Post by: Johnwebley on February 15, 2026, 03:50:10 PM
I couldn't ignore the craving for blue smoke,
so this appeared,
imported from the USA,very low mileage,so far it seems ok,
Post by: Nurse Julie on February 15, 2026, 04:08:54 PM
Post by: Bryanj on February 15, 2026, 04:40:03 PM
Post by: Yetanotherbike on February 15, 2026, 06:34:54 PM
On my driving test, the tester told me he would simulate a real life situation where I would have to do an emergency stop. As I rode down the road expecting him to leap out or something, in my mirror a car distracted me by flashing his lights. When I looked forward again, the tester was in the middle of the road right in front of me with his arms open. As I was caught by surprise in panic I grabbed the brake and did a stoppie that Toprak would have been proud of!
Amazingly, he passed me and even congratulated me on my brake control.
I kept the bike for a year and was planning to get a RD400. My dad said, he would loan me the money if I bought a Honda 400/4, as he liked them. I wasn't really interested, but I was desperate to get a bigger bike, so I accepted the loan. One ride on my first Honda 400/4 and I was smitten and any thoughts of another Yamaha quickly evaporated.
Hope you have as much fun with your Yamaha as I did with mine.
Post by: Laverda Dave on February 15, 2026, 06:45:39 PM
Post by: Johnwebley on February 15, 2026, 06:52:46 PM
The original RD mate, should be fun, somewhere got a dti to set up timing mateIt's the one just before the RD,
No reeds,
I have a DTI,
The mileage is 480
Seems from the condition to be true,
Clean oil in the gearbox, plenty of compression
I shall just tidy it up, polish the scratches etc
Keep it with its patina
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Post by: Rozabikes Tim on February 15, 2026, 08:00:08 PM
Nice one John.
Post by: DomP on February 15, 2026, 09:57:20 PM
Post by: Johnwebley on February 15, 2026, 10:39:00 PM
Nice John, much work needed?Only spent a couple of hours looking around,
I connected a battery, the electric seem to work,
Does need various replacements
A few essentials, others cosmetic
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Post by: K2-K6 on February 16, 2026, 07:04:17 AM
The Yamaha two strokes of that era always have a good intake acoustic, that induction roar as they come on power, quite distinct and charismatic.
A good bike for blatting around on this summer :)
Post by: Spitfire on February 16, 2026, 09:51:04 AM
Cheers
Dennis
Post by: florence on February 16, 2026, 10:22:18 AM
Post by: Bryanj on February 16, 2026, 11:23:11 AM
Post by: Rayzerman on February 16, 2026, 01:56:45 PM
Post by: Johnwebley on February 17, 2026, 12:56:13 PM
Very surprised by the headline
Seems the bulb is fixed in
Also probably need rear shocks and rim,badly corroded,
BTW
the tyres are as new original
Yokahama 3 x18 R
2.75 x 18 f
Ideal for a show queen bike, which never gets ridden
Any offers??(https://uploads.tapatalk-cdn.com/20260217/a5cc278474aaca55d3aa939788991be0.jpg)
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Post by: Bryanj on February 17, 2026, 01:16:11 PM
Post by: Laverda Dave on February 17, 2026, 04:09:15 PM
Post by: Johnwebley on February 17, 2026, 04:34:08 PM
Steve Cooper of the VJMC recently wrote a feature in Classic Bike Guide detailing how to convert US sealed beam unit to one with a lamp holder. It was about 4 or 5 issues ago. Unfortunately I now have to throw my bike mags away after I read them to avoid 'clutter'.Thanks
Will check on the interweb
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Post by: Johnwebley on April 03, 2026, 10:46:54 AM
back from holidays,so to work,
fitted new MB9U battery,
all the electrics work,lights,indicators,starter,
at present the rear indicators have red lenses,are they legal in the UK ??
replacing various missing blots,
next job,do I need to strip the carbs,and check and clean,I have removed the slides ,and looking inside it looks immaculate,
more news soon,as it gets warmer
Post by: Bryanj on April 03, 2026, 11:00:59 AM
Post by: Johnwebley on April 05, 2026, 10:32:09 AM
The tank has rust inside,
Looks intact, but I would like to remove/neutralise it, any advice for doing that?
