halfway Posted Sunday at 08:31 AM Report Share Posted Sunday at 08:31 AM 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 Sunday at 01:18 PM Report Share Posted Sunday at 01:18 PM 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 Sunday at 03:28 PM Author Report Share Posted Sunday at 03:28 PM 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 Sunday at 04:12 PM Report Share Posted Sunday at 04:12 PM 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 Sunday at 05:50 PM Report Share Posted Sunday at 05:50 PM (edited) @halfway www.birkettmotorsport.com - scorpa - parts books - halfway down the page. SY/TY 125F info. Edited Sunday at 05:52 PM by Tr1AL 1 Quote Link to comment Share on other sites More sharing options...
lemur Posted Monday at 12:37 AM Report Share Posted Monday at 12:37 AM 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 Monday at 03:24 PM Author Report Share Posted Monday at 03:24 PM 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 Monday at 05:35 PM Report Share Posted Monday at 05:35 PM 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 Monday at 05:37 PM Report Share Posted Monday at 05:37 PM (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 Monday at 06:46 PM by konrad 1 Quote Link to comment Share on other sites More sharing options...
halfway Posted Monday at 07:09 PM Author Report Share Posted Monday at 07:09 PM 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...
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