Hobbit "Stock-ish" Wabron clone carburetor

Ok, forgive me if I should have just made one big thread for my Hobbit saga, but I didn't realize how many questions I was still gonna have.

When my Hobbit was running the stock carb I always had some slight acceleration issues so I'm trying out a clone from Treatland that I've had good results with before. But they have an extra little adjusting screw on the opposite side from the idle air screw. I've heard varying rumors about what it does. Pilot air/fuel control? Full throttle air/fuel trim? Anyone have any idea? And if anyone knows what it controls, I'd also love to know which way to turn it for richer/leaner.

Thanks folks. You're all pretty awesome.

Re: Hobbit "Stock-ish" Wabron clone carburetor

Why not simply look at the carb and trace the flow path that the mystery screw seems to control . That will tell what is involved : only air ; air & fuel or only fuel .

Then you should be able to figure how much , if any , is needed .

I just posted this chart earlier today :

Re: Hobbit "Stock-ish" Wabron clone carburetor

Well, it kinda looks like it affects air flow from one of the little tubes at the carb throat down to the emulsion tube. I'm not sure if more air into the emulsion tube causes it to draw more fuel, or just adds more air. From empirical observation just now, adding more air to that circuit seems to make it richer. Closing the screw more makes it start stuttering at about 10-15 MPH and won't go faster than that.

Naturally it started snowing at the exact instant I finished putting it back together, so my testing was limited and I haven't checked how the spark plug is looking after a few full throttle rips down the alley.

I do seem to have a bit better acceleration now, with less sag off the line. My top speed might have dropped a bit though. I was pulling maybe 28 MPH with the stock carb, and now I seem to top out at 25. I think it's still progress though. I might have over-oiled the new air filter a little bit too. Or fouled up the plug a bit from putting a tiny bit of oil in the cylinder after changing cylinder/head gaskets and cleaning everything up.

That chart is awesome but only a couple parts of it apply to my bike. I don't (yet) have a slide-type carburetor. I think a Mikuni and a new intake will be my next upgrade once I've got a bit more money saved up. Mainly just to get the damn carburetor out of the frame so I can work on it easier.

Re: Hobbit "Stock-ish" Wabron clone carburetor

Ok one more thing here... I've seen a bunch of posts saying my idle air screw should be somewhere around 4 turns out, to start with. My bike seems to want the screw at about 1.5 turns. With the clone carburetor, and in the past with the OEM carb. That's a pretty big difference, but is it a problem?

Re: Hobbit "Stock-ish" Wabron clone carburetor

> Steve Mcgrath Wrote:

> -------------------------------------------------------

> Ok one more thing here... I've seen a bunch of posts saying my idle air

> screw should be somewhere around 4 turns out, to start with. My bike

> seems to want the screw at about 1.5 turns. With the clone carburetor,

> and in the past with the OEM carb. That's a pretty big difference, but

> is it a problem?

It's only a problem if the motor doesn't like it .

Every motor is different , one way or another . Even a rubber stamp is different , one stamp to the next . You can't expect motors to be identical , let alone after 40 years of obuse .

Re: Hobbit "Stock-ish" Wabron clone carburetor

True enough. I've only had this bike about 3 years, and it spent half that time in several buckets after I got run off the road and wrecked. I haven't fully learned its personality yet.

Re: Hobbit "Stock-ish" Wabron clone carburetor

> Steve Mcgrath Wrote:

> -------------------------------------------------------

> Ok one more thing here... I've seen a bunch of posts saying my idle air

> screw should be somewhere around 4 turns out, to start with. My bike

> seems to want the screw at about 1.5 turns. With the clone carburetor,

> and in the past with the OEM carb. That's a pretty big difference, but

> is it a problem?

Thats why there are thteads to screw in or out ..as PD said each is different..adjust your idle or air screws in or out at very small increments..don't turn a lot at one time..move it a little and the time and wait to see how your motor responds before you move it again

Re: Hobbit "Stock-ish" Wabron clone carburetor

Yup . It usually takes a while to really know ... ;)

Re: Hobbit "Stock-ish" Wabron clone carburetor

> Steve Mcgrath Wrote:

> -------------------------------------------------------

> Ok one more thing here... I've seen a bunch of posts saying my idle air

> screw should be somewhere around 4 turns out, to start with. My bike

> seems to want the screw at about 1.5 turns. With the clone carburetor,

> and in the past with the OEM carb. That's a pretty big difference, but

> is it a problem?

Who says 4 turns out on an air screw? Standard place to start is 1.5 turns out so it sounds like you're right on the money

Re: Hobbit "Stock-ish" Wabron clone carburetor

> Nick MBC Wrote:

> -------------------------------------------------------

> > Steve Mcgrath Wrote:

>

> > -------------------------------------------------------

>

> > Ok one more thing here... I've seen a bunch of posts saying my idle

> air

>

> > screw should be somewhere around 4 turns out, to start with. My bike

>

> > seems to want the screw at about 1.5 turns. With the clone carburetor,

>

> > and in the past with the OEM carb. That's a pretty big difference, but

>

> > is it a problem?

>

> Who says 4 turns out on an air screw? Standard place to start is 1.5

> turns out so it sounds like you're right on the money

Every hobbit ive had 3, has had a lean off the line bog at 1 1/2 out, turnung that screw out 31/2 or 4 turns solves it.

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