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Tech Zone => Skill centre => Topic started by: Sfbrain on January 27, 2017, 11:27:55 AM

Title: How to take your 'Balls Out' and clear jets
Post by: Sfbrain on January 27, 2017, 11:27:55 AM
Hi Guys,

I've got to the carbs on the 350B's restorations, first job is to take the brass balls out so that the air correction jets can be cleaned and cleared.

This is a topic that frequently comes up in the forum so i will document it clearly, with pictures, so you might be encouraged to have a go yourselves.

Strip the carbs of all the jets and choke mechanism etc etc

This is the method i use but i'm sure there are others.

So here we go, these are the brass balls that are discussed and are approximatly 5mm in diameter and solid spheres of brass.

[attachimg=1]

Hold the carbs securely (i have them in my vice) and then, with a fine point centre punch make a small centre punch GENTLY, my tip here is to do it at approx a 45 degree angle to the verticle, this is because if you hit straight down on the ball then you are more likely to knock the ball down into the tube.

[attachimg=2]

I use a battery hand drill because they are designed for drilling and putting in screws, this means the spin of the bit is variable, i.e. the tighter you squeeze the trigger the faster the drill bit/screw bit rotates.

I use a 1.5mm drill bit and very gently place the tip in the centre punch mark and rotate the drill bit VERY GENTLY with minimal pressure.

[attachimg=3]

So with patience and gentle pressure you can increase the drill spin speed until the bit gets a good hold, then gently drill completly through the ball.

When you have gone through remove the drill bit from the drill and place it through the hole in the ball upside down (drill bit shaft first)

[attachimg=4]

Now gently holding the drill bit, rotate the bit and the ball will start to rotate in the tube. Keep rotating gently until it becomes more free.

When it rotates freely gently start to ease it upwards, take your time and eventually the ball will pop out still on the drill bit.

[attachimg=5]

Now the carb body is ready for my ultra sound tank

[attachimg=6]

If you think there wont be any crap behind the balls here is a picture of a cotton bud that has been twisted up the tube after 30 mins in my cleaner

[attachimg=7]

Next post will cover cleaning all the airways and jets

More soon

 ;)
Title: Re: How to take your 'Balls Out' and clear jets
Post by: ozmadman on January 27, 2017, 11:47:14 AM
Excellent, look forwardto the next instalment ;)
Title: Re: How to take your 'Balls Out' and clear jets
Post by: Pielight on January 27, 2017, 02:47:46 PM
Your thread will be a good help for future ball extracters. I used a near identical technique - except I only drilled just over half way through the balls and used a Dremel to drill for good control - I was very pleasantly surprised how easy they come out (I also used a bit of WD40 to help free the balls). Not drilling right through the balls meant they could be reused (and being ready drilled for future balls out ops)  - however I used 5ports excellent idea of replacing the balls with brass grub screws (after tapping holes) that he posted in the skills centre.
Title: Re: How to take your 'Balls Out' and clear jets
Post by: shaunthe2nd on January 27, 2017, 05:53:06 PM
Some great advice there thanks.
Title: Re: How to take your 'Balls Out' and clear jets
Post by: Sfbrain on January 28, 2017, 10:00:05 AM
Episode 2 here, this post will cover clearing the jet/air ways.

First you will need these tools, a set of jet files and WD40/Carb cleaner, and if possible access to an air line.

[attachimg=1]

There are 2 very small air/fuel ways that need to be clear.

The first one i'm going to cover ir the one behind the brass balls. With the balls removed and the tube behind cleaned out (Cotton bud soaked in WD40) you will see at the bottom of the tube a non-removable brass jet. The hole in the centre of this jet is 0.5mm.
This airway travels from the brass jet, through the main casting and comes out in the needle jet tube (the main vertical tube in the casting where the emulsion tube/jet sits).

Taking the 0.5mm jet file, insert into brass jet behind ball

[attachimg=2]

With a little jiggling about you should be able to push the file all the way through to the center tube

[attachimg=3]

Gradually work the file in and out until you are happy that this jet/air way is now clear
(this can take a while, so far i've only managed to clear one of the carbs for the 350B's project, the second is blocked solid so is getting trips to the ultrasonic tank, being soaked in carb cleaner and being 'worked' on with the file)

The second jet/air way to clear is the 'tick over' jet (thats what i call it  ;) )
It is in the engine side of the carb through channel.
There are 3 'holes' in the bottom of the main carb through channel that are just after the main needle jest apperture.

