Vintage Dirt Bike Q & A

Are there many differences between the 78 and 79 CR250?

I just picked up a 78 and wanted some info. Looks like the 1983 is really on the back-burner now. Thanks!


J

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#829 The "Factory Novice"

1988 Honda CR250RJ
1983 Honda CR480
1981 Can-Am 250 MX6-B
1979 Honda CR250RZ
1979 Kawasaki KX250 A5
1978 Husky 250CR
1978 Honda CR250R
1977 Yamaha YZ400D
1977 Suzuki RM125B

Here's the ones that you'll notice:
Frame - 1979 has small tab for sprocket cover
Front sprocket cover
Air box bracket
Cylinder - 1978 has un-bridged exhaust port
Rear chain guide and roller - 1979 L-shaped
Forks - 1979 has 4 pinch bolts for the axle
Shocks - both years same length
Side panel emblems - 1978 has blue color included
Dunlop (1978) v Bridgestone tires (1979)
Ignition A is for 1978 only - B thru F came with both motors.

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Michael Stiles
1979 Honda CR250R Elsinore | 2006 Husqvarna SM510R | 2007 Service Honda CR500R-AF

Michael,

The forks, swingarm and shocks will be put on the shelf right away.

So are my ignition option limited then? I mean can I install a 1980 ignition?

Also is the 79 cylinder a better performer with the bridged exhaust?

J

_________________
#829 The "Factory Novice"

1988 Honda CR250RJ
1983 Honda CR480
1981 Can-Am 250 MX6-B
1979 Honda CR250RZ
1979 Kawasaki KX250 A5
1978 Husky 250CR
1978 Honda CR250R
1977 Yamaha YZ400D
1977 Suzuki RM125B

J,

The Ì79 cylinder has a wider power band with less top-end then the Ì78; in addition to MichaelÌs list above÷the air boxÌs are different (no brace on the inside of the right side edge on the Î78), the Ì79 frameÌs have support gussets on the rear frame section, the Ì78Ìs had white gas caps (if you have any extra, I could use one), and the Î79Ìs have a case chain guard on the right case in front of the counter shaft (to protect the clutch lifter area).

Take care,
Robert

Don't confuse different parts with being able to switch them. You can use any of the ignitions providing the rotor and CDI box "letter" match. PVL does an analog ignition too. Exhaust ports are normally bridged to provide better support to the piston and therefore better reliability. Without comparing the specifics of the 1978 and 1979 cylinders it's difficult to say what impact the brigde has. I would expect minor. 1979 cylinder owners should remember to drill oil relief holes in their pistons to match up with the bridge.

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Michael Stiles
1979 Honda CR250R Elsinore | 2006 Husqvarna SM510R | 2007 Service Honda CR500R-AF

Michael,

Some of the changes I'm planning are using the 1979 cylinder/piston, putting in a complete 1980 ignition, adding a "torque" pipe and possibly a Mikuni carb.

Does the PVL ignition change the power curve like the 1980 should?

J

_________________
#829 The "Factory Novice"

1988 Honda CR250RJ
1983 Honda CR480
1981 Can-Am 250 MX6-B
1979 Honda CR250RZ
1979 Kawasaki KX250 A5
1978 Husky 250CR
1978 Honda CR250R
1977 Yamaha YZ400D
1977 Suzuki RM125B

In my opinion you should use what you have and then try and pick up a E ignition from the CR250RZ 1979 if you can find one. I know of CR250RA 1980 owners who are trying to get away from their stock ignitions in pursuit of more power. Then and only then consider springing big bucks for the PVL ignition. BTW, the PVL requires some machining work on the rotor that John Astleford can do for you (http://www.jastco.com). The Mikuni is a slam-dunk choice, but I would try it with the stock pipe before you spring for the Pro-Form torque pipe. Are you going to race this, play bike it, or just keep it for show?

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Michael Stiles
1979 Honda CR250R Elsinore | 2006 Husqvarna SM510R | 2007 Service Honda CR500R-AF

The plan is to get it on the track eventually. Of course that was the plan with the 125. I have 2 sets of 83 forks plus 82 and 83 front wheels. I will need a swingarm though.

I consider myself a Novice/Low Intermediate, so the pipey powerband would not suit me. I think I'm looking for something between the 78 and 80 powerbands. The broader the better!

J

_________________
#829 The "Factory Novice"

1988 Honda CR250RJ
1983 Honda CR480
1981 Can-Am 250 MX6-B
1979 Honda CR250RZ
1979 Kawasaki KX250 A5
1978 Husky 250CR
1978 Honda CR250R
1977 Yamaha YZ400D
1977 Suzuki RM125B

I am running DG Pro reeds, Mikuni carb and Pro-Form torque pipe and silencer. Everything else so far is stock. The pipe really accenuates the mid-range so it picks up quick, but signs off a little quickly. I am going to to try mix and matching the stock pipe and shorter DG silencer to see what I like the best.

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Michael Stiles
1979 Honda CR250R Elsinore | 2006 Husqvarna SM510R | 2007 Service Honda CR500R-AF

I picked up the bike today and I looked at the motor carefully. I found that the cylinder and head are a different shade of red than the motor. The motor is marked CR250E and the cylinder has an HF1 near the reed. The ignition cover is marked 8A 02 79 "B". Could this motor already have 79 components installed?

J

_________________
#829 The "Factory Novice"

1988 Honda CR250RJ
1983 Honda CR480
1981 Can-Am 250 MX6-B
1979 Honda CR250RZ
1979 Kawasaki KX250 A5
1978 Husky 250CR
1978 Honda CR250R
1977 Yamaha YZ400D
1977 Suzuki RM125B

1978 motors have numbers between 10000031 and 1006782 and 1978 frame numbers between 2000014 and 2006133. The B ignition was fitted to both 1978 and 1979 motors. You can swap 1978 and 1979 components with ease therefore it is quite probable you have bits from both years.

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Michael Stiles
1979 Honda CR250R Elsinore | 2006 Husqvarna SM510R | 2007 Service Honda CR500R-AF