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A D3 Bantam Called Camilla
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Bob-B
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April 8, 2018 - 4:45 pm
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Got the gearbox together earlier today and I have a couple of questions, some of which feel a bit daft, but I don't wish to have to pull it all apart again later in case I've missed something or there is some little nugget of advise to help ensure things work as they should.

Firstly, the final gear on the main shaft is going to require a bit of minor persuasion to go through the bearing on the LH casing (dead fit measured on the calipers), no great problem there but once it's in the bearing I don't really want to be persuading it back out again. If I knock it all the way through the bearing as far as it'll go is that fine or is there a specific gap I need to leave?

The selector shaft has a 1mm gap between the end and the steel insert in the case it butts up against. Enough? Too much?

Any way to be certain that the gears will all select? As I've posted earlier, the selector "flag" has been replaced with the updated version, new selector spring and ball bearing, extra washer under the springs to give more compression. Anything I've missed?

It goes together so simply that all of the above may be a load of cobblers, and it certainly looks pretty hard to get wrong, but I'd rather ask silly questions first. I'm beyond the age where I get embarassed asking them!

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cocorico
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April 8, 2018 - 6:12 pm
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I can't recall the specifics of my D3 gearbox rebuild, but I tested that all 3 gears meshed by putting the 2 case halves together (no crank, etc) and changed gear manually. Photos are ** Please log in to view **.

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Bob-B
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April 8, 2018 - 7:26 pm
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Hello Cocorico,

Just done exactly that, bit of game with the final gear; as I knocked it in the bearing moved slightly out, but soon rectified. All gears are selecting quite nicely, I'm now pondering if my problems with 2nd gear when I rode the bike have been fixed with the little changes and new bits or if the throw of the lever is just so long compared to what I'm used to that it was mostly down to me!

Anyhoo, on to cleaning up the crank properly, I'm away for a few days for work so that won't happen till later in the week.

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cocorico
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April 8, 2018 - 7:31 pm
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Bob-B said
... if the throw of the lever is just so long compared to what I'm used to that it was mostly down to me!

Well, mine requires what is often referred to as 'a positive gear change', by which I think they mean ' it's like an old BMW gearbox, slow and noisy' - and I speak from experience... wink

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Bob-B
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June 3, 2018 - 6:33 pm
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So much for later in the week...

Just measured the end float, and I have none whatsoever. Checked the bearings were all the way home, which they are, proceed or not?

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Bob-B
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June 24, 2018 - 9:29 am
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I have a working Bantam! The engine started on the second kick and seems happy to idle at very low revs. With a gallon of BPs finest and 3 cap fulls of 2 stroke added as it says on the cap for running in, I bimbled off to find out what else needs doing. Got happily and leisurely up to 40 mph, finding all the neutrals on the way but in truth the gearbox was perfect (reminded me of the Guzzi owner phrase "what do you mean you only have 1 neutral?"). 20 miles in the bag but a few jobs to do.

The clutch is slipping a bit, looking at posts here that seems to be a common and almost accepted problem, I'll uprate/replace the springs. My clutch cable was a bit bodged just to get me out, seems like all the pre-made ones available don't fit properly so I'm making one up instead using solder nipples. Anyone else find this necessary?

My front brake is not returning properly requiring me to reach down and push the lever a few times, nice easy job there.

The manual says 250-500 miles for running in from new, any recommendations for how long should I leave the mix at 3 caps given it's a re-built rather than new engine?

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June 24, 2018 - 10:37 am
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Happy day...sunny days!

Modern 2-stroke oils are good enough not to go adding extra for running in.What in effect you are doing is putting more oil through the jets which means less petrol,which means a weaker mixture which means stressing your engine more,not less....but,but,if you`re pootling around,and Bantams being crude old engines,you`ll probably be ok.

Secret is using quality components during the rebuild,making sure the piston-bore clearances and ring end-gap are correct,radiusing the ports.I blueprint my engines,so they are essentially  run-in from the off,and after a quick tootle out to make sure all`s well,start opening them up almost immediately.

I have a Classic Bike mag here with a test on a D7 that has been restored to a state way beyond what came out of the factory.....except whoever rebuilt the engine either got their clearances wrong/used cheapo parts/mixture wrong/didn`t radius the ports....the tester had it nip up on him several times,that`s not a happy engine.

