Only firing on 2 Cylinders

dmax1 · Mar 28, 2011

You just have to take out the letters H-D :rofl_200:

Wrecka · Mar 28, 2011

Rusty McNeil said:
If synch isn't just right and idle is low it's pretty common to idle on two cylinders. should go away when you crack the throttle tho'

I've fixed the same problem your describing tho, missing at speed, a coiuple of times by replacing the plugs and wires, even tho they all "looked" ok......

Interesting , he did say that the carbs where way out of sync and i had turned the idle down a day or two before the problem started..........

RaWarrior · Mar 28, 2011

Carbs out of sync typically cause a rough/slow idle. Without touching the idle adjust, mine idled about 1-200 RPM faster after syncing. Total variance on mine was between about 8 and 10 inHg initially, best I could get was within .5 inches.

Manometers are kind of pricey, a decent one runs about $100. You can buy dial type vacuum gauges on ebay for cheap, if you added small restrictor valves in-line they'd probably work fine. Without either a restrictor insert or valve you keep like 95% closed, the pulses of the engine will make the needle jump around wildly and be totally unreadable.

sdt354 · Mar 28, 2011

RaWarrior said:
Carbs out of sync typically cause a rough/slow idle. Without touching the idle adjust, mine idled about 1-200 RPM faster after syncing. Total variance on mine was between about 8 and 10 inHg initially, best I could get was within .5 inches.

Manometers are kind of pricey, a decent one runs about $100. You can buy dial type vacuum gauges on ebay for cheap, if you added small restrictor valves in-line they'd probably work fine. Without either a restrictor insert or valve you keep like 95% closed, the pulses of the engine will make the needle jump around wildly and be totally unreadable.

http://www.carbtune.com/ Check them out. I was used to the merc stick and liked it, borrowed dial vac gauges w/restricters that worked ok too,but these are great. I bought mine on e-bay for $90 a couple of yrs ago. Money well spent.
Steve-o

Rusty McNeil · Mar 29, 2011

RaWarrior said:
Carbs out of sync typically cause a rough/slow idle. Without touching the idle adjust, mine idled about 1-200 RPM faster after syncing. Total variance on mine was between about 8 and 10 inHg initially, best I could get was within .5 inches.

Manometers are kind of pricey, a decent one runs about $100. You can buy dial type vacuum gauges on ebay for cheap, if you added small restrictor valves in-line they'd probably work fine. Without either a restrictor insert or valve you keep like 95% closed, the pulses of the engine will make the needle jump around wildly and be totally unreadable.

True that most of the time..
...My implication was that if the throttle butterflys are way out from each other, and idle is set real low then you can have some of the butterflies completely closed...I.E. not gonna fire at all....No fuel.....