From MopedWiki

Contents 1 Honda PA50 "Hobbit" 1.1 Hobbit Models 1.1.1 Honda Model Differences 1.1.1.1 Carb 1.1.1.2 Reeds and Manifold 1.1.1.3 Crankshaft 1.1.1.4 Piston & Head 1.1.1.5 Cylinder 1.1.1.6 Drive Assembly 1.1.1.6.1 Drive Face 1.1.1.6.2 Drive Face Bushings 1.1.1.6.3 Variator Weights 1.1.1.6.4 Variator Ramp Plate 1.1.1.7 Air Inlet Tube 1.1.1.8 Muffler

Honda PA50 "Hobbit"

This section presents information about the Honda Hobbit - in its stock configuration. If you are looking for tuning information, go to the Honda Tuning section in the Wiki.

Hobbit Models

Year	Model	Top Speed	Frame Color	Fuel Tank Color	Rear Shock Color	Foot Rest Color	Drive Belt Cover Color	Ignition	Battery	Starting VIN	Starting Engine Number
1978	PA50I	20 MPH	Red	White	White	White	Gray	Points	No	PA50M-1100001	PA50E-J1000001
	PA50II	30 MPH	Yellow	White	White	White	Gray	Points	No	PA50-1200001	PA50E-H1000001
1979	PA50I	20 MPH	Red	Red	Red	Red	Black	Points	No	PA50M-2100001	PA50E-J1000001
	PA50II	30 MPH	Yellow	Yellow	Yellow	Yellow	Black	Points	No	PA50-2200001	PA50E-H1000001
1980	PA50II	30 MPH	Yellow	Yellow	Yellow	Yellow	Black	Points	No	PA50-3200001	PA50E-H1210066
1981	PA50II	30 MPH	Red	Red	Red	Black	Black	CDI	Yes	YC1AB090 BB100001	AB09E-2000001
1982	PA50II	30 MPH	Coral Red	Coral Red	Coral Red	Coral Red	Black	CDI	Yes	YC1AB0905 BB200001	AB09E-2100001
1983	PA50II	30 MPH	White	White	No cover	Black	Black	CDI	Yes	YC1AB090 DB300001	AB09E-2150001
	PA50II	30 MPH	Black	Black	No cover	Black	Black	CDI	Yes	YC1AB090 DB300001	AB09E-215001

Honda Model Differences

Ok, let's say that you have a PA50I, and you want to go faster. By far the easier quicker way to get to 30 MPH is to buy a PA50II motor, including its variator. if you would rather upgrade the piece parts, here's what you need:

Carb

The PA50II carb has a 12mm venturi, versus a 10mm venturi of the PA50I version. It also has a #78 jet versus a #60.

Reeds and Manifold

The PA50II reed uses two petals, flowing through two openings. The PA50I reed uses one petal, flowing through one opening. Don't know the manifold difference, but the Honda part number differs.

Crankshaft

See photo for differences.

The crankshaft on the left is from a PA50II, with the one on the right from a PA50I. The bushings that are shown in the picture are also different - in every way (inside diameter, outside diameter, and length) - see Drive Assembly section (most people call it a variator) for more info on the bushings.

Piston & Head

No differences.

Cylinder

The PA50II has different exhaust port sizes/timings. The PA50I can be easily ported to PA50II specs. The PA50II exhaust outlet, I'll call it the flange area, is larger on a PA50II than a PA50I. For this reason, a PA50II muffler will not bolt up to a PA50I cylinder. This also applies to aftermarket exhausts, too! This means that if you have a PA50I cylinder, you can't just bolt-on an aftermarket exhaust.

Drive Assembly

NOTE: You may need to refer to the parts lists on-line, or linked herein to get used to the terms used. I use Honda terms.

Drive Face

The drive face differs between a PA50I and a PA50II. The PA50I drive face can be modified to accept a PA50II ramp plate. It is pretty easy. Go here: http://itslookingup.com/moped/pa50/rampplate/rampplate.htm Otherwise, the outside bearing in the drive face has a different inside diameter, and the bushing that rides on the crankshaft has both a different inside diameter and outside diameter. See picture below:

Drive Face Bushings

The bushing sizes are:

Model	OD	ID	Length
PA50I	16mm	12mm	16mm
PA50II	15.5mm	10mm	15.5mm

This means that in order to use a modified PA50I drive face on a PA50II crankshaft, both the outside bearing and the bushing must be replaced using PA50II hardware. Similarly, if you wanted to mate a PA50II drive face on a PA50I crankshaft, both the outside bearing and the bushing must be replaced using PA50I hardware.

It is good to note the the outside roller bearing from the PA50II drive face is unavailable in the US at this time. I have called many bearing supply stores all giving me the same info. The HMK1512 is only available in Japan. I do not know about the PA50I roller bearing.

Variator Weights

The roller weight set has different Honda numbers. PA50I wieghts are 8 grams each, and PA50II weights are 14 grams each. The external dimensions are the same, but the PA50I weights have much larger holes.

Weights sizes are the same:

Variator Ramp Plate

The ramp plate has a steeper slope on a PA50II versus a PA50I. This greater slope allows the variator to push the fixed and movable drive faces closer together - increasing the effective diameter of the front pulley set and thus increasing the drive ratio - meaning higher top speed.

Air Inlet Tube

Both Air Inlet Tubes have three holes, but the three holes on a PA50II are larger in diameter. I've pulled these from my mopeds. The actual function for these tubes is to be a "silencer". When you pull them, you will hear wide open throttle - it will be louder than the stock muffler. Check your jetting after removing the tube.

Muffler

The muffler on a PA50II has a larger diameter head pipe, and a larger outlet pipe. In the attached pic, a 7/8" wrench will fit, and 13/16" wrench will not.