You should be ok with your D3,they`re a much lower state of tune.

Maybe a position or two on the splines to angle the gear lever down more will help with your gear changing up through the box.I`m ok with r/h g/change but not so much l/h,I have two welded together toe knuckle joints that`s had me bend a valve on a Guzzi 🙁

Your cables sounds like they could do with pressure lubing or are they kinked/frayed/shot?With the front brake,is the cam lubed?

All the Bantams I`ve owned,I`ve never had a slipping clutch and I used to thrash them.I read about loads of issues nowadays,maybe it`s something to do with modern lubes?Try adjustment, first with the actuating lever centre screw in the l/h cover,make sure you have enough freeplay there and the worm mechanism is returning ok.There`s a return spring attached that may need replacing.Road grit gets in the mechanism too,but you`ve probably cleaned all that in the rebuild.

Blue

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Bob-B
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June 25, 2018 - 7:34 pm
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Everything wot you said Blue. The clutch mechanism and brake cam were fine "on the bench" but now seem to have stiffened up somewhat so they'll be taken apart, new clutch plates ordered along with some new brake pads, the current ones look rather glazed and have that certain asbestos green shade which makes me think I should probably ditch them anyway!

Oil wise, when I have new friction plates I'll take a look in our warehouse, which happens to be full of oils. Modern synthetics definitely do not make clutches slip (unless you use one that isn't suited to a wet clutch of course), I have no idea what the original friction plates have been in previously so that could be part of the problem too, I'm sure the new springs will also help.

I'll drop the fuel that's in the tank and go to two cap fulls, sure that'll help Camilla show her true pedigree!

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Bob-B
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July 2, 2018 - 8:35 am
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I'm rather glad my clutch was slipping now. When I drained the oil there were quite a few flecks of metal in it, turns out I'd rather foolishly installed the clutch spring cup the wrong side of the phosphor bronze bush, must have a had a sudden rush of S*&t to the brain when doing that! Nothing nasty resulted other than a slightly worn spring cup which is now in the correct place.

Upgraded clutch springs and new friction plates in for good measure and soldered up my own clutch cable. Everything feels much more solid now.

One thing I have also discovered post shake down ride, is that my head bearings have now worked a little loose. According to the manual the adjustment requires a piece of flat metal to move the castle nut... might have been fine when the bike was relatively new, not now, no chance of it moving whatsoever!

Does anyone know if one of the castle nut sockets available to buy matches the one on the Bantam or do I need to make something up?

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July 2, 2018 - 10:28 am
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Uh-oh,hope you got it flushed out ok and that none of it found its way into/through the main bearing feed holes.Surprising what you can get away with on a Bantam,good news you discovered it before anything worse happened.

The details below also cover worse-case scenario:-

Castellated nut is either corroded on, or the threads are damaged.You can make a tool from a piece of pipe,I have several for various jobs,never bought one.Use the best penetrating oil you can find,one known to actually penetrate rust,like plusgas.Some use mix of petrol and diesel.Don`t overdo it,you don`t want to flush your headstock bearings of their grease.

Use a rachet clamp between bottom yoke and top frame tube near headstock,then you can remove castellated nut to clean up fine threads of the stem.If you cannot get a suitable die then use a thread file.You`ll probably find the damaged/corroded area is  the few threads you wish to utilise to screw the nut down to take up that free-play.It doesn`t matter if those few threads end up not being in good condition because there`s plenty of overall thread contact.As long as the threads are cleaned up and the threads in the nut are undamaged so it moves freely on the stem.Use a smidgen of grease on assembly.If top bearing assy is dry,you`ll have to drop bottom yoke a bit to grease those too,not just the top set of balls/cup/cone.

Blue

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cocorico
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July 2, 2018 - 4:43 pm
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You can also make one up from a suitably sized socket, if you have an angle grinder. A C Spanner or Peg Spanner may fit too.

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Bob-B
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July 2, 2018 - 5:50 pm
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cocorico said
... if you have an angle grinder.   

Bob man. Bob have many angling grinder. Bob regular wreck new clothes bought by missus for him when using angling grinder. Bob missus often not happy with Bob.

