BS34 to BS34SS Swap

[gorillafan208]

Alright I ended up buying two of the XS650 screws since they were so cheap but sadly I don't think they fit. I can put them in but when I try to tighten them down it just spins and won't seat. I also tried my GS400 mixture screws but it was the same situation. My amateur guess is that it's because the threaded portion of the OEM screw is so long compared to the other screws. Kind of a bummer, back to searching Facebook marketplace for people parting out their 1980 gs450s...

[gorillafan208]

Alright, thank you to user Hokano12 for trading his set of BS34SS carbs for my pair of BS34 carbs, finally have all the parts for them!!! The only problem is that the BS34SS carbs off the 450 are slightly closer together than the GS400 ones so I haven't been able to fit them onto the intake boots. I sprayed some silicon lubricant on the outside of the boot and im gonna try and slightly heat them to see if that makes them more pliable. If that doesn't work, I was wondering if switching the intake boots to the ones that came on the GS450 would make it fit better, but that is just a guess. I just assumed the carbs would fit on the 400 engine as I thought they were basically the same but with a roller bearing crank. Has anybody on here actually swapped BS34SS onto their 400? Thanks again for all the help guys!

[gorillafan208]

Just bumping this, has anyone that has swapped gs450 carbs onto a gs400

[Hokano12]

If I remember correctly the gs450 intake boots are slightly different than the ones on the gs400….no luck at all getting those in yet?

[LAB3]

If you go to partzilla.com and look at the parts fischefpr your bike you can click on the part number (whether it's available or not) and it'll show you what other models that part is used on. Looks like 77 is a one year only piece, from 78 up they fit pretty much everything in the 400-450cc range.

https://www.partzilla.com/product/suzuki/13110-44000

[gorillafan208]

Alright thanks guys, i really tried to get those in there, but still found no success, I guess I will buy the new intake boots and hopefully those will work. Good thing I accidentally bought the o rings for the 450 style boot a while awhile ago. I am just worried that the slightly different spacing between the two carb styles will mean that it will never fit correctly and it will be back to square one. I'll post a photo when I get home of what it looks like when I tried shoving the BS34SS on the intake boots.

[LAB3]

If it's the same cylinder head on a model with the other boots you should be OK. You'll probably want to cross reference the part numbers of the boots from the model and year the carbs came off of to be sure.

https://www.partzilla.com/product/suzuki/11100-44813

[gorillafan208]

Alright, bad news, the GS450s have a head with part number 11100-44860 while the 400s have 11100-44813. Definitely my mistake not checking that the heads were the same, I just kind of assumed that the 450 and 400s were the same engine but with a different style crank. Do you guys think it's still worth it to try putting some 450 intake boots on and getting it to fit or just try to find some BS34s/VM conversion.

[LAB3]

Alright, bad news, the GS450s have a head with part number 11100-44860 while the 400s have 11100-44813. Definitely my mistake not checking that the heads were the same, I just kind of assumed that the 450 and 400s were the same engine but with a different style crank. Do you guys think it's still worth it to try putting some 450 intake boots on and getting it to fit or just try to find some BS34s/VM conversion.

The boot question is a good one, there's a lot of things involved in building a cylinder head with a change any one part of that assembly warranting a part number change.

One other thing I thought of after my last answer is that airbox will also need to accommodate for the difference in width. My only thought going from there would be to see if the original hardware that's used to "gang" the two carbs together would work since that's the place where a change would be most beneficial to line everything up right.

[gorillafan208]

The bike has pods (it came with them) so I don't have to worry about the airbox, but the idea about switching the gang platge is interesting. I thought of that as well, but I wondered how that would mess up the carb sync and such. Unfortunately though, the 400 gang hardware is with Hokano12, so I think I will just buy the 450 intake boots and go from there. Where have you guys bought the intake boots? I checked on dimecitycycles and z1 but didn't see much Suzuki-wise

[LAB3]

Dime City and Z1 are the same entity. Looks like you have a few choices between new and used on eBay.

[gorillafan208]

Well, to anyone with a GS400 with broken carburetors, apparently your only option to replace your stock carbs is to buy a pair from a German company for an outrageous price. I am finally have a pair of BS34 carbs for my bike and am several hundred dollars poorer. Note: BS34SS carbs will not work on GS400s, at least the 1977 model.

[unfocused]

Just out of curiousity, could a single carb be adapted? I've seen this with Norton's and other early european bikes. I've seen an intake setup to put x2 carbs on the GS750 instead of x4.

Also - if not already mentioned but pricey - https://speedmotoco.com/suzuki-gs400...arburetor-kit/

Out of Oregon.

[gorillafan208]

I am definitely not experienced enough or mechanically inclined to figure out if you could modify it to be single carb. I did see the VM swap option, but decided to save 100 dollars and just rebuild the ones I got on ebay

[GRich]

Why didn't the carbs fit? I thought the intake port spacing was very similar, so the GS450 mounting boots would help to get the carbs mounted up.