Karlsberg Posted February 16, 2017 Share Posted February 16, 2017 I'm selling my SR250 to a friend, but we want to fix or at least understand a certain issue first. Problem: When going at near-maximum speed, motor starts couching and eventually goes out. The top-speed has gone from 120 to 80 during the last 4 months. First fix (not counting changing the oil): Today I was opening the case of the air filter for the first time, and I was expecting a black, nasty foam that needs mineral spirits to clean it or replacement. When I opened the case, I was very surprised to see, that there's no foam!? (see attached picture) Just a simple round net, that looks like it's there for holding a foam filter was there. Maybe it's because I am used to work dual sports - but shouldn't there be more filtering going on here? And isn't it likely to be the root of my problem?My idea of a solution: - Buy a foam filter for that model to prevent more shit going into the carb. - Buy and use suitable carb-cleaner and mix it with a fresh batch of gasoline to make a chemical cleaning of the carb. - If that doesn't cut it, clean the carb mechanically / manually. What do you think? Am I on the right track of fixing my bike? Am I missing a filter and is the previous owner an idiot (and me too, for not noticing)? Link to comment Share on other sites More sharing options...
Variomatic Posted February 16, 2017 Share Posted February 16, 2017 Ok, either those top speed number are in KM or you're confused, top end for an SR250 isn't gonna be much over 80-90MPH anyway, and yeah, that air filter definitely looks lacking, this is what it should have: Here's a link to somewhere you can buy one, I've used this site a lot and they've not let me down yet: http://www.wemoto.com/bikes/yamaha/sr_250_se/81-84/picture/air_filter/ (this filter is for a 1981-1984 bike) Link to comment Share on other sites More sharing options...
Karlsberg Posted February 16, 2017 Author Share Posted February 16, 2017 4 hours ago, Variomatic said: Ok, either those top speed number are in KM or you're confused, top end for an SR250 isn't gonna be much over 80-90MPH anyway, and yeah, that air filter definitely looks lacking, ... Thanks! Yeah, I forgot Europe isn't the world, I meant km/t. I'm surprised it didn't complain having all the Barcelona smog injected directly into the carb for 4 months. Link to comment Share on other sites More sharing options...
Variomatic Posted February 16, 2017 Share Posted February 16, 2017 Hopefully the filter fixes that, lets just hope it running lean didn't cause any other issues! Link to comment Share on other sites More sharing options...
Karlsberg Posted February 17, 2017 Author Share Posted February 17, 2017 I was checking out the filter because I thought it needed cleaning. I thought my engine couldn't do the high speeds, because it was clocked up and couldn't let enough air through to a smooth run at high speed - but now I'm concerned about what damage the missing air filter have done to the enige. I've been reading about worn out pistons due to messy and dirty airflows, but right now I just hope it's just the carburator, and that a chemical cleaning (mixing a carb cleaner into the gasoline) will do the trick. I'm getting more and more pissed about the previous owner, and myself for never doing a simple check on the simple parts when buying and inspecting a new bike! Link to comment Share on other sites More sharing options...
blackhat250 Posted February 17, 2017 Share Posted February 17, 2017 What am thinking is, theres been the Lack of air filter,[ missing foam], this would make it run lean, [ like pod filters]. this could result in burnt valves.. as you say loosing power, . I would check compression, am betting the new filter and carb clean will make no difference, Link to comment Share on other sites More sharing options...
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