 playing in the shop with spare carbs
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Joined: Jan 2008
Posts: 1,174 Likes: 15
Learned Hand
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OP
Learned Hand
Joined: Jan 2008
Posts: 1,174 Likes: 15 |
Over the holidays I had some spare time in the shop (due to the arctic cold) and a extra set of 36 mm CVK carbs. So I decided to try my hand at boring them over size. It was interesting, and so far they look pretty good on the flow bench, 223 cfm. Mostly just an excersize. stock carb  boring carb body in mill  making butterfly valve  bored out carb and pieces  assembled carbs inlet side  assmbled carbs outlet side 
05 speedmaster - 1100cc, 11:1 racing pistons, Carillo rods, thunderbike cams, ported and polished head, 2mm over intake and exhaust valves, Barnett kevlar clutch, scepter pipes, oversize manifolds, 45mm HSR's, TTP stage 4 firestarter
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Re: playing in the shop with spare carbs
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Joined: Aug 2007
Posts: 10,730 Likes: 6
Should be Riding
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Should be Riding
Joined: Aug 2007
Posts: 10,730 Likes: 6 |
How big did you manage to go?
Always remember to be yourself. Unless you suck. Then pretend to be someone else.
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Re: playing in the shop with spare carbs
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Joined: Jan 2008
Posts: 1,174 Likes: 15
Learned Hand
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OP
Learned Hand
Joined: Jan 2008
Posts: 1,174 Likes: 15 |
Quote:
How big did you manage to go?
38mm
05 speedmaster - 1100cc, 11:1 racing pistons, Carillo rods, thunderbike cams, ported and polished head, 2mm over intake and exhaust valves, Barnett kevlar clutch, scepter pipes, oversize manifolds, 45mm HSR's, TTP stage 4 firestarter
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Re: playing in the shop with spare carbs
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Joined: Jan 2005
Posts: 2,416
Oil Expert
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Oil Expert
Joined: Jan 2005
Posts: 2,416 |
Impressive job there.  Looking forward to hearing the results!
"Wise men speak because they have something to say, fools because they have to say something."
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Re: playing in the shop with spare carbs
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Joined: Apr 2007
Posts: 3,063 Likes: 8
Loquacious
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Loquacious
Joined: Apr 2007
Posts: 3,063 Likes: 8 |
Micah, I'm impressed with your prowness. Are you going to try them on your current ride to see if they compare with your FCR's? Curious to see if you end up with similar performance gains as Fast Freddie posted. BTW, have you considered selling your services? 
12 Rocket Roadster
03 Bonneville America
69 BSA Firebird Scrambler
73 Yamaha TX 750
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Re: playing in the shop with spare carbs
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Joined: Dec 2006
Posts: 2,150
Oil Expert
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Oil Expert
Joined: Dec 2006
Posts: 2,150 |
Very impressive Micah. I too look forward to hearing about the extra performance gains. Even better, a dyno to compare pre and post your "playing"  would be brilliant cos I like many others I presume are really interested in this side of increasing our bike's performance. Well done and thanks for the interesting pics etc staffo
Staintune Pipes, K&N Pods, 45 pilots, TBS needles and 145 mains.
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Re: playing in the shop with spare carbs
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Joined: Feb 2008
Posts: 2,671 Likes: 15
Loquacious
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Loquacious
Joined: Feb 2008
Posts: 2,671 Likes: 15 |
Just for kicks, did you flow the stock carb, & if so, what did it do?
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Re: playing in the shop with spare carbs
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Joined: Aug 2007
Posts: 10,730 Likes: 6
Should be Riding
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Should be Riding
Joined: Aug 2007
Posts: 10,730 Likes: 6 |
pm sent
Always remember to be yourself. Unless you suck. Then pretend to be someone else.
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Re: playing in the shop with spare carbs
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Joined: Jan 2008
Posts: 1,174 Likes: 15
Learned Hand
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OP
Learned Hand
Joined: Jan 2008
Posts: 1,174 Likes: 15 |
Quote:
Just for kicks, did you flow the stock carb, & if so, what did it do?
I did, 193 cfm.
I will probably tinker with these on the bench more thru the winter, as I have the FCRs on the bike, these are more of a curiousity right now. THere is a air circuit mod that fast fred was doing to fix the mid range dip on these carbs, and I haven't figured that out yet.
