4/6 Won't Idle

[mswyka]

Looks like I am confused again.  I have the 1980 manual for the 440 Invader, 340 Invader and 440 4/6 Invader.  In the carb setting section the 440 Invader says initial setting for air bleed is 1.5 turns and in the 4/6 section it is telling me 3/4 turns.  Were there different manuals for the 1980 sleds?

[gixxer6]

Mark,  I don't understand the source of the confusion.  Doesn't this simply mean that the 440 Invader is to be set at 1.5 turns, and the 4/6 at 3/4 turn? 

[mswyka]

Tom, I guess I had thought that somewhere in this thread someone had said the start for the air bleed on the 4/6 was 1.5 turns.

[mswyka]

Mark,

It sounds like a pumping problem.  Swap a fuel pump in there.  Check the lines.  MUST identify if the problem is fuel or spark!  Get a timing light on it and check the blue flowing of the strobe.  When your sled is peetering out is when to watch the strobe hard. 

Pumping my first guess.  Lord knows how I hate to guess.  Could be stator, coil, CDI the list starts endless but you can eliminate about half with the timing light....

Please report back fuel or ignition.

Checked timing today.  Idling at 3000 timing is about 20 degrees advanced.  As she dies the timing slowly approaches 0 degrees advanced.  I am not seeing any  problems with fuel delivery or leaking past the primer.  Running out of things to check/replace.

[gixxer6]

Mark,  I read your original post again, it sure sounds like an air leak!  My 4/6 ran like that once, it turned out that I forgot to tighten down the carb top on one side. 

Maybe a hole in the pulse line? 

[jimvw57]

The 4/6 Mikuni carbs have a different jetting than the standard Invader. Also 1980 was the only year for the 4/6 motor.

I have had carbs that ended up with the air screw less than 1/4 turn. Pretty much whatever works...

[Checkmarks]

Mark,

Thanks for the timing light check.  So the point was to see if the blue strobe was strobing when the machine died.  This would insure the ignition system was functioning.  Taking it a further step and putting degree marks and watching the timing is commendable. 

You make some interesting point that the timing was approaching 0 degree advance when it was shutting down.  Looks like the trouble is in the Cdi.  The 4/6 motor had a regular progressive timing curve.  @3k 8degree @6k 10degree and @8k 12degree.  If you got to see 20 degree anything you have a problem.  Maybe the stator plate came loose or was not aligned with young eyes.   

The 81-82 Ltd had the fancy retarding curve.  The Cdi that I have for the 4/6 motors marked just the regular invader timing curve at least the two that I have did that.

If your Cdi is the retarding curve and you have say an Interceptor cdi...  The motor would start up with like 31 degree BTDC and idle there until the motor warmed up (Cdi box warmed up) then they back down to something like 27 degree BTDC.  As you spooled up the motor the timing would march down to 10 BTDCC @8300.

Even if you have that Interceptor Cdi the timing would hold 20 degrees BTDC at idle.  Problem still lends itself to the Cdi being the issue.