• It's time to vote for the bikes you want to see in the 2025 XS650 Calendar! Vote here!

New slide carbs or carb refurb kit?

Thomxs

Thomxs

XS650 Member
Messages
8
Reaction score
7
Points
3
Location
Auckland
Hey, it’s my first time posting so be gentle with me. I bought a 1983 Heritage special from a friend. He had the carbs refurbished “professionally” but on opening up the carb we have found parts missing. Seems like my friend was ripped off.

I need a new needle and seat, which would be easy enough but I also have parts missing from the Venturi. I am in two minds about whether I should spend some time finding the parts or whether I should just fork out the cash and buy some nice Mukuni slide carbs?

I have been advised to this from a few people now but just wanted to get some opinions on here :)

Thank you
Thomxs
 
Welcome to the group! There should be good used carbs available for your bike. Try posting in the “wanted” section of the classified section. If you know exactly what you’re missing you may be able to find them here too. Jets etc can be purchased new and as will be recommended here, buy OEM Mikuni vs repops.
 
I assume Mukuni slide carbs means flatslides. It may be just me and mine, but the flatslides on my XS are not ideal...they go great! But the idle changes a lot between cool and run hot, way too much... and this was also the experience the guy who built the engine had...I can live with it, but my parts stash has 2 or 3 sets of stock OE diaphragm tooters... the flatslide are going on the shelf when the oldfeller gitzroundtait. About others doing work on these machines...I have observed that I can screw up cheaper than I can pay anybody to screw up for me. Not only that, but my screwups teach me, his don't. This applies to carburetor work...it's Zen man, you must be the machine, at least a little, it's never rote, it's being inside of the thing, a ghost...sorta. It's mental.

If the stock carbs are sound, it would be a shame not to make them fully complete, even if you don't use them. Many people I know have swapped carbs and then swapped back to stock, having discovered the aftermarket product was not so easy to tune, etc. Most of this was Harley related, tho.

Others here will know more, and maybe source and swaps... not my pigeon ... I'd go with some sort of diaphragm set up, more placid and predictable. (what I'd like to see would be old amal with the ticklers, like on the old Triumphs and stuff, (I miss getting gas on my hands every time I kicked her over, and it's nice too when some dribbles to the pavement...go figue!)) I have seen single carb conversions on XS650, but the frame makes it problematic. A single would be nice, I think, but the frame work - well maybe if I build one of my project bikes, but I am probably too old for it.

Good luck with the project
 
"Professionally rebuilt/refurbished" is not what one might think.
A local shop near me charges $200/hr and several times I"m in there where he tells them they won't rebuild a carb w/o doing the research and finding good parts and that often takes more time than the rebuild. He also won't just order Chinese replacement carbs and install them (old Harleys, atvs etc).
I've seen so many vids and heard other stories of people taking carbs to a local "professional" only to have then must open up the float bowls and either dunk in a carb clean solution or spray with carb clean, then re assemble. They run, but don't run as good as they should (start up, idle, mixture etc)
I would trust only someone who pulls every part not pressed in to clean and verifies all passages and changes all rubber.
I have not used them but just watching the posts from Oldskool carbs is a no brainer if you don't want to invest the time yourself.
For me, doing the carbs is the most satisfying part of the bike restorations I've done.

Good Luck
 
When those OE BS34 carburetors are properly sorted, I think they're very hard to beat. I have an XS1100 running four of them. I cannot remember the last time they were off the bike. It sits for weeks at a time and fires right up. It runs perfectly. I have two XS650s running with those as well. They both go 50 mpg. They both start 1 kick and run great.
Get the parts and fix them. There's more collective knowledge on here about those than anything else. My assumption is you're going to run a basically stock bike.
 
Last edited:
I recently installed Mikuni VM34 carbs. I am happy with them.
The bike started easily from the start, sometimes.
A lot of time was spent changing out the pilot jets and sorting out the petcock to use. Using the non-vacuum petcock that's real common, comes with a straight and two right angle barbs.

The VM carbs are much easier to work on if you are a do it yourselfer with limited carb experience.
You can take them off, adjust or change the pilot jets or float heights and re-install in 10-15 minutes.
I bought from Niche cycle. For some reason they only included pilot jets in 12.5,15, and 17.5.
Called them and they sent me a 20 and 25. I am running the 25 pilot jet, using the middle needle slot and I am still using the 165 main jet that came with the kit.

You have to ready to undertake a custom job like this. Was it easy ? No. But it was easier then working with the BS34's. I gave up on the BS34's after I screwed up and lost the choke lever tiny ball bearings and wasn't successful re-installing them.
It starts easier and it seems like the bike is quicker then with the old BS34's.

During the troubleshooting process, I learned about non-resistor vs resister spark plugs and boots and also fixed some exhaust leaks.
 
Thomxs said:
Great thank you, I gave him a message on Facebook. I’m based in New Zealand though so not sure if postage would work!
Click to expand...
Sorry didn't notice your country of origin. I would look at doing them yourself from NZ, Member Signal lives in Auckland and would have the local connections for Mikuni jets. I will set up a 3 way PM for you and him to have a chat.

Have a look, top right next to your handle name and there should be a number on the mall envelope icon mean you have a PM/message.

I live in Aus, Mikuni Jet supplier is in Townsville. If you can't get them in NZ, but i'm sure there must b a supplier over there
https://mikunioz.com/?v=13b249c5dfa9

Don't b to daunted to do them yourself. Plenty of helpers here and hey will put you right.