From nearest to needle jet towards the engine, they are :-

First one is the pilot jet apperture, (which comes out under the slide)
Second one is at an angle toward engine and is the 'tick over'jet
Third one is the oil feed from the oil pump

This pic is the 'tick over' jet

[attachimg=4]

Its hole size is also 0.5mm and travels down at an angle of about 30 degrees and exits into the smaller tube that contains the pilot jet.
When you have your throttle closed and the carb slides are bottomed out in carbs, then the 'tick over' jets draw fuel up from the float bowl, through the pilot jet tube, up this fuel way and sprays a fine spray of fuel into the engine (when carbs are closed shut)

The 0.5mm jet file also fits in this jet

[attachimg=5]

Although i couldnt photograph it, you can look down through the top of the carb, look into the pilot jet apperture (number 1 in above description) and see the jet file appear in the pilot jet tube  ;)

With these two jet/air ways clear the likely problem areas are cleaned out. Obviously the main appertures for needle jet and pilot jet etc etc needs to be clear and clean. Use cotton buds and WD40/carb cleaner  to do this.

Dont forget this drilling in the Choke carbs' float bowl ...

[attachimg=6]

The hole at the bottom of the cast tube needs to be clear into the tube, this is where fuel for the choke is drawn from.

Next post will be replacing the removed brass balls (with grub screws)

 ;)
Title: Re: How to take your 'Balls Out' and clear jets
Post by: ozmadman on January 28, 2017, 03:07:42 PM
Very self explanatory, a great help ... I have done this with my carbs but the wire you are showing here looks a lot thicker than what I have used and I am surprised you manged to get it through the jets???  My wire measures .4mm and that seems a tight fit.  The choke tube drilling looks smaller??  cheers
Title: Re: How to take your 'Balls Out' and clear jets
Post by: Sfbrain on January 28, 2017, 07:20:41 PM
Very self explanatory, a great help ... I have done this with my carbs but the wire you are showing here looks a lot thicker than what I have used and I am surprised you manged to get it through the jets???  My wire measures .4mm and that seems a tight fit.  The choke tube drilling looks smaller??  cheers

The carb spec for 'air corrector jet' (behind ball) is 0.5mm, maybe start with 0.4mm to get it clear but 0.5 should go through eventually.

The choke tube drilling is not a jet, it is just the feed to the tube. The main choke carb body has a brass tube (which should be clear) that drops down it the cast tube in the float bowl, so the hole at the bottom of the tube is just a feed to allow fuel to be drawn into the tube and then sucked up the brass tube into the choke, So not critical on size just needs to be clear.

 ;)
Title: Re: How to take your 'Balls Out' and clear jets
Post by: 5port on January 28, 2017, 08:10:59 PM
The choke tube drilling is not a jet, it is just the feed to the tube. The main choke carb body has a brass tube (which should be clear) that drops down it the cast tube in the float bowl, so the hole at the bottom of the tube is just a feed to allow fuel to be drawn into the tube and then sucked up the brass tube into the choke, So not critical on size just needs to be clear.
 ;)

Hi Steve.  Great thread! The "balls" subject is one of the things that fall outside the manuals but, probably effect most aircooled RD's! As far as the "Choke" tube in the floatbowl goes, I think it is more of a dashpot. When the "Choke" is on, it opens the path for the fuel to rise up the pick-up tube, mix with air in the plunger housing and then go into both inlets.  The dashpot which the pick-up tube sits in gives a good slug of fuel in the first turns of the engine with the choke on but, as the entry to the "dashpot" is limited at the bottom by the #70 hole, the fuel level in it rapidly drops as the engine runs until, the bottom of the pick-up tube is partly exposed to air (the dashpot is open to floatbowl air at the top) and the "choke" mixture is weakened to match the small #70 flow.  I think this is reflected in the way that the pick-up tube goes into the dashpot, rather than just sticking down into the fuel in the floatbowl and, the starter "jet" size is specified in the carb spec.  Overall, the starter dashpot is an efficient way to arrange a very rich initial start mixture that automatically reduces to just a rich mixture after start, using just an "On" / "Off" lever with no real variable adjustment.   ;)

5port

   
Title: Re: How to take your 'Balls Out' and clear jets
Post by: Jonny Angle Iron on January 29, 2017, 12:34:26 AM
Good info Sfbrain!

