how do i re-time the timing gears and chain after I take it off the motor?

Question

I own a 1969 honda trail 70. I am replacing the piston and rings and need to take the head off...How do I re-time the timing chain gears between the crank and the camshaft? Also, what is the gap on the points supposed to be for a 1969 Honda trail 70?

Answer 1

Its a flywheel magneto so you need brass or bronze feeler gauges. points gap is 0.014" but anywhere between 0.012" to 0.016" works. You can put piston at top of stroke with the head off and see the timing marks on flywheel 'T' (be careful not to get cam chain tangled up in case) . The cam sprocket has either a dot or a circle which lines up with a notch on cylinder head, rotate sprocket clockwise very slightly to keep lower run of chain tight so the timing isnt off due to chain slack.. you will need to reset valve clearances as well, 0.002" intake and 0.003" exhaust. Make sure you have the cam in TDCC position before you strip engine as its a pain to turn if a valve is open (rockers on base circle of cam)

Answer 2

So...you decided to do the work yourself?
-Remove the spark plug (easier to turn the crankshaft).
-Remove the L crankcase cover (to turn the crankshaft, see the timing mark on the flywheel, to adjust the points).
-Remove the in & ex valve inspection covers.
-Turn the flywheel in the direction the engine turns (push the kick start to see).
-Turn the flywheel (in the direction) and watch the in valve go down (as in it's opening).
-When the in valve comes up, keep turning and line up the timing mark on the flywheel (piston is at TDC compression stroke).
-Take note as to which way the lobes on the camshaft are pointing and the timing mark on the cam sprocket (so you'll know how to put it back together).
-Remove the cam chain tensioner, cam sprocket, head & cyl.
-When you reassemble every thing and put the tensioner back in, make sure all timing marks are lined up. Turn flywheel slowly, any resistance, the piston might be hitting a valve. Back up the flywheel and check timing again.
-Valve clearance - in 0.002" - ex 0.003"
-Here's a picture of your motor. Use 1970 ct70 (same bike)
http://www.mrcycles.com/

Answer 3

there should be marks on the gears to line them up, and that'd have to be done with the piston at Top-Dead-Center. Don't know what the gap is on that bike probably about .35 to .45

Answer 4

the gap is .35 according to the book hope that helps and you can use a timing light on the bike for timing it

Answer 5

with every bolt you took out you knew you did know what you were doing and you still kept goin'. i don't pity you a bit...now you got a basket case and i hope who every puts it together for you charges you out the ***...you deserve it.