I have been fixing a 2002 rancher 350fm that i bought on craigslist. It is the one that had the blown up piston and water in the engine. I have it all back together and when i first started it up it was running really good except it would pop some when you would let off the throttle and it idled a little rough. I figured i didn't get the carb clean enough. I had let it sit for a couple weeks since i was kind of burned out on the project and then when i tried to start it again it was difficult to keep running. I would put the choke on and it would run for a second and shut off. Eventually if i gave it enough throttle i could keep it running and once it warmed up it ran but it would miss and pop and sputter some. I figured the carb got worse from having gas in it again.

Today i pulled the carb and did a very thorough cleaning. I did not run the bike before i pulled the carb. When i got it back on and tried to run it i had the same problem, it was very hard to get started and keep running. If i gave it some gas i got it running but it was missing alot and popping and sputtering worse than i had ever seen it. I put a timing light on it because i had not checked the timing after the rebuild. I noticed that every time it missed the timing light did not flash, the timing gun was very erratic which means the spark is very erratic. According to the book the flywheel should read F when the light flashes but mine is reading T(it was very hard to make out the letter since the light was so erratic and since it was blowing an oily air into my face, so maybe it is F).

So now that you have read my whole story, What causes an erratic spark? I read through my clymers manual but it is very unclear on the ignition system and i am not sure how to check anything. My guess is a bad CDI but those are not cheap so i don't want to just throw money at the problem. I would appreciate it if someone could list the possibilities for an erratic spark and how to test for them or where to find that info. All ideas are appreciated.
Thanks!!!

 

don't all speak at once

 

Tightin your timing chain up and the T/F stands for, T for topdead center and F stands for fire every time I clean my topend out I always set the timing to T on the flywheel so every thing is set up right.

 

Tightin your timing chain up and the T/F stands for, T for topdead center and F stands for fire every time I clean my topend out I always set the timing to T on the flywheel so every thing is set up right.

 

Tightin your timing chain up and the T/F stands for, T for topdead center and F stands for fire every time I clean my topend out I always set the timing to T on the flywheel so every thing is set up right.

 

I can't, its an automatic tensioner. The chain and tensioner are all new. Thank you very much for your idea though.

 

is your fuel line clogged

 

I don't think it is. A am 99% sure it is spark related since the timing light flashing is very erratic and when it misses really bad there is no flash. To me that says spark problem. I ordered a factory manual since those are around 100% better than the Cymers so i will see what it says when i get it. I would love to hear some more ideas and i really appreciate those who have taken the time to reply.

 

Thanks for the PM
I have been getting a lot of tough jobs at the shop, from other brands, nobody in the area has been able to figure out. People are dragging these units out of the woodwork to give me a shot at them. It has been a challenge (right up my alley)

On your Rancher, when you installed the flywheel, then slipped the stator on the case into the flywheel, did the flywheel move away from the keyway on the crank ? The bolt for the flywheel is installed after the stator cover is installed. Possable the flywheel pushed the keyway back a little and is a tad off from time. If this is the case, the flywheel may be spinning past the ignition pulser not only out of time, but with too much air gap and wil not read for spark all the time.
Easy check would be to pull the spark plug and the timing cap. turn the engine to top dead center on the flywheel "T" mark, slip a screwdriver in th espark plug hole and rock the engine back and forth to feel true or near true top dead center on the piston and compare it to the top dead center mark on the flywheel.

Also, flip the kill switch back and forth a lot in case it it coroded from when this quad was submerged.

PM me the findings

----- Gimpster -----

 

That is quite the compliment when people bring stuff no one can fix to your doorstep. You must have a great reputation in your area and now is when all that hard work to get it really pays off. I wish you the best of luck.

Thanks for the ideas on my rancher. I really hope it is not flywheel related, i really don't want to pull the engine again. I will look at that and the kill switch when i get back on Monday. Taking a small vacation this weekend. I will send you a pm with my results.
Thanks-Luke