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6th April 2012
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Chief Master Mechanic
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Join Date: Aug 2005
Posts: 463 Sportster/Buell Model: xlcr Sportster/Buell Year: 1977 Sportster/Buell Model #2: Hardon sporty/norton hybr Sportster/Buell Year #2: 1962 Other Motorcycle Model: panhead Other Motorcycle Year: 1952
Reputation: 95
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twin carbs on a iron head
currently collecting parts to build a trad styled cafe racer around a iron head motor and a fetherbed frame
looking at running a reversed rear head on the front so that I can run an exhaust out each side of the bike
this will also allow me to run twin carbs
what size carb would be hest for this and what would people recommend
please don't recommend amals as they were crap 40 years ago and I'm in the process of replacing the amals that have never worked on my bsa with mikunis
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6th April 2012
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Senior Master Custom Bike Builder
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Join Date: May 2010
Location: Pottstown PA.
Posts: 5,138 Sportster/Buell Model: xlch Sportster/Buell Year: 1960
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before the thing will even run,you need to change the cam timing,on the rear cylinder,because the intake and exhaust valve locations ,are now reversed. its not a,simple swap.normally 2,front heads are used.
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72 1000cc barrels and heads, s&s 41/2'' flywheels, sifton cams, s&s super B w/ zippers thunderjet w/yost powertube, andrews gears,and shafts, competition engineering kevlar wet or dry clutch, 72 oil pump, morris magneto w/auto advance and single fire module, cycle electric generator w/electronic regulator,73 cu.in.
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6th April 2012
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Biker
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Join Date: Mar 2012
Posts: 44 Sportster/Buell Model: xlh Sportster/Buell Year: 1977 Other Motorcycle Model: gl1100 & xs650 Other Motorcycle Year: 1980
Reputation: 12
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If it were me, I'd bring the rear pipe through the frame to have it on the left and keep the single carb.
If you're dead set on doing the work to swap the heads, look for carbs for 500cc singles & use two of them.
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I'm not a real mechanic, but I play one in my garage.
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6th April 2012
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Senior Master Custom Bike Builder
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Join Date: May 2010
Location: Pottstown PA.
Posts: 5,138 Sportster/Buell Model: xlch Sportster/Buell Year: 1960
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looking at running a reversed rear head on the front so that I can run an exhaust out each side of the bike
where have you seen this before?
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6th April 2012
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Chief Master Mechanic
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Join Date: Aug 2005
Posts: 463 Sportster/Buell Model: xlcr Sportster/Buell Year: 1977 Sportster/Buell Model #2: Hardon sporty/norton hybr Sportster/Buell Year #2: 1962 Other Motorcycle Model: panhead Other Motorcycle Year: 1952
Reputation: 95
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Quote:
Originally Posted by brucstoudt
looking at running a reversed rear head on the front so that I can run an exhaust out each side of the bike
where have you seen this before?
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I haven't seen it done but it probably has been done
but have looked at all the options and this looks the cheanest way of getting the exhaust headers where I want them |
6th April 2012
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Senior Bike Builder
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Join Date: Nov 2006
Posts: 1,942 Sportster/Buell Model: KHK Sportster/Buell Year: 1954 Sportster/Buell Model #2: XLC Sportster/Buell Year #2: 1958 Other Motorcycle Model: XLRTT Other Motorcycle Year: 1966
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Yep, it'll work and look like this one, early 70s from my friend Jim Haubert:
He used 2 Tillotsons... NICE!!! But if you used 2 rear heads, cam timing will stay the same...
Patrick
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Flat Head Forever...
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6th April 2012
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Chief Master Mechanic
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Join Date: Aug 2005
Posts: 463 Sportster/Buell Model: xlcr Sportster/Buell Year: 1977 Sportster/Buell Model #2: Hardon sporty/norton hybr Sportster/Buell Year #2: 1962 Other Motorcycle Model: panhead Other Motorcycle Year: 1952
Reputation: 95
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would s&s b's be too big?
or would I need to get down to something around 32-35mm
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6th April 2012
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XL FORUM TEAM MEMBER
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Join Date: Jun 2009
Location: Sunshine Coast
Posts: 1,610 Sportster/Buell Model: XLB, XLCH, Sporton Sportster/Buell Year: 1962 Sportster/Buell Model #2: XLCH Sportster/Buell Year #2: 1966 Other Motorcycle Model: XLCH (Another one) Other Motorcycle Year: 1966
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Ironhead
Don't know about Amal's (The new ones that is) being rubbish. Bruce runs them on his dual carbed outfit and he holds the lap record at Broadford. From memory they're 38's but I can ask him if you like.
Had he asked me before he did this I would have told him that HD tried this arrangement back in the late 60's and it really didn't help. To really get any benefit you do need to use the reversed head trick. But the truth is if it's just performance your after I'd spend the money on making it BIG first. You can build a 100HP Ironhead when no limited to capacity rules.
__________________
"I know only too well the evil that I propose. But my inclinations get the better of me."
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6th April 2012
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Chief Master Mechanic
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Join Date: Aug 2005
Posts: 463 Sportster/Buell Model: xlcr Sportster/Buell Year: 1977 Sportster/Buell Model #2: Hardon sporty/norton hybr Sportster/Buell Year #2: 1962 Other Motorcycle Model: panhead Other Motorcycle Year: 1952
Reputation: 95
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Quote:
Originally Posted by Ferrous Head
Don't know about Amal's (The new ones that is) being rubbish.
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was thinking about mk1 amals - and they are crap
never thought about mk11 |
6th April 2012
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Senior Master Custom Bike Builder
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Join Date: May 2010
Location: Pottstown PA.
Posts: 5,138 Sportster/Buell Model: xlch Sportster/Buell Year: 1960
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is that a,choke plate in the velocity stack?
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