williamgejone...
L Plate Warrior
Joined: 22 Aug 2018
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Teflon-Mike
tl;dr
Joined: 01 Jun 2010
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 Posted: 14:46 - 22 Aug 2018  Post subject: |
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I am rather perplexed how you can 'fix' a compression problem, without a complete engine rebuild.... loss of compression is usually because the piston rings aren't sealing in the cylinder, and the rings are either gummed up in the piston, and or the cylinder and/or piston rings are worn beyond limits, and/or the valves aren't sealing, usually 'cos the valves burned out or the seat's pitted or worn beyond.
Also raised conundrum how you diagnosed a compression problem... Little CG has a 125cc cylinder and a mere 12cc combustion chamber; getting an accurate compression reading, even with a 'decent' compression tester, used properly, wide-open-throttle, and cranked more than a simple prod on a kick-start, is rather hard, given the experimental error possible from removing a spark-plug that likely tripples combustion chamber volume; unlike on a car, where cylinder is likely 4x the size, combustion chamber volume 4x the size and the spark-plug the same.
However.... this is diagnosis by voodoo... you have bike infront of you, we dont; and description of problem is at best vague....
Do you have a Haynes Manual... for a CG preferably! If not why not? Start there.
Next up; what';s the history of the bike? '96 model is over 20 years old. Plenty of scope for lay-up dereliction to cause problems, particularly low compression, gummed rings and pitted valves; and or wear and tear of years and miles to see it clapped out.
Basic routine servicing, is also a useful thing to do, to eliminate possible problems before you have to find them, especially if you have other, probably more serious problems to deal with.... and its all in the book.
Do you have the Honda tappet tool BTW? If not get it. Tappets should be adjusted every other oil change, which on these things is about every 1000 miles... and lack of tappet tool and or lack of tappet tickling or worse bad tappet tickling without the tool, sees tappets chewed to bludgery.
Good news is that a new barel and piston kit for these little engines is something daft cheap like about £30, and since its a push-rod motor; you can do a top end rebuild in a week-end, with some basic tools and know how... mostly found in the Haynes..... and have pretty much a reconditioned engine for the effort, and NOT have the hassle scratching head trying to fault find compound problems caused by old age, wear and tear and numpty mechanics over the years.. all for the small scary of getting intimate with bits usually hidden from sight and covered in oil. BUT pretty cheap, and not too time consuming, where trying NOT to look at oily bits and find 'problems' by guess work and voodoo tends to take 10x as long and cost 10x as much money, to get to the point of "Well, its chit-or-bust, I gotta take it to bits or chuck it away' in the end anyway....
Your call.
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Current Bikes:'Honda VF1000F' ;'CB750F2N' ;'CB125TD ( 6 3 of em!)'; 'Montesa Cota 248'. Learner FAQ's:= 'U want to Ride a Motorbike! Where Do U start?' |
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jaffa90
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Joined: 06 Apr 2016
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MCN
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bladerunner
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