QuestionHi Bill, I have acquired a Honda CB175 - 1972 vintage. The bike has come to me in a completely stripped down state including the engine.
My question is how do I refit the camshaft sprocket to the camshaft when there are no visible marks to relate one to the other, I can see the sprocket is a press fit onto the camshaft unlike similar Honda models which retain the sprocket with two bolts. The sprocket has the mark "O" each side near the teeth
Thanking you
Bill Falconer
AnswerBill, fitting a camshaft to an engine with a 360 degree crankshaft is pretty simple. The cam lobe sets are 180 degrees from each other, so the engine fires alternately on each crankshaft revolution. The double-ended coil fires every revolution, as well, firing whatever piston is at the top of compression stroke and the opposite side on the end of the exhaust stroke, commonly called a "wasted spark" cycle. Then, they switch jobs on the next revolution.
Make sure that the camchain tensioner is pushed back down and locked with the tensioner bolt.
Put the pistons at TDC and position the camshaft (valve adjusters backed all the way off) so that the O punch mark is at 12 o'clock position, relative to the center-line of the crankshaft/camshaft centers. Install one camshaft bearing side to hold the cam in place, then install the cambearing on the opposite side.
0
( cam )
(crank)
Adjust the valves on the camshaft side where the lobes are DOWN. Turn the engine over ONE complete turn and adjust the valves on the opposite cylinder. Put the cams/rockers together with plenty of oil/assembly grease.
Once the top cylinder covers are all in place, with nuts all torqued down, release the camchain tensioner and relock the bolt and lock nut. Set point gap to .014" and rotate the points plate so that the points just OPEN at the F mark on the flywheel. Ensure that the spark advancer unit is able to move freely between retard and advanced phases. Use point cam lube on the rubbing surface.
Bill Silver
