qtws Posted February 22, 2008 Share Posted February 22, 2008 hey there folks, I'm newly registered and delurking - in need of some advice. I have an sr125 (1997) which following a simple carb strip (crud in the fuel) and rebuild is sounding a bit funny. I'd got the engine running and warm, and was adjusting idle speed (screw in side of carb ~1.25 turns out from fully in), pilot screw (1.5 out) etc, and then gave her a rev up. Cue much rattling from the top end, so I stopped the engine, and when it was cool found that the inlet valve adjuster lock nut had come loose and worked its way to the top of the adjuster. So, I adjusted the valves, rotating the engine to TDC on the compression stroke and setting the gaps, tightened the lock nuts properly. So far so good. When I started the engine again and got it idling nicely, I was aware of an intermittent noise from it. Walked outside the garage, where I could hear the engine put-put-putting away like it used to, but every now and then I could hear a sort of "dink" noise, like two bits of metal hitting each other at high speed. No real rhythm, just the unsettling noise every now and again. Oil is new, changed <100 miles ago. Timing seems to be ok, all connectors/jubilee clips/header bolts etc. properly tightened. 42k miles. Anyone come across this sort of thing? What might it be? The one thing I noticed about the cam followers, was that they were quite "loose" at anything other than TDC on the compression stroke - there seemed to be a lot of free play in there, which I'm not sure is normal - or is it on sr engines? And if it is't normal, where could the problem lie (without taking the head off)? TIA, Nigel Link to comment Share on other sites More sharing options...
jinxed Posted March 7, 2008 Share Posted March 7, 2008 hey there folks, I'm newly registered and delurking - in need of some advice. I have an sr125 (1997) which following a simple carb strip (crud in the fuel) and rebuild is sounding a bit funny. I'd got the engine running and warm, and was adjusting idle speed (screw in side of carb ~1.25 turns out from fully in), pilot screw (1.5 out) etc, and then gave her a rev up. Cue much rattling from the top end, so I stopped the engine, and when it was cool found that the inlet valve adjuster lock nut had come loose and worked its way to the top of the adjuster. So, I adjusted the valves, rotating the engine to TDC on the compression stroke and setting the gaps, tightened the lock nuts properly. So far so good. When I started the engine again and got it idling nicely, I was aware of an intermittent noise from it. Walked outside the garage, where I could hear the engine put-put-putting away like it used to, but every now and then I could hear a sort of "dink" noise, like two bits of metal hitting each other at high speed. No real rhythm, just the unsettling noise every now and again. Oil is new, changed <100 miles ago. Timing seems to be ok, all connectors/jubilee clips/header bolts etc. properly tightened. 42k miles. Anyone come across this sort of thing? What might it be? The one thing I noticed about the cam followers, was that they were quite "loose" at anything other than TDC on the compression stroke - there seemed to be a lot of free play in there, which I'm not sure is normal - or is it on sr engines? And if it is't normal, where could the problem lie (without taking the head off)? TIA, Nigel Might it be "pinking"? I.e. pre-ignition. Can you check your ignition timing? To be honest, mine makes so much noise anyway that I probably wouldn't know if it was doing the same. 42K miles is quite impressive on that beast; has it been apart recent for major engine surgery? If you have set the valve clearances correctly, then there shouldn't be much play as you describe. (The clearances are posted in another thread.) Is there more clearance on one side of the valve top than the other? Maybe the camshaft bearing is worn? (One of mine was; the end that the chain fits over would move up & down with the camchain removed!) Link to comment Share on other sites More sharing options...
Moderator drewpy Posted March 8, 2008 Moderator Share Posted March 8, 2008 The one thing I noticed about the cam followers, was that they were quite "loose" at anything other than TDC on the compression stroke - there seemed to be a lot of free play in there, which I'm not sure is normal - or is it on sr engines? And if it is't normal, where could the problem lie (without taking the head off)? TIA, Nigel you sure you got tdc?, double check by removing the spark plug and holding thumb over hole and turn engine over to the correct timing mark (its not necessarliy TDC either) Link to comment Share on other sites More sharing options...
Trilby Posted April 25, 2008 Share Posted April 25, 2008 i have the exact same problem, you desribed it perfect....like metal hitting something. My 2001 SR has only just done 5000 Miles....i thought it was the tappets so i sorted them, then i put it down to maybe the cam chain but that and the timing in general are all fine....then next the mixture in the carb....this does seem to sort it out but it seems to somehow reset itself after an hour or so. I think im just gonna get a new carb and see if it does it again. It is a very intemitent noise and it only seems to occur on tick-over. and when the bike has warmed up it seems not to happen as often....can anyone help? Link to comment Share on other sites More sharing options...
qtws Posted June 4, 2008 Author Share Posted June 4, 2008 thanks for the replies folks - been away rebuilding the XJ (MoT today - no problems!) and doing work stuff, so the sr has sat in the garage since then. lessee....TDC? yes - checked by "plug out pencil in" method - matched timing mark. Will thumb check for compression at this point tonight. I had considered pinking - will need to get a drop of decent fuel in the tank. A worn camshaft bearing could be a possibility (- like XJ front wheel bearings ) for the apparent lack of stability in the valve clearances once set correctly. The previous 200 miles were at 60mph cruising - 100 there, 100 back, on a 42k engine (just for the fun of it) Carb settings are std, and AFAIK, the engine has not had recent surgery - although the guy I bought it off did have the head off for some reason - must check what it was... If I can get it going, I may well just whack in the earplugs and not worry too much - the bike was bought for a 10mile round-trip commute, but it was running like a sewing maching prior to all this. Cheers, Nigel Link to comment Share on other sites More sharing options...
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