Unable to hold steady

[godsend1]

When attempting to hold a steady RPM it feels like it's missing, popping. A little bit of popping when off throttle and decelerating. It has come on gradually and is now pronounced, it is especially evident in 1st,2nd.

It pulls normal, I think. Sync is good, new plugs,wires.

Thanks Tom

 

[maleko89]

Tom, did you gap your plugs?

Try some Seafoam in the tank or Peashooter method. Steady throttle is your pilot circuit. Does it do it at all rpms?

 

[4gasem]

Tom, did you gap your plugs?

Try some Seafoam in the tank or Peashooter method. Steady throttle is your pilot circuit. Does it do it at all rpms?

Your carb vent tubes are on and in solid shape right? :ummm:

 

[godsend1]

Your carb vent tubes are on and in solid shape right? :ummm:

Thanks for the reminder. What is the id for these?

MArk, ya they're gapped.

 

[godsend1]

Put in a new fuel filter, carb vent hoses(finally, it cleared up the weird behavior at freeway speeds ), did the pea shooter, I regularly run seafoam through a tank. Just added another treatment.

Same behavior, I forgot to add originally that it runs much smoother when the engine is cold both with choke on and after I turn the choke off, after it gets nice and hot, or normal temp it starts the weird behavior.

Tom

 

[Akatora]

Hello,

If the engine is running nice when cold, but experiencing problems when hot it sounds like there is generally one of these two main problem paths existing:

1) Carb adjustment is on the rich side. For this there are the following things to do first:
- check the air inlet passage for possible foreign objects and that the filter element is not glogged
- clean the carbs and check that the main jet is not loose
- check the mixture screw positions (original setting = about 2.5 turns out, more out = richer low end mixture, more in = leaner low end mixture)
- inspect the fuel level
- check the needle positions and possible shimming of the needles (lower clip position = richer mid range mixture, higher clip position = leaner mid range mixture). The original needles do not have adjustable clips, but there might be some shimming placed under the needle clip.
- inspect the flow rate of the main jets (original flow rate 152.5) as they might be worn, see http://www.vmaxforum.net/showthread.php?t=4130

2) Ignition problem is occurring in one (likely in only one) cylinder probably due to damaged coil winding. To check this you should prepare a multimeter ready, warm up the engine until the problem occurs and measure the following:
- pick-up coil resistances, see http://www.vmaxforum.net/showthread.php?t=3876

- ignition HT coil resistances on primary side and secondary side
(There are four of them, one for each cylinder, and each one has got primary side and secondary side. Factory specification for primary side resistance (between red/white and orange wires) is between 2.4 and 3.0 ohms at 20 degr. Celsius. The specified resistance of secondary (HT side) is between 10.5 and 15.8 kilo ohms (without plug caps) at 20 C. This resistance can be measured between red/white wire on primary side and the actual spark plug wire (HT wire).)

 

[godsend1]

Akatora,

Thanks for the info. I will try the shotgun first, then start getting into the electrical if that does not do the trick.

Tom

 

[godsend1]

The shotgun has cleared the issue. Thanks to all who listened , helped.