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Blue Heeler
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July 2, 2018 - 8:06 pm
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Oh dear,sparks flying(the wrong way) in your household then....hacksaws only for you from now on,haha 😉

Blue

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cocorico
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July 2, 2018 - 8:53 pm
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Bob-B said
... Bob regular wreck new clothes bought by missus for him when using angling grinder...

Wear a good apron (or a frilly pinny if you like). wink

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Mags 1
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July 5, 2018 - 10:22 pm
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Most angle grinders have a moveable spark guard, my three Black and Decker ones move around a quarter circle, just by pushing on them.

I wear an old 100% cotton smock, like Arkwright's in 'open all hours'. This helps a lot in hot weather.

Four now on the road and at least several in bits.

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Bob-B
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July 9, 2018 - 6:31 pm
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Took Camilla out for a second shake down ride having fitted a new clutch and springs and soldered up a cable and fitted new front brake shoes. Took the lad on the back (9yrs old) for his first ever motorbike ride other than up and down the street... also his first ever motorbike breakdown!

Nuts!

Heard a clonk not far from home and the clutch cable went loose, enjun was fine and continued to run sweetly. Before that the clutch was dragging a bit, complete opposite of what I had on the last ride!

Stopped the enjun and adjusted the screw in and the clutch seemed to be fine again. Bit odd.

Then the enjun refused to start so we wheeled Camilla back by a short cut across the fields to home. the lad was a diamond, helping all the way and not complaining, bit of an adventure for him really!

On brief inspection the spark plug was ringing wet and there was an amount of fuel in the crank case when drained. My hope is that the float isn't sealing off properly and she's getting too much fuel.

What's best to sort this? Lap it in with the help of some brasso or similar to the cap?

I will be taking off the clutch cover again to find out what that clonk was, hopefully nothing serious has happened.

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Bob-B
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September 3, 2018 - 8:27 pm
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As usual a little while in between actually achieving anything!

I've lapped in the float needle with jewellers rouge, checked the clutch, a bit of a tweak to the timing and headed on out again. I still seem to have problems with flooding the engine, but think that's just me using the tickler a bit much.

Another break down!

This time I got about 2-3 miles from home before the enjun sputtered and died on me. However, I actually had the forethought to stuff my pockets with a few spanners on this run out! Removed the crankcase drain plug and there was no fuel in it so I hadn't flooded the enjun this time at least. I did note that the fibre washer was shot so maybe a leak into the primary compression was why it stopped? Put the bolt back in without the knackered washer. Removed the spark plug (burning my fingers while doing so, rag added to the list of things to bring with me), that was dry, a little sooty but seemed OK. Tickled the carb a little. Kicked it over and Camilla started and ran again so I headed home.

Now, there is  possibility that I was a complete idiot and left the fuel tap closed before I started out, but I don't think I'd have got so far before it ran out of fuel..? I've since checked the fuel cap vent which is fine anything else which could have caused the engine to die like that?

To cover off me just being an idiot I'll take a run out later in the week, work allowing.

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sunny
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September 4, 2018 - 7:36 am
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hi  BOB   a  bit  big  i know       A  roll  of  PTFE     tape  fits  all   the  threads

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Bob-B
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September 4, 2018 - 2:32 pm
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Just spoke to the very helpful fellas at AMAL, they've recommended increasing the main jet to 100 due to the +.06 overbore of the enjun. Parts ordered, PTFE tape prepped for the drain screw, I'll whip the carb off tonight in readiness for new needle loveliness.

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Bob-B
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September 25, 2018 - 1:54 pm
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New needles and jets work a treat! After an exploratory 10 miles or so to check Camilla over I decided to try something slightly more adventurous and given that the old girl has only gone a short distance so far without breaking down I decided to hang off all reasonable and sensible ideas for a first proper run out and entered the VMCC  Taverners Road Trial!

Hopelessly outclassed by faster machinery Camilla ran like clockwork, even starting first kick (hadn't hot started her before this point), which much more exotic machines couldn't say.

The ride to the start was further than I'd ever been, and it was wet, hadn't done that either!

Here's a photo of her parked up at the start, with the essential plank of wood for the stand, and one from when I got home. I only did the morning ride because I was starting to cramp up on such a small machine. Overall just shy of 100 miles total.

Only problems were the slide alignment screw for the carb went missing and the speedo, which was running perfectly, suddenly started telling me I was doing 60mph, then went completely bonkers and told me all sorts of speeds!

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