Author Topic: Bullet parts for a custom bike  (Read 1117 times)

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Adrian II

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Reply #30 on: November 01, 2021, 12:22:50 pm
Ah, the Triumph TRW - a low-powered military machine, I don't think we saw Steve McQueen on one of those!

Later versions of the M21 had some rear suspension, in plunger form, though a lot of them were used as Automobile Association sidecar tugs. If you wanted an old Brit side-valve/flat head thumper with swinging arm suspension, try a late Ariel 600 VB.

https://s1.cdn.autoevolution.com/images/moto_gallery/ARIEL-VB-600-10245_1.jpg



A.
Grumpy Brit still seeking 500 AVL Bullet perfection! Will let you know if I get anywhere near...


Borrmann Motorcycles

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Reply #31 on: November 01, 2021, 01:02:53 pm
Such beauties! Honestly if i could count up all those beautiful bikes of the old era, I'd need to use my motorcycle encyclopedia.

To be fair, the motorcycle history is astounding! So many models that were designed, if it's because they were a cheap way of person transportation, a way to travel, a style to travel or a way to see the world in new eyes.

For many it was their life, their passion to give such creations....


And money aswell. Until the car became rentable for the lower class and many of the motorcycle manufacturers started struggling with that buisness alone.


AzCal Retred

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Reply #32 on: November 01, 2021, 03:38:15 pm
     Now this fellow "Bulli" has available a running, fully functional Pre-Unit Bullet motor with a 120mm custom crank (up from 90mm), rod & piston that displaces 735cc. That would make a nice basis for a running, streetable custom machine. All you need is an existing Austrian licensed Pre-Unit Bullet and the rest is drop in. Externally the engine looks stock. The much larger flywheel will give you the slow idle that's so much fun. The larger engine's torque is ideal for "pottering about", and would pull a lot more gear than a standard 500 Bullet at lower RPM. Bulli is located in Germany I believe, you can PM him and also see the engine run in the links on his post. Since you stand about 6'5" & weigh in at nearly 21 Stone ( 285 lb.  ;) ), you'll likely need to fettle handlebars & seat arrangement to suit yourself. Stock 500 Bullet fork & shock spring rates are quite stiff, so likely very close for your needs. Many tall riders manage the Bullet quite well as is. The beauty of a custom like this is you get a "brand new" antique with exceptionally nice power. Parts are readily available and relatively cheap. Two valves, carburetor & points, and a giant rolling element bearing crank designed in this epoch that can be endlessly lugged with no concern.
     There's nothing to stop you from stretching out the mild steel frame & swingarm a bit if it suits you better. The stock 19" wheels can accept 4.00x19 tires, giving tremendous load bearing for luggage or just hard use. The "bench seat" on mine provides plenty of room to stretch out and move fore & aft, and also increases seat height a bit.
     This would be a custom that is both unique & affordable. The parts situation means you can modify to your heart's content. Worth a look.

Located in the Pre-Unit section here:
Bulli: 750cc Bullet engine RUNNING
on: October 10, 2021, 12:35:08 pm
 Quote
...we have built a perfectly running engine to be used in a regular PreUnit RE Bullet frame. There is nothing to see from outside. But inside you will find WOW ;D 8) ;) It has a stroke of 120mm and a bore of 88/89mm giving 730 - 755cc cylinder capacity. See it running: https://www.youtube.com/watch?v=dVjR6yUKEUA
We had been running it for about 15 minutes, checked the oilsystem und everything else... untill it had been getting really hot. It ran absolutly perfect. So the first running-in had been done now. After cooling down, we thigtend the cylinderhead nuts again with the recommend torque.
I will now put this oneandonly750cc-Bullet-Engine in my garage or livingroom..... because i dont`t have a bullet with a broken engine to test the engine furthermore.... this engine is perfect to be used in a sidecar-bullet anyway, because it is not good for rpm over 3.500/3.750 after completely runnig in ...... but has very much power from low rpms on.


