BS 34 carburetors

Do you remember what jetting for that needle position
Is it a US Version or European / Oceania

Thinking out loud about Needles and Markets I got the impression that the version being non adjustable being emission laws
regulated and leaner. there is a lot of variables
US bikes were setup leaner and the law prohibited changes.
So if I get it right the designer are designing 2 different objects with different internals
Object A and Object B He has the task to get it working and running on respective markets
Normally he has little interest in matching these between markets
Because very few are going to drill out and adjust needle as a customer in the US
by warranty and legal reasons back then on a new bike.
Not that common either ship bikes between countries then.
I think the designers order was do the setup and test it manufacture and ship.
Perhaps taking the parts from another bike setup
My guess is that the US Bike runs leaner than the other for the same jet.

More Air ( Extra holes ) is no problem if you can adjust Needle and other
But it is dangerous if you cannot adjust

Jan i have an Oceania and Canadian model. They both have the 5lX11 needle and 336YO needle jet.

I have translated the Japanese 4E3 Standard model parts file, the Japanese used for their market and the Euro Standard model, (80/81), with the Adjustable needles, to English. I will post it up when i get home. Haven't got my external HD with me.

This parts manual has the recommended jets for these Jets/needles but the jet sizes are basically the same as the US used. I run 132.5 Main and 130 Air jet
 
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So a 135 main Jet can be to large .I have had the feeling it lacked a little on top .
Am I the only one having it with essentially stock setup..
Perfect on middle but to rich according to plugs.
Will an oversize main jet give that symptom. Lacking oooomph on top ?
I have kept it rich to avoid overheating but is it to rich ??
And yes I will service the suspect electrics
 
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This is the only translated version of a BS34 parts file showing part no's for the adjustable needle and 336YO jet and the pilot screw.

I'm not really a carb guy. You will need to use the information and work it out from a base point. 5Twins probably has the answers but he also say,s you have to work the different jets from a base then go up and down in sizes till the engine tells a story then go up or down one till it is happy.

Seems that because the US was the main market and they had such strict EPA mandated emission laws there is no reference to the Pilot screw or a part no. No parts manual has that info and using the info from this parts file, 5Twins did a search and came up with an alternative Mikuni BS carb Pilot screw from another carb. ..............This fits the BS34 carbs for the XS650
1 Pilot screw replacment Part 1.jpg
 
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Started servicing
The Idle mixture screw was set differently the right was 1/3 of turn more restricted.
The washers against the O -ring is not there .Unless both fell out during the work I don't believe so
The O rings is flat and hard ..
I have 2 sets carburetors
Since I was uncertain how it looked inside I tried to open the first set carburetors
and there the washer was in on the first carburetor the other screw I cannot at the moment get out .
The slots has been destroyed on both mixture screws so someone has tried to adjust those carburetors. Slots are looking like an X. Twisting .Inwards is rather OK But outwards difficult maybe even impossible
the one I got out worked with max pressure inwards on the screwdriver and with effort loosening it.
I applied light oil over night WD-40 type .. Since it can be moved inwards ---perhaps I can get it out eventually
If so the plan is to get new O -rings and use the washer from the set that have them. For now.

If there is any trick loosening Slots now looking like an X feel free to give advice and
Also on the O -ring Size I have seen it here on the forum and perhaps find it later on

Plan B 2 new sets as in Above. 12R -14105-00
 
Many drill in too far when drilling out the cover cap and hit the top of the mix screw. This damages the screwdriver slot. It usually only gets worse when you try to adjust it because the screwdriver won't grip it well enough. For what they cost, I'd just get some new ones. They come with new metal washers and o-rings but if you just want to replace your o-rings, a 1mm x 3mm size works.
 
The slot on the top got worse and worse ..and I had to do something else
Perhaps all know how but put it here can help someone

I Used a small drill hand held machine trying to drill a center hole for smashing in a philips bit or so
But since the top was uneven the drill wandered off to the side making the hole a bit off center
Could not get the Philips screwdriver to hold
So I opted to drill another hole 180 degrees from the first one
I slant the drill slightly inwards and take care not hitting the aluminum hole edge
I then have 2 holes ..and if pushing the drill carefully against the metal in between the small holes using it as a mill
I then get an elongated slot and there i Got god Grip on the screw. With a screwdriver

The hand held machine is risky. So be careful .But If one has a shop machine and clamping it
The method with two holes or three removing the in between metal and it can be a way forward.
Being soft brass and being caerful not breaking the drill

Cannot see any washer though which was the reason for taking it out
I am now down 2 O-rings and one washer
Have to make some hook se what still is down there Letting it soak some more in light oil
And reevaluate.

