in boots. I figured that if its reading 130 without even kicking it my hardest it must be good. So is this reading completely inaccurate? Should I think about just bolting the cylinder back on with those 4 bolts and leave everything else disconnected and give it a few more kicks? (I'm guessing with the carb off, it would be about the same as full throttle?
Anyways, long winded story, hopefully you can answer the various questions in there. Really the just of it is I'd like it to hopefully smoke less, since it seems excessive. And I'd be willing to put a small amount of money into the engine, like $100 or less total (including that valve), if it would do me much good, but in all reality I'm happy enough with the performance not to want to spend any more than that.
Thanks.