PS - Take a look at what member "Grumbern" creates also. There is some real talent, like having a camera following Leonardo da Vinci around.
« Last Edit: November 01, 2021, 03:47:01 pm by AzCal Retred »
A trifecta of Bullets: a Red Deluxe 500, a Green Standard 500, and a Black ES 350.


AzCal Retred

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A trifecta of Bullets: a Red Deluxe 500, a Green Standard 500, and a Black ES 350.


AzCal Retred

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Reply #34 on: November 06, 2021, 03:52:14 am
Nice write up on riding one of these old beasts.

https://www.mcnews.com.au/the-bsa-m21-600-side-valve-slogger/
Riding the beast meant I had to start it. Having been told that BSA side valves were reliable and easy starters I approached this matter confidently. The kick start had an awkward throw and started to function too late to offer a good swing. Not that it mattered much. With all my weight and energy I could hardly move the thing and then only with a tired wheeze from the motor and this is a low compression motor! Using the de-compression lever I almost fully decompressed the motor and pumping away like a two-stroke I managed to get the beast to fire. What a wonderful noise, the engine settled down immediately to a beautiful slow “Ka-chuff, Ka-Chuff, Ka-chuff.” With a little judicial use of the advance/retard lever the engine note deepened and reduced to one stroke a minute, or thereabouts. I was beginning to enjoy that whopping 112 mm stoke after all. When the throttle was opened the front wheel began to agitate, the centre-stand began to migrate the whole bike across the driveway and the rear tail-light began to dance a jig. I began to get the impression that some vibration might exist some where in this machine.
Climbing aboard the sprung saddle I pushed the bike off of its stand and levering the gear lever up into first with an almighty graunch away the bike went. A little attention to the clutch would have given me time to actually use the throttle; however the superb grunt of the motor carried me across the lawn without stalling and gave me time to take control.

First gear was very slow for sidecar work and could be avoided for solo work. Top gear was reached very quickly as the motor’s sheer torque makes gear changing mostly unnecessary Changing gear however is good fun as despite the low power and speed the grunty motor lifts the bike up on its girder suspension under acceleration giving a superb imitation of a powerful bike. Especially as all this is accompanied by a wonderful exhaust beat.
A trifecta of Bullets: a Red Deluxe 500, a Green Standard 500, and a Black ES 350.


Borrmann Motorcycles

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Reply #35 on: November 06, 2021, 08:14:26 am
This is a wonderful qoute, lad. This is exactly what I intend.
Especially the detail of the girder suspension and the sidecar, the slow hammering, the vibrations.


Borrmann Motorcycles

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Reply #36 on: November 10, 2021, 01:51:15 am
So. I now finally feel comfortable enough to show the first results of the design progress. Please keep in mind that these are very early, but will in the end have every screw, every bearing and every part located and finished.
The only parts that won't actually be the 100% correct size until the civil engineer gives his okay to the project, are the parts I buy from other motorcycles. Also to note that the Pressure plate on the cam side and the Crankcase L 1 aren't close from being finished, as much that the blunt grey at the crankshaft bushing is actually Crankcase R 1, just not started yet, as much as the actual measurements of the counter balance.
On the other hand the crankshaft weights are already calculated as good as possible, as only the final practical balancing will effectively define how many holes and/or tungsten bits i need to use on it.

The royal enfield flywheel isn't implemented yet, but the 2nd flywheel, which is needed for the extra force it needs to wind over at the compression stroke. The blue, unrecognizable skribbles are the skatches of the Springstarter gearbox, leading behind the cylinder.

It's now 3 am and I'm exhausted from both the work and the 3rd vaccine shot, so good night, see ya.
« Last Edit: November 10, 2021, 01:59:29 am by Borrmann Motorcycles »


AzCal Retred

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Reply #37 on: November 10, 2021, 07:16:24 pm
Are we looking at the front or back view? Usually the starter is at the front. If so, the cams are on the left side of the engine, the drive sprocket on the right. This reverses the entire power train to the 6-speed HD gearbox you were planning to use. If the starter is actually located behind the cylinder, this makes more sense, but tends to bake the starter.

