halfway Posted June 15 Report Share Posted June 15 Hi, got an unknown age 125 4 stroke with a yamaha engine, monoshock. Trying to find out some servicing info or links to manuals for these, engine oil, brake fluid, carb settings etc. It does have quite a loud ticking from the top end, which comes and goes a bit but is there right through the rev range. It runs ok except a bit hesitant at low rpm. Any obvious problems with these engines that would give the ticking? Quote Link to comment Share on other sites More sharing options...
konrad Posted June 15 Report Share Posted June 15 Regarding ticking, have you checked the valve clearance? Regarding low-rpm hesitation... 1 Quote Link to comment Share on other sites More sharing options...
halfway Posted June 15 Author Report Share Posted June 15 Valve clearance and cam chain were going to be my first checks in a couple of days, hopefully just the valves not adjusted to spec. Any ideas what spec should be? Quote Link to comment Share on other sites More sharing options...
konrad Posted June 15 Report Share Posted June 15 TT-R125 manuals are available online. Valve clearance (cold) IN: 0.08 ~ 0.12 mm (0.0031 ~ 0.0047 in) EX: 0.10 ~ 0.14 mm (0.0039 ~ 0.0055 in) Check the cam chain tensioner too. 1 Quote Link to comment Share on other sites More sharing options...
Tr1AL Posted June 15 Report Share Posted June 15 (edited) @halfway www.birkettmotorsport.com - scorpa - parts books - halfway down the page. SY/TY 125F info. Edited June 15 by Tr1AL 1 Quote Link to comment Share on other sites More sharing options...
lemur Posted June 16 Report Share Posted June 16 Screw adjuster valve clearance tightens with wear as the valve wears into the valve seat. Valves do travel at half speed of the crank, is the ticking in time with the crank or valve train, that can help to narrow it down some times. Your bikes parts manual shows only one spring on each valve, most have 2 springs wound in opposite direction to each other (stops the valve from rotating), I'd be looking for a damaged valve spring if it turns out to be a valve noise. Quote Link to comment Share on other sites More sharing options...
halfway Posted June 16 Author Report Share Posted June 16 So the valves were slightly tight, the cam chain and tensioner all seem good. Can't see anything broken with the valve springs but a bit hard to see into the rocker space. Interestingly the cam was one tooth out on the chain but setting that right has made no difference to the tick. Carb through the ultrasonic cleaner and it startes first time and goes to a nice tickover after a bit of tuning the mixture screw. Pulls great, revs hard and ticks over well. Sometimes gives a cough if you give it a load of throttle at tick over but only 1 in 10 times. Lifts it's front wheel with just throttle quite happily and feels like it has good compression with the kickstart and doesn't smell at all of oil or burning. Ticking is still there, changed the oil and it was old. Had a silvery shimmer to it with some bits. Passing a magnet through the oil and nothing picked up, silver bits and clutch material are all 1 to 2mm bits. But probably hasn't had new oil in ages. Ticking is hard to place, using a stethescope it sounds clear all around the crank cases. Seems a bit louder at the front top of the engine but I am struggling to place it. At first I thought rings or small end but it isn't any louder noise listening directly to the barrel. It doesn't change at all with clutch in or out, or in gear. Ticking is heard clearest with my head above the tank, not to the side of the engine, although you can hear it is ticking as soon as it starts from anywhere near the bike. 1 Quote Link to comment Share on other sites More sharing options...
lemur Posted June 16 Report Share Posted June 16 If it is above the tank and not to the side, you're not just hearing a wasted spark ignition are you? If timing is off the crank it is a wasted spark system. 1 Quote Link to comment Share on other sites More sharing options...
konrad Posted June 16 Report Share Posted June 16 (edited) 3 hours ago, halfway said: Interestingly the cam was one tooth out on the chain.... Clearly, someone before you has had it apart. Is the top end getting sufficient oil? IIRC, there is an oil pressure check bolt in the head. There's no oil filter but, there is an oil screen that can be cleaned if you remove the clutch cover. Edited June 16 by konrad 1 Quote Link to comment Share on other sites More sharing options...
halfway Posted June 16 Author Report Share Posted June 16 I would be surprised if it is just a spark making the noise as it's quite pronounced. Be great if that is all it is though. Will probably pull the clutch cover and have a look, clean the gauze as well. I didn't notice an oil flow bolt but again good call, will take a look. There was plenty of oil in the rocker cover. Quote Link to comment Share on other sites More sharing options...
halfway Posted Tuesday at 11:46 AM Author Report Share Posted Tuesday at 11:46 AM Just an update, engine has had a full strip and clean, new gaskets and seals, valves lapped etc. It had smoked a little but new valve stem seals have fixed that. And found the ticking, it has had a new barrel and piston at some point and the piston with standard gaskets was just touching the cylinder head, making a nice clear ticking sound! Took a while to find what it was and as a temp fix and to double check that was the problem it has gone back together with 2 base gaskets, a new one and the old one. Ticking gone. 1 Quote Link to comment Share on other sites More sharing options...
konrad Posted Tuesday at 01:12 PM Report Share Posted Tuesday at 01:12 PM 1 hour ago, halfway said: ...piston with standard gaskets was just touching the cylinder head, making a nice clear ticking sound! Thanks for reporting back! Just FYI, that condition is really hard on the rod bearings. Quote Link to comment Share on other sites More sharing options...
halfway Posted Tuesday at 03:59 PM Author Report Share Posted Tuesday at 03:59 PM 2 hours ago, konrad said: Thanks for reporting back! Just FYI, that condition is really hard on the rod bearings. Yeah it's not great. There was no witness marks or scuffed bare metal and the bore almost looked new so looks like it hasn't even been run in yet which is good, ie hasn't run much. Turning the engine over there was no tick, turning it fast with an electric drill on the crank and plug out and only the lightest of ticks. Seems that in this case was lucky and it was only just touching. Quote Link to comment Share on other sites More sharing options...
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