Nice to see well documented posts like these. They make the seemingly impossible accessable to the masses which can solve a whole load of "mystery problems" folk get from time to time.

 
Title: Re: How to take your 'Balls Out' and clear jets
Post by: Sfbrain on January 29, 2017, 12:46:53 PM
Here is the 3rd and final Episode (Replacing your Balls !! )

You will need ......

Brass 5mm grub screws (I use allen head)
5mm tap
Loctite
Allen keys
Thread guage

[attachimg=1]

First thing to do, for peace of mind, is to use a thread guage to check the thread pitch on the grub screws.
You wouldnt want to tap a wrong pitch thread into your carbs.
Mine are M5x0.8

Gently start to tap the thread ....

[attachimg=2]

You will need to tap to roughly 4 to 5 complete turns of the tap, but if it goes real tight STOP !! you may have reached the bottom.

Once tapped, i go to my air line and blow out any swarf created when tapping, then i just check the jet is still clear with my 0.5mm jet file.

Next put a grub screw on the end of an allen key and apply a thin film of loctite

[attachimg=3]

And screw into your tapped hole, screw in until it starts to tighten.

[attachimg=4]

And then 'The jobs a Goodun' !!

[attachimg=5]

Nice thing is, the next time you need to clean the jets it is much easier to do  :D

Hope that shows that it is not difficult to 'Get Your Balls Out'

 ;)
Title: Re: How to take your 'Balls Out' and clear jets
Post by: Motty on January 29, 2017, 06:40:36 PM
You have made the job look easy  :o
Thank you for taking the time to document it  :)
Although I suspect that the rivet counters will now start inspecting everyone's carburetors for "modifications"  :D
Title: Re: How to take your 'Balls Out' and clear jets
Post by: shaunthe2nd on January 29, 2017, 10:21:13 PM
Good posts, thanks, love these tips.
Title: Re: How to take your 'Balls Out' and clear jets
Post by: Ozhammer on February 09, 2017, 01:30:59 AM
Steve, what length are the brass grub screws and where can they be purchased from?

Cheers
Ozhammer
Title: Re: How to take your 'Balls Out' and clear jets
Post by: Sfbrain on February 09, 2017, 08:37:08 AM
Steve, what length are the brass grub screws and where can they be purchased from?

Cheers
Ozhammer

Not sure of length, they are approx 5-6mm in length.

Bought them on Ebay, they came from China, all i did use was 'M5 Brass Grub Screw', then made sure mine were Allen socket heads.

 ;)
Title: Re: How to take your 'Balls Out' and clear jets
Post by: paul n on February 09, 2017, 09:01:58 AM
Thanks for the clear instructions Steve. 4 carbs done then a trip to Allens for some new jets. Just waiting for my grub screws.  ;D
Title: Re: How to take your 'Balls Out' and clear jets
Post by: Blackhat400 on October 25, 2017, 08:55:26 PM
 What would the symtoms  be IF   oNe of the balls were loose .,  as i had running issues, took the carb to a mates ultrasonic cleaner,  , put carb back on ,and it  floods , fouling the plug, ,  he had messaged me, to say hes found a brass ball in the sonic-bath, , so it musta been loose,  its the small one not the big one at 6"oclock,
this problem has been erratic for weeks,  runs sometimes [ on 2 cylinder ] then , pops and runs on one,   
Title: Re: How to take your 'Balls Out' and clear jets
Post by: johnb on October 27, 2017, 10:45:55 PM
Why would you want to clean the 0.5mm dia passage from behind the brass ball to the emulsion tube?

As it's a dead end hole sealed by the brass ball how can it affect carburretion in any way?

To me it makes no difference whether the hole is blocked at the end with the brass ball or at the front or halfway through with dirt.

Am I missing the bleeding' obvious?
Title: Re: How to take your 'Balls Out' and clear jets
Post by: Pielight on October 28, 2017, 12:58:23 AM
It's not a dead end...there's a drilling on the brass ball side of the 0.5mm jet that connects to the air box via the float bowl and rubber hose (air supply to emulsion tube) - hence the presence of the said jet.
Title: Re: How to take your 'Balls Out' and clear jets
Post by: Neil53 on October 28, 2017, 09:04:11 AM
Believe me, that 0.5mm jet needs to be clean for the bike to run properly at low revs

I chased a low speed running problem for a year or so and it was just caused by that jet being blocked!!
Title: Re: How to take your 'Balls Out' and clear jets
Post by: Dagosr on October 29, 2017, 04:10:27 AM
Here is the 3rd and final Episode (Replacing your Balls !! )

You will need ......