Is your bike an import or NZ bike. Makes a slight difference to the Needle and needle jet type, Oceania Needles are adjustable and the needle jet has 4 extra emulsion tube holes. Jets are usually the same size as the US counterparts, could be down one on the mains from US factory setting. This is an important distinction for any US members who may chip in their help. Also is a big difference to the ignition and charging systems between the US and Oceania models.
 
Last edited:
Reread your first post and see the bike is an 83. It would either be a US, (64 front, 48 rear, spoke wheels), or Canadian, (mag wheels) with a drum brake rear. Canadian 83's were bought straight from Japan to dealers in NZ, new registration, on request i think. I bought one in 1990 that had the registration with 0000 on the clock, rego papers
 
I live about 6 hours travel from Auckland.
I buy jets and carbs from Mikuni in Aus.
Post a photo of your carbs showing the places where the parts should be. We can then ID the carbs I have some sets here that may have the parts you need.
 
650Skull said:
Sorry didn't notice your country of origin. I would look at doing them yourself from NZ, Member Signal lives in Auckland and would have the local connections for Mikuni jets. I will set up a 3 way PM for you and him to have a chat.

Have a look, top right next to your handle name and there should be a number on the mall envelope icon mean you have a PM/message.

I live in Aus, Mikuni Jet supplier is in Townsville. If you can't get them in NZ, but i'm sure there must b a supplier over there
https://mikunioz.com/?v=13b249c5dfa9

Don't b to daunted to do them yourself. Plenty of helpers here and hey will put you right.

Is your bike an import or NZ bike. Makes a slight difference to the Needle and needle jet type, Oceania Needles are adjustable and the needle jet has 4 extra emulsion tube holes. Jets are usually the same size as the US counterparts, could be down one on the mains from US factory setting. This is an important distinction for any US members who may chip in their help. Also is a big difference to the ignition and charging systems between the US and Oceania models.
Click to expand...
Wow, I can’t believe the extent of knowledge on this forum, thank you for all the help. I will have to ask my friend whether it’s an import or not :)
 
Signal said:
I live about 6 hours travel from Auckland.
I buy jets and carbs from Mikuni in Aus.
Post a photo of your carbs showing the places where the parts should be. We can then ID the carbs I have some sets here that may have the parts you need.
Click to expand...
Oh that would be amazing, I have a attached a photo of what I think is a missing seat and Jet and then there another photos trying to illustrate how the needle is not secure and can be moved up and down through the Venturi. I am an amateur with this so might be getting the names wrong. Really want to give it a go though as the purpose of this project was to learn and DIY.
 

Attachments

  • IMG_8551.jpeg
    IMG_8551.jpeg
    732.7 KB · Views: 63
  • IMG_8550.png
    IMG_8550.png
    3 MB · Views: 61
  • IMG_3293.jpeg
    IMG_3293.jpeg
    252.5 KB · Views: 54
  • IMG_3294.jpeg
    IMG_3294.jpeg
    250.5 KB · Views: 87
Those aren't BS34s, they look like a '78-'79 set of BS38s, but the slide looks to be from a '77 or older carb. The needle is "loose" most likely because it's missing it's little e-clip. This is the early slide type that I think you have. You can see the little e-clip I think may be missing on that "loose" needle .....

Early Slide.jpg
 
The trouble with 40 year old carbs is, they are 40 years old. And parts for the BS carbs are expensive, in Oz at least,: $150 Oz for slides and diaphragms, $250 for BS38 slides and diaphragms. That's why I did a VM conversion.
One of the more popular mods for the XS650 is converting to VM34s. There is reason for that: VMs are a relatively simple carb, easy to jet, easy to tune, cheap parts, easy to repair and very little to go wrong, I wouldn't convert for a performance upgrade, you'd be lucky to see any difference. But otherwise the conversion really has no downside, except for perhaps cost.
I've never heard of anyone having any problems with the VMs.
 

Attachments

  • 375875304_3624631237796896_1237316664892604144_n.jpg
    375875304_3624631237796896_1237316664892604144_n.jpg
    207.1 KB · Views: 65
Signal said:
I live about 6 hours travel from Auckland.
I buy jets and carbs from Mikuni in Aus.
Post a photo of your carbs showing the places where the parts should be. We can then ID the carbs I have some sets here that may have the parts you need.
Click to expand...

650Skull said:
Reread your first post and see the bike is an 83. It would either be a US, (64 front, 48 rear, spoke wheels), or Canadian, (mag wheels) with a drum brake rear. Canadian 83's were bought straight from Japan to dealers in NZ, new registration, on request i think. I bought one in 1990 that had the registration with 0000 on the clock, rego papers
Click to expand...
I have attached a photo of the bike, it’s in good condition apart from the carbs. Hard to start but does run! It’s an import from the US or Canada I think. I am pretty sure they are bs38 carbs but no idea what year. I am just going for what my friend told me.
 

Attachments

  • IMG_8588.jpeg
    IMG_8588.jpeg
    741.6 KB · Views: 51
  • IMG_8589.png
    IMG_8589.png
    2.9 MB · Views: 51

Similar threads

Niels B
BS38 Carb - considering rebuilding
2
Replies
22
Views
1K
Niels B
Niels B
ForestHasAnXS650Too
New-Old XS650 Journey - Carb exploring and wrong parts, pointers?
Replies
6
Views
380
5twins
5twins
R
Carb issue
Replies
15
Views
674
gggGary
gggGary
B
XS650 BS34 CARBS
Replies
4
Views
530
BACK SHIFT
B
ForestHasAnXS650Too
New-Old XS650 Special journey - My initial problems
2
Replies
22
Views
1K
jetmechmarty
jetmechmarty
Back
Top