Next I have ordered a wheel rim,so into the unknown, having a go at wheel building, all the spokes and nipples have been loosened and checked, will be stripping the brakes and overhauling lubricating the cams etc,
Advice welcome
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Post by: Bryanj on April 05, 2026, 10:53:03 AM
I bought Julies wheel building jig so if you dont mind the travel cost you can borrow that but note i am away from about 10th April till 8th May
Post by: Johnwebley on April 06, 2026, 01:15:41 PM
Sounds sweet,
The LH will need stripping and cleaning, I think the slow running jet is blocked
Runs great with choke, but not otherwise
Loads of blue smoke
Smells wonderful (https://uploads.tapatalk-cdn.com/20260406/cb7b851ffcf3a6603a2b3fc36ae48821.jpg)(https://uploads.tapatalk-cdn.com/20260406/bc79a1e70cbcb432ae16c6b92c45e7a0.jpg)
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Post by: Skoti on April 06, 2026, 05:53:48 PM
well done indeed, mind you that wee Yamaha will give your CB200 a run for it's money.
Thanks for posting the photos.
Post by: Laverda Dave on April 06, 2026, 06:52:22 PM
Post by: Johnwebley on April 06, 2026, 07:16:16 PM
it seems like the mileage is correct,
appart from a bodged footrest mounting,everything seems ok,
the LH side of the bike seems to be corroded more on the left,but I have been using BDX and so far everything has come lose.
now the down side,I can't find much info,about the CS3 or CS5,while the motor was running,,the charge light didn't go out,
as it uses a combined dynamo and starter,,I am trying to find the details,ohms etc,to try and sort the issue,
anyone have any knowledge,or links??
thanks
Post by: Skoti on April 06, 2026, 07:52:53 PM
Not that they'll be of much use after all that time, but nevertheless it helps confirm the mileage is true.
Edit
Just noticed from your earlier post they are actually similar treaded Yokohama tyres.
Maybe look for a Haynes workshop manual, similar to a 1973 UK spec RD200.
Post by: Johnwebley on April 06, 2026, 08:28:30 PM
I have the Haynes
Covers CS3, CS5 And RD200
unfortunately, it claims the starter/generator is so complex
Take it to your local Yamaha dealer
LOL
but I have found a Yamaha CS5 manual, needs a lot of reading, but should help
Fingers crossed
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Post by: Bryanj on April 06, 2026, 08:58:50 PM
If it is like the RD 200 you need a "special" tool to hold the advance mechanism open whilst setting the timing with dti down plug hole, i will tell you how on Thursday mate
Post by: Johnwebley on April 06, 2026, 09:39:34 PM
They claim to use matchsticks
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Post by: Bryanj on April 06, 2026, 09:53:47 PM
Post by: Yetanotherbike on April 06, 2026, 09:55:24 PM
Post by: Johnwebley on April 06, 2026, 10:18:15 PM
Matchsticks dont work mate, believe me!!I am smarter than that
I will use a lighter!!
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Post by: Oddjob on April 07, 2026, 04:47:54 AM
Post by: Bryanj on April 07, 2026, 06:00:49 AM
Still got the Yamaha dti in box somewhere
Post by: Johnwebley on April 07, 2026, 07:07:48 AM
Thanks for your input
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Post by: neat street on April 07, 2026, 07:30:58 AM
While it is chilly,and windy I am sitting and planning ahead,
The tank has rust inside,
Looks intact, but I would like to remove/neutralise it, any advice for doing that?
