Valve Clearance and Setup

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Na$hY14

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hey can valves make my bike back fire and stutter if not set up right?
because my bike stutters and backfires at high 3rd and half 4th.
ive checked out everything, carby is all tuned up, the plug is brown
no air leaks in the exhaust and adjusting then sensor on the irk does
nothing to stop it.

if so what are the inlet and exhaust clearances?
thanks
 
valve clearance for a lifan 140

all i know is that itz .003 for intake
and .004 for exhaust but is that in inches or mm?
 
yea its in inches, go to your local hardware store and they should have a set of feeler gauges. and then when your doing the valves find the 3 and 4 thou gauge and it should slide in and out not too easily but you can feel it scraping. im sure one of the other guys on here could probably go into more detail with that if you need it or correct me if ive made a mistake but i think i got it.

hope this helps,
matty
 
yup buy some feeler gauges and do it but ur bike has to be cold
 
oh yeh i know how to adjust valves but i was wondering
if incorrect valve gaps cause my bike to stutter and backfire at
high RPM?
 
it did to my bike but it was right thru the rev range
 
i dunno but since i did mine it kinda does that, except we have done them to the correct clearance and it still does it, like when you hit hight rpm and then shift into the next gear it'll die down n sometimes backfire. im not sure.
 
I just had the same sort of issue with my own bike cutting out high in the rev range, went through everything, carby, electrics, fuel air mix etc. Messed with the fuel air mix and carby for a whole afternoon to try get it right but to no avail. Took it back to Pete as SAFB and it turned out to be a valve clearance issue. I have a Jailing 125 engine not Lifan, however it was explained to me that the process itself is not ridiculously hard but having the correct equipment as in feeler gagues etc is important. I have no idea how to go about this process but the way i looked at my own situation was that i would rather take it to someone who knows what theyre doing and have it done properley so then i can concentrate on riding my bike and having fun! Might be worth taking it to someone to get sorted properley mate if your not confident on doing it yourself...
 
oh yeh i thought it might be my valves
because ive checked out everything
and yeh still had the cutting out at high RPM

ill go readjust my valves tmoz and let you guys
know how it went.

cheers
 
i done my valves today
just had a lil more compression back
but it still doesnt run good
up high. stutters like the jets are blocked
but there not. so whats the problem?
 
it has to be air fuel mixture if not that maybe your spark in terms of spark regulation or even lack of at high rpm

it's a tuff problem i hope someone has a bit more insite
 
around .0025 to .003. You wont ur exaust valve to extend more then the intake.

Replaced you spark plug? Thats what happens when the plug dies. Also check your coil. Check for leaks in the carby, spray some wd40 or somthin on it, and if theres a leak, you will notice a increase of rpm. If its theexaust, you wont feel a great diference, just it wont run crisp. If its the engine, you will feel it.. it will "die" in power terms.
 
Last edited:
Please deleate, i got confused and posted twice about the same thing :(
 
nah checked my carby and exhaust. no leaks there.
changed over plug and it still does it. it started
happening when i put the irk on. ive moved the sensor
all the way either end and it still does nothing.

i have no idea whats going on.
 
so you guys reckon my cdi
is busted since it wnt let
me go past a certain speed?
and when i rev it idling it still cuts outs
or could my coil not produce enough
electricty for my plug?
 
mate change ya coil, this solved the problem on my bike, trust me it will get worse as time goes on. mine started doing this at high rpm in 3rd and 4th then went on to happening in all the gears. there cheap get one off a yamaha bike they work really well and last longer
 
mate change ya coil, this solved the problem on my bike, trust me it will get worse as time goes on. mine started doing this at high rpm in 3rd and 4th then went on to happening in all the gears. there cheap get one off a yamaha bike they work really well and last longer
can u use any coil?
if so ive got a spare suzuki 1 im might chuck it on
 

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