IGNITION TIMING HELP !!!

The bike is an XS400 Maxim. Got spark, got fuel, trying to run but won't, still turns over after turning off key (backfire?). If this was my old car I would swear that the timing was off. My question is: can the timing be set or is that no longer necessary with the CDI ignition? If it can be done, how does one do it...I haven't gotten a manual for this bike yet so I'm depending on the expertise of others. Any help will be greatly appreciated or even if someone can point me to where I can get some info. Thanks.

 

do you have the plug caps on the correct plugs? Almost sounds like you have the #1 plug on the #2 cyl

 

You can screw up the timing having the engine apart and not assembling it correctly. You should check the orientation of the intake and exhaust cams with the timing mark on the pick up. With the pick up on the mark, your #1 cylinder should be at TDC.

 

Thanks Dinoracer and Fraps for the replies.

I don't think the plug wires have been switched, the PO was riding this bike up until about a month ago.

I know this will make me seem like a complete newbie (I'm really not) but just where in the #$@ll do I find the timing mark? Like I said, I don't have a manual yet so I don't know where to look. There is no side plate to take off that I can see except for the starter motor...there is a small threaded cap on the left side of the motor but when I remove it there is some kind of solid plate behind it. Do I have to crack the engine cases to reset the timing? Really can't wait to get the manual. Thanks.

 

Derenz:

That solid plate behind the little slotted plug is the "timing plate", and should have an "F" and a "T" stamped on it somewhere, that you can see through the hole when you remove the slotted plug.

The "T" indicates Top Dead Center of the Number 1 (LH) cylinder.

The "F" has a U-shaped mark that indicates the firing range for the #1 cylinder.

There should also be a notch on the edge of the hole where you took the plug out. This notch is used to reference the "T" and "F" marks.

From the manual...

1. Ignition timing is checked with a timing light by observing the position of the crankcase cover mark (the "notch") and the marks stamped on the timing plate.

2. Connect the timing light to the #1 (Left Hand) spark plug wire.

3. Start the engine and keep the engine speed at 1,200 rpm.

4. The crankcase cover mark ("the notch") should be within the U-shaped mark (by the "F") on the timing plate. If it exceeds the limits or does not steady, check the timing plate for tightness and/or the ignition system for damage.


Hope this helps!
Herb

 

Just wanted to say thanks to all who tried to help. As it turned out the only think wrong was that the small fitting that is up inside the spark plug cap (a threaded brass fitting that snaps over the spark plug) was broken in half). So although I was getting spark to that cylinder, it wasn't hot enough to fire. I replaced the cap and it fired right up, timing is spot on! The plug wires, by the way, are brand new as are the plugs. So, I learned a valuable lesson here: don't ignore the little things when trying to diagnose a problem and don't assume that "new" means perfect. Now if I can just unstick that front brake caliper I'll be on the road! Thanks again.

DeRenzo1