Next I have ordered a wheel rim,so into the unknown, having a go at wheel building, all the spokes and nipples have been loosened and checked, will be stripping the brakes and overhauling lubricating the cams etc,
Advice welcome
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Hi John, just seen this part of your post. I used white vinegar, fill tank to brim for a day or so, clean with presure washer. came out like new inside, just put some oil with diesel in the tank to stop any flash rust appearing.
Post by: Johnwebley on April 07, 2026, 04:10:39 PM
Thanks, just ordered 10ltrsWhile it is chilly,and windy I am sitting and planning ahead,
The tank has rust inside,
Looks intact, but I would like to remove/neutralise it, any advice for doing that?
Next I have ordered a wheel rim,so into the unknown, having a go at wheel building, all the spokes and nipples have been loosened and checked, will be stripping the brakes and overhauling lubricating the cams etc,
Advice welcome
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Hi John, just seen this part of your post. I used white vinegar, fill tank to brim for a day or so, clean with presure washer. came out like new inside, just put some oil with diesel in the tank to stop any flash rust appearing.
I assume neat is best
No pun intended
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Post by: Johnwebley on April 14, 2026, 11:34:24 AM
Tank cleaned inside, Thank you Mr Street for the info,
Now a carb issue, LH is corroded, float pin stuck, need to be careful, don't want to break the pins
Advice needed,
(https://uploads.tapatalk-cdn.com/20260414/6909cad36ddeffb7d61b70006c2ce55f.jpg)(https://uploads.tapatalk-cdn.com/20260414/b8e591ad6743045adf0d85ea0420bdd6.jpg)(https://uploads.tapatalk-cdn.com/20260414/f93d430148ad67aaa568734f1b8a663a.jpg)
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Post by: K2-K6 on April 14, 2026, 11:49:31 AM
Or boil it in water in an old saucepan.
Post by: Skoti on April 14, 2026, 02:17:42 PM
Ok,a little bit of work over the last few days
Tank cleaned inside, Thank you Mr Street for the info,
Now a carb issue, LH is corroded, float pin stuck, need to be careful, don't want to break the pins
Advice needed,
(https://uploads.tapatalk-cdn.com/20260414/6909cad36ddeffb7d61b70006c2ce55f.jpg)(https://uploads.tapatalk-cdn.com/20260414/b8e591ad6743045adf0d85ea0420bdd6.jpg)(https://uploads.tapatalk-cdn.com/20260414/f93d430148ad67aaa568734f1b8a663a.jpg)
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I would try and gently heat the carb with a hot air gun, being careful not to loosen the soldered parts on the brass float. Maybe fashion an old beer can to direct the heat away from the float?
Your tank looks good, wish I done that with mine 10 years ago instead of the sealer which is starting to lift now.
Post by: Laverda Dave on April 14, 2026, 03:43:28 PM
This could be followed by a good dose of carb cleaner on the pivot and then another hot bath. You'd have to really careful if using a naked flame with the solder on the float being so close by.
Post by: McCabe-Thiele (Ted) on April 14, 2026, 05:13:20 PM
Upgrades include a Bosch Paint stripping heat gun,
lastly my Plumbers Calor Gas Torch.
None of the above worked on the seized center stand pivot on my 400, I had to resort to a hack saw and impact tool.
Post by: Johnwebley on April 15, 2026, 10:26:30 AM
Another option
A Chinese copy of the carb is online at £25,
So it might be worth a punt to see how good it is,
But, no rush, a little later I shall be making carb broth,
Don't fancy the taste!!
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Post by: Skoti on April 15, 2026, 11:26:38 AM
Thanks for all the help
Another option
A Chinese copy of the carb is online at £25,
So it might be worth a punt to see how good it is,
But, no rush, a little later I shall be making carb broth,
Don't fancy the taste!!
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John,
good luck with the Chinese carb, I've never had one yet that I've been able to make work properly on two stroke engines.
They're now in a box under my bench marked "junk".
