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Big bore and carb question

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Old 01-14-2017, 01:12 PM
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Originally Posted by pegskraper
what is manifold port-matching to the heads? Afaik the shop ported the exhaust, put in better valve springs, valve guides, ground the valves and the seats and decked the heads for higher compression
Port matching is just what the term implies; match the intake manifold outlet to the intake port on the head to eliminate any restriction. The CV40 will work just fine at 95", I have attached a chart that illustrates the difference in performance between a CV40 and a Mik 45; not the same comparo but you will get the idea; the difference is not worth the cost of a new carb. You would likely gain more from port matching and a proper tune on a dyno than more carb.
 
Attached Thumbnails Big bore and carb question-cv_vs_mikuni.jpg  
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Old 01-14-2017, 06:59 PM
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Originally Posted by djl
Port matching is just what the term implies; match the intake manifold outlet to the intake port on the head to eliminate any restriction. The CV40 will work just fine at 95", I have attached a chart that illustrates the difference in performance between a CV40 and a Mik 45; not the same comparo but you will get the idea; the difference is not worth the cost of a new carb. You would likely gain more from port matching and a proper tune on a dyno than more carb.
dead nuts on!!!!
 
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Old 01-14-2017, 07:54 PM
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Originally Posted by djl
Port matching is just what the term implies; match the intake manifold outlet to the intake port on the head to eliminate any restriction. The CV40 will work just fine at 95", I have attached a chart that illustrates the difference in performance between a CV40 and a Mik 45; not the same comparo but you will get the idea; the difference is not worth the cost of a new carb. You would likely gain more from port matching and a proper tune on a dyno than more carb.
I'll probably do the S&S carb next year, theres a manifold that goes with it. Maybe I'll port match the intake then
 
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Old 01-14-2017, 10:04 PM
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Old 01-15-2017, 08:41 AM
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Originally Posted by pegskraper
I'll probably do the S&S carb next year, theres a manifold that goes with it. Maybe I'll port match the intake then
S&S makes a manifold for CV carbs,its got bigger runners,get one now & port match it now.if you wait till later,you`ll have to pull the heads (heads cant be port matched on the bike)
 
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Old 01-15-2017, 12:16 PM
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I was just looking on ebay for the S&S cv carb manifold, and ran into this company that rebuilds cv carbs for performance. This is my first harley so I've got a lot to learn, but I'm wondering if I get my existing cv carb done by these folks and port matched my manifold to my heads when I get them back (before I put them on the bike), if that would be a good alternative to going with the S&S upgrade?

http://www.ebay.com/itm/HARLEY-DAVID...item3f0ef5e36d
 
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Old 01-15-2017, 08:12 PM
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Originally Posted by pegskraper
I was just looking on ebay for the S&S cv carb manifold, and ran into this company that rebuilds cv carbs for performance. This is my first harley so I've got a lot to learn, but I'm wondering if I get my existing cv carb done by these folks and port matched my manifold to my heads when I get them back (before I put them on the bike), if that would be a good alternative to going with the S&S upgrade?

http://www.ebay.com/itm/HARLEY-DAVID...item3f0ef5e36d

Seems you just don't want to listen. Most of the replys are telling you that the CV carb is quite adequate for your build and you will better benefit from port matching your manifold, stock or S&S, and roll on. The S&S carb or reworking your carb is a waste of money; the cost just won't produce much gain. So, get the S&S manifold, port match to your heads, re-jet and get it close then put the bike on a dyno to dial the carb in.
 
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Old 01-16-2017, 09:33 AM
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Originally Posted by pegskraper
what is manifold port-matching to the heads? Afaik the shop ported the exhaust, put in better valve springs, valve guides, ground the valves and the seats and decked the heads for higher compression
Match the manifold ID, to the intake port ID.
Our Stage I and Stage II heads come with 1.710" intake port diameter, which is about the largest you can port the OEM CV manifold out to.
That CV carb is a very good carb, once dialed in, which is very easy to do.
Scott
 
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Old 01-16-2017, 10:55 AM
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Originally Posted by pegskraper
I was just looking on ebay for the S&S cv carb manifold, and ran into this company that rebuilds cv carbs for performance. This is my first harley so I've got a lot to learn, but I'm wondering if I get my existing cv carb done by these folks and port matched my manifold to my heads when I get them back (before I put them on the bike), if that would be a good alternative to going with the S&S upgrade?

http://www.ebay.com/itm/HARLEY-DAVID...item3f0ef5e36d
You should listen to the advice you are getting - Pro Drag & Hillside are 2 of the best there is with this stuff - Eastcoast Jim
 
  #20  
Old 01-16-2017, 06:33 PM
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Originally Posted by djl
Seems you just don't want to listen. Most of the replys are telling you that the CV carb is quite adequate for your build and you will better benefit from port matching your manifold, stock or S&S, and roll on. The S&S carb or reworking your carb is a waste of money; the cost just won't produce much gain. So, get the S&S manifold, port match to your heads, re-jet and get it close then put the bike on a dyno to dial the carb in.
I appreciate all the advice I'm getting from everyone here. It's not that I don't want to listen, I was just asking a question. My carb was running fine last summer so I'm sure it will be fine once I put it back on. I ran into the carb rebuild guy by accident, and it caught my eye. I guess what he does is mostly cosmetic or tiny little tweaks that probably don't add up to much, it's just my inexperience with these bikes that makes me ask questions.

I could port match my stock manifold to my heads by myself with a die grinder and a burr it seems, I saw a couple of youtube videos about it. If i did that and wanted to go to an S&S later (most likely won't but whatever), I'm assuming the S&S intake ID would be larger still, so I'd still have material on the head intake port I could remove to be able to port match it.

Again, thanks for the input, I didn't post on here looking for people to tell me to buy a new carb, for real I just am curious, I have a mechanical background (millwright) and have worked on big stationary engines for a couple of years in the past so I always ask a lot of questions.
 
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