Edit :::: upon clearing the workbench ..I found the washer It was sitting on the magnetic tip of a Philips screwdriver that I had used to pry in the hole to loosen things I had not noticed it sitting there coming out
 

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Did find one more small washer ..it had turned 90 degrees and was sitting higher up in the hole with little larger diameter
pos 5 in # 23 -Thank You for that

Flashlight and Magnifying glass I could see it. 3 found so far .. in two sets I am not good at these small " Watch Repair " Sizes items

The O-rings are hard and if you ask me looks more like Fibre washers ..But can still be rubber. and hardened over the years.
Could not find the sets to buy unless expensive .. so I have ordered 4 O- rings from Holland 2 spare
The Slots are fine for the Screwdriver .
Seems as a little water have come down there a little white corrosion .Going to polish that
The spring is not mint but it is not moving that much ill try it. Have them in oil now.

I had the carburetor in a small tub ( Plastic Lunch box ) Using an old toothbrush and solvent to clean
it.
That was a big advantage ..when the small springs and balls flew out from the choke axle.Installation.
And clips for the needle. And so .It landed at the bottom of the box instead of the floor
Where perhaps the missing Washer is .

Should have thought of this before the tub is needed for the cleaning but I have taken it out for the adjusting ..use less solvent
Keeping it in there ..and ...when adjusting saves time trying to find small objects that fallen out or as the springs ejected.

Have 135 main Jet and moved the needle to No 2 slot ..Can still be to Rich se what happens ..
Come the O -rings the last setting and then wait for the spring
Still a few months ca 2- 3 before bike comes out and the wiring service happens
Thank you for the input.
 
As I mentioned earlier, if it's never been done, you should consider replacing the butterfly shaft seals. You can remove and inspect the condition of the outer one on each carb without having to remove the butterfly plate and shaft. On the left carb, remove the cable arm and spring to expose the seal. On the right carb, remove the e-clip and plastic washer on the outside end of the butterfly shaft. The seal needs to be very soft to work right and they harden up with age. You can judge how hard it's become by pinching the seal between your thumb and forefinger, changing it's shape from round to oval. If it's soft and good, it should be easy to pinch and make oval shaped.
 
As I mentioned earlier, if it's never been done, you should consider replacing the butterfly shaft seals. You can remove and inspect the condition of the outer one on each carb without having to remove the butterfly plate and shaft. On the left carb, remove the cable arm and spring to expose the seal. On the right carb, remove the e-clip and plastic washer on the outside end of the butterfly shaft. The seal needs to be very soft to work right and they harden up with age. You can judge how hard it's become by pinching the seal between your thumb and forefinger, changing it's shape from round to oval. If it's soft and good, it should be easy to pinch and make oval shaped.

Thank you Sir
I did replace them while rebuilding 2 years ago. I had problems getting the valve plate ( brass disc ) in and out
I will take a quick look so I did not put the seals in backwards by mistake
While they are on the bench
I did not take out the idle jets then - In hindsight a mistake because the Clymer manual said they should not be touched.
Being factory set. I have it written down on paper how many turns so I can get the same setting if needed.

There was dirt in there ---- and perhaps one missing washer ---flat O -rings ... uneven setting right / left
A bit start problems on right cylinder. Have good feelings so far about this.

Speaking of mistake I put the main jet in and tightened the bowl screws. But i did not take out and clean the jets
Probably not dirty but never the less. Have to open it again taking them out. Do it To be certain
 
By "idle jets", I assume you mean the mixture screws. There is no adjustment on the actual jets (main, pilot, needle jet) other than changing them to a different size.
 
