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 Post subject: Carbs and cc's
PostPosted: Wed May 09, 2012 5:19 pm 
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Joined: Sun Nov 14, 2010 5:45 pm
Posts: 16
Images: 7
I'm building a Harris TT with a 650cc engine and was wondering which carbs will fit the 650cc best?
The engine is still original, but i'm planning to tune it (worked intake, bigger valves, etc).
- the original 36 mm.?
- 40 mm. PHM?
- 38 mm. VHSB?
- 39 mm. race VHSB (fitted on my race 600 Pantah. Great performance!!!)?

Thanks.

William


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 Post subject: Re: Carbs and cc's
PostPosted: Thu May 10, 2012 1:16 am 
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Joined: Wed Nov 03, 2010 3:19 pm
Posts: 177
Location: Auvergne, France
a pair of 38 VHSB will take place on my 750 big valves ;)


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 Post subject: Re: Carbs and cc's
PostPosted: Thu May 10, 2012 10:18 am 
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Joined: Fri Oct 15, 2010 12:20 pm
Posts: 1115
Location: Vermont, USA
Hi William,
I think you are asking a rather complicated question. A lot depends on your riding and what you'll be doing with it. Since I have a Harris TT with a carefully rebuilt 650 Alazzurra engine, I'll throw a couple things out here. My engine is basically stone stock with the 36mm carbs and only matched up ports. It makes a really nice race engine with good mid range. Two of us ride it, me (novice) and Robbie (skilled fast expert). I'm basically working on cornering skills, so it's perfect for me. But Robbie is still very competitive with it at occasional AHRMA BOT3 races. I decided when I feel the need for more h.p. it could always be added, but it is by no means a dog as it is now. If you are building your Harris from the ground up, you will have lots of chassis set up to do and countless things to get squared away. In my opinion, all that would be a lot easier with a good sound non-temperamental engine that's not a distraction.
Bill


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 Post subject: Re: Carbs and cc's
PostPosted: Sat May 12, 2012 6:41 pm 
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Joined: Thu Oct 14, 2010 1:39 pm
Posts: 19
Images: 15
Location: UK
I have a tuned 600 TT2 rep with 41mm Malossis & a std 600 with PHF36 pumpers, also a small valve 750 with the same 36s.
My observation is that the 36s provide a very friendly response from shut onwards. The 41s don't work until half throttle & then they chime in right through to WFO.Great in the dry a pain in the wet for a moderately skilled rider - me.
The small valve 750 wouldn't benefit from much bigger than 36mm as the valves are too small anyway - same size as the 600. I suspect the 650 will be the same.
Bigger valves on the 650 would help top end flow but at less than WFO use the smaller carbs would still be my choice.
Mike


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 Post subject: Re: Carbs and cc's
PostPosted: Mon May 21, 2012 10:45 am 
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Joined: Fri Oct 15, 2010 12:20 pm
Posts: 1115
Location: Vermont, USA
I should correct my above post about my Alazzurra engine being "stone stock". I forgot we did put in the 900ss cams that we had in the old blown up 750 race engine. My memory is pretty bad and I need Lou and Cranky Roller to keep track of that kind of stuff for me.
Bill


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