Banshee bogging after 3/4 throttle

[Deejaedub1]

Ok, I have done a ton of research and I am still unable to fix the problem. After I state what happened I will list all the mods to my knowledge.

 

I have a 98 banshee. Going riding one day I got both K&N filters full of silt from the logging trail we rode on. I cleaned out the filters and called it a day and limped back to the truck. Next day I am unable to go full throttle without it bogging out and losing power after 3/4 throttle. First thing I put in brand new K&N filters, new br8es plugs and new coil and wires and still falls flat. I took both carbs completely apart and cleaned them out. The spark plugs were both rich when I took them out. I changed the plug gap from .30 to .25 to see if that would change anything, thinking maybe weak spark. Nothing. Haven’t checked float height yet but don’t figure that would have changed. That’s what boggles me. The only variable that has changed is that the filters got super dirty. Compression was 150psi both sides. The slides look synced. This bike was actually jetted for 4500 feet above sea level and I haven’t ever rejected it after I moved to 1400ft in 2011 because I didn’t know I needed to until my latest research. It ran perfect until this last ride. Should I lean out the mains a hair? While riding I pull out the choke and it gets worse. I talked to my Yamaha dealership and they suggested electrical. Hence the wire and coil change. Before I try leaning it out with the risk of melting my engine or throwing a ton of money into new parts I figured I would reach out here.

 

I have 280 mains, not sure what the pilot and needle are at but will check later today. Cool head. T5 pipes and silencers. Rebuilt top end with forged pistons and bored .20 over. Stock carbs with TORS (I don’t plan on changing that soon as my 6 year old likes to drive). Airbox removed with only dual K&N pods with prefilters. Boyesen power reeds. 13/42 gearing. I’m at 1400 feet above sea level and 80° weather. I mix 50/1 with 91 octane as did the previous owner. All mods except for fresh top end and bore were done by previous owner pre-2007. Can’t think of anything else.

[Keno]

So, did you clean the filters and then re oil them?

Nvm, just saw that you replaced the filters. 3/4 to full throttle should mostly be controlled by the main jet.

 

 

 

 

 

 

[Deejaedub1]

1 hour ago, Keno said:

So, did you clean the filters and then re oil them?

Nvm, just saw that you replaced the filters. 3/4 to full throttle should mostly be controlled by the main jet.

 

 

 

 

 

 

That’s what I learned from my research. What should I lean the mains out to first?

[ginger]

i would do a leakdown test, see if you may have pissed off a gasket to suck air.  or trans oil. 

[Deejaedub1]

On 9/3/2019 at 11:23 AM, ginger said:

i would do a leakdown test, see if you may have pissed off a gasket to suck air.  or trans oil. 

I’ll order a kit and do it this weekend. Wouldn’t that make it run lean if I had an air leak somewhere?

[Deejaedub1]

Leak down test passed, 7 psi over 7 minutes with zero loss. What next?

[gusto]

Change you mains.

before you got those filters really dirty how often were you cleaning them? 

Go with a bigger jet and see what happens. If you think your plugs are wet try smaller