Started and have driven ca 15-20 miles
It is always difficult to asses a change without BIAS but i can Confirm that the cleaning and new O -rings made a Difference.
I have some shooting in the left exhaust ..Need to tighten up clamps and bolts Nothing major.
Had a couple of missed ignitions on acceleration .. But not at the end of the ride Nothing to get nervous about at this point in time.
One two tanks later things settle.

I had the overflowing gas on the left carb .Float valve not moving first ..But now.

The idling is much more even and also if above idle -- say idle is 1500 rpm -it also runs better at 2000 --2500 range and i get the Impression it sets off better on full acceleration ... pretty certain .
Impression is also it starts better.
I Opened the left mixture screw on the left carburetor .trying to affect the popping in the exhaust perhaps need to turn that back later on

The tank sticker I found in India for some Other Yamaha .. that was much cheaper the holes did not match perfectly so I had to drill one of them
But from a distance it is not evident
Perhaps can make it one more season

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80 miles
Idling perfect Adjusted the ignition a little Perfect throttle response.
Left side float valve did not close one time. did notice it in the PRI petcock position
BUT have stumbling when giving full throttle from 4000 rpm .
Starting Electrical fault finding. .. connector from the fuse holder. I know has problems .. Looks as . Mr Grizid was right
I don't think it is season starting up problems only time for a update
 
Stumbling in the upper midrange, say from 4K to 4500 RPMs, under heavy throttle is usually an indication that area is too rich. This can happen when you increase the main jet size but don't lean the needle setting a step. The circuits in your carb overlap. Changing one also influences the one next to it slightly .....

Carb_Circuits.jpg
 
Stumbling in the upper midrange, say from 4K to 4500 RPMs, under heavy throttle is usually an indication that area is too rich. This can happen when you increase the main jet size but don't lean the needle setting a step. The circuits in your carb overlap. Changing one also influences the one next to it slightly .....

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Thank you Sir valuable information.
I have the stumbling on acceleration also from 5000 and up
I have had the feeling that i was lacking on top before this winter service also but without stumbling
Had black spark plugs
It is not difficult to move the needle .

have

Main 135
Pilot 42.5
Air 130
Needle in the third slot from the non pointed end.
About the same as stock exhausts little more open
Stock air filter
 
Did some measurements in the wiring
Have battery voltage Which is good .. Well over 12 V on Brown in headlamp .But I don't have that on the Kill Switch wires .I don't have a Kill Switch
I have those wires together with a small bolt
ca 0.5 V drop on the handlebar kill wires and the same on both sides delivered to the Boyer Bransden Coil.
Dropping that to high 11 .s
Did not have time to measure what on the Boyer Box. But probably low to.
When it stops raining the soldering iron comes out. Perhaps new wires in.

I am pondering trying another needle setting also since it probably is rich I am paranoid getting it to lean ..
After I have sorted the power delivery.
 
Yes Sir
Another Info that perhaps should go into the Tech section " Slam Dunk "

https://www.xs650.com/threads/locks-and-keys.60861/

Please give info on special points of interest I have two ignition locks one has obvious weak springing functionality on the key no solid places
it snaps into when turning the key but key turns .

The second has fine turning key and snaps into the positions but have weak electrical functionality
The one sitting in the bike appears to have voltage drop ,
If I can refurbish one at the workbench ill just unplug the connector on the bike
Plug in the refurbished one and measure the voltage drop.

Is there any spring that needs to be replaced or stretched
If it is mentioned above just disregard it

Can those be raised a little .If I recall right it appeared as they were worn low

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I'd suggest taking both your extra switches apart. There may be worn parts in the one that has no position "clicks", notably the plastic bumps on the back of the contact "spinner" .....

Disassembly11.5.jpg


These fall into notches on the metal plate above the "spinner" and that's what gives you the various position "clicks" .....

Disassembly11.jpg


It should have some grease on it. If run dry for a long time, maybe the plastic bumps have worn off? It's also possible someone was in there before and assembled things wrong, putting the metal disc in upside down.

The only spring in the assembly pertains to the "push-down" feature of the lock cylinder to activate the fork lock. It has nothing to do with the key turning or the key "clicks". It simply pops the lock cylinder back up flush with the top of the housing after you push it down in.

I've never heard of raising the contacts on that contact plate, and I'm not sure it's possible.
 
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