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Post by marcmorgan12345 on Feb 23, 2017 16:21:07 GMT 1
hi there all I am new on here so go gentle with me.my name is marc and I have 3 125lc,s all to be restored.the one I am on at the moment is a mk2 with working ypvs.the bike is all done now apart from paint and a niggling engine problem that I hope can be sorted with some help on here.i have rebuilt the engine with new bearings big end ,little end ,piston,seals ect you get the picture.the bike will start and idle well but when its revved up, on the over run/throttle closed position there is a knocking noise coming from the bottom end and its also the temperature getting hot quite quickly aswell. I have tried different setting on the carb ie different jet sizes ect ,but to me its like the timing is out but I understand that there is no adjustment.i have hit a brick wall with it now and any help would be appreciated. |
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Post by davey on Feb 23, 2017 21:47:35 GMT 1
Sounds mechanical rather than carburation , is it a more of a clunking than light rattle
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Post by marcmorgan12345 on Feb 24, 2017 3:12:29 GMT 1
hi there yes its kind of like more of a erratic clunk I suppose,definitely not a rattle.i have just taken of the clutch and checked everything and alignment marks ect and also the flywheel and rotated the engine and all seems to be ok.
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Post by wonkywheel on Feb 24, 2017 20:53:06 GMT 1
First things first... welcome in, great forum with a wealth of experience.
Are you saying Its clunking after you rev off? Has the balance shaft has been aligned- clutch basket checked for free play- used a Yam PDF parts manual to make sure all parts are present and have been fitted in the correct order?
I had a nasty bottom end noise a while back- panic- it must be the crank?! Na, the baffles were rumbling.
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Post by marcmorgan12345 on Feb 25, 2017 4:30:01 GMT 1
hi there wonkywheel,yes a clucking noise after the rev off. I have taken the complete clutch off and checked the alignment/timing marks ect of everything and all was how it should be.not sure about the free play in the clutch basket though but I do have four all together and they all seem to be the same as in movement. I am pretty sure that nothing is missing or fitted incorrectly,so what should I try or check next.
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Post by wonkywheel on Feb 25, 2017 10:59:44 GMT 1
Restorations can sometimes test our patience. I had engine virbration on a rebuilt only to find out i hadn't tightened the engine mountain bolts- idiot!
Strange- as you said- all bearrings etc have been changed. Some guys have fitted a mk2 con rod which is the wrong size, although i dont think it would even start.
Process of elimination- maybe disconect the ypvs servo motor- fix the PV to check it isn't that.
If you still think it mighti be timing check the flywheel and stator windings- do a resistance check- at least you will know your ignition is ok.
If you think its running too hot- check that the thermostat is opening and the water pump impeller shaft has not broken from the plastic housing- latter is rare.
I'm sure you will sort this
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Post by marcmorgan12345 on Feb 25, 2017 20:28:31 GMT 1
hi there when I got the bike it did indeed have the wrong con rod fitted so that had to be changed.like you say its just got to be a process of elimination.i will just have to check and double check everything again and hope I find something.thanks for your replies I will update on here when I know some more.
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Post by jollyr6 on Mar 6, 2017 13:47:34 GMT 1
Welcome to the forum I hope you get your gremlin sorted it can be a pain in the pisser when you've done all that hard work and something isn't quite right chin up youll find it
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Post by mattybeckett on Mar 6, 2017 19:56:29 GMT 1
Welcome, problems like this are a pain as i know and have experienced in the past, regarding your problem have you grabbed hold of flywheel to check for slight play? even though you have fitted new main bearings the old ones could of seized at some point in the past and that causes the outer race of bearing to spin in crankcase are wear it! worth checking!! I had the same problem on a yb100 years ago and couldn't afford to get new cases, i ended up shimming the gap with a feeler gauge blade and it ran for years sweet as a nut  |
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Post by marcmorgan12345 on Mar 15, 2017 11:52:15 GMT 1
hi there sorry for the delay but I have been away, no I haven't checked that but I certainly will I have got nothing to loose. thanks.
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Post by mattybeckett on Mar 15, 2017 23:07:52 GMT 1
hi there sorry for the delay but I have been away, no I haven't checked that but I certainly will I have got nothing to loose. thanks. Hi and welcome aboard, I would suggest you make a youtube clip for people to hear what you are hearing and maybe someone will recognise the sound, Don't forget to post a link on here if you do make a clip. Would certainly be more interesting than what's on the box tonight lol |
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Post by marcmorgan12345 on Feb 23, 2018 23:12:28 GMT 1
hi all I know it been quite a while to say the least, but I shelved it up until now because it was just doing my head in.
I got it back out the other day with a thought of the flywheel being wrong as all along the problem seemed to be a timing issue and guess what it was the wrong one fitted. all these months of pulling my hair out. I am just relieved its running now and it went first kick with the correct part fitted, just goes to show that sometimes buying a none runner can be more of a headache than you think.
well its running sweet now and all I have to do now is paint the tank and plastics.
cant wait to see it finished.
thanks for all your help and thoughts on this over the last few months.
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Post by simon998 on Feb 24, 2018 11:24:51 GMT 1
Glad to hear you got it sorted man! Fire up some pics of your fleet.
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Post by broughton on Feb 24, 2018 16:22:37 GMT 1
pleased for you mate glad you got it sorted
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