eifion Posted June 23, 2008 Share Posted June 23, 2008 Hi all, I hope someone can shed some light on my SR125 getting less and less powerful as time goes on. It's a 1992 model with 18k miles on the clock, I've had it about 2 years and at first it used to bowl along at 60, 65mph quite happily. Then I got problems starting it, if it started it was OK, but often it wouldn't start. So I got a 2nd hand carb of ebay and put that in, sorted out the starting problems. Starts on the button, first time every time. But, it's not as quick as it used to be, and it's getting worse, up to the point where now it will just about hold 45mph in 4th gear, and if I put her up into 5th it won't pick up any more speed at all. It's getting dangerous on NSLs as cars are doing silly overtakes. I've always thought the new carb was a set a bit rich, as if I give it any choke at all it dies instantly, so I checked the main mixture screw, it was 2.5 turns out. I set it to 1.5 turns out but it's not made a difference. I closed it by another quarter turn, and it's still really gutless. What I've tried: Spark plug is clean, good spark, correct gap. Fuel flows steadily from fuel tap. Tried running it without the air filter foam element, no difference. I've changed the oil religiously every 1000 miles. Any ideas as to what is causing my SR to get slower and slower would be much appreciated. Thanks Link to comment Share on other sites More sharing options...
Live to ride Ride to live Posted June 23, 2008 Share Posted June 23, 2008 Hi all, I hope someone can shed some light on my SR125 getting less and less powerful as time goes on. It's a 1992 model with 18k miles on the clock, I've had it about 2 years and at first it used to bowl along at 60, 65mph quite happily. Then I got problems starting it, if it started it was OK, but often it wouldn't start. So I got a 2nd hand carb of ebay and put that in, sorted out the starting problems. Starts on the button, first time every time. But, it's not as quick as it used to be, and it's getting worse, up to the point where now it will just about hold 45mph in 4th gear, and if I put her up into 5th it won't pick up any more speed at all. It's getting dangerous on NSLs as cars are doing silly overtakes. I've always thought the new carb was a set a bit rich, as if I give it any choke at all it dies instantly, so I checked the main mixture screw, it was 2.5 turns out. I set it to 1.5 turns out but it's not made a difference. I closed it by another quarter turn, and it's still really gutless. What I've tried: Spark plug is clean, good spark, correct gap. Fuel flows steadily from fuel tap. Tried running it without the air filter foam element, no difference. I've changed the oil religiously every 1000 miles. Any ideas as to what is causing my SR to get slower and slower would be much appreciated. Thanks Hmmmm.. is it using any more oil than usual? Smoking a lot? (thinking piston/ barrel wear) Check your brakes arnt binding on...thats a great one....faster you go, hotter they get, slower you go.... Throttle cable sticking or not threaded properly... Does it rev cleanly? After that lot im stumped. Link to comment Share on other sites More sharing options...
yoda Posted June 23, 2008 Share Posted June 23, 2008 Apart from checking that the throttle will go to max on the carb and the timing is correct, have you checked the exhaust for blockage? Is it coaked up? Link to comment Share on other sites More sharing options...
eifion Posted June 24, 2008 Author Share Posted June 24, 2008 Thanks for the ideas, that'll give me another couple of things to check. It doesn't get through oil terribly and never smokes so I don't think it's piston wear, rear brake used to bind, but sorted that out when I changed the brake shoes a month or so ago. Link to comment Share on other sites More sharing options...
jinxed Posted June 26, 2008 Share Posted June 26, 2008 Thanks for the ideas, that'll give me another couple of things to check. It doesn't get through oil terribly and never smokes so I don't think it's piston wear, rear brake used to bind, but sorted that out when I changed the brake shoes a month or so ago. Check your valve clearances; are they wildy out? Check compression too, in case the valves aren't closing fully. A carb strip & clean isn't a bad idea either. How's the air filter? Is the bike noisier than before? Link to comment Share on other sites More sharing options...
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