Brass 5mm grub screws (I use allen head)
5mm tap
Loctite
Allen keys
Thread guage

(Attachment Link)

First thing to do, for peace of mind, is to use a thread guage to check the thread pitch on the grub screws.
You wouldnt want to tap a wrong pitch thread into your carbs.
Mine are M5x0.8

Gently start to tap the thread ....

(Attachment Link)

You will need to tap to roughly 4 to 5 complete turns of the tap, but if it goes real tight STOP !! you may have reached the bottom.

Once tapped, i go to my air line and blow out any swarf created when tapping, then i just check the jet is still clear with my 0.5mm jet file.

Next put a grub screw on the end of an allen key and apply a thin film of loctite

(Attachment Link)

And screw into your tapped hole, screw in until it starts to tighten.

(Attachment Link)

And then 'The jobs a Goodun' !!

(Attachment Link)

Nice thing is, the next time you need to clean the jets it is much easier to do  :D

Hope that shows that it is not difficult to 'Get Your Balls Out'

 ;)
SFbrain,
I have read in other posts on other 2 stroke sites that these balls need removed for the whole cleaning process but others do not reinstall the balls or any other type plug to close this area back off..??  Can they simply just be left out? or is there a reason that this should be plugged back up?  Thanks
Title: Re: How to take your 'Balls Out' and clear jets
Post by: 5port on October 29, 2017, 08:54:32 PM

I have read in other posts on other 2 stroke sites that these balls need removed for the whole cleaning process but others do not reinstall the balls or any other type plug to close this area back off..??  Can they simply just be left out? or is there a reason that this should be plugged back up?  Thanks

If you don't replace the big ball on this standard carb, the air feed to the Air corrector gets the pressure at the bellmouth and, can get crudded-up with oil (it is only 0.5mm).  When I experimented with this and prototyped the grubscrew method, I tried a set of carbs with the ball/grubscrew left out. It caused a rich flat-spot at around 4500. It was cured by replacing the grubscrews.  ;D
With the ball/grubscrew fitted, the air pressure to the air corrector (from the filter tubes) is probably higher than the bellmouth feed.
OTOH, if you are doing the Dale Alexander / Dave Freist  change to Primary type Needle jet, you DO leave the ball out and block the old air feed (on the inside edge of the floatbowl).  ;)

5port
Title: Re: How to take your 'Balls Out' and clear jets
Post by: Jonny Angle Iron on November 14, 2017, 08:22:26 PM
Great write up Steve, very clear and concise! I'm going to be doing this to a few carb sets over the winter. Just to satisfy my curiosity, would you happen to know what is behind the the smaller ball? and will this need cleaning out also?

Cheers

Jon
Title: Re: How to take your 'Balls Out' and clear jets
Post by: 5port on November 22, 2017, 09:04:23 PM
Great write up Steve, very clear and concise! I'm going to be doing this to a few carb sets over the winter. Just to satisfy my curiosity, would you happen to know what is behind the the smaller ball? and will this need cleaning out also?

Cheers

Jon

 The "smaller ball", next to the big one, covers the front of the drilling for Idle air, back to the Pilot jet.  You clean that passage by removing the Idle air screw, its spring and the Pilot jet then blow clear with carb cleaner and/or airline.  ;)

5port
Title: Re: How to take your 'Balls Out' and clear jets
Post by: Jonny Angle Iron on December 05, 2017, 09:40:43 PM
Great write up Steve, very clear and concise! I'm going to be doing this to a few carb sets over the winter. Just to satisfy my curiosity, would you happen to know what is behind the the smaller ball? and will this need cleaning out also?

Cheers

Jon

 The "smaller ball", next to the big one, covers the front of the drilling for Idle air, back to the Pilot jet.  You clean that passage by removing the Idle air screw, its spring and the Pilot jet then blow clear with carb cleaner and/or airline.  ;)

5port

Thanks 5port!
Title: Re: How to take your 'Balls Out' and clear jets
Post by: Reving Kevin on July 19, 2019, 12:00:35 AM
Thanks, very helpful post.

