lifan 125cc engine

C

caiblue

Member
Jul 22, 2008
4
0
hi, i have just fitted a brand new 125cc lifan engine in my sons pitbike & on trying to kickstart it am finding that there is no compression in neutral, there is plenty of compression when in 1st or 2nd gear & i am unable to kick it in these gears,
i am also unsure about the wiring on this engine as the colours differ from the original cdi unit but this should not affect the compression should it?
i was just wondering if it was anything that i have done while fitting it?
although it was a straight swap with new carb & cdi +coil.
any help greatly appreciated. also any ideas where i could find a wiring diagram for these bikes?
cheers,
gordon.
 
C

caiblue

Member
Jul 22, 2008
4
0
re 125cc lifan

it makes no difference if i hold the clutch in when kicking in neutral, but if i hold the clutch in when kicking in second the bike kicks forward & there is compression, but no chance of it starting, cheers.
 

Patman

Pantless Wonder
LIFETIME SPONSOR
Dec 26, 1999
19,765
1
I suspect the "compression" you feel in gear is actually clutch/gear drag. Are you sure there is NO compression in neutral? Does it have spark? Is fuel getting thru the carb? Lot's of possible issues so just break it down to a step by step trouble shooting process and you will get it sorted. If no spark then look ar the wiring first. Next, I have seen the air gap on the magneto pickup being an issue. Take a piece of paper and fold it over 4 times or use a matchbook cover to set the gap, it should be on the left side of the engine. If one of these doesn't get you there then start looking at the CDI or coil. If it does have good spark then check the compression with a gauge. If it's low it could be mis-adjusted valves or just a bad engine. Again I have seen both of these issues. The engines are so cheap in some instances that complete replacement is easier and less costly than the repairs.
 
C

caiblue

Member
Jul 22, 2008
4
0
got it sorted, thank you. it was the clutch cable, needed more play on this engine than it did on the last one which meant that the clutch was half way on before i pulled the lever, my wiring seems to be ok or it wouldnt have started, just the throttle cable & exhaust to sort now.
thanks again,
gordon.
 

Patman

Pantless Wonder
LIFETIME SPONSOR
Dec 26, 1999
19,765
1
Be sure to use a new crush washer where the header fits to the exhaust port.
 
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