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From T-6s to CPI's


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Ha, try and get some of the first generation CPI's to fit correctly! I had to fanagle the hell out of mine to get them to fit how I wanted and they still rub the head, even with spacers & junk in there. I like them though, so I don't really mind. Plus I don't have that big-ass gay logo on the sides of them. I like the blank look way more. If I wanted to advertise for someone I would have covered my shee with stickers.

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the older cpi's had fitting issues and weld leaking issues.. though the newer ones shouldnt have that problem anymore according to cpi..

 

also it sounds like your lean.. or at least from somone that runs at sea level it sounds lean.. most all the people i know of that have inframes and stock carbs (or have ran them) ran bigger than a 400 main with mild to drag porting.. 27.5 pilots as well..

 

but then again that is a sea level..

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the older cpi's had fitting issues and weld leaking issues.. though the newer ones shouldnt have that problem anymore according to cpi..

 

also it sounds like your lean.. or at least from somone that runs at sea level it sounds lean.. most all the people i know of that have inframes and stock carbs (or have ran them) ran bigger than a 400 main with mild to drag porting.. 27.5 pilots as well..

 

but then again that is a sea level..

If your running the airbox your jetting is close.

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First of all THanks For all the responces! THat's awesome and i think you guys cleared it up for me. By the way i am still running the airbox (snorkel removed, and 12 vents). I was riding with the guy I sold my t-6's too and the cpis do pull through the gears faster and rev quicker with my setup.. my plugs look pretty good, but i might go up to 330's because they are a bit lighter than they were with the t-6's. I think i will stick with the setup for the rest of the season, or until I see a set of drag ported jugs out there that fit my budget.. I also see that 35pwk carb kits can be bought for 335.00 so thats definitly a possibility too. With the mild port job i got now i think that just throwing on some 33-35pwks would be a waste of time as i think i'd lose alot of power on the bottom. I truely can;t believe that CPI's arn't better made after their years of service.. its like they are trying to fit them in their shop on a banshee with a bent frame.. that really wouldn't surprize me.. i just got the 2 tubes as close as I could and clamped the sam hell out of them... them dont seem to leak anymore.. After 2 rides both of my front frame mounts broke.. I took one off and drilled two small holes in it, then put two small bolts threw and tightened it.. needless to say 1 more ride under the belt and the one bolt is MIA and the other is 80% backed out.. time for the lock-tite treatment.. What a pain in the ass..

 

OH yeah and someone asked if i bought them new or used for how much.. I bought them off an ebay store for 528.99 the aucton started at 527.99... The guy always has them on there, but now it seems like they are just a buy it now item... perhaps i did get the lemons of the bunch. He also sells the carbs for the price i stated above.. as does magic racing..

 

One fairly simple question to leave with, once i manage to get a dune/drag port what size domes should i use in my Noss Head to keep compresson up but not need race gas? I almost won 18 cc domes off ebay for the future build, but was wondering it that was the size i should be bidding on.. pump octane is 91-94 here for premiums(depending on station).. i think the 94 has additives to bump it to that number, so the 91 high test would be my preference to stick with.

 

 

Thanks again for all your folks help

 

Brad

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1. 18cc domes will need race gas unless you're at 4000ft or above. If you're near sea level, stick to 21cc domes.

 

2. Call Jeff @ FAST racing for the carbs. I can tell you he'll kill Magic's price on those....335 isn't their price, they're 379 and includes a cable.

 

http://www.magicracing.com/Keihin-35PWK-AS...p_731-1567.html

 

Don't forget, you won't just be buying carbs. You'll be buying new intakes, and new boots for the airbox if you plan on keeping it...or, new K&N filters for the back of these carbs.

 

Honestly, if you're gonna go with a drag port, CPI pipes and 35PWKs, you need to ditch that airbox, period....

And...if you're gonna build a drag style/dune style bike, get smaller domes and pony up for the race gas...:)

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I will definitly check into Jeff @ fast before buying carbs..

 

I was told that once you do a serious port job on the cylinders, you lose alot of compression, thats why i was thinking 18 cc to bump it back up, is this not true? Also I think i'll go to the foam Pod filters over the k&n's it gets damn dusty around here..

Thanks

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On average...each cc you go smaller give roughly another 10 to 15PSI...ROUGHLY....

 

You won't lose that much in compression...probably a few to several PSI...but you won't lose the 40 or so PSI you'd be gaining by going to a 18cc head...

 

Talk to Jeff...he can probably give you a good idea of how little you'll lose due to porting be it a play port, dune port or drag port.

 

Here's the chart that tells roughly how much compression you'll get from domes.

Keep in mind, this chart, as said, is on a fresh bore, stock stroke, stock port motor.

Scroll halfway down.

 

http://www.nossmachine.com/banshee_heads.htm

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