BS 34 carburetors

Jan_P

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And for the uninitiated: the needle jets "tap" out from the main jet side into the venturi. Just remove the main jet and its brass washer, thread the main jet back in (without washer) and give it a (hopefully) gentle tap to start. An 1/8" wood dowel can also be used as a punch. Some pre-soaking in penetrant lube doesn't hurt if gummy in there.

Have another set carbs on the bench
Just to be clear here .. that means taking off the float bowls
and working from below.
Not possible to do without that --- removing of float bowls Or ??
Pliers ??
 

Jan_P

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"Pliers ??"
Put down the pliers, back away from the carbs! Before all is lost................

Actually a good advice step away a while and think it over.

Should be in the Tech Section .REMEMBER Everything you do can go wrong
after
Poor man you have bought yourself a 40 year old Motorcycle .. Why did you not listen to your girlfriend / wife??

Took out the ones on the carb set not in the bike as per JP method no problem

a bit white on one end and black on the top inside the flow pattern
I Guess 4 -50000 km Nothing visible in the small holes I can se
No problems with the carbs

How do you clean them ? Ultrasonic Cleaning ?

Since the climate is getting colder I may take off the carburetors and take them to the shop for cleaning .Get it properly done
With all jets this one also out

The ones in was not so black on top I would have noticed that .. But the small holes can still be dirty.




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Jan_P

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I Probably follow gggGary on this Walk away
Main Rule .. CSF -- Cheapest Simplest First.

I have a running motorcycle not perfect but running
I could take out the needle jets standing on my knees here on the yard no biggie .but I am not convinced yet it is the problem.
They would be designed differently if was a common problem more easy to take out.
That was probably why I did not do it when on the bench

I have more to do on the air Filters. No sense try to cut that corner .Spark plugs and filters nothing strange
No shop would try without that New first.
A bigger air jet. could be tested I have a set coming in.
Adjustment. Float height ?
Reading the tech manual.

I can meanwhile set up another set carbs still with a running bike .. not perfect but running
Should the CSF rule not solve it. With the CSF I can notice if anything changes and change approach

Perhaps bite the bullet and replace the wiring

How do you feel about squirting carb cleaner chemical in from the topside on the needle jets. is that a waste of time
 

jpdevol

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How do you feel about squirting carb cleaner chemical in from the topside on the needle jets. is that a waste of time
Regarding the needle jet; if we suspect gunk in between the jet tube and the carb body, spraying from the outside may not work and there is no way to verify it's clean while installed. A little more work to disassemble, but one can be certain the problem is eliminated.
 

Jan_P

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OK Ladies and Gentlemen
Installed the US Sice Air # 135 Jets and massively better not perfect but massively better.
The stumbling on 2 k -- throttle on is almost gone
And the stumbling within 2 k - 3k also virtually nothing
The throttle response from Idle standing still perfect
And acceleration from 3 k up is pretty much perfect.
Straightens the wrinkles on the face.

BUT it is missing a bit on full throttle around 5 k and over. ( as I had before this smaller Air Jet ) so that needs to happen this winter.
It is stock pilot stock main jet and stock needle setting now.

As per #136 Mr 5T

When you were inside the carbs, did you pull and clean your needle jets?
 

5twins

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OK, with the new air jets, you probably need to re-set the mix screws because you have altered the idle circuit mixture strength. That may very well cure that last little bit of stumbling you have.

The U.S. spec BS34s run better even on a totally stock bike if you increase the mains a step (132.5 stock to a 135). You might try that to "fix" your missing 5K and above performance.
 

Jan_P

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OK, with the new air jets, you probably need to re-set the mix screws because you have altered the idle circuit mixture strength. That may very well cure that last little bit of stumbling you have.

The U.S. spec BS34s run better even on a totally stock bike if you increase the mains a step (132.5 stock to a 135). You might try that to "fix" your missing 5K and above performance.

Thank you Sir
I call this progress. Se what kind on weather is coming ..
 

Jan_P

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Thank you everyone for the help.
I could have read more in the Tech section .But I have been Busy reading documents about en estate.
People have tried to haul my A** to Court this last week. Stressful. Not being used to that. Managed to get out of that for now.

Season is over we are going towards single digits in Celsius.

Washed it today .And drove a bit to get it dry and Emptied the tank
I was thinking if i needed to take the carbs out.
But I decided not to It runs reasonably OK 8 on a 10 scale.
I still need to adjust the mixture screws and a Larger main jet.

A few more miles on it and I can do that with the carbs still in .
The larger Air jet was a step in the right direction.

Throttle response is very good.
Starts easily and Idles very fine.
Just still a little stumbling at times 2k --3 k interval .
The Mixture screws can do it
All in all not perfect but who needs perfect on an old bike.
And if not I can live with it for now enjoy some riding .. Next year.

