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87 Banshee Rebuild....... and she lasted 15 min


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I dabbed some sealant on the key way and around the bearing in the tranny like I've seen some of the videos I watched do. I really doubt it's going to be a problem w any of that - but I've been wrong before

 

 

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I'd say your covered there then. And those seem to be factory gears anyway. Pretty sure the Hinson gear sets are all straight cut.

 

It looks like you're pointed in the right direction. Too much timing, too little octane, convergent squish angle - all contributing factors. Probably not even an air leak, but test anyway. Does the underside of the piston show any heat?

 

What do the plugs look like? So far there is really no sign of deto there. The water probably just put the flame out.

 

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Well that's the deal. The left plug (good cyl) looked good. Dry light light black color. The right plug was black but the grounding electrode was burnt about half way back towards the side. Idk if that was from the water hitting it or what

 

 

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Water caused deto or deto caused the water. I'm sure the head was torqued, right? Any loose or stripped studs? (Still leaning toward bad dome angle though)

 

And I think you mentioned those orings not being able to seal that much pressure. A very smart guy years ago told me that the face of the dome clamped down is what seals in compression, and the oring is just to keep water out. That makes better sense to me than a little piece of viton holding up to the heat and pressure of combustion.

 

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Water caused deto or deto caused the water. I'm sure the head was torqued, right? Any loose or stripped studs? (Still leaning toward bad dome angle though)

 

And I think you mentioned those orings not being able to seal that much pressure. A very smart guy years ago told me that the face of the dome clamped down is what seals in compression, and the oring is just to keep water out. That makes better sense to me than a little piece of viton holding up to the heat and pressure of combustion.

 

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Yeah I was leaning towards the top of that cylinder being partially warped or the head. The only step I didn't take was lapping the head and cylinder before I put it together. Everything was torqued exactly like the manual said. Yeah I figured it was a metal-metal seal and the oring was just for insurance and to keep water out but man it's hard to imagine it ever would seal right with the jugs being separately bolted down and the head being one piece covering both jugs.

 

 

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Edited by Clueless87JFrame
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Yeah I was leaning towards the top of that cylinder being partially warped or the head. The only step I didn't take was lapping the head and cylinder before I put it together. Everything was torqued exactly like the manual said. Yeah I figured it was a metal-metal seal and the oring was just for insurance and to keep water out but man it's hard to imagine it ever would seal right with the jugs being separately bolted down and the head being one piece covering both jugs.

 

 

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I figure you torqued it in order and to spec since you seem to know more about this than most new Banshee guys. Good luck and keep us posted.

 

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I figure you torqued it in order and to spec since you seem to know more about this than most new Banshee guys. Good luck and keep us posted.

 

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Thanks man and will do. Yeah I woulda never bought this thing if I didn't think I could have handled the rebuild somewhat easily. I always spend the extra time or money on a motor to replace everything that way it's ready to roll but I may have made a mistake with not lapping the cylinders or head from the start

 

 

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I've seen plenty of cylinders that the decks were compromised in the oring groove area from the old factory head gaskets. A wise man once told me the stock head gaskets under certain conditions will walk around causing that issue. I've listed my concerns and what information you need to get me. Essentially you built a blow torch

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Do yourself a favor call fast racing, one stop shop and done . He's got anything and everything you need plus knowledge of parts he sells

How do I reach this fella ? I will get the measurements for you tomorrow afternoon and see what I need from there. May try and find a head, carbs, and the correct domes after that

 

 

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