05 speedmaster - 1100cc, 11:1 racing pistons, Carillo rods, thunderbike cams, ported and polished head, 2mm over intake and exhaust valves, Barnett kevlar clutch, scepter pipes, oversize manifolds, 45mm HSR's, TTP stage 4 firestarter
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Re: playing in the shop with spare carbs
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Joined: Feb 2008
Posts: 2,671 Likes: 15
Loquacious
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Loquacious
Joined: Feb 2008
Posts: 2,671 Likes: 15 |
Thanks.
I understand that bone-stock heads flow in the vicinity of 185cfm, & all-out pro-ported heads flow up to 300cfm.
Presuming that the 193 cfm figure that you found for the OEM carbs is under optimal conditions then the stock carbs are pretty much maxed out.
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Re: playing in the shop with spare carbs
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Joined: Jan 2008
Posts: 1,174 Likes: 15
Learned Hand
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OP
Learned Hand
Joined: Jan 2008
Posts: 1,174 Likes: 15 |
Quote:
Thanks.
I understand that bone-stock heads flow in the vicinity of 185cfm, & all-out pro-ported heads flow up to 300cfm.
Presuming that the 193 cfm figure that you found for the OEM carbs is under optimal conditions then the stock carbs are pretty much maxed out.
that is probably right, my test flow conditions are on just the carb directly open to atomsphere (no filters, air boxes, manifolds, nothing, basically air going thru a hole) so the stock carbs match fairly close to the stock heads in this respect. that said there are still performance gains to be made via the carbs even with a stock head, just there is a limit in there.
05 speedmaster - 1100cc, 11:1 racing pistons, Carillo rods, thunderbike cams, ported and polished head, 2mm over intake and exhaust valves, Barnett kevlar clutch, scepter pipes, oversize manifolds, 45mm HSR's, TTP stage 4 firestarter
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Re: playing in the shop with spare carbs
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Joined: Apr 2007
Posts: 286
Adjunct
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Adjunct
Joined: Apr 2007
Posts: 286 |
Just curious, what kind of equipment do you need to bore out the carbs?
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Re: playing in the shop with spare carbs
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Joined: Aug 2007
Posts: 10,730 Likes: 6
Should be Riding
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Should be Riding
Joined: Aug 2007
Posts: 10,730 Likes: 6 |
Quote:
Quote:
Thanks.
I understand that bone-stock heads flow in the vicinity of 185cfm, & all-out pro-ported heads flow up to 300cfm.
Presuming that the 193 cfm figure that you found for the OEM carbs is under optimal conditions then the stock carbs are pretty much maxed out.
that is probably right, my test flow conditions are on just the carb directly open to atomsphere (no filters, air boxes, manifolds, nothing, basically air going thru a hole) so the stock carbs match fairly close to the stock heads in this respect. that said there are still performance gains to be made via the carbs even with a stock head, just there is a limit in there.
Fast Fred was making 4-5hp more on the dyno when he put bored stock carbs on a bone stock bike.
Always remember to be yourself. Unless you suck. Then pretend to be someone else.
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Re: playing in the shop with spare carbs
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Joined: Jan 2005
Posts: 1,382
Learned Hand
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Learned Hand
Joined: Jan 2005
Posts: 1,382 |
Micah, I know that this was a project to see if it would work but, why not just get a pair of 38mm Keihin's off of
e-bay and play with them?
Tony G
'03 America
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Re: playing in the shop with spare carbs
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Joined: Jan 2008
Posts: 1,174 Likes: 15
Learned Hand
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OP
Learned Hand
Joined: Jan 2008
Posts: 1,174 Likes: 15 |
Quote:
Micah, I know that this was a project to see if it would work but, why not just get a pair of 38mm Keihin's off of
e-bay and play with them?
because I had them (36 CVKs) laying around doing nothing after the switch to the FCR's.
plus this work was easier than changing the pitch on a pair of carbs.
