Motorcycle Repair: 1986 Honda Shadow 500cc, brent bowman, lump of coal

Question
I am considering buying a Honda Shadow.  It has been in a barn for the last 20 or so years.  I want to check the compression before I buy it.  How would I do that? It probably needs a new battery, change crank oil, drain and flush radiator, new gear case oil, etc.  It supposedly has low miles, but I have not seen it yet.  Aside from checking the compression, what else should I check?  And what should the compression be and should I squirt oil in the cylinders when I check it?  Take out plugs.?  Also, where can I find a compression tester that will fit into the spark plug holes?  And if it is good, what should I do to get it started?  Thank you very much, Brent Bowman

Answer
Brent, any bike that's been in the barn for 20 years is going to need a lot of work to get it ready for the road. I have a few of those in my barn too. There are a few diamonds out there but you should assume it will take some effort and cash to get it running again.  Parts for these bikes are getting harder to find and not everything is available from Honda anymore. So you need to decide if it a diamond or lump of coal.

A compression test is a good start.  You need to be able to crank the engine over with the starter since that year didn't have a kick starter.  You'll need to jump the bike to a car battery but don't have the car running or the voltage regulators can interact and it can damage the bikes regulator. Don't crank too long or if the engine doesn't turn freely don't hold the starter button on too long or it will burn up the starter. That bike has 12 mm plugs so you'll have to go to a motorcycle shop or a good auto parts store to find a tester that will go that small.

Once you have the plugs out and the engine is able to crank, hold the throttle wide open and crank the engine until the compression reaches the highest level.  It should be around 140 psi or there abouts. Anything over 120-130 will be okay.

I wouldn't add any oil at this point it will just mask potential problems that you should find out about before you buy it.  From here the story can take any number of turns.  


Good Luck
Rich