Double Spark

[Mech79]

Ok so I have an 89 warrior that has sat for 8 years. I recently got it out installed new rings, valve guide seals, rebuilt Carb and replaced all the rubber parts in the carb. I have checked and double checked timing, valve clearance, disassembled carb again and recleaned it just to make sure, but at 1/4 throttle or less or stabbing the throttle the bike dies. Once I feather it to get it above idle it seems to run fine, but retun to idle and samething. I have notice that it pops back through the intake so I played with mixtures but nothing. Vehicle ran great when I parked it but I had another quad so I did not need this one till now. I have also checked for bent valves but they are fine. So after that here is the kicker. I am getting one strong spark and one weak spark. The weak one at top dead center and the other at the end of exhaust begining of intake stroke. Any ideas? or is that normal because I think it is lighting off the fuel mixture as it enters causing the air to be pushed out of the cylinder hense the popping. Remeber off Idle it runs fine. I guess it can have the ocasional hicup.

 

[duneracerweston]

Spray starting fluid around the intake manifold while idleing, if it revs up any, manifold has a tear in it and needs replaced, as for spark, thats normal, it fires every tdc not just the compression stroke.

 

[liftedhigh]

It shouldn't spark twice like that on a 4 stroke only 2 strokes spark on every rotation. most times when a 4 stroke double sparks it means something is unplugged. But your problem sounds like a stuck accelerator pump. Take the cover that covers the throttle linkage off and watch and see if the linkage is pushing the the accelerator pump rod down.

 

[Gen1Pat]

Correction, a 4 stroke CAN have 2 ignition pulses per engine cycle. One to ignite the air and fuel on the compression stroke. The other, when the piston nears TDC on the exhaust stroke, to burn off any unburnt fuel to help with emissions (this is called "waste spark" if my memory hasn't failed me) . Weather the warrior is set-up this way or not, Idk.

Mech79, also make sure the the accel pump circuit is free of debris/blockage, and that the spray nossle for it is facing the engine.

 

[beastlywarrior228]

The warrior does spark every rotation

 

[sparkymichigan]

I'm with Weston on this one.
The pickup coil tells it to fire right around tdc. But not every stroke is a compression stroke like a 2 stroke.

 

[Gen1Pat]

So it does have a "waste spark" then. Wasn't too sure if the cdi was programmed to do it or not. Makes sense because it's a single cylinder, SOHC engine and can be timed 180* out.

 

[lbjamm]

^ Indeed. Generally crank trigger means every rotation has fire. Same as a Briggs and Stratton.