Author Topic: BS34 or BS38 ?  (Read 73 times)

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Offline Ted Bundy

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BS34 or BS38 ?
« on: February 05, 2020, 10:01:29 AM »
I can't get my BS38 to work properly.  >:( :-[I have cleaned, cleaned and tested them 10 times now. (new parts and diaphragms)
I can get my hands on a nice clean set of 34 mm. from a XS650 US custom. Will they work allright on a XS500?   :o
Yamaha XS500 1976

Online guylr

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Re: BS34 or BS38 ?
« Reply #1 on: February 05, 2020, 03:29:21 PM »
They are not a bolt on replacement but they work if modified. You will need the rubber mounts and the jetting for the 1978 XS500E. The spacing is wider on the 650 so building a set out of those is not easy because you need to narrow the throttle shafts and brackets. The XS500E carbs will fit but the airbox is also different on the 78 model and is not a simple swap to the 76 and 77 bikes. Your best bet is to find another clean set of BS38s as they work just as well as the later carbs when right. The factory went to the BS34s because they were simpler and cheaper not because they made more power.

Guy
Now Retired Yamaha guy. Cut me and I bleed "Cinquasia Red"

Offline Ted Bundy

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Re: BS34 or BS38 ?
« Reply #2 on: February 05, 2020, 04:10:40 PM »
Thanks for the advice :)
Yamaha XS500 1976