enigne diagnosis

It is me and my B414..I have it running - sort of. I hope you can take me the rest of the way.

here is where I am at.. the thing at high or full idle runs terrible. To the point, you would think I had 2 wires swapped. Miisses bad and backfire a some thru the tailpipe.

Here is what I know:

all 4 cylinders at 125 psi
fuel is clean
at the top of compression , #1 lines up perfectly on the timing marks and rotor positon
wires are 1-3-4-2 ( the inforamtion I have says that is correct
idle is pretty good ( I am good with it)
Idle screw out 1 1/2 turns
high speed needle is out 2 1/2 turns. I have tried alot of different setting with the high speed needle to no avail
has petronix ignition
new plugs
new fuel pimp
Zenith carb
One kind of strange thing...as it runs I pulled off one wire at a time. I really cant tell a differnce when I remove #4. I did check the spark by removing and grounding the plug and it does spark

Gosh, I cannot figure it out. Seems like it should be correct - but I am sure when I drive it the neighbors this I am shooting at them ( it is that bad).

Is it carb ( fuel) .....is it ignition???? Something else. Hope you real motorheads can provide some help..cause I have removed myself from the motorhead list as a failure.

Thanks in advance

What is the voltage of your battery? If your battery is not 12.5 volts the pertronix will not fire correctly.

sorry , i should have added that I put in a brand new battery - but good point, I will check voltage.

Timing at high idle must be advanced or it will do as indicated in your question. A timing light will help tell the story, it should be a little advanced from TDC when at slow idle, and probably beyond 25 degrees when running fast. The centrifugal advance is responsible for this change.
Another way to see if it is timing related is to start it as it is, and move the timing when it is misbehaving in the advanced direction to see if it cleans up. If so it may be that the springs and weights in the base of the distributor (behind the points plate) are not advancing. Don't try to start it when it is artificially advanced as you could break the starter with kick back. Jim

Hi, I looked up in my B-414 manual for petrol engine:
firing order: 1-3-4-2, number 1 is front of engine.
tappet hot 0.022
spark plug 0.024 to 0.026
point gap 0.014

Manual says to check engine timing but does not give the spec.

JimB

Now I think you may have it . when you say front of engine- do you mean fan side? If so, that is it (!) because this is wired with #1 being on the gas tanks side ( toward the rear).

Thoughts??

Yes, according to Operator manual, #1 is the fan end of the engine.

JimB

(quoted from post at 08:21:10 06/10/13) Now I think you may have it . when you say front of engine- do you mean fan side? If so, that is it (!) because this is wired with #1 being on the gas tanks side ( toward the rear).

Thoughts??

Click to expand...

Number 1 cylinder is toward the front of the tractor. The firing order is 1-3-4-2.

If you start numbering the cylinders from the back and keep the firing order the same, just using the reversed number order, all of the cylinder will still be in the correct firing order.

I just went through the same thing with my M. My backfiring problem cleared up when I found the reluctor loose on its backing plate. Quick test, remove distributor cap and try to wiggle the reluctor. If it moves even a little bit put two nuts on the ends of the screws holding it to the backing plate. Don't bother to take the plate out because there are no slots in the screw heads to tighten. Ellis