85 Kx85 missfireing ...? Help please

K

keane

Recently brought a kx85 as something to mess about on. Was out all Sunday last week with no problems, cleaned and wd40 her before she went in the garage for the week. Got her out Saturday and she wasn't running right... :( hard to explain but it's not a bogging problem, sounds like it's missing ... Then it would run fine for a little while and start doing it again. Would be hard to start and wouldn't run right and then a few mins later would start first kick and run normal. She then didn't want to start at all. Any ideas lads ?? She has good compression Ect and think it could be electrical ...?
 
Mihylo33

Mihylo33

sounds electrical..... maybe a little water in the gas... did you check the spark once it got warm?

1: drain gas, clean carb, refuel and see if it happens again.
2: if after the cleaning it does it again check for proper spark (bright blue) and go from there.
Good luck
 
K

keane

Will have a look, clean carb n check spark :) I know it's had a few electrical bits, coil Ect so maybe cdi unit ? I disconnected the kill switch as on tick over it sounded like someone was pressing the kill switch on and off for example
 
O

ossagp

keane:
Will have a look, clean carb n check spark :) I know it's had a few electrical bits, coil Ect so maybe cdi unit ? I disconnected the kill switch as on tick over it sounded like someone was pressing the kill switch on and off for example
Click to expand...
What does the spark plug look like?
 
O

ossagp

It is the first thing to tell you what is happening inside while the rig is running. We were used to doing that to tell what was going on with our bikes long before logging on and waiting got so popular. :ride:
 
K

keane

Right had a little look tonight checking carb, spark and plug. Plug was new last week and it's black, not a nice brown...? It has a spark but it's not as bright as I thought it would be ( not an expert) but wouldn't say it's no stronger then a lighter is. Jets Ect are fine, is the float ment to have some resistance when upside down.? When I took the carb off and looked at the float it didn't seam to have no resistance :/
 
Last edited:
SRAD97750

SRAD97750

Moderator
Staff member
Black plug is too rich.
Sputtering smallbore 2T is a rich condition.
Float should move freely and will slowly get richer and richer as time goes on.

Set the float correctly for sure, clean the carb again, and give it a whirl.
-BIG DAN:thumb:
 
O

ossagp

Be glad they go rich instead of lean as time goes on, as SRAD noted!! in this case you just foul plugs and it misses like someone ringing a bell at high rpm. It should have as close to no resistance to movement as possible on this model. In fact I cant remember any motorcycle carburetors that have damped floats.

If you can imagine that the tang that makes the contact with the float needle has pressure on it anytime the fuel is on and that it gets a lot of up and down force applied as bumps are hit that the float level starts moving again as soon as you start running the motor after resetting it. The most competitive racers had them reset at least before each event.
 
K

keane

Cleaned carb lads with no luck .... She starts and will run and then just cut out again .....:/ seams very smoky too ... Was fine 2 weeks ago and ran mint, then the next week had a missfire and slowly got worse as day went on and struggled to start. Piston rings possibly ?
 
O

ossagp

keane:
Cleaned carb lads with no luck .... She starts and will run and then just cut out again .....:/ seams very smoky too ... Was fine 2 weeks ago and ran mint, then the next week had a missfire and slowly got worse as day went on and struggled to start. Piston rings possibly ?
Click to expand...
 
O

ossagp

you dont mention setting the float with cleaning. usually the only thing that cleaning will do to help an over rich condition if you think about it is that you may get debris off of the float needle and seat that will help it shutoff more fully. if yours still hasnt been set and set correctly with pieces that in good working order you may have it running even richer now than it was. but if you did replace the piston and rings it would probably run a little cleaner for a few hours, but it would still need the float set. you may be missing out on how important that is to a well tuned bike.
 
jackson409

jackson409

Time before last my bike I was running great and then the next time I took it out It was running like crap it was also about 30° colder. Temp determines what will Run like. Have you had any temp change in your area!
 
Top