Starting Point For Idle And Main Jets

[OneTimeUser]

I'll start again by saying the search function does not work (or work very well) for me. So forgive me if this question has already been beaten to death in other threads.

What I'm asking for is a knowledgeable guesstimate at idle and main jet starting points for my (soon to be) new set up.

Set up: Tillotson 212 with 24mm Nibbi and free flow exhaust with a hot dog muffler.

I've got a pretty good assortment of jets, I'd just like to take some guess work out of the starting point.

Thanks in advance.

 

[Sparkwizard]

Not a racer, but I usually try them as delivered, right out of the box. I check float height, all screws lighly bottomed, then 1.5 turns out.
BUT...I am a 2 stroke guy, so most of my performance carbs are Tillotson pumpers. I don't swap jets on them, I just twist a screw and keep on riding.

 

[Edwin Spangler]

What kind of Nibbi?

Id start with a 28 and 75.

My ported/modded 196 has a 35 and 90

My ported modded 212 has a 42 and 85. I think im a little lean towards the very top end.

 

[OneTimeUser]

Round slide 24mm Nibbi. I went with 35 pilot and 125 main. Runs pretty well, but starts kinda hard. Idles fine.
I may up a number or two on each. Won't start without choke even when hot.

The Tillotson is stock inside except for governor removal.

 

[Whitetrashrocker]

38 98 in mine.

 

[panchothedog]

Round slide 24mm Nibbi. I went with 35 pilot and 125 main. Runs pretty well, but starts kinda hard. Idles fine.
I may up a number or two on each. Won't start without choke even when hot.

The Tillotson is stock inside except for governor removal.

Every engine I own needs to be choked to start, hot or cold. I wouldn't worry about it. Concentrate on throttle response and reading the plug.

 

[OneTimeUser]

The whole purpose (for me) for electric start was that I can just hop in the thing and go. If I have to stand in the back and mess with the choke I might as well just pull start it. So, gonna either figure out how to get it to start sans choke (at least while hot) or get a cable set up.

I think I may have caused this problem by going with a 24mm Nibbi instead of a 22mm. Not sure.

I don't think it's an exaggeration to say that the future of the free world hinges on my finding a solution to this problem.

Here is a picture of my key set up. Spiral wire wrap to tidy up is on its way from that bit A in the sky.

Empty tin can is (duh) my coffee cup holder.

Yellow overspray is a fairly rare and highly coveted factory option.

 

[Hellion]

Get a remote choke. Run a choke cable to the ”dash” or where your control panel is. All you need is a generic rigid wire choke cable, a Z bend formed on the end, a hole drilled into the end of the choke lever (about a 1/16” drill?) and some cable clamps (mount one on the blower cover or engine tins and the other at the controls).

Agreed on the convenience of electric start from the driver seat. I’ll tell you another benefit, it is way too common around here hearing about runaway karts. You’re at the rear of the kart pulling the rope, it starts and it takes off on you. This happens all too often for myriad reasons: stuck throttle cable, broken throttle return spring, faulty clutch, etc.

Whoops, does the Nibbi have a traditional choke lever?

 

[OneTimeUser]

Thanks. The Nibbi has a straight pull up knob. I found a complete pre made cable kit for the Nibbi with the screw on cap, cable, and the little brass plunger dohickey for sale for $40 or so bucks. I'm going to try to make one DIY. If I F it up, I'll buy the kit.

And, I've had the run away cart thing happen with this very cart. Up the ramp to the shop, caught a bit of air, and slammed into the frame for the garage door about a foot off the ground. It broke the left front wheel suspension completely off the frame. Whoops. Lesson learned. I posted pictures of the point of impact on the garage door frame awhile ago in another thread when someone doubted my story.

I blame the runaway on a cheap clutch that was stuck in "high" gear. I put a super series 30 clutch on it and am much happier with the way it works. Once is enough for that run away so I now set the parking brake (every time) when I pull start it.

