110cc DHZ pit bike keeps bogging down.

[Sly93]

I have a 110 that bogs down.
It did it at the top of the gears then i adjusted the valves to what I thought was tdc but it didnt line up with the notch on the case but the valves fully opend then closed then i adjusted the inlet at 4 thou and exhaust at 6 thou and now its worse as soon as you gas on it just bogs out ? Also when you have it sitting idling it blows heaps of smoke and aswell as when you rev it so guessing new rings and it feels like when you kick it every second kick or so it kind of jams so i would probaly piston and rings am i right or can some one educate me please lol
Does any one have and idea ? Any thoughts would help.
Cheers, Kurt
This is the bike.
?

 

[my67xr]

so have you set the valves with it all lined up properly now ?
once you have adjusted them you will need to adjust the carby to suit

with the smoking issue, check that your breather at the top rear of the engine isn't blocked or kinked.
do you have the correct amount of oil in it?

 

[gottagetacheaperhobby]

wasnt on the right stroke when you did the timing is my bet, the magneto/flywheel mark should be at 12 o clock and your cam gear marking at 9 o clock with piston at top of its stroke (feel with screwdriver very gently through spark plug hole)

 

[Sly93]

It sits and idles but sit hi revs but thats how i got it i adjusted the air ratio on it to 1 and a half turns out and the timining isnt out on it and yea i did the hole screw driver bit down the plu hole and i can feel it witch is when i set the vavles ?

 

[Sly93]

Could the valves be bent ?

 

[my67xr]

high idle could be the idle speed screw, or a vacuum leak

have you tried loosening the idle screw,
if it doesn't make any difference the throttle cable may be adjusted up too tight.


start the bike and spray some wd40, carby cleaner or degreaser on all the joins on the intake
the carby to fuel bowl, carby to manifold spacer/insulator, manifold to head
if the idle changes in any way then there is your vacuum leak.
you may need to replace an o'ring, or gasket to fix it

 

[gottagetacheaperhobby]

'it feels like when you kick it every second kick or so it kind of jams'
thats what made me think clearances were set wrong, sounds like there is/was slight contact at the top of the piston stroke???

 

[my67xr]

Could the valves be bent ?

might be if the cam and flywheel marks weren't lined up properly when you adjusted the valves?

 

[gottagetacheaperhobby]

his first post says the marks werent lined up properly, he just set them at what he thought was tdc from piston feel....

 

[Sly93]

Ok ill try that tomorrow see if that helps it and when i say i put it where i thought it was tdc is because when i turned the fly wheel over the couple of times to get tdc it didnt line up on the fly wheel and the notch on caseing but the valves opened then closed and the marks didnt line up so i did the driver down the plu hole and gently checked if it would knock and it did so then i did mtly valves ? so could the fly wheel be off maybe the key way is buggered ?

 

[gottagetacheaperhobby]

did you use the cam wheel mark as well?

 

[Sly93]

Well this is where i am at , no matter how many times a spin the fly wheel t dose not line up with the notch on the case the closes i have got ut is on the f on the fly wheel lining up with the notch and at witch i can feel the piston at the top of its stroke through the plug hole with a driver and the inlet valve has got play but the exhaust one has got no play at all evan when i adjust the tappet pretty much right out so could the exhaust valve be bent ? . And with it sitting on the f and the piston at the top of the piston stroke the timing is now out by around 2 teeth but i dont wont touch the timing at the moment incase the fly wheel is wrong ?
Any suggestions ?
Cheers, Kurt

 

[Sly93]

This is the f mark on the fly wheel and casing

 

[my67xr]

pull the spark plug out when you line up the T to the marking at 12'o'clock
the marking on the can gear, is that lined up to the mark at 9 o'clock ?

 

[Sly93]

No matter how many times i spin the fly wheel t to get it at 12 'o' clock it is always at by like 5 past 12 and the cam sprocket is off about 3 teeth and the key way is fine so whats going on ? Should i just buy a new head ?
Cheers, Kurt

 

[my67xr]

i have heard that some flywheels' keyways are a little off where they should be, but have never seen one.
do you have a matching flywheel and stator on it ? neither have ever been changed ?

chuck the spark plug back in and kick it over till you feel it's on the compression stroke, and pull the spark plug out.
put a straw or something down the spark plug hole and let it sit on the piston, hold it there as you turn it over
feel if the straw on the piston moves up then back down as you turn the flywheel towards the T

 

[Sly93]

I dont no if they have ever been changed i bought it like that and i did what you said and it still wont line up with the t and even if i try and sit it on the t it just flicks back to the f ?

 

[gottagetacheaperhobby]

just a thought, can a pit bike cam chain skip a couple of teeth like a car's timing belt if they are worn or a little slack?

 

[my67xr]

it could but would have to be very stretched to do it
one possible thing, is that if the cam chain tensioner bolt on the underside of the engine was removed, and the engine turned over during the time it was out, then it could easily skip a tooth or 3.

 

[gottagetacheaperhobby]

i wasnt sure, just brain storming