new to me 96 Timberwolf 250 weak spark (New Stator & Coil) need help!!

[myridge]

I picked up a 96 Yamaha non-running Timberwolf 250 2x4 for cheap ($200) and I have fiddled with it for days with no real success. When I got it, it was missing the coil so I purchased a replacement coil on ebay, hit it with a spray of carb cleaner and it fired up and idled for a min. Cleaned and rebuilt the carb, new fuel lines, and now it has a weak spark and will not start. It will never fire on electric start but will occasionally on recoil start. I see no visible spark at all.

I ordered a new stator thinking that was it, but still the same. (Spare Stator now) How can I test the CDI? Could it be something else? I have checked all the connections under the seat, the grounds, the battery, etc. What else could it be?

[myridge]

Forgot Compression is good 119psi so its within spec

[leevarnado]

do you have a good battery in it.

[Ghostv2]

Sounds like it could be a bad rectifier too. My dx wouldn't fire with the electric start but would with the recoil like yours.

Sounds stupid but maybe you overlooked it, did you try a new correct spark plug? Could be a little fouled up.

[myridge]

https://youtu.be/wMdEcP0VRAw?list=UU...ZgfjGw2KlXXcqQ Attached is a quick video of it running poorly, I got it running now, actually it starts almost first pull every time but will not fire on electric start at all, I have NOT replaced the rectifier just yet but will if needed. I have replaced the stator, coil & plug, rebuild the carb but now I need to check the valve as I hear allot of slap while running and occasionally it pops and backfires through the carp so I think it has lots of timming chain slap and stretch. Any other thoughts?

[nd4speed]

You cant test a CDI, they often dont go bad, and if it runs at all the CDI is not the issue.

god that reminds me of my 225 yamaha. After it got rolled once it would backfire out the exhaust sometimes when I shut it off.
Always figured it was the carb never did the valves.

[myridge]

image.jpg Well I just finished adjusting the valves to spec and it's still not much better the valves were really loose though.

[myridge]

InTake is .008 exhaust is .013 timing chain seems loose on the left side but right side where tensioner is tight. Plug is gapped and new. I may pull the carb off again and go through it once more. It's basically the same as my dx225

[myridge]

It starts and idles ok on recoil start but will not accelerate it bogs and dies or pops through the carb like its out of time

[fieldy]

If it isn't a local ATV it might need a different size main. Raise or lower carb needle and see if anything improves. Try another main jet. Check tank flow and cap vent. Cheap things I would check and try.

[myridge]

This thing is driving me nuts. I took the carb off and cleaned it again and just made sure all the jets were clean and adjusted the throttle pin down up one slot. Started on electric start Idled great took for a spin around yard and it ran good headed back to garage and it died. Went to restart and same issue no start on electric only recoil and its bogging and popping. Pulled carb off went through it a third time may have had junk in main jet, Reassembled and again runs great good test ride then boom again same issue. Next is a fuel filter but I don't see anything in the tank or gas but something is causing this.

[fieldy]

Does it start right back up after it dies???
Take the tank off and start sloshing and dumping out small amounts of fuel outside away from your work area, be careful! Can you find a safe way to gravity flow a small amount of fuel from another small gas tank with an inline filter? That eliminates some possible causes.
Leave the atv gas cap a little loose on this next start, just until you see if it dies again.

What brand name is on carb? Maybe you have a bad fuel level in the carb because of floats/needle valve type problem. Check that then look at trying another carb or buying a rebuilt carb//needle.
The electrical problem...try to download a manual and trouble shoot with a multimeter.

Just sounds like its not getting fuel or carb fuel level. Manual can help you check fuel level. You are doing some good, it will be worth it! Good luck.