It does sound like it is sticking.

ok thanks will try it but before i disassmble the carb again i lubricated the plunger in it moved up and down freely by hand but somtimes it would get stuck a bit until you pull on it does this sound like normal operation?

the plunger isnt removable is it?

Thanks!

Have a look at the pic attached, you can see the the PVC joiner wedged in the relevant port.

The one on the side is just a breather to allow the piston to move up and down freely don't worry about that one.

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hi thanks!

the engine is rebuilt few months back so rings and seals are good pcv i checked and cleaned with carb cleaner the smoke is black when you rev the engine when cold!

also which port is it you suck on too see the operation of the power valve plunger is it the one on the side of airehorn throat or at the bottom?

i also removed the power valve that screws in under the plunger in the carb body with petrol and compressed air!

also the carb has new gaskets and i cleaned every thing so the bowl is super clean!

Thanks!

You should check the functioning of the power valve plunger which is fitted to the air horn. A bit of light oil around the shaft helps to smooth the operation. To check its operation I use a little 4mm joiner and some dripper hose from the hardware shop and simply insert that in the port and suck on it to see that the piston action is okay. I would do that first before shelling out $300.

Also, it is a good idea to remove the power valve itself and blow it out to ensure there is no debris in it causing it to leak.

How clean is the bowl ?

I usually clean all of the crud out with some caustic soda . Immerse for a few minutes only and rinse well. That caustic soda is powerful stuff. Watch your eyes and hands as it will burn. Take care.

Also the fact there is smoke from the exhaust is concerning . What colour is it ? If running rich then I would expect black smoke . If it is blue then that is oil and you have another problem , most likely rings or valves.

Have a good look at the PCV valve to ensure that is not blocked or jammed and that the hose is not split.If the PCV valve is open all the time it will run like crap and blow smoke because of the oil it draws up from the crankcase.

hi i have made the top cover and carb body flat with a emery stone and is very even but it seems to run rich cold it has smoke when you rev engine and it starts witout choke if you start with choke it dies!

but when warmed up the carby seems to be better running like its got no smoke from exhaust!

but when the revs are held you can hear the engine revs go down then sudenly up and at idle its smooth then suddenly it will like sort of bog down then pick up!

could this be a stuck power valve?

should i just buy a new carb from bjprojects for $300?? is it worth it and will it run without any problems then?

Thanks!

Just a further thought. If you are going to make a plate like in the pic , make it about 300mm long . That way you will have room on the plain end to surface the main body as well.

ok thanks for the pic i will give it a go tommorow!!!

thanks!

Here is a pic of the plate I made to surface the air horn. You see the length from the ruler. Width is 100mm and the thickness is 8 mm.

The slots started out as two holes at each end of what is now the slot. They are about 3/8". Just need to visualise where you start moving the air horn and where you finish as you move it back and forth across the plate.
I then drilled a series of holes between the two end ones and then with combination of a fret saw and file cut out the bits in between and filed to give a reasonable surface so the bits hanging through don't catch.

(Whilst this is not a precision ground surface plate, a piece of 100mmx8mm stock is flat enough to achieve a sufficiently flat surface to ensure the two parts can be mated together and seal.)

Then it was just a case of getting a sheet of wet and dry and start rubbing. I may have used some 120 grit with the kero as that really aids the cutting ability of the wet and dry.
As you start you will see where the wet and dry is cutting and where it is not so you will have a visual guide as to how you are going.

When I first surfaced the main body the only thing I could come up with for a surface plate at the time was a piece of plate glass which happened to be a sliding glass door in a cabinet I have in my shed. Worked a treat.

The main body is the easiest one to do.You just have to strip it down so that the various plugs and bits sticking out aren't in the way . When I did mine I was doing some other mods so had actually removed the fuel discharge nozzles as well.Otherwise just taking out the air bleed screws should give you the clearance you need. Once in that state surfacing was a breeze and in 5-10 minutes it was done.

All of this was inexpensive but does take a bit of time. Well worth the effort however.

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hi thanks i would be thankful if you could post a picture of the plate so i can get an better idea how you did it!

the main body isnt that bad the the air horn thats really bad all the screw holes ears are higher than middle!

Thanks again!