Newbie needs help!!!

[james1981]

Hi first of all im a newbie and any help is extrememly appreciated, and thank you in advance.

heres my problem, i have a cheap chinese 4 stroke 125, went to ride it this morning, fine first five mins then died. spark plug and cap looked rubbish, replaced them kicked over and started fine but will not idle and spluttery at hig revs. but before i did this i was going to strip engine only removed one screw before i thought i could not be bothered. but the screw i removed looks like it controls some arms near bottom of engine that rest on a cog in bottom end of engine. now i tried to kick the bike before replacing this screw(forgot about it) put it back in and wondered if this screw or bolt had anything to do with the firing of the engine. i have attached a crude drawing of what the screw or bolt looks like and the arms and the cog in the order they are on the engine. does the piston need to be at TDC before tightening the screw or vice versu. any help is really appreciated thanks you.

[stirlinggaz]

hi,
i have owned a few chinky bikes & generally find its a bad move dismantling the engines.
do you know what model of engine it is? 157FMI? 156FM1/2?
I dont understand your drawing, so any chance of a pic or 2?
im struggling to think of the bolt you are referring to, tbh, i cant think of any bolt that would have the effect you described.......
cheers,
GAZ

[.]

this is just guessing in the dark here but....

To me it looks like this bolt probably locks the shaft that those arms pivot on to avoid damaging the soft alloy casting.

If so a few miles with it rotating probably won't do too much harm, but getting it back in place may prove difficult.
TDC on compression would be a good place to start because if it is part of the valve train this will take pressure off the moving parts.

If it does lock the shaft down then the shaft must be removable, perhaps behind an access cover/screw head.
The end of the shaft may be marked to identify its assembly position. Try looking for one but do not slide the shaft out or attempt to remove it, otherwise those arms could drop down into the engine.

[ZRX61]

[crackpotterpi...]

here is the proof that a little knowledge is dangerous,when I say a little knowledge I mean how to open the drawer containing the screwdrivers!! lol
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1990 jc20 nsr125-sold,2003 cg 125-sold currently no bike.........might get another 2 stroke me thinks much more fun

[Billing]

If its a copy of a CG125 engine, then I think that screw goes through the pushrod guide, the little cog should have the cam lobe next to it I can't remember exactly what the cog does, possibly something to do with the gearbox

To the CG manual!
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'84 TS50X, '91 TZR125, '89 CBR400RR, '91 VFR400R NC30, '98 R1
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