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Discussion Starter #1
Trying to start my 69T120 and got nice fat spark but no gas is getting to the spark plugs, they are both dry. I poured a little bit of gas down each spark plug hole and still won't start. With the air boxes removed I can see gas spitting out of the carbs. When I put my hand over the carb mouth I feel air pushing out (as I kick it over). I don't feel suction - which I think I should feel. I beginning to think the intake cam may be out by 180 degrees ????
 

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Pull your spark plugs out and you rocker box covers off so you can see the rocker arms. If you have a center stand, put the bike up and get it into top gear. Roll the rear wheel to turn the engine over until the pistons are at top center. You can look in the plug hole with a flash light or put a screw driver in the hole, just don't use the kick starter to get top if you use a screw driver. One cylinder will have the valves completly closed and you should be able to feel side play in the rocker arms. The other cylinder will have both valves slightly opened. The exhaust will be closing and the intake opening. If this is how yours is, your cams aren't 180 out.
 

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Discussion Starter #3
Thanks for the info. With the right cyl on TDC both intake and exhaust valves are closed.

With both valves closed on the right cyl, I can see on the left cyl that the both valves are barely open.

From this I gather the timing is correct.
 

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I think its best to concentrate on one cylinder at a time.
Begin with the right-hand piston.
34 degrees before top dead-centre (BTDC), the inlet valve begins to open. (exhaust stroke)
[*if not the left one is, give it another turn]
34 degrees after TDC the exhaust valve closes.
Piston going down on the [1] induction stroke.
----------------------------------------------------------------
Through bottom dead-centre (BDC)...piston going up, on the [2] compression stroke.
55 degrees after BDC (ABDC) the inlet valve closes.
Now ignition timing...between 38 degrees BTDC and TDC the engine fires, depending on the speed of the engine.
The mixture ignites and burns to max at TDC, max compression.
-----------------------------------------------------------------
Piston going down on the [3] power stroke.
55 degrees BBDC the exhaust valve opens.
-----------------------------------------------------------------
Through BDC again, piston going up on the [4] exhaust stroke.
Repeat.
The left piston is 360 degrees out of phase with the right.
A timing disc might help.
 
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