Tackled the job on my 250E carbs with no problems. When I drilled mine out I stuffed the main opening with rag to prevent swarf going in to the other openings (yes, I cleaned the other passages after the drilling op, not before). Also, try to clear the swarf out by blowing from the inside of the carb, not from where the ball was drilled out towards the small hole. A camera dust blower is useful for clearing the various passages if you don't have an air line.

The cheapy carb jet cleaning brush set from ebay was about useless as none of the rod cleaners were small enough, the brushes were ok for the emulsion tubes etc. I stripped some stranded wire and used that. Didn't completely solve my carb issue, but easy enough to do and a job ticked off the list. Thanks for a helpful guide.

(https://i.imgur.com/6BxzD8Um.jpg)
Title: Re: How to take your 'Balls Out' and clear jets
Post by: CBM on July 19, 2019, 06:37:21 AM
Thanks, very helpful post.
The cheapy carb jet cleaning brush set from ebay was about useless as none of the rod cleaners were small enough, the brushes were ok for the emulsion tubes etc. I stripped some stranded wire and used that.
(https://i.imgur.com/6BxzD8Um.jpg)
The bristles from a wooden wire brush (a whole "bunch" come out together) can be really good for things like carb & washer jets and nearly always available in a toolbox nearby. ;)
Title: Re: How to take your 'Balls Out' and clear jets
Post by: elram on November 16, 2020, 12:14:35 PM

I have read in other posts on other 2 stroke sites that these balls need removed for the whole cleaning process but others do not reinstall the balls or any other type plug to close this area back off..??  Can they simply just be left out? or is there a reason that this should be plugged back up?  Thanks

If you don't replace the big ball on this standard carb, the air feed to the Air corrector gets the pressure at the bellmouth and, can get crudded-up with oil (it is only 0.5mm).  When I experimented with this and prototyped the grubscrew method, I tried a set of carbs with the ball/grubscrew left out. It caused a rich flat-spot at around 4500. It was cured by replacing the grubscrews.  ;D
With the ball/grubscrew fitted, the air pressure to the air corrector (from the filter tubes) is probably higher than the bellmouth feed.
OTOH, if you are doing the Dale Alexander / Dave Freist  change to Primary type Needle jet, you DO leave the ball out and block the old air feed (on the inside edge of the floatbowl).  ;)

5port



Hi 5port,

I am riding a  RD350A, US import with 360-02 carburetors. The carburetors in my bike do not have the bigger brass balls. I presume that the previous owner did remove the balls and did not plug.

My bike runs great. But, i am able start the bike without the choke even after having been parked for a week.

As you suggested in another thread, I took the air screw three full turns out and was still able to start the bike first kick, then removed both air screws and able to start with choke.

Engine dies the moment choke is on.

I inspected the choke plunger and found intact.

Do you think not plugging the ports has anything to do with the above anomaly?




Title: Re: How to take your 'Balls Out' and clear jets
Post by: Motty on November 16, 2020, 06:40:35 PM


I am riding a  RD350A, US import with 360-02 carburetors. The carburetors in my bike do not have the bigger brass balls. I presume that the previous owner did remove the balls and did not plug.

I think you will find the 360-02 carbs did not have the brass balls fitted, they came later

Have you done a "plug chop" to see how rich your bike is running?
Title: Re: How to take your 'Balls Out' and clear jets
Post by: elram on November 17, 2020, 08:29:04 AM


I am riding a  RD350A, US import with 360-02 carburetors. The carburetors in my bike do not have the bigger brass balls. I presume that the previous owner did remove the balls and did not plug.

I think you will find the 360-02 carbs did not have the brass balls fitted, they came later

Have you done a "plug chop" to see how rich your bike is running?

Thanks Motty,

Plug chop was not done, but this is how the plugs look like after a short ride in 3/4 throttle position.


Title: Re: How to take your 'Balls Out' and clear jets
Post by: zed1015 on November 17, 2020, 10:47:01 AM
Unless you do a plug chop under load at the rev range you want to check then the colour of those plugs only indicates the running conditions at or near idle.
Title: Re: How to take your 'Balls Out' and clear jets
Post by: Motty on November 17, 2020, 06:21:16 PM

The plugs look a reasonable colour to me. Three quarters throttle should be on the main jet