Author Topic: What carbs to use on a 798 cc 550 hybrid ?  (Read 1831 times)

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Offline Emokid

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What carbs to use on a 798 cc 550 hybrid ?
« on: October 31, 2011, 05:26:31 AM »
Im building a 550/650/900 hybrid engine for my cafe project .
It will have a 550 bottom end , 650 crank ,cylinders and head , and 915 sleeves and pistons .
The head will have a streetcam and mild porting .
 But what should i use for carbs ?   
I am thinking about 750 carbs like paulages used on his 711 cc build , but also about a more modern double barrel carb maybe a weber or dellorto ?
Any thoughts on this guys ? I will have plenty of space to build a inntake for one double barrel , since its a 550 frame and nothing much in the frame triangle under the seat .
So to sum up : good performance , easy to sync , reliable, and not to expensive ( perfer it to be in the below 500 range)
-76 550f ,transforming into the 798 "Nazgul" cafe
http://forums.sohc4.net/index.php?topic=97563.0

Offline Ricky_Racer

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Re: What carbs to use on a 798 cc 550 hybrid ?
« Reply #1 on: November 04, 2011, 11:43:50 AM »

29mm Smoothbores get my nod, although they slightly might break your $500 barrier. RR
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Offline mlinder

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Re: What carbs to use on a 798 cc 550 hybrid ?
« Reply #2 on: November 04, 2011, 08:42:13 PM »
If the 915 sleeves are about the same thickness as as stock, that leaves about 3.4mm inbetween the outside of the  sleeves, and less than that between sleeve and camchain tunnel. Is that enough?
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Offline scottly

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Re: What carbs to use on a 798 cc 550 hybrid ?
« Reply #3 on: November 04, 2011, 09:38:31 PM »
, but also about a more modern double barrel carb maybe a weber or dellorto ?
Any thoughts on this guys ? I will have plenty of space to build a inntake for one double barrel , since its a 550 frame and nothing much in the frame triangle under the seat .
In my experience, Webers work best when one barrel feeds one cylinder... Two new DCOE Webs would run about $800, last time I looked, plus you will need a custom manifold.
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Offline Emokid

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Re: What carbs to use on a 798 cc 550 hybrid ?
« Reply #4 on: November 05, 2011, 08:56:42 AM »
If the 915 sleeves are about the same thickness as as stock, that leaves about 3.4mm inbetween the outside of the  sleeves, and less than that between sleeve and camchain tunnel. Is that enough?
It will leave 4,4 mm between and 7 towards the cam tunnel , im just gong by my tuning guy and he claims it will be ok. Only time will show  :)
-76 550f ,transforming into the 798 "Nazgul" cafe
http://forums.sohc4.net/index.php?topic=97563.0

Offline mlinder

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Re: What carbs to use on a 798 cc 550 hybrid ?
« Reply #5 on: November 05, 2011, 09:28:57 AM »
If the 915 sleeves are about the same thickness as as stock, that leaves about 3.4mm inbetween the outside of the  sleeves, and less than that between sleeve and camchain tunnel. Is that enough?
It will leave 4,4 mm between and 7 towards the cam tunnel , im just gong by my tuning guy and he claims it will be ok. Only time will show  :)

Weird, I just mic'd a set of 500 jugs here and got totally different numbers.

Well g'luck :)
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