Guest Posted March 15, 2015 Share Posted March 15, 2015 Hi I am new to this forum, i have replaced the piston on my cg 125 2006 (not timming chain) after a rebore, now i have no compression, any ideas ? Quote Link to comment Share on other sites More sharing options...
Tango Posted March 15, 2015 Share Posted March 15, 2015 Welcome to TMBF mate.......pop over to the newbies section and introduce yourself to the gang when you can...... How much was the overbore?....did it need an oversize piston? Also check your valve timing and clearances as you'll lose compression if the valves aren't seating fully.......and make sure the head gasket is ok too..... Quote Link to comment Share on other sites More sharing options...
Guest Posted March 15, 2015 Share Posted March 15, 2015 Hi Tango,rebore with new piston,on the n/s of the engine there is a slotted disc, what is it for? when i had the engine out i did turn it !!!! Quote Link to comment Share on other sites More sharing options...
Ricky Posted March 15, 2015 Share Posted March 15, 2015 You did time it up properly didn't you? Quote Link to comment Share on other sites More sharing options...
Guest Posted March 15, 2015 Share Posted March 15, 2015 time it up ? i only removed the head and barrel,why would i check the timing ? Quote Link to comment Share on other sites More sharing options...
Guest Posted March 15, 2015 Share Posted March 15, 2015 just to mention, my engine is the push rod, not timing chain Quote Link to comment Share on other sites More sharing options...
Ricky Posted March 15, 2015 Share Posted March 15, 2015 Apologies, not clued up on CG125s assumed it was chain. Quote Link to comment Share on other sites More sharing options...
eastanglianbiker Posted March 15, 2015 Share Posted March 15, 2015 did you use a new gasket between the head and cylinder? have you located the pushrods correctly?have you installed the piston rings correctly on the piston without breaking any as you put the barrel back on these are just some of the reasons you may not have compression Quote Link to comment Share on other sites More sharing options...
Guest Posted March 15, 2015 Share Posted March 15, 2015 New gaskets all round, when engine is turning over the valves open and close, on the n/s of the engine just above the gearlever there is a slotted disc that turns when you remove the long locking bolt, whats it for ?? Quote Link to comment Share on other sites More sharing options...
Mr Fro Posted March 15, 2015 Share Posted March 15, 2015 That's not the clutch you're looking at is it? A picture would be good...For compression after a rebuild I'd add checking the head is torqued down right and to re-do the valve clearances as these will have changed with the new gaskets. Quote Link to comment Share on other sites More sharing options...
Lumor_uk Posted March 17, 2015 Share Posted March 17, 2015 you turned the stator fly wheel. depending on what was attached you may have got the TDC top dead centre back to front.would check the valve clearance first though. Quote Link to comment Share on other sites More sharing options...
eastanglianbiker Posted March 17, 2015 Share Posted March 17, 2015 you turned the stator fly wheel. depending on what was attached you may have got the TDC top dead centre back to front.would check the valve clearance first though.doesnt matter how much the engine is turned on a pushrod engine as the cam has not been emoved from the chain or drive cogs so cam timing will not have altered,you dont need to line anything up on a top end rebuild on a pushrod engine so the problem has to be either compression or lack of spark Quote Link to comment Share on other sites More sharing options...
Lumor_uk Posted March 17, 2015 Share Posted March 17, 2015 been 5 years since I replaced the rings on my CG. re reading this thread I'm going to say he hasn't put new piston rings on? Quote Link to comment Share on other sites More sharing options...
eastanglianbiker Posted March 17, 2015 Share Posted March 17, 2015 or not spread the gaps out on the rings so the comp can pass straight up side of piston Quote Link to comment Share on other sites More sharing options...
Guest Posted March 21, 2015 Share Posted March 21, 2015 Hi thanks for all replys, but my question is,on the n/s of the engine just above the gearshift,there is a round disc with a slot in it, a bolt locks it so it cant turn,when the bolt is removed the slotted disc can be turned ,i know its something to do with the cam timing, but what ?? Quote Link to comment Share on other sites More sharing options...
Mr Fro Posted March 21, 2015 Share Posted March 21, 2015 Again, pictures would be really helpful. Quote Link to comment Share on other sites More sharing options...
Lumor_uk Posted March 29, 2015 Share Posted March 29, 2015 Cam chain tensioner?Try this site www.lingshondaparts.com/honda_motorcycl ... mod_01=667 Quote Link to comment Share on other sites More sharing options...
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