Note: this was originally written for the SOHC 400/450's so some information may not apply
Congratulations, you are the proud owner of a Honda Twin
. One that may or may not have been maintained properly
. Of Course, the previous owner (PO :evil: ) told you that everything is absolutely perfect and the oil was just changed and he rides it every day and has never had a problem with it. Yeah, right :lol:
OK, so it started, you rode it around a little and it seems ok. Or maybe it didn't and you bought it anyway.
So let's cover the things that you should take a good hard look at to make it safe and sound.
First you need the Factory Service Manual (FSM) since it has the most accurate information. If you don't have one PM me or one of the moderators
ENGINE:
Check the compression, spec is 185psi, to see where you're really at. Don't be expecting that number though. 135 is pretty much the lowest you can get and still have it run, albiet not good but run. You want both cylinders to be reading very close to each other.
Adjust the valves. Simple to do and rarely did the PO ever do it even though the Maintainance Schedule (MS) calls for every 6K. Now is a good time to put in new properlu gapped plugs.
Change the oil and filter even though the PO said he did. You have no idea what he used. Correct oil is a motorcycle rated 10-40w conventional oil. No blends or synthetics allowed since this is a used motor and a wet clutch. When you go to start it, leave the kill switch off while cranking until you see the pressure light go out. Now you can actually start it.
Check the balancer chain adjustment. See the FSM that you've downloaded.
Check the cam chain adjustment. See the FSM that you've downloaded.
TRANSMISSION and DRIVE:
Check the clutch adjustment. See the FSM you've downloaded.
Check the chain adjustment. See the FSM you've downloaded.
Check the condition of the chain and sprockets carefully. The chain should have a max side to side play of @3/4" and each link should be able to move freely. The rear wheel should have no stiffness/drag in certain positions since that indicates the chain is binding. The sprockets should have a nice even valley between each tooth and the teeth should have a flat area at the tip, no pointy teeth allowed.
BRAKES:
Inspect the linings/pads for wear, cracking and delamination. Delam is where the actual lining is seperating from the backing plate.
Lube the contact points of the pads/linings
Lube the caliper slides and pins
Change the brake fluid. Should be done on a regular basis. See the FSM you've downloaded.
Adjust the brakes. See the FSM you've downloaded.
FRONT FORKS and STEERING:
Drain and refill the forks with the proper amount and type of oil. Yes, it normal for it to come out looking and smelling really bad. That's cause no one ever did it. :lol: See the FSM you've downloaded.
Inspect the steering head bearings, lubricate and adjust. See the FSM you've downloaded.
Check the torque of the triple trees clamping bolts. See the FSM you've downloaded.
REAR SUSPENSION:
Remove the rear shocks. Try compressing them against the ground. Won't move? They're frozen up and have to be replaced, They compress really easy? They're blown and need replacement. They move some but stiffly? May be they're OK.
Remove the rear swing arm to clean the swing arm bushings and pivot points. Replace the zert/lubrication fittings since the old ones have a habit of freezing/plugging up. See the FSM you've downloaded.
WHEELS:
Spoke/Wire wheels need to have each spoke checked for being intact and tight. Missing spokes are a big no-no. Loose spokes are a no-no. Test each spoke for tight and then tap it with a wrench. You should hear a ring note. Each spoke should have the same sound. If you get one that doesn't have it, it's an indication something is wrong with it. Possibly cracked.
Inspect for rim damage like dents in the edge.
COMSTAR wheels need to have the rivets checked for tightness. Loose rivets mean rim failure and no they cannot be replaced.
Inspect for rim damage like dents in the edge.
Check the wheel bearings for smoothness of rotation. There isn't such a thing as "it seems ok" or "just a little roughness". That's like being a little bit pregnant.
TIRES:
Inspect them carefully. Your life depends on them
! Here's a link with good info about them
http://www.roadrunner.travel/magazine/r ... 6/page/32/
The tires generally can be increased in size by 1 number, 100/90 to 110/90, but there's no real point to doing that unless you need more load rating of the tire or ride exuburantly/aggressive.
Tube type tires should have a new tube every replacement even though they look ok.
Always check the tire pressures before riding!
ELECTRICAL:
Check the battery. If it's the normal lead acid type and more than 2 years old it's done even though it seems ok right now. If it's an AGM type then get it load tested. When in doubt replace it.
Check the fuses and connections. Typically the fuse connections are corroded and need to be cleaned to get a good connection and not overheat. The standard auto fuse is not the correct length and can cause problems.
Check that the lights all work including the brake light from both the lever and foot pedal.
CABLES:
Take the cables off the bike. I know, the throttle cables are PITA. :lol: Disassemble them where possible, clean and lubricate with motor oil. The ones that don't come apart flush them with a solvent, let them dry for a couple of days and lube them with a good quality cable lube.
FUEL/INTAKE:
Thank's to 'steveo' for this addition
Take off the fuel tank cap and petcock sediment bowl and look for rust and contamination.. use a flashlight.. at the very least least install an inline filter in the fuel line if the tank is rusty or the sediment bowl is full of "stuff". actually, just install the filter anyway.
Take out the air filter and inspect it, if it's dirty, the bike will run like crap.. they're very sensitive to air filter condition
Take the plugs out of the 'drain tubes' that come off the airbox, if equipped. a bunch of oil, water, and disgusting crap will probably come out of them.
Attach some short peices of tube to the float bowl drains, and crack 'em open. if the fuel that comes out is not completely spotless and clean, just pull the carbs right off and start taking them apart, it's worth it. if there's any particulate in the float bowls, that means there's probably stuff clogging your jets
Even if the carbs are clean, think about balancing them soon.. on an old bike, they're probably way out
Now that you've become intimately familiar with your new bike and everything is in order, go ride and have fun knowing that everything is good and will get you home.