Attached are HD big twin drawings, the stroke is already in the neighborhood you are after, you'd just be modding the crankcases for a bigger cylinder. The crank OD could likely be made larger, which will result in much more "flywheel effect" than a small diameter, auxiliary "add-on" unit. There are already 2L versions of this HD engine around, you'd just need to whomp-up a larger cylinder configuration. Using the front cylinder gives you a nice "sloper" configuration. The full journal width connecting rod would be about the only other piece you'd need to whittle from the solid, and likely there's an existing Model T or Flathead Ford hot rod part that's close. Using the HD engine as a starting point means everything except the top end is proven fully functional & reliable, a really big deal when sorting out a project. Starting from scratch means ALL of your new design HAS TO WORK 100% right out of the box, a very tall order indeed.

A puzzler to me is why the electric starter at all, if we're going for the traditional big single look. At 6'4" & 300 lbs., you have plenty of heft to spin the engine over with, and it rather detracts from the basic concept. You can simply buy a 55HP KLR650 with all the modern accoutrements, a savagely nice, refined, well sorted, reliable "Big Thumper" machine. You won't out-build Kawasaki there. There's not much sense in recreating the wheel, spend your money on actual improvements, not just an "art project" for your own amusement.

Bulli's Pre-Unit 735 engine & a 5-speed in an appropriate frame sized for YOU would be comfortable, easily startable by you, have a nice gear selection available, and have plenty of power. That engine's a nice piece, they've really done their homework. A frame is a much easier job than an engine from scratch. You could even make up an alloy frame like this 1967 Greeves Challenger has. ( https://www.mecum.com/lots/AZ0319-366439/1967-greeves-challenger/ ). That's just wheels and a jig to hold the bits in place, or spec it out to a frame builder. An alloy frame would drop 20-30 pounds off the existing bullet frame and provide some vibration absorption effect. An alloy leading link front end would be a real show stopper.

Using existing, developed engine parts as a starting point means you would end up with something you could actually ride to an event & keep running without a portable machine shop full of mechanics or an on-call tow service.

A trifecta of Bullets: a Red Deluxe 500, a Green Standard 500, and a Black ES 350.


Borrmann Motorcycles

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Reply #38 on: November 10, 2021, 08:43:58 pm
We have a view from the front. The spring starter assembly would go behind the zylinder, which design I would've called a homage to the old bullet case. But it is quite the point, that the spring starter is technically an overkill, so i could leave that out for sure.

Harley does have reliable gearboxes, but the newer bakers drive so far I've seen have already the mounts for an electrical starter within the cast. Not using it would be foolery on my side. And besides, not unlike royal enfield, it is nice to have a Kickstarter, but close to a necessity to have an electrical one. Especially when for example touring with others. You're the last to go, or the one everyone needs to wait for.

And because of the HD engines... Yes, their crankcases are developed for sizable engines.
They're imperial beasts on their own, but not just that their crankcase is built for the V2 Slope, but also that they're mostly imperial measurements.
Looking to the enfield we have the translation to metric systems as early as 1974 with metric crankshaft bearings. Over the course of the next decades they completely switched to metric systems.

It is by far easier for me to design a crankshaft in metric, than trying to salvage the HD in imperial.

Yes, the gearbox is imperial, but except for performance parts already existing and the mountings for it, I'm not doctoring around in it.
The only idea surpassing this would be using the internals of the drive and design the crankcase further to have the gearbox internal, but i think I'd draw a line before that.
...... Except I'm really bored and make an io 1500 P2 (H)  then I'd reconsider that idea..... Maybe that one then as a sloped design single cylinder just out of the Harley..... But I digress, this would just be playtime I'm talking about right now.

This isn't just getting a sizable motorcycle for myself.
It isn't just some art project for me or a bet to win.

