Mounting VM34's on the XS650 - which intakes?

tintin · Full Member Joined: May 07, 2007 Posts: 96

I've searched as much as I can and haven't found a distinct answer to this, so apologies if it's been covered.

I have both VM36 and VM34 carbs for my XS650 project. The 36's don't have the starter circuit (choke) and are proving difficult to get running. Mounting them to the bike was easy - just bought the Mikuni carb boots for the VM36 which have the right 70mm bolt spacing etc. for the XS650 engine.

The Mikuni intakes for the VM34 carbs however have 60mm bolt spacing, so they don't fit. Looks like I can order intakes from 650 Central and some other sources, but was just wondering what most folks do?

At MikesXS there is a set of intake boots there with the barbs on them for balancing which is nice, but they describe them as working with VM34, 36 and even 38mm carbs? I can't see how that would work given the obvious differences in size.

The cheap eBay aluminum intakes are described as working with either 36 or 34mm carbs.

650 Central has great options, including the very nice 34mm specific HiVo intakes, but at $130 a pair, they're pretty pricey.

Looking for ideas - would love to buy some less expensive intakes for now as I'm not 100% sure about the VM34's. Do most people just modify the Mikuni boots to work? Only 5mm difference on each mounting bolt, so maybe just elongating the mounting hole will do the trick?

yamaman

I've just got the stock yamaha intakes on my VM34's, work fine!
Pretty sure it would be a bastard to squeeze the 36's on though!

The H/D ones at 650 central should be fine for $60 pair!

aybe Mikes ones can thake the stretch of the extra 3mm the 36 & 38's have (it's only 1.5 mm all around really)

www.iwt.com.au/manifold.htm

tintin · Full Member Joined: May 07, 2007 Posts: 96

Really? I checked my stock intakes and they were too big for the VM34's. The intakes were off a 1978 engine I think (not sure what year the carbs were from).

Looking at that manifold table (thanks!) it looks like another option might be the VM32/205 manifolds. They have the right 40mm spigot size for the VM34's and a 75mm bolt spacing, compared to the stock 70mm. Should be easy to enlarge the mounting hole by 2.5mm on each side.

They also add 7mm of depth to the intake which might be nice - the longer intakes are said to improve lower-end performance, at least when you get into the long ones sold by 650 Central etc.

Part no. Manifold no. Bolt hole centres Thru bore size Carb spigot OD Flange depth Typical carb size

002-052 VM32/205 75 34 40 32 30 - 34
002-053 VM34/200 60 34 40 25 30 - 34

yamaman

Maybe my intakes are from BS34 carbs & yours are BS 38?

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