Help , Blow on the piston

[NitroObsidian]

Hello ! I come often on the forum, it is a great source of information for me

I from belgium and i have Banshee 421 for road only. I need your help to understand what it can cause this kind of problem :

 

 

Why did I have a degraded piston and dome ? 

This is my setup :

Assassin's cylinder 68mm

Piston 68mm WISECO 

Keihin PWK AIRSTRIKER 38mm (mainjet 200) with UNI pod air filter 

dome 21cc

Vforce 4

intake Chariot  (no boost bottle)

exhaust Shearer OOF smallbore

spark plug BR9ES or BR10ES 

High voltage coil Dynatek

ignition advance +3°

squish 1.27-1.35

 

 

My spark plug are black in low speed and brown in hight speed... The banshee generally turns at 70-80 °c and I reached 90 °c one time because I was in a traffic jam on the road.

 

Can you help me to determinate the nature of my problem ? Thank you !

[bigweav81]

Wow.....did you leak down test before dis assembling. Not say you had an air leak, but always a good idea. Have you taken your pistols out, and what do the rings look like? Seems like something bounced around, and around in there knocking the shit out of it. If that's detonation that's the most spread out detonation I've seen. Following, and ready to learn something. I'm sure far more experienced guys will chime in.

Sent from my SM-S820L using Tapatalk

[bigweav81]

Wow.....did you leak down test before dis assembling. Not say you had an air leak, but always a good idea. Have you taken your pistons out, and what do the rings look like? Seems like something bounced around, and around in there knocking the shit out of it. If that's detonation that's the most spread out detonation I've seen. Following, and ready to learn something. I'm sure far more experienced guys will chime in.

Sent from my SM-S820L using Tapatalk

Sent from my SM-S820L using Tapatalk

[NitroObsidian]

i don't have air leak.. On the damaged piston, i have one ring "glued".... As if it had overheate..

On the other hand, for about a century of kilometer, I have like misfires. I do not get to the bottom of 5th and 6th gear, my banshee jerks as if the ignition did not give enough power.

it's incredible i don't understand why this... I drive with unleaded gasoline 98 with 2% octane additive VP Racing

[Keno]

That looks like debris bounced around in the cylinder. Check bearings for missing pieces

[kawa110]

You get "in traffic jams often"

Can't really lane split to keep the air flowing.

Wonder if one could do the battery conversion and mount a fan behind radiator with a switch for traffic jams or just set to a thermostat.

 

 

Shake the exhaust pipes upside down and see if anything falls out.

 

Found a missing piece of Broken piston like that before.

[kawa110]

Who makes those clutch and stator covers?

[trickedcarbine]

Do a full tear down and inspect the bottom end components. I'd imagine there is something stray dancing around from the bottom end, or parts were not completely cleaned up on assembly. 

Very cool build. Hope you can get it sorted out. 

[Ayesully810]

you ever get this figured out? btw nice youtube channel