What's up with these domes I got

[junkyarddog]

I just got in the mail some domes for my 66mm bore setup and there missing one lip for oring, so I guessing that it's because the bigger piston and there's not enough room since piston is bigger? So now it depends on the head and dome to make the cylinder oring seal?

[sleeper06]

If your using blaster Pistons that seems to be how they come for thy configuration. What kind of Pistons are you using? You need to make sure the angles and step match whatever your setup is

[trickedcarbine]

Pic of dome? Lots of big bore stuff has just a lip on the inner side of the o ring.

[junkyarddog]

It's stock cylinder with wiseco 66mm piston nothing fancy 13deg piston

[junkyarddog]

 

 

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[junkyarddog]

 

 

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[junkyarddog]

Se the old pic with normal 2 lips to hold oring said and the new one has only one and depends on the head to help hold seal, to me this seems shitty but hope y'all have run them this way without issues

 

 

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[VegasJeff]

Second pic is big bore domes with the missing outside lip. I ran those with 68mm blaster pistons "like sleeper said" for my cub setup.

[locogato11283]

Se the old pic with normal 2 lips to hold oring said and the new one has only one and depends on the head to help hold seal, to me this seems shitty but hope y'all have run them this way without issues

 

 

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They will be fine. Make sure you install the o-rings properly and you're good to go.

[jbooker82]

66-68mm big bore domes usually don't have the outer lip. I'd imagine they do this so the o ring can be pushed out slightly farther. That would help with o ring life due to it not being exposed to hot combustion gases.

[trickedcarbine]

Not really sure that is a valid assumption. Yeah the O ring is moved over further, however the bore is expanded with it as well.

[sleeper06]

You better verify angle on those domes from pic they look like 11deg bolster piston profile and you stated you have 13 deg pistons . Is there writing on side of dome

[sleeper06]

Also from my experience most off the shelf 13 deg banshee domes are relief cut a lil over 66 mm so you don't need your domes cut every bore job that doesn't mean don't measure it . Where did you get the domes

[sleeper06]

Did you call n say big bore domes , then u got what you asked for, 98% of people consider big bore 66-68 and utilize long rods and go with a 573 series piston with 11*

[junkyarddog]

Yes the domes say big bore/13 deg/21cc it's the right deg, I just came from sand trax (local Atv shop) they said I can run stander end domes from 64-66 mm and anything bigger than 66mm is when I would need a BB Dome so now im like wtf? But I read online that 66mm was the start of BB domes so idk