Motorcycle Repair: 1966 150 dream

Question
Looked at a 1966 150 Honda Dream, needs parts, can find on ebay
Bike has sat for extended period of time, when they started it puff of blue smoke, concerned as it could be a creaked ring, but, I'm thinking valve seals as it sat to so long?
Would appreciate your opinion, also any idea what it would cost to have someone do the repairs?

Thanks

Answer
Chris, the Honda CA95 Benly Touring 150 (not a "Dream".. those are 250-305s) engine is relatively sturdy, but they don't hold a lot of oil and if it gets too low, bad things can happen. Not knowing the mileage or the history of how it was used and stored leaves a lot to be determined.

First thing to do is to check the valve clearances, set at .002" then do a compression test. Also look at the spark plugs after it has been running to see if there are signs of oil burning or excessive fuel fouling.

When engines sit for years and years, the rings can get glued into the piston ring lands, preventing them from expanding and contracting to keep the compression pressures where they belong. A compression test will tell you if there is leakage past the rings or valves, if the readings are really low. 130psi is the factory standard.

These engines don't have valve stem seals, so unless the valve guides are really worn, oil past the intake stems is not a usual source for oil burning.

Please note that when bikes are fired up the first time after a long sleep, it is very common for them to smoke as the old oil solids, gasoline residues, etc are burned off in the exhaust system. If the rings are sticky, they can free themselves up to a certain degree once the engine has been run for an hour or so.

As long as you have nice clean oil in the engine and it is tuned properly, just run it for awhile to see if the smoke clears up on its own. If the bike has over 10k miles and looks like it hasn't been apart before, it may need rings and/or oversized pistons/rings if the bores are excessively worn.

If you find someone who is knowledgeable and is reasonably priced, the costs could run $500-800 depending upon what is worn down inside the engine. Other moving parts are camchain, tensioner roller, rocker arms, valves, all of which may need replacing.

Old bikes and parts are not cheap and finding someone who knows how to work on them can be difficult and expensive, so budget accordingly.

Bill Silver