HELP NEED PITPRO !140cc

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XCHSER

XCHSER

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Hi Guys

My Problem is that the bike wont start. The carby spotless fresh fuel got sprak but wont start. If i put fuel in the head it will fire up and run of the fuel in the head but as soon as that burns the bike turns off its like the bike wont suck petrol from the carby also have changed carbs still no fire just runs only of the fuel i put in the head..

I have no idea what to look for so if anyone can help me out please let me no what to do or what i should try next.

Thanks chaser
 
First off ... check to ensure that the fuel is TURNED ON at the tap ... LOL ...

Then check to make sure that fuel is flowing into the carby thru the line out of the tank ... To check the tank ... Remove the fuel cap and the line off the carb ... drain the tank then blow back thru the line to see if it's hard or easy ... then try it again with the cap and breather on to check that your tank breather isn't blocked and forming a vacuum in the tank ... I've seen that happen a few times ...

It's a good idea to remove the tank off any new or used bike when you first get it ... drain it then swish clean fuel around inside and tip it into an ice cream container or white bucket to flush any crap out ... do that several times to be sure ...

I've come across weird problems with cars that have sealed tanks ... They'd start up , idle and run great until you took them for a good acceleration run ... They'd rev out cleanly and haul ass then suddenly they'd bog and die in the ass ... then run good again after you slowed down ... then the same would happen every time you repeated the test ... It turned out to be a combo of junk in the tank and the breather lines or charcoal canister blocked ... you can tell straight away if you hear a suction or pressurisation noise as you remove the fuel cap ...

The following is highly unlikely since you double checked with a second known to be good carb ... but I'll say it anyway ... The carbs float needle can also be jammed or the float level can be set too low ... Unscrew the drain screw in the bottom side of the float bowl to see if fuel runs out ... water in the float bowl can also sit there displacing fuel and cause zero fuel flow but it usually causes spluttering and dying when you rev the engine ... The fuel needs to be at the right level in the bowl otherwise the jets suck air ... sometimes bits and pieces of plastic tank shavings can sit in the line and block off or restrict flow into the carb ...

Also check your valve clearances ... engines are a one way air pump ... but only IF the valves are sealing and timed right ... if the inlet valve is being held open or is not seating ... then the air flow reverses back out thru the carb instead of sucking fuel and air into the cylinder ...

Last of all if the above checks fail ... check for air leaks at the joints between the carb and head AND the throttle cable seal at the top of the carb ... any leaks will cause the engine to suck air with minimal fuel since the jets get bypassed ...
 
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Hi i thinks its got something to do with the valve clearances due to the fact the the bike wont even start with aero start sprayed down the carby. I thought it might of been a bent inlet valve but it took the top cover off and its seems to be moving freely not stuck or bent. So im Guessing that the clearances are out due to the fact that you said if the inlet valve is being held open or is not seating ... then the air flow reverses back out thru the carb instead of sucking fuel and air into the cylinder ... That would explain why the bike was starting with petrol tipped into the head.

Do you Have any specs on what the valve clearances should be or any advice on how to check them and re adjust them if there incorrect.?

Cheers Aaron
 
put it at tdc on the compression stroke:) check it on the flywheel. the mark T should be at 12 oclock
worth taking the timing sprocket cover off and the dot on it should be at 9 oclock...if its at 3 oclock it needs another turn on the crank.

clearances about .004 on average...

youll need a 9mm spanner and a pair of pliers, some feeler guages(or two sheets of paper), back of the locknut, adjust the screw till its not loose and not tight on the feeler guage(sliding fit) then tighten the locknut back up

before loosening anything, just check the valve rockers.... if they have some movement at tdc, its all good.

and first up...hows the compression on the thing?

whered the aerostart come from, you hijacker of threads?:p
 
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Hi sorry i was a mates house on his comp coz i had to give back his carby , the one i tried on my bike. Umm with the valve clearances where am i putting he feeler gauge in between. I now inlet is .003 n exhaust is .004 but just don't no where i putting the gauge in between lol sorry its my first time lol dont no anything really about 4 stroke lol.
 
undo the two caps(one on top, one on bottom), that have either a 17mm nut or two 8mm bolts(depends what engine that detail)

and that exposes the adjuster for the valves. you slip the guage under the adjuster and above the valve end.... its a tight fit, usually have to bend the guage to get in there.
 
No Problem will do that now check the timing when the t is on the 12 the cover is on 3 O'clock i can get you a pictures doe that mean it not my valves its the timing ? what step should i take next will upload picture in 1 min to show you i need help lol if i have to adjust the timing and that bare with me lol
 
read what i said again...T at 12 and the dot on the sprocket at 9! if its at 3, you have to turn the crank one full turn cause its on the exhaust stroke, ie, both valves are open....sorry, confusing, i know:eek: my bad...

so at 9 oclock. 9.
 
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lmfaoooo ahahahh ok will go check that lol and will go check valve clearances lol i thought i had to adjust the timing and spin the whole crank around and put the chain back on lmfaoo lol dw my bad lol i thought it was weird
 
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Yes they should be stickied ...

The pic of the flywheel is right except the "T" has to be lined up dead in line with the notch in the case and the pic of the head shows the dot on the cam sprocket 180 degrees out facing to the right at the 3 O'clock mark ... One full crank turn will get the marks in the right position to set the valve clearances ...

Inside the cam cover bore towards the front of the engine there's another mark (line) which the mark on the cam sprocket should be lined up with at the same time that the "T" on the flywheel lines up with the notch on the case ...

There seems to be a lot of people with starting problems due to poor valve adjustment maintenance or from bending the valve after reassembling their engine wrong OR over revving their engine and floating the valves ...

This guys engine mysteriously has the same specs as the one which Le Garage just sold ???? ...

bike wont start. Valve leak? HELP!!! - Planet Minis
 
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