Post by: Johnwebley on April 15, 2026, 11:44:38 AM
Boiling away
The floats appear to leak,air bubbles coming from them,
As for the copy carb ,I was going to use it for spares,
And the body incase damage to the original,
I did buy a set for the CB200, they worked ok,
(https://uploads.tapatalk-cdn.com/20260415/8435e405999802ce960c93c986a55e72.jpg)(https://uploads.tapatalk-cdn.com/20260415/a6dfdbf72983acc478069d19688b7ed4.jpg)
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Post by: K2-K6 on April 15, 2026, 12:04:27 PM
Aha, the gourmand method ;D chuck a couple of eggs in to boil and save energy, is that Michelin Starred œufs ? :D
Solder should be 180c melt, so safe in boiling water. But shows a compromised float though, and may need a re soldering before use.
Post by: Johnwebley on April 16, 2026, 03:00:44 PM
Carb almost sorted, float pivot released
Only issue now is new gaskets, oh,and one of vents is still blocked,
Possible sonic cleaning will sort that,
Replaced the oil feed pipe without having to remove the clutch cover,
On PDI,the steering damper was wrongly assembled, also the throttle cable was routed wrongly, both sorted,
When the bike runs, the charging light stays on, it has a combined dynamo/starter,the starter works ok,it has been suggested I check the brushes, and also the regulator
So been working on that (https://uploads.tapatalk-cdn.com/20260416/695ccfb3b3f011679276a158de05aad7.jpg)(https://uploads.tapatalk-cdn.com/20260416/c94b0efbf9cb9b6edf7854d17cbde161.jpg)(https://uploads.tapatalk-cdn.com/20260416/037344be65a9021302b21b92cd836501.jpg)(https://uploads.tapatalk-cdn.com/20260416/9e3443f1342d1414c461830dc534f51b.jpg)(https://uploads.tapatalk-cdn.com/20260416/c21ccc681d42016c8eb63b31d912af4c.jpg)(https://uploads.tapatalk-cdn.com/20260416/cb2c84db7304f5c3df3f8043759a8d49.jpg)
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Post by: Johnwebley on April 18, 2026, 08:00:54 PM
Soaked the vinegar for a few days
Vast improvement (https://uploads.tapatalk-cdn.com/20260418/facbfb518cf804edb996c0b746198fbb.jpg)
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Post by: Johnwebley on April 21, 2026, 05:40:18 PM
the Chinese VM20 carb arrived,I odered it incase the original got damaged,
it doesn't look to bad,obviously would need a mod for the choke,drill out an insert brass tube,
I would be using the original jets and brass ware,
useful safety net for £25 or so,
I have had the original cleaned in a sonic bath,assembly to follow,
a few pics of the chinese carb,
BTW,I notice they do replacement pertol tapes for the 500 etc,
Post by: Oddjob on April 21, 2026, 06:01:04 PM
Pertol tapes Jon? I presume you meant to say Petrol taps 😀😀
Post by: Johnwebley on April 21, 2026, 06:05:23 PM
My fingers are way behind my thoughts
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Post by: Oddjob on April 21, 2026, 06:14:30 PM
Post by: Johnwebley on April 29, 2026, 02:18:47 PM
So the spare Chinese carb donated a new spare,
Leaking solved
Short video to follow
Just got to sort the charging issue
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Post by: Johnwebley on April 30, 2026, 02:16:47 PM
It's the very devil refitting the stator,
Retracting said brushes is tricky,
Basically no real improvement
The charging light dims,but doesn't go out
Anyone got any thoughts?
(https://uploads.tapatalk-cdn.com/20260430/2239b8a75551608fbbfbf7240fbedb64.jpg)(https://uploads.tapatalk-cdn.com/20260430/8bb19e855a05955942c6e561badd27c5.jpg)
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Post by: Skoti on April 30, 2026, 02:39:08 PM
Have you got any electrical test data for the stator, rectifier and voltage control unit?
