Quote:Most common problem is the fuel level is too high. Look through the sight-glass and the level should be at the halfway mark. 2mm above half is too much. See Float for details

Another cause of these leaks is a warped carburetor top (somewhat common on the Hitachi 306). When the top warps, the vacuum leaks from the power valve passage, causing it to run super-rich all the time. You can verify this by removing the top and inspecting
* make sure gasket is not torn by center hole
* put a straight edge on the top and look for warpage
* Ensure center plunger rod is not stuck (stuck down means rich)

Attach file:

---

  24081 vacuum passage for Power Valve.jpg (32.15 KB)

Replaced whole distributor to no avail. Yep have replaced all plugs. Seems like a flatspot to me, runs extremely rich (black smoke for miles) and dies underload. No backfiring at all. Have also noticed leaks around the top carburetor gasket and throttle plunger so im guessing that is the problem

Hey Dazza

Can you be a little more specific with what you did with the dizzy?
Points?
Condenser?
Cap?
Rotor Button?

Also, do you know if it is a misfire or flat spot? Have you changed the plugs since you found No.4 oiled up?

Cheeers

Hi all. when I got home after it was playing up, #4 was very oily, to the point that it wasnt firing at all. Just seems to be that cylinder. Compression tests came back fine. Have changed fuel pump and filter and that made no difference

Good idea. It's easy and costs nothing and might pinpoint a problem

Spark Plug Inspection

Attach file:

---

  spark_plug_condition.jpg (83.72 KB)


  DensoSparkPlugChart_modified.jpg (60.43 KB)

I’d Take the plugs out and that should tell u what direction to head. Probably fowled up From worn or incorrectly set point gap . A series Is very simple I’d be surprised if anything major. No Grease on the dizzy lobe will make the points close not long after changing em .

I suspect fuel filter issue or bad fuel pump

I had an issue on my 1200 where it would play up after a thrashing.

For me it turned out to be a sticky float needle.

Fuel level should be half way up the window in the standard carb.

For me, i had inconsistent fuel levels, sometimes empty and other times completley full.

Long shot, but thought id pipe up with a similar issue i had.

fuel lines could have fungus, mine did when I bought her
as she sat for 5 or more years without getting started.
Once the fuel lines where cleaned the higher rpm range
was possible rather than just idle perfect etc.

Out of curiously did you check the coil, per chance does it get hot?

Check the float level as well; it may point to the problem. Things like clogged fuel filter or bad fuel pump would cause an issue under load. My 720 pickup once clogged the filter on the way to work, was fine one second and then it wouldn't take more than 1/8 throttle.

As you already changed the dizzy in theory that would elmintate the points being it but of course who's to say the points in that distributor are good.