Help tuning Lectron carb

[shawn-n-amber]

Can anyone help me find a good starting point for the length of the metering jet and how many turns out on the power jet? I have a 68mm cheetah cub, 4 mil hot rod crank, 115mm long rods, msd coil, v-force 3 reeds and 40mm letron alcohol carbs. The current problem is that it is blowing fuel out of the pipes, which are Shear custom out of from drag pipes on the left side. Any information would be appreciated!

[Snopczynski]

Can anyone help me find a good starting point for the length of the metering jet and how many turns out on the power jet? I have a 68mm cheetah cub, 4 mil hot rod crank, 115mm long rods, msd coil, v-force 3 reeds and 40mm letron alcohol carbs. The current problem is that it is blowing fuel out of the pipes, which are Shear custom out of from drag pipes on the left side. Any information would be appreciated!

 

Call packard racing or patriot racing. They ought to know.

[dajogejr]

get yourself a good digital micrometer.

Measure the tip of the needle to the brass insert on the slide where it threads in.

 

Start with 48mm length.

 

Any needle will work to get the bike to idle.

 

Warm the bike up, and wrap the throttle 3 to 4 times real quick. It should be crisp and clean, not blowing a ton of raw fuel out the pipes (a little is ok for methanol)

 

If it's blowing raw fuel out, turn the needles out 1/4 turn at a time until it's revving clean. Then you're done.

Remember, the flat side of the metering rod MUST face the engine, so once you make the needle longer, push the needle up and turn it so the flat is facing foward, you'll feel it "click" back in place.

 

Keeping these needles the same length is critical. I get mine within .02mm or so of each other.

 

Then, turn the power jets all the way open. Keep turning them in until it pulls nice and hard. That's your safe point.

 

If you go too lean on the metering rod..it'll surge and feel "tinny" and rev funny....1/4 to 1/2 turn at a time is what I'd recommend.

 

Just use the two outside screws on the carb tops until you get the needle set, then use the third to fasten it (in front of the cable)

 

On my 10 mil cub, alky, with Packard Lectrons same carb as yours but bored to 41.3, I believe each of my needles are at 47.3mm or so...

It's crisp every time out...