Honda MB5 How-To Section
--- The Battery, Lights & their story:
If you run your MB5 without a battery, you will blow out the headlight,
taillight and other bulbs. You can get battery eliminator diode that wires in
and then stops this from happening. If you did blow the headlight, it is
discontinued from Honda, get one from Perk LLC (see links), he has a replaceable
bulb headlight from Europe. Replacement bulbs for that headlight can be
purchased for him, kind of a special bulb. The cheap battery is
only about $10 from a motorcycle shop. Yuasa # is YB2.5L-C, you may see some of
the off brands labeled RCB2.5L-C or RB2.5L-C, same thing. I have heard of some
other maintenance free 12 volt batteries that fit in there, you just need to run
about the same amperage. When you turn the key on, the dash lights, turn
signals, horn and taillight/brakelight should work, but the headlight doesn't come on
until the engine is running. Replacement turn signal and taillight bulbs can be
bought from your Honda dealer or an auto parts store. Oh yeah, and don't forget
to check the main fuse that comes off the battery. For a wiring diagram, see the Resources Page.
--- The basics:
Simple maintenance will keep your MB5 running like a champ for a long time.
- Change with the spark plug about every 2500 miles, stick with the original NGK
plug if it is stock, BR8HS.
- Clean the air filter every 2000 miles, more often if you are in dusty
conditions. Use a good motorcycle foam air filter oil, not the gear oil that the
service manual says.
- Keeping the chain adjusted and lubed (recommend Bel Ray Super Clean) every 1000
miles will give you the most life out of your chain. Remember the adjust it to
specification and aligned properly.
- Now that these MB5s are quite old, you should grease parts of the chassis that
may be a little dry. Use a good waterproof grease (I like Maxima or Torco) on your
steering head bearings, center stand pivot, rear brake pedal pivot, control
lever pivots, wheel bearing seal lips, speedometer drive gear, swing arm pivot,
and rear cam pivot for the drum brake. Use a good cable lube, not WD-40, I
recommend Dri-Slide, on the clutch, throttle, tach and speedo cables. Keep those
clutch and throttle cables adjusted too.
- Changing the front fork oil would be recommended, use a good 10wt motorcycle
- Check the tire pressure often, (especially because these are small tires),
this will give you the best life and handling of your tires.
Oils: I personally recommend Motul 600 for use in the stock oil
injection, it is a high quality synthetic oil the can be used in oil injectors,
if switching oils, I don't recommend you mix synthetic and non-synthetic. So
when in doubt drain the tank and bleed the oil pump (check the oil pump
adjustment while your there). Oil tank capacity: 1.2 quarts or 1.1 liters
If you have gotten rid of the stock oil injector and you are pre-mixing, use
Motul 800, it is even better than the 600, recommended mix is
For the transmission: I recommend Motul Transoil, it is a high quality oil that
works great! It will use 1.0 quart /
0.9 lit when you change it and 1.1 quarts / 1.0 lit when it is disassembled.
Change this oil every 5,000 miles or 9000 km.
There are many good oils out there and you don't have to use a synthetic, these
are just my personal recommendations.
--- So your MB5 doesn't start - well here's were to start
Your two-stroke motor needs 3 things in the right amounts at the
right time to run:
1) Start with compression, remember, check it with wide open throttle. 110 psi
is the minimum on your compression guage. If you don't have that, at least pull
off the head and inspect. Check the piston, rings, cylinder, etc. 185 psi is the standard compression when it was new.
2) If compression is good, go to ignition, pull the plug out and get a new one,
rest it against the head with it attached to the spark plug boot, you should see
a decent size blue spark when you kick it over, (with the key and kill switch on
of course) if you don't, you need to check
your stator, CDI, coil, wiring, etc. (Check your service manual, but a wiring
diagram is available on the Resources Page)
3) Fuel needs to get to the cylinder in the proper amounts, first check to see
it flows out the fuel valve at the tank, then open the drain plug on the bottom
of the carb, if those are good, pull the carb off and check the float level,
float valve, clogged jets and clogged passages, worn out jet needle and needle
jet. Also remember to check for broken reeds, but that is rare. (Check your service manual for
-Most common to find when your MB5 has been sitting for a long time is plugged
fuel valve, float valve, and plugged up carburetor. Take the carb. apart, clean
it (THOROUGHLY) & replace any o-rings/gaskets.
--- Counter Balancer Alignment
Align the gears as shown in the picture: