High-Performance Carb For Mitsubishi Engines

The TLE43 has a stock two-barrel carburetor and filter with no adjustments except idle speed.

I installed ADA S1 expansion chambers on both engines of The Dragon Lady". They could use better-performing carbs and air filters to make use of their improved exhaust.

The front engine bogs a little at high sustained speed, which I think might be a fuel delivery problem from the reserve tank. Both engines have 1.5" friction rollers and WOT is maybe 9400rpm at 39mph. I'm up at that speed for just a few minutes enroute to and from work. On the boulevard stop and go traffic, engine speed gets up to 8900rpm and 35mph.

Front engine has 39.37" of rubber exhaust tubing connected to the bleed port. The tubing leads to the silencer/muffler strapped below the frame near the crankset. The smoke would blow directly into my face, so I had to reroute the front engine's fumes.

The exhaust tubing is so effective at silencing the front engine that most times I disconnect it from the muffler.

The rear engine has the normal silencer/muffler connected by four inches of rubber exhaust tubing.
 
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The TLE43 has a stock two-barrel carburetor and filter with no adjustments except idle speed.

I installed ADA S1 expansion chambers on both engines of The Dragon Lady". They could use better-performing carbs and air filters to make use of their improved exhaust.

The front engine bogs a little at maybe 8000rpm. It has 39.37" of rubber exhaust tubing connected to the bleed port. The tubing connects to the silencer/muffler strapped below the frame near the crankset. The smole would blow directly into my face, so I had to reroute the front engine's fumes.

The exhaust tubing is so effective at silencing the engine that most times I disconnect it from the muffler.

The rear engine has the normal silencer/muffler connected by four inches of rubber exhaust tubing.

I was referring to the Walbro # on your stock carb (it's on the side)
There are a few options.
1. WYK-58 is great, barrel carb, high/low/idle adjustments.
You might have to make an adaptor plate to line up the pulse hole.
2. WT-603 or 668 (almost identical), h/l/idle but this is a butterfly carb.
Both would be optimal for that motor.

I use both on my 39-50cc 2 strokes, and they do very very well.
You just have to learn how to tune them well if you don't know how,
or you'll be in big trouble.
The butterfly version has a bit more throttle response,
and on the WT series you can tap a fitting into the bottom plate of the carb and engine's cases to do an external pulse line,
which makes lining up a pulse hole on the mani's a moot point.
Like this...
http://www.capturedbyrobots.com/images/603cagped.jpg

Bogging is dangerous on this motor without a tunable carb.
You are most likely running very lean at WOT.
 
The WYK-58 carb was also mentioned in a thread on pocketbikeplanet.com. It was also installed on a hopped-up Mitsubishi engine.

Thanks, I'll keep researching.

davesmotors.com sells the WYK for $39.
 
What's a pulse and why does carb and crankcase have to be connected?

Is there a carb that'll bolt on without fabrication?
 
The 'pulse' line is a small pressure port running from the crankcase to a diaphram on the fuel pump. As the piston moves down, the pressure rises in the crankcase, which moves the diaphram in the fuel pump 'out'

Then, when the piston rises, the pressure drops, which in turn allows the fuel pump diaphram to move back 'in'.

On the other side of the diaphram there's a small chamber with an in and out port, with one-way valves on both (one pointing in, one pointing out) along with the priming bulb.

As the diaphram moves in/out, it alternately pulls fuel into the chamber, then pushes it out. The chamber also acts as the fuel reservoir for the carb.

TWO BARREL CARB...
I believe the second 'barrel' in this carb is only used to provide filtered air (no fuel) to the engine during the initial scavenge stage of the cycle, when exhaust gases are purging out of the cylinder
 
Thanks for explaining, loquin.

The new Walbro wyk-58 carb arrived. I'll see how it fits.

Right now I'm having engine stumbling problems with the rear engine. Maybe this carb will cure my troubles.
 
Well the new carb bolts onto the Mitsu's dual-port(air/gas) manifold, but the carb's larger port doesn't even come close to matching the manifold's gas port. :geek:

I definitely need a new manifold.

Now to find one!:geek:

capturedbyrobots, I replaced the sparkplugs. Both engines are running lean due to the expansion pipes.

Stumbling problems probably due to poor fuel delivery from the reserve tank. I probably will have to prime the engines' tanks manually until I come up with a permanent solution.
 
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Well, the WYK carb needs an adaptor to mate to the Mitsubishi intake manifold.

Will a G43L or GSR40 carb spacer fit my manifold?

Does anyone know if there's an aluminum or insulator adaptor that'll work for me?
 
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