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Porting and High Comp. head ?


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Hey im new to this banshee thing, have owned 4wheelers in the past just not a banshee until now. Got a question looking for some advise. Got a banshee with Stage IV port and polish, cool head 15cc domes, vito's power pistons. Wanting to know if I put in different size domes (16cc-22cc) if I Could run it on pump gas? Will it still run good since it has the stage IV port and polish with not so much compression? Im at about 1000ft sea leve.l Also crank is stock, got about 30hrs on it? Will these mods put my crank at risk of failing just curious? Thanks

Edited by chevz7194
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Yes, you can change the domes to run pump gas. I am not sure exactly which domes for which octane but I think anything over a 21cc you can fun on 94...don't quote me on that. You will notice a small difference but it won't affect the powerband or port work all that much. You will mostly loose bottom end but you are going to notice the difference.

 

You really should have your crank welded runnin a ported/piped engine. It might hold up but hat "might" word scares the hell out of me.

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I dont claim to be a banshee expert in any way. But i have built many motorx engines and I would think that would give you around 200lbs which i think would be overkill.I am going with 18cc domes on my stock crank at around the same elavation and I think thats a little ify.I like to run around 175lbs on 106 or better fuel I used to pratice on my bike with that compression and run 110/93mix and never had i prob.In my opion if you drop to 150 or155 you will see a considerible diff in power low to mid mostly but this is in the neiborhood of where your limits are on 93.But I would atleast go to a 18 or 19 and run atleast a mix on ur gas.The higher your compression the more stress on your crank in any engine wether it be ur banshee ur honda or ur cr.

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Thanks guys for your info. Do you all think it would be wise to go ahead and replace the crank along with the new domes or to just replace the domes and lower the compression? Do you think the crank will hold up? Owner claims to of had only 30hrs on the bike so less than 30hrs on the motor with all the work done. Thanks for the great info.

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Have you removed the head and seen the domes? 15cc domes would be pretty unusual. Unless the porting was pretty crazy or the Banshee came from a pretty high elevation, 15cc domes would yield too much compression for good performance and would probably trash a stock crank in a short period of time.

 

I would check and be sure they are really 15cc domes. Larger domes would be a quicker and cheaper resolution if they are that small.

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