help !! miss firing apollo db x18

[par1]

hi my new apollo will not run miss firing under load it seems to ideal ok and rev up in neutral but miss firing under load in gear called the teck at superior power he said bad cdi i changed it no help also changed carb to a mikuni vm 22 gas air screw is set 2 turns out needle jet 3rd slot main jet 110 .


my next fix? check valves should they be .004 intake .006 exh.

[Weldangrind]

Let us know how it performs after you set the valves.
Have you changed the plug to an NGK?

[dirtbkr188]

The valve setting should be .003" - intake and .004" - exhaust


The NGK plug should be a CR7HSA

[par1]

hi up date. so i set the valves at .003 .005 . then took the carb off and reset the air gas screw to 1.5 turns out. then i put the #98 main jet back in [ that is how it came] i also put the needle jet to slot 1 most lean. so with all this done i wish i had a new spark plug with that said this cleared up 85% of the mis firing i hope the ngk will help with the rest when i get a new plug i will up date.

[par1]

sorry i should have said i set valves 2 days before and that did not help with the mis fire problem

[Douglass]

My Apollo DB-x18 has an NGK plug stock. I also have the Mikuni VM22 Carb installed with a 20 pilot, a 112.5 main, and have the needle clip in the 4th slot from the top (1 down from the middle). My air fuel screw is set around 1 1/2 or 1 1/4 turns out . Mine runs solid with this setting, and I am at sea level (68 ft).

Do you know what size your pilot jet is?

What is your elevation?

Did you ever pull the spark plug when the missfire was worse to see how the plug looked?

Did you check the plug gap?

To confirm, you are having the problem with both carbs?