Carburettor spacing

[Billy Bob]

Hi Guys
I have a set of BS 38 carburetors that I'm trying to fit to my project , but it seems they are 20 mm to narrow to fit into the manifolds . Have I missed something . The BS 34s have the correct spacing .
Regards
Andrew

 

[Downeaster]

What year is the bike you want to put them on?
Are the BS38's off a Yamaha 650 or another bike?
Are the BS38's bolted together with a piece of aluminum angle?
Pictures?

 

[Billy Bob]

Thank you for your reply downeaster I will take a few pictures tomorrow . I'm building a bike with all the bits I have left from previous builds

 

[gggGary]

Well those aren't BS38's lol.
Are they these? https://www.mikesxs.net/xs-performa...I-FvF3J-HkN1iegLJ-hx-b_TroRpwq8BoC1UYQAvD_BwE

 

[Billy Bob]

No they are cheap and nasty kehins pwk . I don't want to use them because we never got them to run right on other bikes

 

[gggGary]

BS34's and BS38's use different manifolds the BS38 manifolds are bigger ID. Yeah couple pics of your BS38s

 

[Billy Bob]

Thank you I'll do that tomorrow morning .
Thanks
Again
Andrew

 

[Billy Bob]

Yes they are pwk as I see . Have you tried them gggGary ?

 

[Billy Bob]

Here they are 120 on the butterfly . Below is a set of cvk carbs . I also have bs34 and VM 32 and vm34 ..

 

[gggGary]

If you want a good running bike without a lot of work, start with a decent set of BS34's, properly cleaned and jetted with foam air filters and a reasonable exhaust the XS motor runs great on them..

 

[peanut]

If you let us have an image of the other side of your BS38 carbs it would be easier to identify the year and model .
The spacing of the two inner holes of the angle bracket on a set of 78-79 BS38 carbs should be 90mm centre to centre

 

[5twins]

From your pic, I'm pretty sure now that they are XS500 carbs. They use the #120 butterfly plates and both carbs have the fuel line feeding in the right side. XS400 carbs would be BS34's and have a #135 butterfly plate. They have only one fuel line, attached to the outside of the left carb and feed the right carb through a cross-over hose.

The jetting you find in them could further verify they are XS500 carbs - 122.5 main, 30 (no hole) pilot, Y-6 needle jet, and 4J24 needle.

 

[Billy Bob]

Thank you all for your advice . This certainly helps
Andrew

 

[onkelheri]

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