Hello Folks

I was wondering what the spec is for the idle speed for a D2 pony. I can't get mine to run much below 1750 RPM, and that seems a little fast to me.

Cheers - Foster

Is your hand throttle control set right at the carb. so it pulls the fuel off. Sometimes they get on the wrong side of the arm on the carb or could be something in the governor itself not functioning and or linkage & spring.Take a good look at things or get someone to help you who is familiar with it.I don,t have no specs here for RPMs but the idle does need to be working right.

Throttle control rod blocks the throttle and governor linkage from going to "fast" when you pull it out to idle position. There is also a setting screw on the throttle shaft on the carburetor itself to set the minimum throttle opening/idle speed.

Most of the ones I have heard that have a good carburetor run pretty slow, (more often run best at idle and have trouble under load:D )I would guess well under 1000 rpm at idle.

I can check tomorrow.

Hello Guys - thanks for the thoughts

Yes the throttle control linkage is on the correct side, and I have played with the speed adjustment screw (no 3 in the operator book) I have been avidly following carby talk, and recently removed the carby bowl and cleaned it and its jets throughly.

However I didn't have sufficient courage to force the wire I had into the idle passages, and niether did I understand the idle screw on the carby body itself - well I have since learned (I think) that it only controls air, so I need to have a further go at its passages, and get some suitable plastic wire to do the idle passages in the bowl.

It just won't run at low revs.

Any faults in this logic ??

Cheers - Foster

go for it, clean the passageways from the idle circuit into the throttle plate area of the carburetor. I believe there are some tiny holes in the adjustment needle that meter/deliver fuel. That should help you get it to run slow. If it will run fast, you have fuel in the bowl, so check from the idle jet in the bottom center of the bowl and on through to the venturi area.

The idle mixture screw does change the air through the passageways so screw it out for more air/less gas, in for less air/more gas. This adjustment method is dependent on the idle circuit jet being in place in the bottom of the bowl and not enlarged by overzealous cleaning etc.

Hi NZCat,
the low idle discharge jet is located at item 6 in the attachment. It is a brass plug with 2 nicks machined into one side that discharges the fuel/air mix below the butterfly, this is where most crud blocks the idle system. If the carb has sat with water in it rust fills the drillings and is hard to move without jet removal.
If you look at the outside of the jet in the carb. body you should see a cast protruding orientation line, put a light center punch mark at 12 o'clock before removing it. You will need to make up a suitable punch to punch the jet from the outside to the inside of the carb body. Then clean away to your hearts content.
Hope this helps ,
Eddie B.

Hello Eddie

Thanks for posting up that diagram, I only have an operator manual, so that picture was the single biggest learn'in step I've been able to take for my pony, which is now running really really nice, just cackling at about 900-1200 RPM (estimated) at idle, and humming at 3350 full out. Now I have it sweet I can start attending to the fuel system of the main, I'm gonna tackle the bypass first.

Just for the record I didn't remove the bottom jet - no 6, it was in real tight, and I was scared I'd bugger it, so I just roto'ed it out with nylon fishing line from the top, and then flushed it (from inside the bore) at as much pressure as I could get on it with brake clean. Some air would have been good but I don't have a compressor. I finished off by polishing it with steel wool from inside the bore of the carby (ok I did have a wee pick at it with a fine awl too, but very sparingly, I think it would be real easy to ruin it).

It looked like it had two passages, one above the throttle butterfly in the closed position, and a smaller one below it. Does anyone know what it should have and what they look like ??

Cheers - Foster

Hi Foster,
congrats on getting passages cleaned without having to remove jet, I was always worried too about damaging them as most clients refused to buy a rebuild kit just to get them, sometimes there is no choice if the passage is chocked enough with rust etc.
Just looked at a carb in the shed and I can't detect or recall another discharge passage above the butterfly in these carby's, maybe it is a rust pit or casting flaw?.
I am not aware of any spec. for low idle speed but where ever the engine is happy ticking over at without stalling or coughing at RPM increase to high idle is ok. My guess would be about 500rpm.
Cheers,
EddieB.

Eddie (and Guys)

Sorry about more questions . . . . I rechecked the idle speed with a tach and it was still 1750 ish , running nice though. I don't want to seem like I'm fixated on this, but I would like to get it right so it'll last.

I suspect I still don't have the jet a #6 right, mine looked to me as if the fuel comes out the side of it ie between the brass plug and the cast carb body, does this sound right, or should it have a fine hole in the middle of the brass ??

Cheers

Hi again Foster,
I just bit the bullet and punched the jet inwards and found the following on this unit I have here :-- the idle discharge jet is a brass plug with 2 nicks machined into one side as you observed. This is what makes them so hard to clean out. I have succesfully used a wire from a wire brush held in a small pair of vice grips or a Primus pricker, to jiggle crud out of the jet, a drill can be used carefully down the idle passage drilling, followed by jiggling a piece of piano wire or guitar string to get out the last of the crud, after drilling out the upper plug. You can replug it with a ball of lead or solder afterwards.
Sorry about the mislead on the jet removal direction, old memory cannot always be trusted, DO NOT REMOVE JET FROM INSIDE OUT it will be destroyed!!!! I will try and edit my previous posting above.
Cheers,
Eddie B.