kjhussey Posted July 29, 2007 Share Posted July 29, 2007 This bike's been great. 8400 miles, started immediately every time, 70 to 80 miles per gallon. The other day I'm riding home from work at 45 miles per hour and the engine just quit. No loud noises or anything. It just quit. I could see plenty of Gas in the tank but when I crank it using the electric starter it sounds like it turning way to fast. It's never sounded that way before. Kind of like there wasn't any compression. I pulled the plug and can feel some "air" coming from the plug hole. I can see spark in the plug gap when cranking but the cranking is too fast and it just doesn't even sound like it wants to start. Any one else have this problem? I'm afraid it's major. What say ye? Thanks Link to comment Share on other sites More sharing options...
chuck_zc Posted July 29, 2007 Share Posted July 29, 2007 Sounds like you may have a timing chain problem. It may have either broken or jumped a couple of teeth on the timing sprocket. Link to comment Share on other sites More sharing options...
Michael Cahill Posted July 30, 2007 Share Posted July 30, 2007 I agree with above, try readjusting the timing it and making sure the timing chain tensioner is properly adjusted. Link to comment Share on other sites More sharing options...
kjhussey Posted July 31, 2007 Author Share Posted July 31, 2007 I agree with above, try readjusting the timing it and making sure the timing chain tensioner is properly adjusted. Thanks Guys. I didn't even think about the timing chain. It could just break while cruising along? Wouldn't it make a loud noise or grinding sound or some noise if it broke? Anyway, how involved of a repair is "readjusting the timing chain?" I do tune-ups, oil changes and installation of accessories. I've never "tore into" an engine. Do I need a professional? Thanks again, Kevin Link to comment Share on other sites More sharing options...
danny1989 Posted August 1, 2007 Share Posted August 1, 2007 This bike's been great. 8400 miles, started immediately every time, 70 to 80 miles per gallon. The other day I'm riding home from work at 45 miles per hour and the engine just quit. No loud noises or anything. It just quit. I could see plenty of Gas in the tank but when I crank it using the electric starter it sounds like it turning way to fast. It's never sounded that way before. Kind of like there wasn't any compression. I pulled the plug and can feel some "air" coming from the plug hole. I can see spark in the plug gap when cranking but the cranking is too fast and it just doesn't even sound like it wants to start. Any one else have this problem? I'm afraid it's major. What say ye? Thanks your spark plug is fooked Link to comment Share on other sites More sharing options...
yoda Posted August 1, 2007 Share Posted August 1, 2007 That'll teach you for doing 45 !!!!!! Link to comment Share on other sites More sharing options...
fosdyke Posted August 6, 2007 Share Posted August 6, 2007 Hi Just a thought - have you checked compression with a gauge? - could be piston damage. Otherwise if you have changed the plug I go with the timing chain. Link to comment Share on other sites More sharing options...
kjhussey Posted September 29, 2007 Author Share Posted September 29, 2007 your spark plug is fooked Mechanic found the problem and showed me the pieces. A valve-stem snapped which cracked the guide. The valve traveled down into the piston where damage was done. I'm ordering a new head, piston, valve etc. to the price of $840 dollars including parts and labor. OUCH! What would cause a valve stem, right up near the top, to just snap off? Kevin Link to comment Share on other sites More sharing options...
jinxed Posted September 29, 2007 Share Posted September 29, 2007 And there was me just about to shout "broken valve", "BROKEN VALVE". I have two SR125 engines that have broken valves (one broke the inlet, the other the exhauset I think); I've not had this trouble on any other bike I hasten to add. I wish I knew why they break; mine broke right at the top where the spring retaining washer sits. I can only guess that the frequent banging causes them to work-harden and go brittle. Maybe if the clearance is too wide, they work-harden faster than they should. (My feeler gauges are rusted real bad & I can't tell which is which anymore!) One of my heads has a damaged valve guide too; maybe this increased the friction on the valve, putting it under more stress. Maybe? As it was a 20 year old bike, I just threw a new valve in & crossed my fingers. (I.e. ignored the damaged valve guide.) 4 weeks later the camshaft gear slipped, which put the timing WAY out & the piston hit the valve and broke the rocker arm. I could go on ....... it ran out of oil recently & seized ....... How much more can this engine take!! $840 is a big ouch! Is it not cheaper to get 2nd hand engine? (Hence I now have three engines in various states of disrepair.) Link to comment Share on other sites More sharing options...
TamzSR125 Posted February 16, 2008 Share Posted February 16, 2008 ok well i dnt know much about mechanical faults but when doing 40mph on my sr, the engine cut out again no reasons, petrol etc etc was fine it turned out the ignition barrel was slightly worn and as i had gone over a slight bump it cut the engine just a thought maybe Link to comment Share on other sites More sharing options...
Recommended Posts