Better to test rather than guess, a simple multimeter would probably suffice.
Post by: Johnwebley on May 01, 2026, 10:53:54 AM
Gosh that's a beefy looking rotor for a wee bike.It is a starter/dynamo,
Have you got any electrical test data for the stator, rectifier and voltage control unit?
Better to test rather than guess, a simple multimeter would probably suffice.
I guess a similar system that Villiers used for the engines in the Bond cars
Possibly Isetta,BMW etc used the same for the bubble cars,
The Villiers had a switch, like golf carts, that would start the motor in reverse rotation, so no reverse gear needed
I have a multi meter, most of the readings seem to be somewhere near
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Post by: K2-K6 on May 01, 2026, 11:04:28 AM
Siba dynastart problems often stem from worn brushes, faulty control boxes, or weak batteries, resulting in poor cranking or failure to charge (indicated by a persistent red light). These units, common in microcars and small boats, are prone to dampness, corrosion, and overheating. Key solutions include rebuilding the unit, upgrading to a solid-state controller, and ensuring correct wiring, particularly using specific Siba coils to prevent burnout.Common Siba Dynastart Problems and SolutionsFailure to Charge:Control Box Failure: The mechanical control boxes are a frequent source of failure. Test if voltage exceeds 13V at the battery when running; if not, the control box or wiring is likely faulty.Worn Brushes: Third brushes can wear down, causing poor contact with the commutator.Overheating: If the unit gets extremely hot, a faulty controller may be causing over-charging, which can ruin field coils. Solid-state regulators are recommended as an upgrade.Poor or No Cranking:Weak Battery: Dynastarts need high power; check for a fully charged battery (approx. 12.6V).Corroded Terminals: Inspect wiring from the battery to the starter solenoid and motor.Solenoid Issues: If clicking occurs but it won't spin, the solenoid may be faulty.Ground Issues: Ensure a good ground between the engine block and the solenoid.Ignition Problems:Siba-Specific Coils: Using conventional car ignition coils can destroy the stator or control box. Siba systems require dedicated Siba coils.Condenser Failures: These can cause running issues.General Maintenance:Dampness: Units are sensitive to moisture.Overloading: A faulty relay can cause the unit to push too much power.Rebuilding: If the internal wiring is damaged, the unit may need to be rebuilt, often by a specialized auto-electrician.If the engine starts with a pull-starter, the issue is isolated to the Siba unit. If the unit makes a huge spark but doesn't turn, it could have an internal
A bit wordy, but may contain some relevant direction in which to look.
They were "Siba" dynastart in common use from my understanding, the neighbour at bottom of our garden when I was a kid was MD of the UK manufacturer and used to talk about them to my dad. Another neighbour had a few Issetta BMW cars too.
Post by: Skoti on May 01, 2026, 11:41:59 AM
Gosh that's a beefy looking rotor for a wee bike.It is a starter/dynamo,
Have you got any electrical test data for the stator, rectifier and voltage control unit?
Better to test rather than guess, a simple multimeter would probably suffice.
I guess a similar system that Villiers used for the engines in the Bond cars
Possibly Isetta,BMW etc used the same for the bubble cars,
The Villiers had a switch, like golf carts, that would start the motor in reverse rotation, so no reverse gear needed
I have a multi meter, most of the readings seem to be somewhere near
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Back in the seventies I worked on a few later RD200 models with the coffin shaped tanks, but can't recall if I ever encountered charging system problems.
Wish I could suggest something to help you.
Be interesting to learn what the problem turns out to be tho.
Good luck.
Knew an old bloke that had a Bond Minicar years ago, it was also possible to kick start it but you had to clamber out of the car and step under the bonnet to do it. Very amusing to witness.
