W9 runs rough

C Clark

Member
Hi all. Working on a W9 that I found which hasn't run in over 30 years. I have honed the bores, and installed new rings, and gone over most things in the motor. I have completely dismantled the carb, cleaned out all the ports and assembled again with a new carb kit and to the adjustments as suggested in the workshop manual. I have had the magneto serviced and it is going good. I have made up new steel pipes from the tanks and checked out the fuel bowl.
My problem is when I started it it would backfire and miss and ran awful. It run better with nearly full choke and will not idle (runs all the time at high revs).
Since then I have tried adjusting the carb but nothing makes much of a difference. I have installed a whole other carb but it's exactly the same. A good flow of fuel is running into the carb. I have tested the leads and cap on the mag (running copper leads). I have swapped the mag, plugs, cap and leads from a good running tractor. Mag timing is right. I have checked the governor and controls. Nothing makes any difference to how it runs. Obviously it's running lean the way the choke has to be on but I don't seem to be able to adjust the mixture. Also why won't it idle - are they both related? I've been trying to work this out for a couple of days now but it has me stumped. Any thoughts would be appreciated. Thanks. Cameron
 
are you using the factory fuel pump or gravity feed fuel? also, did you install an aftermarket in line fuel filter?
 
have u tryed the main fuel jet at 4 turns open? is the governor tab to carb in its correct slot? and are the valves adjusted correctly?
 
intake gasket leak at carb and or to head? try shooting ether at these gasket areas if speed picks up you have found leak area, or as suggested rust thru between intake and exhaust. vacuum gage check? low vacuum would indicate intake leak as well as some other possibilities.
 
Do the hand over air intake of carb and make sure you have a good suction and also that your hand gets covered with gas as your trying to start it. Low suction means a gasket or manifold problem. The fact you say it runs better choked says lack of fuel or weak spark. The spark needs to be a good blue/white and jump a 1/4 inch gap or more at all the plug wires.
You also need a good gas flow so pull the carb drain plug and make sure you have a good flow that will fill a pint jar in less then 3 minutes
 

Hi. No I'm not using the factory fuel pump. Pump was missing when I got the tractor and so I have just plated it. When I undo the drain plug to carb I have a good flow with gravity. No in line fuel filter just the gorse on the fuel bowl. Thanks
 

Hi all. Thanks for your feed back. Should have mentioned I installed a new exhaust manifold, with new gaskets. Cleaned up surfaces on carb and installed new gaskets. I will try the ether idea though to check for leaks. I have tried adjusting main mixing adjusting screw but doesn't seem to make much difference where it is. Blew out all ports in the carb with compressed air, everything was clean and clear. Have adjusted the valves. Spark is a good colour and make a significant difference to the running when I earth a plug out. Will measure the flow out of the carb drain plug today. Thanks for you help. Keep it coming.
 
wild guess here but is the venturi missing out of the carburetor? it fits between the bowl and throttle body. if the link works to the case i-h site, it is number 42 on the diagram. the link is for a super m, but it is a similar carb
poke here
 
Just a couple thoughts here; you say your
mag timing is correct, but do you have ALL
of your wires in the correct spot on the
cap? Sometimes you can think you have
something timed right, the way it should
be, but sometimes previous people that have
worked on things don't get oil pumps lined
up correctly, throwing off where your rotor
SHOULD be. Take #1 plug out and crank it
over until it has compression on your thumb
if you hold it over the hole. When you feel
that compression, stick something in the
hole and roll it slow by hand until you get
the piston to the top. When it's there, the
timing mark on the crank pulley should line
up as well, and also the rotor and terminal
in the cap that has the plug wire going to
#1. I can't remember for sure, but it seems
like the one that -normally- goes to number
one is the top right terminal. Champion
plugs? I've had some that looked like they
sparked good, but wouldn't under
compression. Get some C87 AC's if you have
Champions. Maybe I totally missed your
questions, but maybe not?
 
Long shot here. You do have the correct mag. IIRC the W9 uses a CCW rotation mag instead of the CW rotation mag of the rest of the gassers.
 
(quoted from post at 14:50:33 10/31/17) Long shot here. You do have the correct mag. IIRC the W9 uses a CCW rotation mag instead of the CW rotation mag of the rest of the gassers.

Yes I agree with CVPost...I would like to add there are several styles of H4 Mags CCW as well as CW also there's a difference between gas and diesel. The one made for the gas engine (15 degrees) has a different spark impulse than that of the diesel (35 degrees).
I found that I had a TD9 diesel mag on a T9 which works but runs hotter.
Don't know if that helps but lots of luck..
 

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