 

[Hellion]

...when someone doubted my story.

That was me! Didn’t really doubt it but ... pics is pics.

 

[OneTimeUser]

Found the Nibbi kit to convert to cable for $15. Ordered from GPS. Yay. Comes with no cable but that's not a problem.
After an hour or two of break in the Tillotson is now starting and running very well with 35 and 125 jets. It's got much more pull than the Predator did--although in fairness I don't know the history on this particular Predator. It sat for (many?) years before I got it and may have many hours on it.

 

[Damiango]

A good starting point is 38-40 pilot and 125-130 main. From there, tune based on engine response and plug reading since the intake and exhaust will affect the final jetting.

 

[Edwin Spangler]

A good starting point is 38-40 pilot and 125-130 main. From there, tune based on engine response and plug reading since the intake and exhaust will affect the final jetting.

I would suggest that main for a 420 maybe. Thats what my PWK had in it when I installed it and I ran it like that for a while.

My billet/ported 212 only has a 102 main.

 

[Edwin Spangler]

So hows it working?

 

[OneTimeUser]

With 35 and 125 idle and main jets, respectively, it seemed to be doing well. I didn't ride it much before I started in on moving the steering from left to center.

I've had the steering apart for a week or so whilst I cut and grind and weld and calculate and swear and sweat (100-plus in Texas this time of year) and the thing has not moved.

 

[Wicked_Daddy]

I am in Texas also and running a Nibbi 24 on a 212 with a hot cam. With a 40 idle and 130 main with the needle on the 3rd groove, it ran awesome on the high end but was generally lean and was hard to start, with choke, and the idle was rough. The plug was white. It literally had very little carbon on the plug portion that mates with the combustion chamber and the resistor would remain white as new. I fiddled with the air screw to no avail. I went to a 45 idle jet, set the air screw at 1.5 turns and raised the needle to the 4th notch. The result was a perfectly tan resistor, instant starting with just choke-start-no choke and smooth idle thereafter. Notice the short, very free flowing exhaust (LOUD), and the Nibbi manifold. Both allow a lot of flow. The throttle response is strong and I got another 3MPH out of it for a total of 54MPH with the current gearing.

 

[OneTimeUser]

Continuation...Now that my Tillotson 212EE is sort of broken in it has begun to idle high. I had the same problem with the Predator that the Tilly replaced.

Set up is Nibbi 24mm round slide with cheap billet (?) manifold that came with an Amazon 22mm carb kit. BTW the Amazon carb kit worked well for a while then started giving me problems so I upgraded to Nibbi but kept the manifold. The Predator had the same intake and exhaust set up as the Tilly now has and had the same problem.

I can back the idle screw out all the way and it still idles high. I've tried several low speed jets which don't lower idle and I'm sure that the slide is bottomed out.

If I adjust the fuel/air mix screw I can get it to idle even higher (enough to cause the kart to start to creep a bit).

So, I've got the fuel/air mix adjusted at less than optimal to keep the idle low.

I've never seen this problem before. Any ideas for me?

Thanks in advance.

 

[Whitetrashrocker]

Check the manifold.
Sounds like an intake leak.
Is it a rubber intake? Ive had issues with them. The mating flanges sometimes arent flat.
Some carb clean sprayed around the area while the engine running will find that leak. Ive used the propane torch un-lit too. Just blow the gas around the area.

 

[OneTimeUser]

WTR,

Thanks. Will do. Mr. Brown taught me that trick in auto shop in 1972. Can't believe that I didn't think to try it in this case. I see hand-cut gaskets in my future...

 

[OneTimeUser]

WTR,

You were spot on. I had leaks at both ends of my cheap Amazon manifold. The rubber gaskets are junk. I fixed one by tightening, but the other remains despite some torque and some gasket sealer.

It is better over all, but I'm now on the hunt for a new manifold.

I've been eying the 6 or so inch long curved ones. Any advice or recommendation about that?

Thanks again.