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Newbie question on domes and a few other things


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I am looking to get more power out of my banshee. I have a few questions.

 

I had a question about domes. I know they change the compression, but can someone tell what exactly that will do for me? What size domes would I need? Where do they go? Can I install them myself?

 

My next question is, should I get a port job done or different carbs? From what I understand is I should get the port job first and the carbs later? Is that correct.

 

2003 banshee

FMF SST Pipes

K&N Pod Filters

Cool Head brand Cool head

 

I need to do this one step at a time because I also have a black rifle addiction :flamewar: . I am sorry for the FNG questions. Thanks for your help.

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dome are the part of the head where your air/fuel gets compressed for your power stroke (which is everytime your piston comes to the top on a 2 stroke) you can change the actual dome to be bigger or smaller depending on what gas your looking to run and how much bottom end your trying to get. By bumping your compression (running a smaller dome) you will gain power on the bottom end of your powerband. How ever the more comp the higher octane you need to run.

 

If you have a coolhead then swaping domes is simple. if you have a stock head you cant swap anything.

 

as far as porting there is three things that need to all be working together.

 

Your intake (carbs) your porting and your exhaust (pipes)

 

if any one of these does not complement either of the other two your losing power. Depending on the type of riding will determine what carbs porting and pipes you should be running.

 

Try poking around the site for a few days and dig up some old post. Pretty much every single thing you need to now being new to the banshee has been aske and answered.

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You're from Utah, right?? Asuming most of your riding is going to be @5000' elevation, I would recommend 19cc domes, they will put you around 145 psi and you can still get away with running pump gas. If you ever ride much lower elevations you may want to consider larger domes or you will have to run race fuel. You won't really loose power running a ported motor with stock carbs, but a larger set will compliment a port job better. All of your mods should be carefully decided to work well together for your style/type of riding. My mods are in my sig, My next mod (and soon hopefully) is a set of 32mm flatslide carbs.

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You won't really loose power running a ported motor with stock carbs, but a larger set will compliment a port job better.

this is not correct. If your porting is very mild then yes it will not casue you to lose power but if your running a nice agressive dune port then your stock carbs are choking the piss out of the motor and your without a doubt losing power.

 

will it run? yes. will it run at 100% no.

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this is not correct. If your porting is very mild then yes it will not casue you to lose power but if your running a nice agressive dune port then your stock carbs are choking the piss out of the motor and your without a doubt losing power.

 

will it run? yes. will it run at 100% no.

That's not how I meant that statement. An aggressive dune port with stock carbs will be an improvement over stock, agreed that it is not as big of an improvement as it could be with larger carbs. Six of one, half a dozen of the other. If you only have the $ for one or the other then I would say go for the porting first because it will be a more dramatic improvement, then the carbs will compliment it later. Larger carbs on a non ported motor would be a waste of $$ IMO.

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Is there an install doc on this website on how to install the timing plate? I've been searching and can't find one. Do I need to rejet if I get an adjustable timing plate +4? Do I need any special tools? Thanks for the info anyone.

You can make youre own adj timing plate out of the stock one, I may have one layin around you can have. Gives you about plus 4 degrees. port it then have youre stocker bored out to 29.5s it run great. I ran my 350 like that for a long time. Ran awesome. I have to agree with 19cc domes too.

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Just get the ricky stator adjustable timing plate. They're only around 35 bucks. I have mine set at +5 right now and it runs great.

 

At our elevation we can go a little more without fear of detonating. I only have 19cc domes too, so that helps.

 

Definitely get a port job, and look for some 30-34 mm carbs (either 33pwk's or 34mm mikuni tm flat slides would do good)

 

 

That's the setup I'm going with. I have everything done except the carbs and porting right now, can't wait to finish her up!

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I am looking to get more power out of my banshee. I have a few questions.

 

I had a question about domes. I know they change the compression, but can someone tell what exactly that will do for me? What size domes would I need? Where do they go? Can I install them myself?

 

My next question is, should I get a port job done or different carbs? From what I understand is I should get the port job first and the carbs later? Is that correct.

 

2003 banshee

FMF SST Pipes

K&N Pod Filters

Cool Head brand Cool head

 

I need to do this one step at a time because I also have a black rifle addiction :flamewar: . I am sorry for the FNG questions. Thanks for your help.

Hey, Welcome to the HQ...my favorite Banshee Site!!

 

To answer your questions we would need to know your altitude and what type of riding you do.

 

You can get a woods/trail port, dune port, or drag port done to your cylinders to put the powerband where you want it for your riding type....low, midrange, or top end power delivery.

 

You have 2 greats parts to start out with...your FMF SSTs and your Noss head. Keep your exhaust...they work great for all around riding and respond well to a modified motor. They are very similar to T5s...and not worth trading out for unless you need a specialized exhaust, like CPIs or Shearers.

I would prefer to have SSTs, but I have the standard Fatty's.

 

Your Noss head allows you to replace the domes in it to alter your compression. Smaller domes give you higher compression. It is also a way to adjust for porting mods and altitude. Porting usually changes the port timing so you may have to adjust for that. Do you know what ports are? Do a search and understand the 2-stroke principal and it will be clearer.... See the chart below on domes:

 

Approximate Cranking Compression

 

These pressures are estimates based on fresh stock bore, piston, porting, and deck height.

 

It is recommended to check your compression after installation.

Sea Level 1000' 2000' 3000' 4000' 5000'

18cc 197....178...171...170....165...145

19cc 183....167...160...158....152...137

20cc 169....156...149...146....140...129

21cc 156....145...138...134....128...121

stock 130....125...118...112....106...100

I pulled this info from the Noss Website: http://www.nossmachine.com/banshee_heads.htm

 

1. Get your porting first,

2. get a set of domes to match your compression ratio,

3. jet your carbs to match the porting,

4. pick up a set of Boyesen Power Reeds, ($50.00 or spend $200 on VF3s. I run Boyesen's myself)

5. and run an aftermarket filter setup.

Do all of these mods at the same time!!

You will have to address your air box...keep it, mod it, ditch it, or replace it with an aftermarket one. Your riding type will determine which choice you decide.

 

Next, get a timing plate and advance your timing +4 degrees.

 

Finally, a set of carbs may be on your purchase list.

 

If you are running a woods/trail port, you can run your stock carbs or maybe get a set of 30MMs. The larger you go, the more peak HP you gain but you start to lose low end throttle response. You may want to go larger than that, but at your higher elevation, I don't think you would benefit from it. The best carb is the SMALLEST you can run and have the least restriction to your motor.

>>BALANCE Grasshopper<<

 

I run 33PWKs, have a lot of mods on my motor, ride at sea level in the sand only and am happy I didn't go larger than that.

Guys that drag run as large of a carb as they can...they go from idle to wide open only.

Good for racing, not good for trail riding.

 

Good Luck on your new quad!!

 

I speak Black Rifle/Gun too!! AR, HK, AK, PSS, Super 90, Glock, SIG, Para-Ordinance....etc :thumbsup:

Edited by jayzx750
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