05 speedmaster - 1100cc, 11:1 racing pistons, Carillo rods, thunderbike cams, ported and polished head, 2mm over intake and exhaust valves, Barnett kevlar clutch, scepter pipes, oversize manifolds, 45mm HSR's, TTP stage 4 firestarter
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Re: playing in the shop with spare carbs
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Joined: Mar 2008
Posts: 149
Adjunct
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Adjunct
Joined: Mar 2008
Posts: 149 |
Quote:
I'm impressed with your prowness. Are you going to try them on your current ride to see if they compare with your FCR's? Curious to see if you end up with similar performance gains as Fast Freddie posted.
Quote:
Fast Fred was making 4-5hp more on the dyno when he put bored stock carbs on a bone stock bike.
Sorry for the thread hijack, but does anyone know Fast Fred's current status? I'd like to hire his services, but he has not returned my phone call or answered my pm. I know he had some medical problems last year. Hopefully he's OK.
BTW, nice work Micah.
'05 America, 904, K&N pods, British Customs Bomber Exhaust
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Re: playing in the shop with spare carbs
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Joined: Aug 2007
Posts: 10,730 Likes: 6
Should be Riding
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Should be Riding
Joined: Aug 2007
Posts: 10,730 Likes: 6 |
Fred has been unreachable for months now, email, phone call, text message all go unreturned.
Always remember to be yourself. Unless you suck. Then pretend to be someone else.
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Re: playing in the shop with spare carbs
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Joined: May 2007
Posts: 6,432 Likes: 1
Worn Saddle
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Worn Saddle
Joined: May 2007
Posts: 6,432 Likes: 1 |
Quote:
Fred has been unreachable for months now, email, phone call, text message all go unreturned.
Doesn't he have some kind of chronic health problem that has flared back up?
A positive attitude may not solve all your problems, but it will annoy enough people to make it worth the effort. Herm Albright (1876 - 1944)
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Re: playing in the shop with spare carbs
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Joined: Mar 2008
Posts: 149
Adjunct
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Adjunct
Joined: Mar 2008
Posts: 149 |
Is there anyone else doing what he does? Micah, If you ever get to where you feel as though you've perfected what you're doing and would be willing to sell your services (that sounds kinky  ), please let me know! I'm sure others would be interested as well. Thanks.
'05 America, 904, K&N pods, British Customs Bomber Exhaust
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Re: playing in the shop with spare carbs
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Joined: Jan 2008
Posts: 1,174 Likes: 15
Learned Hand
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OP
Learned Hand
Joined: Jan 2008
Posts: 1,174 Likes: 15 |
Quote:
Is there anyone else doing what he does?
Micah, If you ever get to where you feel as though you've
perfected what you're doing and would be willing to sell
your services (that sounds kinky ), please let me know! I'm sure others would be interested as well. Thanks.
I am working on it. With any luck I will have it dialed before the end of winter and can offer this service, as I have had many pm's about it.
05 speedmaster - 1100cc, 11:1 racing pistons, Carillo rods, thunderbike cams, ported and polished head, 2mm over intake and exhaust valves, Barnett kevlar clutch, scepter pipes, oversize manifolds, 45mm HSR's, TTP stage 4 firestarter
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Re: playing in the shop with spare carbs
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Joined: Jan 2008
Posts: 1,174 Likes: 15
Learned Hand
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OP
Learned Hand
Joined: Jan 2008
Posts: 1,174 Likes: 15 |
anyone interested in trying out these over bored carbs? I think I have them as good as they are going to get on the bench. They respond to air flow correctly now, I had to tweak the slides some.
I would be up for someone to take them and try them out. If they dont bring up the power then I'll take them back, if you like them we can work something out. Ideally someone in the southern WI area would be interested, to save shipping. (but I supposed they would have to wait until the snow melts off to try em.)
05 speedmaster - 1100cc, 11:1 racing pistons, Carillo rods, thunderbike cams, ported and polished head, 2mm over intake and exhaust valves, Barnett kevlar clutch, scepter pipes, oversize manifolds, 45mm HSR's, TTP stage 4 firestarter
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Re: playing in the shop with spare carbs
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Joined: Jul 2008
Posts: 55
Member
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Member
Joined: Jul 2008
Posts: 55 |
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Re: playing in the shop with spare carbs
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Joined: Jul 2008
Posts: 55
Member
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Member
Joined: Jul 2008
Posts: 55 |
What was the final flow achieved on the bench?
Does anyone know what the CFM for Mikuni 39mm carbs is? I was told 213 for 42mm units...
S.
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