View Full Version : Backfiring

12-17-2008, 05:44 PM
I am just loving my force. The timing screws came loose and now it is out of time and backfiring. Does anyone else have the timing marks (three lines) instead of the degrees?

12-17-2008, 07:47 PM
"on the three timing marks, from left to right they go as follows, first mark is 32, the longer one in the center is 30, and far right is 28, like graham said set timing to 30 center line while cranking and that will give you 32 at running, good luck"

12-18-2008, 06:45 AM
Cool. Thanks. I read in the manual you have to remove the spark plugs and crank it over like that. I saw that you are supposed to put the motor in gear (wot) and turn it over. Do you leave it in nuetral to set the cranking line? Thanks in advance for all my dumb question.

12-18-2008, 08:47 PM
"yes you have to pull the plugs, also ground your spark plug wires,dont try cranking without grounding them or youll possibly fry the modules. now bypass the neutral saftey switch, its located at the bottom of the tower shaft, two yellow wires on it,throw a jumper wire on there,advance the throttle to wot,so it wont be in neutral, hook up your timing light to the number 1 spark plug wire,even though there grounded,now you can crank away and adjust your timing"

12-18-2008, 09:10 PM
Thanks. I was going to take it to a mechanic. That is all I can figure why it backfires out the exhaust for.

12-19-2008, 03:34 AM
"Backfiring from the exhaust is usually timing.

If the backfire appears to come from under the powerhead, or out underneath the carbs that is normally the sign of a blown powerhead base gasket or a powerhead that is not torqued down within spec to the exhaust housing."

12-19-2008, 04:50 PM
Yep. The backfire came from the exhaust. Scared the crap out of me too. Ijust put a new stator on and think maybe a wire is crossed somewhere. I am also wondering if the wires on the rectifier are hooked up right. I can't find any pics of one with the wires on it.

12-20-2008, 06:14 PM
"Larry, the rectifier has nothing to do with the ignition. The two yellow leads simply go to the rectifier in any order.

With the motor running, if you see about 13.5 volts at the battery (normal charge cycle) then it's fine.

The stator itself simply produces AC current which is converted and stored in the CDI modules. So again, even if you have the blue striped one on the terminal that the red striped one was on previously (or the solid blue where the solid red was - depending on the mfg of the stator), that in itself will generally not cause an issue.

If you mixed up the trigger/sensor leads if they were disconnected, that WILL cause a major problem that could mistaken for timing...

To correct the backfire I would confirm the trigger/sensor is hooked to the right points of the terminal strip, then check the timing and ensure the carbs are adjusted properly. A lean carb could contribute to the backfire although I would not suspect it would be entirely at fault."

12-20-2008, 07:40 PM
Thanks. I will check everything out and hopefully find something.

12-20-2008, 07:48 PM
"larry i had the same problem, wouldnt start,and i only got a major back fire and i do mean major. when changing the trigger the two sets of org/grn wires were swapped going to the modules, found it and put on correctly,started right up,just something to possibly check, good luck"

12-20-2008, 08:40 PM
Sounds like the same problem I had. My neighbor saidhe almost jumped out of the window it was so loud. Thanks.