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View Full Version : XS650 / xs1100 / BS34 carb question.



convergecult
05-07-2010, 4:15 PM
This may be a newb question but does anyone know if the BS34 carbs on the xs1100's can be used in pairs on the xs650's? These's someone near me asking $120 for the bank of 4 and I'm curious as to whether it's worthwhile. Thanks in advance for any input.

GearHead
05-20-2010, 10:18 PM
you can split a bank of carbs, but the spacing (between Carbs) is gonna have to be the same, or really close, like 5mm or less, center to center. Reason is, the throttle plates ( butterflies) are linked together by overlaping tabs, the cable is hooked to one carb and the rest are linked. So you cant spread them too far apart.
Other issues are the fuel inlet(s). Depending on the setup, the is one or tow inlets. Usually they are between the outside pairs. So if you wanna use the inner pair, you have to fab single inlet spigots, to replace the "T" s.
The Internals could be very different too. Like pilot air jet and pilot bypass outlets, needle jet/ jet needle.
Like they say, anything is possible, it just takes time and money, lol.
Depending on your fab skills, you might want to get a pair of individual carbs. Like the British parralell twins do.

What is up with the original carbs, that makes you wanna swap them anyhow?

justinspace
05-20-2010, 10:55 PM
the 650 came with bs34 on the later electronic iggy models, not noted as being as good as the bs 38 on points models..or somwhere there abouts. buut the jets and needles may or may not be the same....thats the details you need to know...

DaveyRiot
05-20-2010, 11:16 PM
check the jetting, bs34's are common on yammies. They even come stock on the sr250.

BrettMavriK
05-21-2010, 2:35 PM
It's all in the needles...
I just rebuilt my BS34's with XS John's needles. (ebay)
The stock needles do not have multiple clip settings and were made to be a stricter emission requirement. Johns needles are custom machined and come with multiple clip settings and optional spacers.
My performance gains were well noticed and I'm very happy with my purchase.

convergecult
05-21-2010, 11:56 PM
I'm very curious about John's needles, I've read nothing but good things. Sooo instead of buying the bank of BS34's for $120, I bought a whole '79 xs650 for $180 and got it running last night. I'll start posting pics soon...

GearHead
05-22-2010, 8:42 PM
I'm very curious about John's needles, I've read nothing but good things. Sooo instead of buying the bank of BS34's for $120, I bought a whole '79 xs650 for $180 and got it running last night. I'll start posting pics soon...

To achive proper jetting you need needles that are djustable ( machiened grooves and clip at top).
So that you can rais and lower them. Most stock needles are mixed ( no grooves or clip).

$180 for a bike that runs, sounds like a sweet deal!

DeathMarch
05-26-2010, 10:19 AM
Could someone post the link to "john's needles?" Thanks.

convergecult
05-26-2010, 10:26 AM
This auction has ended, but you can message him through this anyways...http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=290415685620&viewitem=&sspagename=STRK%3AMEWAX%3AIT

DeathMarch
05-26-2010, 8:21 PM
Thanks man. I appreciate it.

convergecult
05-26-2010, 8:55 PM
No worries, I need to get a set of these myself....