434 international gas

[toole]

I have a "Dirty exhaust " . I have had the carb off 20 times and cleaned needles , eyes , holes , inlets and what have you ...I have changed plugs and wires
and it's still burning dirty ...It's a Zenith carb and burning too rich and I'm lost as to the problem... Any suggetions.. Have a great day

 

[old]

I have a "Dirty exhaust " . I have had the carb off 20 times and cleaned needles , eyes , holes , inlets and what have you ...I have changed plugs and wires
and it's still burning dirty ...It's a Zenith carb and burning too rich and I'm lost as to the problem... Any suggetions.. Have a great day

Have you checked the air cleaner and made sure it isn't clogged up>??

 

[Janicholson]

old's idea is worth investigating. also a high float level will allow excess fuel delivery. If there has been a replacement carb put on it, the main jet may be too big. We really need more operating info. Is the tractor new to you? a history lesson is needed. When did this start. are you idling it around, or putting it to work? there is a Idle mixture screw that could be leand to reduce low speed rich mixture. Jim

 

[Fritz Maurer]

Oil bath air cleaner often gets neglected (especially this one which is totally concealed) and runs out of oil leaving the dirt to plug the media directly.

Put a timing light on it and make sure that it's right , late timing will blacken plugs. But you give the impression that it is running fatter than that.

If everything else is up to snuff you will have to open the carb for the 21st time and see what you missed. A Zenith VNP is like many things built in Britain... way more complicated than it has to be. Lot of loose pieces in those things and is easy to overlook something. Get yourself a detailed diagram of the carb and make sure everything is in there.

The emulsion block needs to be tightened carefully... just can't tighten the top and then the side or the reverse ... you need to tighten all the screws a little at a time and draw the block up into the corner for maximum seal of both gaskets.

If you literally have black smoke at all ranges, look for a BIG leak... like a missing check ball in acceleration pump circuit or a wrong float needle (too short).