I think I'm opening a can of worms......

[Crashedkiwi]

Hi All;

As my project draws closer to being complete I keep on getting tempted by the shiny pics of new carbies on MikesXs. To date, I've had nothing but great service and great products from these guys - But I note that opinion seems divided on both MikesXs & the carbies here.

So given that I've had outstanding advice from the collective wisdom here; are these carbie sets a) worth it & b) make a difference?

I've kept the motor stock at this stage (apart from the much needed electronic ignition) as I want the project finished; i.e., no bigbore /cam work (as yet).
Appreciate your input as always.
Cheers

 

[Signal]

Gary Hoos, 650 Central or Mikuni in Oz are all unlikely to let you down. I have had good experiences with all of them supplying carbs that are pretty close to set.
Things may have changed but Mikes XS is my last resort.
I think the best replacement carbs are a set off a GPZ 500, there is a thread on here about the conversion. I took VM 36's off a 750 road bike and put the GPZ carbs on it was so much better.

 

[jpdevol]

are these carbie sets a) worth it & b) make a difference?

Depends on what you have now; if you have a servicable set of BS34's with the Oceana needles/jets, properly tuned, IMO you're better off sticking with them and spending the VM34 money elsewhere.

I spent a lot of money on this build, yet chose to stay with stock carbs (Oceana needle set-up) - they work perfectly - even with velocity stacks, straight pipes, Kibblewhite, VAPE 277, etc

 

[Crashedkiwi]

Gary Hoos, 650 Central or Mikuni in Oz are all unlikely to let you down. I have had good experiences with all of them supplying carbs that are pretty close to set.
Things may have changed but Mikes XS is my last resort.
I think the best replacement carbs are a set off a GPZ 500, there is a thread on here about the conversion. I took VM 36's off a 750 road bike and put the GPZ carbs on it was so much better.

Gary Hoos, 650 Central or Mikuni in Oz are all unlikely to let you down. I have had good experiences with all of them supplying carbs that are pretty close to set.
Things may have changed but Mikes XS is my last resort.
I think the best replacement carbs are a set off a GPZ 500, there is a thread on here about the conversion. I took VM 36's off a 750 road bike and put the GPZ carbs on it was so much better.

Cheers; I know those suppliers. MikesXS has been good for me; I got most of my bits from there - a few from Heiden as well. I find the Euro pricing of Hoos & Heiden a little steep for me - shipping to NZ is about the same from either the US /Euro.

 

[Crashedkiwi]

Depends on what you have now; if you have a servicable set of BS34's with the Oceana needles/jets, properly tuned, IMO you're better off sticking with them and spending the VM34 money elsewhere.

I spent a lot of money on this build, yet chose to stay with stock carbs (Oceana needle set-up) - they work perfectly - even with velocity stacks, straight pipes, Kibblewhite, VAPE 277, etc
View attachment 233866

Ahh yes I believe I may be staring at this exceptionally fine build on my office wall - Miss January I believe ? Thanks for your view; part of my reticence around the carbie issue is that I’ve them well sorted on my other ‘75 XS after cleaning and rejetting. They work darn well - ok so you have the slight vacuum induced feel to the acceleration curve, but so what? If I want blistering speed, I get on the Ducati. So putting my hand in my pocket far enough to reach the coin purse has to be for a valid reason; there is always something else to buy & frankly I’d rather put the coin into the aesthetic of the build - its about the ride cache not the 1/4 time!

 

[toglhot]

The diaphragms on my BS38 were shot, JBM weren't shipping to OZ at the time and diaphragms were only available with slides from other sources. At $120 a piece, I didn't want to spend that sort of money on 50 year old carbs that I thought were rubbish anyway, so, I bought a set of VM34s from Mikunioz. At $600 they were expensive but they did come with manifolds and rubbers.

When fitted the cables sat squarely in the middle of the petcocks, requiring the carbs to be leaned over at quite an angle. Not on my bike, so I tossed the manifolds and machined up a couple of new, longer ones that set the carbs further back, thus clearing the petcocks. So,I could have saved myself $100 and just bought the carbs minus manifolds.

I've since discovered that Gary Hoos has rubber manifolds that fit, apparently, placing the carbs further forward so the cables clear the petcocks. I think they are actually BS34 manifolds. They are 1mm or so bigger but fit well from what I've heard.

Mikuni oz supplied the carbs with spare mains of different sizes, but if you need to change pilotsnof needles, they'll have to be bought separately. The hose clamps they came with were rubbish.

I tried the angled adapter on the top of the carbs as well as just the cable with no luck, seems it's a common problem and well documented.

 

[Crashedkiwi]

Thanks - that sounds like a journey! Appreciate the insight; much I can learn form this.

 

[joebgd]

What are Oceana needles? Never heard of em. Can you post a link?

 

[jpdevol]

What are Oceana needles? Never heard of em. Can you post a link?

Sorry, that term was "made-up" by me (OP is in Oceana). I should say Non-US; the US BS34's had fixed 5HX12 jet needles and 207-Y-0 needle jets that were really lean stock. The rest of the world (1980) got 51X11 5-position adjustable needles paired with 336-Y-0 needle jets that were significantly richer and performed better (esp. midrange)

http://www.nichecycle.com/ncs/categ...ng-tuning/needles/102-3912-needle-by-ncs.html

https://yamahaxs650.com/product/needle-jet-336-y0/

 

[joebgd]

Lol, I thought something like that after I made the post, I thought you where probably referencing the Canadian ones. Years ago I bought 2 Canadian emulsion tubes and the mains would not screw in2 them. Idk how and it's probably remedied since but they had different threads.

 

[5twins]

Actually, technically speaking, I think the "Canadian" or "World" 336-Y-0 needle jet may be slightly leaner than the U.S. spec Y-0 because it has more air bleed holes down it's sides. The Y-0 has rows of 3 and 4 holes while the 336-Y-0 has rows of 4 and 5 holes. Assuming that both have the same size metering orifice (Y-0), the additional air bleed holes on the 336-Y-0 should mean it produces a slightly leaner air/fuel mix. But, the "Canadian" or "World" 5IX11 needle is shorter and so much richer than the U.S. spec fixed 5HX12 that the overall result is still a richer midrange.

Now, looking at pics of the 5IX11 needle, I assumed it's taper and diameters were the same as the 5HX12, and that it's added richness was due to it's shorter length. But, studying dimensions from a needle spec chart that (I think) JP linked to in another post, I see they're not. The taper points appear to be the same but the 5IX11 diameters are smaller, and that would make it richer. I pulled the 650 needle specs from that massive chart and made a "condensed" version for easier reference and comparison. I also included the XS400 5Z1 needle as it is a viable alternative for the last few carb sets .....