BS34 Float Help

[bul_racer]

Hi All,
I'm a newbee trying to rebuild carbs on my 1980 XS650G. I know there's a LOT of previous discussion about this but after reading a bunch of it I'm just confused. Some say confused is just another word for stupid & maybe I am bc I don't know how to proceed. The bike ran when I parked it years ago, but poorly.

One of my floats makes a funny noise when I shake it and when I place it in water it floats with that side lower than the other so I'm pretty sure there's gas inside. Maybe this was the problem way back in 2004. I tried to find a hole or evidence of a leak but can't see anything. I placed it in hot water but no bubbles appeared. I don't know how to repair a leak I can't find. Some posters say I shouldn't try bc heating to solder is likely to create additional leaks or at least cause them to become more open.

I'd hoped that it wouldn't be a major project to get this bike running as I already have several projects taking up my garage floor space. My inclination is to just buy a new float but I've tried and tried to find a source for a replacement float. Hard to believe that Mikuni wouldn't provide the part since there seem to still be a lot of these bikes on the road. Mike's shows one but reading the detail my bike is not among those listed. Saw a post where someone said they ordered this and it seems to be for bs38, not bs34. I don't want to order a part that won't fit.

It seems that some folks are using plastic floats to replace the brass but I don't know which ones to get. Is there one that fits or would it need to be modified? Also not sure if there's a float height spec for the plastic or if I'd have to hook up a gas line to the bottom of the float bowl in order to visually check float height.

Any help would be appreciated.

 

[kopcicle]

You would get referred to me eventually so ...
http://www.xs650.com/threads/carburettors-from-the-grave.34737/

In order to see a hole in a float you need to dunk it in gas or alcohol , seal the container, and pull a slight vacuum. I use a mason jar. I've repaired brass floats but not in the last 40 years, had something to due with the results.
If the carb is indeed a BS34 you can use any of the floats for the KZ1000P(police) from '84-2005.
On older carbs beware of the overflow tube, it's sometimes cracked.

post pics just to keep us old farts amused

 

[Jim]

Partzilla sells the Yamaha Brass floats for 40 to 50 bucks. They also sell the Suzuki BS34's for half that. I'm running these in my 80SG. Hint... they're the same Mikuni part.

https://www.partzilla.com/product/suzuki/13250-37100

 

[kopcicle]

So there you are. One post and answers from the grey beards.
Now write an introduction and post pics or it never happened ;-)

 

[Jim]

Now write an introduction and post pics or it never happened ;-)

 

[bul_racer]

Hey, Thanks for the quick responses! I will look into these options. If the Suzuki part is correct I'll probably just do that.
Pretty sure it's a bs34. The bike is an 80 and I think that's what they came with. There's no markings that I can find like on the VM series carbs.

Kopcicle, not sure what pictures you're interested in. My Yamaha is not anything special. It's been sitting for a long time. I'm not looking to do a restoration or anything fancy. I'm just wanting a cheap bike I can ride on the street. My other bikes are off road, mostly motocross bikes and mostly vintage. I can post pictures of some of those if you're
interested.

 

[5twins]

You can get that float even cheaper from Part Shark .....

https://www.partshark.com/oemparts/p/suzuki/13250-37100/float

If that's the block-off plug I see still installed over your mix screw, you'll need to remove that. You can't do a proper cleaning with the mix screw still installed and you can't pull it out with that plug in place .....

 

[bul_racer]

Thanks 5Twins! I'm assuming your username refers to your inventory, not your progeny.

Thanks for the advice! Not only saving me money, but helping me do it right! And thanks Kopcicle for getting me to post the pictures!

 

[5twins]

Yes, the $12 or so you save on a couple floats will more than pay for 4 butterfly shaft seals. Again, this is a Suzuki part, same exact part used in the Yamaha carbs, but much cheaper .....

https://www.partshark.com/oemparts/p/suzuki/13651-51010/seal

 

[bul_racer]

Gonna try to replace all the rubber parts if I can get them.

 

[bul_racer]

So I drilled out one of the plugs to access the mix screw. Cleaned, though not much dirt. Not really sure what this is for. Is it to affect air mixture? Also, I didn't count the number of turns when I took it out so not sure if it should be screwed in all the way or???

 

[Jim]

Yes, it's the idle mixture screw. It's about 3 turns out to start with iirc.
Partzilla has pilot screw set that includes the screw, spring, washer and o-ring that I think is a pretty good deal.


https://www.partzilla.com/product/yamaha/12R-14105-00-00

 

[gggGary]

Heads up; yes the spring then a stainless steel washer and an o-ring are living in the bottom of that hole, they kinda like like it down there so a tiny hook helps persuade them out.

 

[Jim]

heads up yes the spring a stainless steel washer and an o-ring are living in the bottom of that hole they kinda like like it down there so a tiny hook helps persuade them out.

.041" safety wire or a paperclip is just the ticket here.

 

[gggGary]

.041" safety wire or a paperclip is just the ticket here.


View attachment 194711

ZACKLY, you found it before I found my pic!
Hint; make the bend then clip the 90 leg off short. ;^)

 

[5twins]

Not air mixture but rather fuel/air mixture, for the idle or pilot circuit. These carbs have a true mixture screw. It adjusts and regulates part of the fuel/air mix coming from the pilot jet into the main bore. Air is mixed with fuel at the pilot jet. This fuel/air mix is delivered into the main bore through 4 tiny holes. Three are clustered together at the top of the bore around where the butterfly plate closes. They come directly from the pilot jet and the amount they flow can't be adjusted or regulated. The 4th hole is off to the side and enters the main bore after passing by the mix screw. The amount coming out here can be adjusted or regulated using the mix screw. This gives you control or adjustment over roughly 25% of the flow. This is only enough for fine tuning, and if not enough to correct an overly rich or lean condition, you must change the pilot jet or air jet size. That will change the overall strength of the mixture being delivered through the 4 tiny holes.

 

[gggGary]

The three you CAN'T adjust in the background and a seated needle in the one you CAN adjust.

Kinda looks like the ceiling of a one lane car tunnel.
My version of a hook with the idle mix parts.

 

[bul_racer]

Once again you guys are a wealth of information! No O ring came out with the needle, spring and washer. If not for you guys I wouldn't have known it was there. Can't see it in the parts schematics. Damn! these carbs are more complicated that the simple 2-stroke carbs I'm used to.

 

[Jim]

No O ring came out with the needle, spring and washer. If not for you guys I wouldn't have known it was there.

Time for a little "fishin' expidition." The factory plug was there, so the o-ring has to be too. It might be in a million pieces, but it's there.

 

[bul_racer]

I will look for it.