Left Side Intermittent. Please Help!!!!

[SK2008BANSHEE]

I’ve had a 2008 Banshee for a couple years now. Practically stock except for pipes and exhaust. Ran great for one whole season with no issues and then it’s started dying on me after it heated up (like it had flooded). It would restart but run like shit after. 

 

I took it to Yamaha dealer. Was told my compression was bad (I think 90 & 100) and said my carbs needed adjusting. So I did a top end rebuild on it. Now compression is better (120 - aftermarket cylinders - I now I should have just machined my factory ones - Wiseco pistons and rings factory spec).

 

My left side just wont run right!! Poor response, sputters and gas coming out the overflow tube. Like it’s running too rich. I’ve rebuilt my carbs 4 times (twice with new kits) have checked my float height and set to 22mm. Jets are all factory stock spec. I started thinking it may be an electrical problem so then I started there. New ignition coil, new wires, caps and plugs (gapped to spec). I tested my stator and the pickup coil was out of spec. Ordered a Yamaha one. No change in performance. Tested all components of the TORS system and unplugged and ran it... no change still gas out of the overflow tube. Spark is good. Right side runs like a dream. Carbs slides are synced (I don’t have the airflow meter but that can’t be that big of an issue as they idle both the same). Starts great and idles great. Choke was cleaned and functions well. 

 

Have a aftermarket K&N and boots are good. Reeds are good, no cracks. Choke sync tube is new and good. 

 

Im so lost and angry at this point. I feel like I’ve tried everything and I’m ready to give up. 

 

Any help would be much appreciated. 

[SKEETER]

Give up. Sell. Buy boat. Thank me later. 

[gusto]

Sounds electrical to me. Can you try someone else’s CDI box, or harness? Check your grounds?

if your getting gas out the overflow you floats are stuck. BUY NEW floats and assembly. 

What are your mods and what’s your pilot and main jet sizes?

[SK2008BANSHEE]

Me too. I’m an electrician by trade and intermittent issues are usually that. But it’s not. Eliminated TORS, Park Brake, re did the whole wire harness, new stator and ignition coil and wire etc. CDI Box is either an on or off as far as I’ve read because the ignition fires both cylinders so I’d be having issues in both. The only electrical thing that could fuck with one side would be the TORS switch above the carb. 

New float... yes maybe. Put them in water and they don’t bubble and float. I would love another set of carbs to help trouble shoot. 

 

The only test test I haven’t done is a Leak Down. Would a Lower Crank issue cause issues on the Left side??

 

My pilot and Main Jets and Banshee stock. They are new and same spec as Cylmers Manual sorry I don’t know the number off the top of my head. 

[gusto]

So you have stock pilots and no aftermarket pipes, reeds, or air filters?

CDIs do weird shit. Run fine at idle then shit the bed, run fine then don’t run etc. If you have a buddy with a banshee just swap out quickly to eliminate. 

You said you bought new coil and wires? Or used or aftermarket? I’m asking because that’s the classic scenario of cutting back on the coil wire to eliminate the intermittent spark.

[hoppedupandcutdown]

I read, pipes, K&N, and stock jets. Need to address that. Might not be your problem, but it will be A problem.