This is rocket Science Needles this and that Substandard parts kits

If there is a obvious mistake buying the larger main Jet please tell.
Thank you everyone for the help.
 

5twins

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For storage, I fill my tank and drain my carbs. The full tank protects the inside from condensation and rust. I don't use stabilizer, never found it was needed. The full tank of gas has never gone bad on me just sitting through one winter. However, the small amount of fuel in the carb bowls can go bad, that's why I drain them.
 

Jan_P

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For storage, I fill my tank and drain my carbs. The full tank protects the inside from condensation and rust. I don't use stabilizer, never found it was needed. The full tank of gas has never gone bad on me just sitting through one winter. However, the small amount of fuel in the carb bowls can go bad, that's why I drain them.

There is electrical heating in the shed where i store the Motorcycle so there is the fire hazard and the risk Neighbours complaining.
The wife there has some personal Problems .. So I have to adapt. Nose like a Bloodhound.
Even though it is a shed where chemicals and petrol + lawn movers and so. Can be stored.
There is no way to Achieve anything with reasoning with her. pointless to try. Perhaps she is allergic. I just try to avoid those problems..
Just do it.

It helps to have the tank empty. Not possible to complain.And the empty tank is later in a heated dry room.
Is not in there at all. She can find other demons to fight with. Leave me out of it. Take the pills.

I did run at idle till it stopped .But there is some left of course. But have not had problems doing so .
It is not so hot in there ca 13 C .
 

Jan_P

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Started to clean a new set of 34 s tonight
Snowing outside
Main Jet installed
one was 132.5
one was 120
Both pilot jets 42.5
Why not have the same MJ on both on the same set
Never heard of that.
Is that not strange ? According to an Clymer Manual they had 3 Sizes
140 130 120
caution in Clymer
Warning for a lean mixture can overheat
 

Jim

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Started to clean a new set of 34 s tonight
Snowing outside
Main Jet installed
one was 132.5
one was 120
Both pilot jets 42.5
Why not have the same MJ on both on the same set
Never heard of that.
Is that not strange ? According to an Clymer Manual they had 3 Sizes
140 130 120
caution in Clymer
Warning for a lean mixture can overheat
Iirc the 132.5 was standard mains on the 34's.... and no, both should match.... at least for our XS'.
 

5twins

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132.5 is stock for the U.S. model but the rest of the world may have gotten 130's (along with the adjustable needle and different needle jet).
 

Jan_P

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Is there any good way to clean inside and outside
shine it up. ?
Varnish in Bowls small holes
Any Chemical that is better than other
I have kerosene in Bowls and it appears to have effect combined with working a wooden stick like from o Popsicle

For the small parts I have a Ultrasonic cleaner not the best quality but I reckon good enough.
I cant think of any soda blasting close.

Seems to be in good shape. Over all. .A few new jets and seals o rings butterfly valve seals
Diaphragms and float valves.Looks OK

If any good place to Buy orginall parts overall -- and in Europe please tell.

IMAG0154.jpg
 

Adamc

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Is there any good way to clean inside and outside
shine it up. ?
Varnish in Bowls small holes
Any Chemical that is better than other
I have kerosene in Bowls and it appears to have effect combined with working a wooden stick like from o Popsicle

For the small parts I have a Ultrasonic cleaner not the best quality but I reckon good enough.
I cant think of any soda blasting close.

Seems to be in good shape. Over all. .A few new jets and seals o rings butterfly valve seals
Diaphragms and float valves.Looks OK

If any good place to Buy orginall parts overall -- and in Europe please tell.

View attachment 230523
Hi @Jan_P
I use Yambits for most of my standard new parts: https://yambits.co.uk/
They are very helpful when you phone them or email.
 

Jan_P

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Problems Again separating Carbs
Strange that they used a locking compound

Could not find my JIS Bits but had other that fit well
Tried ratchet with bit in
Tried hand held battery powered drill
Tried heat + Electric heat gun and thin oil

Did not try the impact wrench had it stand by

The first came out with the pliers far right Strange looking thing I Never really have heard of or seen before in 40 years
but it is actually working can be worth trying.
Jaw grips maybe also but this is a little smaller. about 7 inch
longer handles would have helped

https://www.biltema.se/en-se/tools/hand-tools/pliers/polygrip-pliers/polygrip-tool-parrot-2000028251

When the slot is gone
The screws are between the handle same pliers Round head Philip ( JIS) type
Grabbing the head with the pliers using both hands as hard one can and a little more then loosening it

The second I Hacksawed a slot on Tried with ratchet and other .but did not work Heat and Oil and the same Pliers again
using both hands as hard one can and a little more then loosening it

The far left "Nut Pliers " had a little to large grip end here
https://www.biltema.se/en-se/tools/hand-tools/pliers/special-pliers/nut-pliers-2000018144

I sound as a salesman for the company ---But I am not other brands can be better and cheaper just saying that I Have had success with these.


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