Post by: Johnwebley on May 01, 2026, 01:08:20 PM
Thought I would see what the control box did,
According to manuals,the centre unit is a cut out,
The big one on the end is the starter solenoid,
Other voltage relay
So with the engine running at fast tickover, about 1700
I pressed the voltage relay switch, nothing happened,
Then the middle one
Charge light out,
But about 4 seconds later, the main/only fuse blew
Time to ponder again
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Post by: Johnwebley on May 01, 2026, 01:22:23 PM
Interesting morningPictures
Thought I would see what the control box did,
According to manuals,the centre unit is a cut out,
The big one on the end is the starter solenoid,
Other voltage relay
So with the engine running at fast tickover, about 1700
I pressed the voltage relay switch, nothing happened,
Then the middle one
Charge light out,
But about 4 seconds later, the main/only fuse blew
Time to ponder again
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(https://uploads.tapatalk-cdn.com/20260501/93cb3428557467a94d194c3630403efc.jpg)(https://uploads.tapatalk-cdn.com/20260501/31606ff9171362f9f8965ab499ed7f06.jpg)
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Post by: Johnwebley on May 10, 2026, 12:10:54 PM
after a little running,the charge light does dim,but never fully goes out,
got another test to check,
then a possible stator rewind? or Rotor,,or both,
but the other alternative is fit VAPE electronic ignition and generator,dowside is you lose the electric start,
more details soon
Post by: Skoti on May 10, 2026, 06:54:35 PM
But not cheap especially for the NSU 125ZDB.
But I'm aware you have problems with your ankle so perhaps electric start is important?
Post by: Johnwebley on May 10, 2026, 07:16:43 PM
I can just lean over the seat and push the lever with my arm
Starts easily enough
But I like to press the button!!
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Post by: Bryanj on May 10, 2026, 09:55:56 PM
Post by: Johnwebley on May 11, 2026, 03:16:56 PM
He suggests clean thoroughly,
Current can leak away using debris from the worn brushes
More news in a few days
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Post by: Bryanj on May 11, 2026, 04:42:24 PM
Post by: Johnwebley on May 14, 2026, 03:04:00 PM
cleaner spray brought up everything like new,
rotor segments all good,no leakage to earth
cleaned the stator and brushs
brush 1 and 3 seem to be the power ,nice and clean,no leakage to earth,brushes 2 and 4 are earthed,so not so critical.
started again,guess what,no change,still no charge
Post by: Bryanj on May 14, 2026, 03:48:50 PM
Post by: Johnwebley on May 14, 2026, 04:15:21 PM
but it seems slowish,
but I am comparing it to the 500 and 200,which have different systems,
the only electrical thing that really needs replacement is the ignition switch,it has been knacked ,with the centre core removable and all the pins missing
would that make a difference? my thoughts are it only turns a contact unit to switch it all on
Post by: Bryanj on May 14, 2026, 04:39:49 PM
Post by: Bryanj on May 14, 2026, 04:56:50 PM
aircooledclub.com/manuals/cs3b.pdf
I have screenshot the reg part and will read testing at work on sunday and get back to you
That should be aircooledrdclub.com/manuals/cs3b.pdf
Post by: Johnwebley on May 25, 2026, 05:13:06 PM
No current being fed to activate the generator,
So I have sent it off to a place in Lincoln,
He specialises in old dynamo and control boxes,
Strips them out and converts them to solid state,
With updates, such as reverse polarity protection
Also will keep the electric starter
I also have been busy, putting a new rim on the rear wheel,
First ever wheel build
Also before and after wheel (https://uploads.tapatalk-cdn.com/20260525/ebb3fe14de9fcd7127892a06717eb44b.jpg)(https://uploads.tapatalk-cdn.com/20260525/e0dae87f61cd9c402c7c85195ad158a7.jpg)(https://uploads.tapatalk-cdn.com/20260525/0d36e3f394741fef5faeae3de40da8f4.jpg)
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Post by: Bryanj on May 25, 2026, 09:03:26 PM
Post by: Johnny4428 on May 27, 2026, 07:14:34 AM