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


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The issue with that is domes need to be properly cut or else youl be back to where you started faster then you think.

 

Not only that but it cause the bike to run extremely poorly among cause catastrophic failure.

 

 

You're going to be 100x better off getting proper domes from the get go rather then cutting some yourself.

I'd add that they are cheap ($65 a set) and can be at your door in 1 to 2 days. Even if I had the tooling and know how I still wouldn't make my own for what they cost.

 

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I'd add that they are cheap ($65 a set) and can be at your door in 1 to 2 days. Even if I had the tooling and know how I still wouldn't make my own for what they cost.

 

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Oh if that's all there is to it - I'll order them from whoever on here or eBay has them. Just didn't want to get the run around on some little aluminum domes and also didn't want to wait a month to get parts back if all that needed to be done was a little degree change. I need some for the 66.5 mm bore too. Didn't know how hard that was to come by. But either way this dang thing is about to get on my nerves already. Just want to get it running longer than 15 min hahaha

 

 

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Edited by Clueless87JFrame
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I wouldn't trust some random seller advertising "pro design style XXcc banshee domes" on ebay. Driveline and noss seem to get the domes out pretty quick from my experience with them and will cut them anyway you like. Give sleeper your specs and you should last at least 30 minutes this go around if you don't skip the leak down test this time :rotflmao:

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I left the timing alone from where it was originally. +5*

 

 

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After re reading this, there are a few things I see. First, that^ is quite a bit of timing on a motor still cranking 160psi with exhaust work.

 

Second, if you know what to look for, a leak down may not be a big deal. But to someone who is just learning these things like your self, it is worth doing your first couple times. You said there was "No need" to do a leak down since you knew it needed to be rebuilt. But a leak down would show you exactley where the failure is from. You are doing all this top end work, did you do new crank seals as well? I couldn't begin to count how many buddy's bring me motors they say they just rebuilt everything twice and still have repeated failures. I throw the leak down on it and it's a crank seal. Funny part, typically the crank seal that's puking is the same one that there are failures on.

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You care to elaborate on that? I'm new to these little motors and I'll take any advice I can get. Motor died when that oring popped where you can see there

 

 

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Pretty much seems like you know the O rings let go. That photo shows all the grey crud blowing between the water jacket and bore on the cylinder. Hard to tell if the scuffing is from ring damage or where coolant ran down. Coolant is actually quite abrasive when put between aluminum and steel.
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After re reading this, there are a few things I see. First, that^ is quite a bit of timing on a motor still cranking 160psi with exhaust work.

 

Second, if you know what to look for, a leak down may not be a big deal. But to someone who is just learning these things like your self, it is worth doing your first couple times. You said there was "No need" to do a leak down since you knew it needed to be rebuilt. But a leak down would show you exactley where the failure is from. You are doing all this top end work, did you do new crank seals as well? I couldn't begin to count how many buddy's bring me motors they say they just rebuilt everything twice and still have repeated failures. I throw the leak down on it and it's a crank seal. Funny part, typically the crank seal that's puking is the same one that there are failures on.

Well I guess what I meant was - since I was already rebuilding it - I bought all new seals and gaskets, like I would normally do on a rebuilt. I don't reuse seals - ever. I just didn't imagine it would be a seal since there isn't any signs of fuel/oil leaking anywhere around any of the seals on the motor after looking closely at it right after she popped.

 

 

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Well I guess what I meant was - since I was already rebuilding it - I bought all new seals and gaskets, like I would normally do on a rebuilt. I don't reuse seals - ever. I just didn't imagine it would be a seal since there isn't any signs of fuel/oil leaking anywhere around any of the seals on the motor after looking closely at it right after she popped.

 

 

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Did you split the cases and do the bottom end to?
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Pretty much seems like you know the O rings let go. That photo shows all the grey crud blowing between the water jacket and bore on the cylinder. Hard to tell if the scuffing is from ring damage or where coolant ran down. Coolant is actually quite abrasive when put between aluminum and steel.

I was turning it pretty good when I heard the pop/spew sound it made when that oring let go. Engine quickly coasted back down to nothing and died. Would not start back. But the weird thing was - when I disassembled the engine the first go round - both orings around the cylinder domes were in perfect shape

 

 

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But the ones I took out were the high temp style red orings. New ones I received were black and I asked the fella about it and he said "well we use to use red but the black work just as good"........ now here we sit with a f'ed up brand new piston that left pecker tracks on my freshly bored/honed/ported cylinder 15 min later. Fml

 

 

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Edited by Clueless87JFrame
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Is your primary gear OEM or the Hinson one? Aftermarket ones are notorious for leaking past the seal. A few globs of Yamabond on the key will fix it if that is the case.

 

I've blown more than one oring and always had piston crown and dome damage. I was not able to tell what happened first though...the broken oring or deto. You have no pitting on your piston or dome.

 

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Is your primary gear OEM or the Hinson one? Aftermarket ones are notorious for leaking past the seal. A few globs of Yamabond on the key will fix it if that is the case.

 

I've blown more than one oring and always had piston crown and dome damage. I was not able to tell what happened first though...the broken oring or deto. You have no pitting on your piston or dome.

 

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Primary gear appears to be factory. I may have another picture let me check

 

 

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