This is literally that one thing i worked and saved my money on to do.
That one project that Always was in my mind, made me plan every route in life to this point.
If I'd be good enough in electronical design and programming, I wouldn't use royal enfield parts.
If I wouldn't need to play by the rules, that altering the frame would make me lose the permission to achieve a lower Euro code, as the serial number can make the regulations apply from the period the frame was built in, i would make the frame myself.

It is a tall order, but one I can cope with.

These aren't just dreams anymore, which i had 10 years prior. These are the few chances I can take on.
It's true that I won't be surpassing any modern Motorcycle company but also I'll be needing at least some type of development, designing, archiving, reworking and the dedication to it, to show those pesky inspecting authorities, that it is worth to look and testing it.

Until now they are merely worth throwing a dice on getting through to them.


AzCal Retred

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Reply #39 on: November 10, 2021, 11:27:16 pm
Borrmann -
Does this mean the engine only has to comply with the emissions standards that existed when the frame was built?
" as the serial number can make the regulations apply from the period the frame was built in "
If so, that implies that a frame from the 1960's would make life easier.

How much can you modify a frame?

Is there any reason you can't use points? If it was OK in 1960...? Points/coil are easy/cheap/plenty good enough. Even triggered every crank revolution from a crank-driven cam they'd work very well. Then all you need is any AC rotor and a generic voltage regulator box.

The SAE/Metric really doesn't matter. All bearings are available worldwide, a shaft is machined to a specific tolerance on a lathe, the operator doesn't care  if it's SAE or metric, he just needs the actual dimensions he's working in and suitably accurate tools.

Welding up HD cases and boring out the cylinder spigot is simple stuff. Any bottom end work, you have 50 years worth of HD parts, just order what you need. You'd have a free hand with the top end, so make it all metric if that suits you.

" to show those pesky inspecting authorities "
The "why" is still amorphous. I can categorically state that after 65 years of observation of the human condition, proving to a disinterested 3rd party official that you can do something is a waste of your time. If what you really want is to chuff about on a creation entirely of your own design, I can see that. But there's a lot of ways to achieve that end, and they're all a case of degree.

One way is to build & register the machine in a country where they are very lax in what goes on the road, then have it in your garage "for a friend". You could build exactly what you want.

In any event, you'll end up with rolling one-of-a-kind artwork if you do this. The only "payback" will be personal enrichment. There are some savagely talented folks out there, take a look at the new Norton, and the various Royal Enfield based hand made V-twins, to name a few. What have you built so far? Any pictures?  This is a "hella job" if it's going to be a first effort. What's your shop situation?
A trifecta of Bullets: a Red Deluxe 500, a Green Standard 500, and a Black ES 350.


AzCal Retred

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Reply #40 on: November 11, 2021, 01:56:43 am
You keep referring to civil engineers approving your work. It's unclear what you are getting at.

In the USA, the NTSB or some Federal authority checks brand-new-to-the-USA-for-sale-to-the-public designs for roadworthiness and "safety", and the EPA gets a pound of flesh determining if the machine does more harm to the pristine USA Los Angeles air than a Kenworth. I can't see "authorities" doing actual engineering tests on anything you build outside of basic mechanical safety component inspections. They couldn't possibly be set up to evaluate physical performance criteria like handling, braking, cornering ability, functionality, HP, shifting ability, etc., etc..

What tests would YOUR custom have to pass? Just a basic "safety MOT" like the Brits have? Would it need to be certified as a new engine design and have long-term emissions requirements?

What if you found a 1940's 500cc sidevalve basket case, there's likely no emissions requirement because of the age, and got it licensed & on the road, THEN shoehorned in your motor? It would be a street-legal chassis with no emissions because of the age, would they look at it for annual MOT safety? Would they even know enough to question a different engine that looks "about right"?


A trifecta of Bullets: a Red Deluxe 500, a Green Standard 500, and a Black ES 350.