valve clearance TDC and idling problems

[bigd]

HI
Here's my prob.
Up until today my bike would only idle with the choke on.
So i tried playing with idle and mixture screws and clip position etc all made no or minimal difference.
So i set it back to standard settings (2 turns mixture and 2 turns idle, clip on middle pos)

Next thing I did was check valve clearances and as far is I know i did everything right
The thing is when I was setting the flywheel to the TDC mark it wouldn't sit right on the mark the flywheel wanted to roll in either direction on its own.
which made it hard to check the clearances cos the slightest bump the flywheel would rotate off TDC.

Anyway after all this I kicked it over and now i can at least idle (very high only) without the choke, but im still getting the same problem i was before where the bike bogs coughs splutters with onlt the slightest amount of throttlle and the idle screw is almost all the way out and still idling high.

any ideas ???
Cheers thanks for reading hope it makes sense

 

[Peter1230]

try adjusting the idle via the cable adjustments.

 

[sean01]

sounds like to set the valve clearance while the valves were on the rock...hence the reason the magneto wouldnt sit still...
were you taking the cam cover off to line the cam gear mark up?

 

[bigd]

yup
cam gear notch and dot mached up when the flywheel indicated tdc.

 

[DvDRip]

what carby and engine? are you using fresh fuel and what type of fuel? does your exhaust manifold ever come loose where it bolts into the head?

I have trouble keeping my flywheel on tdc too, would it even matter if the flywheel was 3degrees out? if it's in the area of tdc wouldn't the rockers be in the same place for a fair bit left or right of tdc?

 

[bigd]

fake mikuni carb ?24mm on a lifan 125cc 1p54fmi
yeah fresh fuel
ill have to check exhaust manifold but pretty sure it would be ok cos i got a new gasket not long ago
not sure bout having it off the tdc mark,
i just got a mate to hold it there
i was just wondering maybe it was put on wrong or somthing in the factory ? not sure i'm certainly no expert but shouldnt it just sit at tdc without having to hold it there ?

 

[pbk]

try adjusting the idle via the cable adjustments.

that can be sketchy doin that coz when you turn it sometime tightens the cable (or take up any slack there) so will probly wanna take off on you when turning hence why they say you should have a little bit of slack anyway (just a few mm's)

 

[sean01]

well just to clarify, your magneto actually has 2 TDC..
crank does 2 turns to 1 cam turn...
remove yr cam gear cover and line the mark up on the cam gear to the mark on the head...it should be at 3oclock..

 

[china boy788]

sean, when you put the head back on, how can you tell its on the firing stroke from the box???

srry for offtopic

 

[sean01]

doesnt matter as long as the piston is up

 

[bigd]

no worries thanks for your time sean but dont you mean 9'oclock ?
yeah got the cam sproket cover off and the notch and dot match up
so when i rotate the flywheel 360 deg another the dot is at 3 o'clcock,
so when the dot and notch are closest together the dot is at 9 oclock. it to the right

 

[sean01]

lol, yeah 9 oclock... getting late and my son has his psp in my ear...
sounds like you have it sused tho

 

[creole]

i had similar probs like yours.
turned out to be a combination of stuck /dirty throttle cable, and dirty carb slider. Both wouldnt let the carb slider thingy return to its normal down position, meaning i always had high idle.

Also check for inlet manifold leaks. they will cause high idle.

splutter sonuds more like ur idle jet is clogged. you get that alot of the time, or the fuel bowl pickup could also be clogged with nice peices of dirt and petcock glue and china fuel tank plastic and fuel cap bits of rubber and if your lucky the fantastic plastic chrome paint ont he fuel caps which love to swim int he fuel tanks.

 

[Peter1230]

that can be sketchy doin that coz when you turn it sometime tightens the cable (or take up any slack there) so will probly wanna take off on you when turning hence why they say you should have a little bit of slack anyway (just a few mm's)

Smarty....

 

[pbk]

Smarty....

haha...i was trying to say it with out being a dick so i thought putting one of these would make it a bit nicer

 

[bigd]

just cleaned the carby the other day spose i'll have to do it again just to be sure.
i'll check the intake manifold for leaks while im at it
thanks again for the replies
its really startin to shit me though !!!!

 

[Peter1230]

haha i know ur kidding!