Carby Help

[tez]

Hey Guys, I just picked up a second hand Atomik Nitrous Motard for $500, i have one problem with it and its just a puff of smoke comes out the air filter once i kick-start it.

It starts fine but i'm just wondering if i leave it, will it effect the bike? i had looked around on the forum and found that it could just be that the valves are out..? Any help would be much appreciated !

 

[my67xr]

i would adjust the valves anyway on a used bike,
they are possibly too tight ?
it should help get rid of the puff out the carby when starting

do you need a link for inlet/exhaust valve adjusting ?

 

[tez]

yeah good point they mightbe! , yes please if you wouldn't mind

 

[my67xr]

here is a video link from OO Racing, it will give you the basic idea on how to do it.
http://www.youtube.com/watch?v=QJciyJRJh8Q

but set the clearances to this-
imperial measurements- .003" clearance on the intake valve, and .004 " clearance on the exhaust valve
metric measurements- .076mm intake valve, and .1mm exhaust valve

 

[DHZ_XR8cing]

Craig has your problem all sorted in the above answer's for sure.
Make sure you dont leave it too long because eventually there will be a build up of fuel and the air filter will catch fir then you will be up for a new filter.

 

[tez]

no worries, thanks guys

 

[zwebx]

if its done alot of hours it could be the inlet valve not sealing so good and bending like a mushroom (you know flairing out) like what i had on my lifan

 

[tez]

hmmm it also backfires and pops at high RPMs, i recon ill just take it in to get a good service and go from there

 

[zwebx]

hmmm it also backfires and pops at high RPMs, i recon ill just take it in to get a good service and go from there

probably dont worry about it
if you loose compression when hot (a little too tight) or dont have any compression to begin with is usually when there wayy to tight

 

[tez]

sick ill just see how its goes

 

[my67xr]

the backfiring and popping could be caused by a vacuum leak too.

start the bike and warm it up.
then spray some degreaser or carby cleaner on the bottom join of the carby where the fuel bowl joins
on the carby to manifold area and the manifold to head join.
if the idle changes in any way then there is a leak there.


popping on decelleration is usually caused by the exhaust flange leaking.
there is a copper gasket in between the exhaust header pipe and the cylinder head,
if the bolts are loose then it can let air in and pops out through the muffler.

 

[tez]

i checked again one was wasn't very tight but i couldn't get to the other one because of the bash plate. ill take it off tomorrow and fix them both up

as for the carby, ill have to check that tomorrow.. if that is the case, would i be better off just buying a new carby?

 

[my67xr]

if there is a leakat the fuel bowl, it could just be a matter of tightening the 4 screws on the carby base ?
or if it is at either end of the manifold, a simple gasket replacement could be needed.
you could make your own new gasket if you can use a box cutter

sometimes the manifold side of the carby warps a little too.
it is easy to face it flat again by rubbing the face across some 320 grit sandpaper, wrapped around a hard sanding block

 

[tez]

sweet sounds good to me, thanks for the help!