Author Topic: Project "Laubfrosch" - the trials hybrid  (Read 6674 times)

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grumbern

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Reply #45 on: July 08, 2019, 06:09:36 PM
It's a "Rotenbach" AC/DC 200 P, 5-in-1. Basicly the standard TIG welder you get in different styles and brand names. What made me buy it instead of a different one was the posibility to use an air-powered plasma torch.


grumbern

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Reply #46 on: July 12, 2019, 01:47:15 PM
Engine plates type "Special" :)



grumbern

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Reply #47 on: July 14, 2019, 11:05:51 AM
Now, second layer of paint applied:




That's how they look on the bike. It's still missing the bolt to the gearbox and the one through the frame is too thin - didn't have anything fitting at hand right now. But you get the picture:




The bottom view shows the purpose of the latches. They give some more rigidity, but mostly a good posibility to mount the side stand and skid plate to:




I also melted some aluminium... Not exactly beautiful, but it's doing the job and to my defence I have to say, that a) welding a 20mm deep hole is darn hard and b) cast alloy, espacially these old ones are ugly to weld, bubble alot and contain a lot of junk.








Today nothing else will happen here, but next week I can start the machining.
So long,
Andreas
« Last Edit: July 14, 2019, 11:08:20 AM by grumbern »


Adrian II

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Reply #48 on: July 14, 2019, 02:43:36 PM
Quote
I also melted some aluminium... Not exactly beautiful, but it's doing the job and to my defence I have to say, that a) welding a 20mm deep hole is darn hard and b) cast alloy, espacially these old ones are ugly to weld, bubble alot and contain a lot of junk.
.

Once that is all cleaned up and re-machined it will look a lot better. Were the holes too damaged for helicoil inserts?

On the Bullet rear engine plates there are hexagonal holes to lock the hexagonal footrest bar in position, as well as a spacer tube between the plates, do you have some other arrangement in mind?

A.

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grumbern

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Reply #49 on: July 14, 2019, 07:48:57 PM
Yes, the threads were done for and I don't have any 5/16-BSF inserts nor tools for that. I didn't want to use M8, so this was the way to go.
The distance tube will be made from Aluminium and instead of the hex rod I'll simply use a round and shorter one. The footrests will be set backwards below the swinging arm axle, so there's no need for an unnecessarily complicated mounting plate with hexagonal cut outs.


grumbern

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Reply #50 on: August 08, 2019, 10:01:31 AM
It's been a long time since anything happened here. But as I am on vacation finally I have some time to concentrate on the Laubfrosch again.
So I first went with the fabrication of the axle and bushes for the front wheel. The DR's hub fits pretty well, but is 2mm less wide and only has a 12mm axle, instead of 9/16". So that's too thin for the Bullet's clamps. So I turned two bushes from Aluminium, allso providing the needed distance on the inner face. First reamed the bore to 12mm:




The outside is turned to 14,3mm (9/16"):




Finally slotted it using a hand saw, so the axle, simply a piece of 12mm 1.4301 round stock, can be clamped:




Thas looks pretty much like this:




I mocked up the Engine a bit more as well. Apart from the slender primary case, there's a nother fine detail that found it's way there. Can you find it?




And as the mail man brought some pieces of stainless tubing, I could start to try a little on the exhaust. I like how it turned out. Fit neat an tight, but has enough clearence to the carburettor and especially: The pushrod cover! I wouldn't want to block this by any means, because easy maintenance is a must!








I'm still a bit worried about the muffler though, because I don't need a fried leg! Well, it will get a shied anyway, maybe that's good enough.
So long,
Andreas


Adrian II

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Reply #51 on: August 10, 2019, 11:21:59 PM
DEFINITELY fit a heat shield. You could justifiably use exhaust pipe wrap for the middle section, but it wouldn't look so good. I usually had some bits of melted plastic to scrape off the old Electra-X's woodsman high-level exhaust pipe from boots or over-trousers. 

A.
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Adrian II

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Reply #52 on: August 14, 2019, 02:23:23 AM
If you were to make your exhaust system a copy of the Woodsman rather than the normal Trials type you could have the muffler/silencer further back where it would be more out of the way.

A.

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grumbern

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Reply #53 on: August 14, 2019, 12:01:13 PM
Yeah, I thought of this option, but it builds just so big. So I think I'll just go with the trials-type muffler.


grumbern

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Reply #54 on: October 05, 2019, 04:44:37 PM
The view inside the combustion chamber. All nice and new:




As my magneto is newly wound and re-magnetized I took care of the rebuild. First the old bearing races had to go, which wasn't that easy at all. Those races sit i little paper cups to insulate them and the rotor from the housing, as erosion caused by a missguided current could lead to premature waer of the bearings. Those cups of course were not to be used any more, and the one on the drive side was destroyed anyway when driving out the race:




First the measuring:




And then cutting new ones from a suiting piece of paper:






It wasn't easy to find a piece of paper of 3/10 of a mm, but I found a greeting card that had the right dimensions.
The new race titted with the paper cup:




And a picture of the rebuilt rotor. Primary and secondary windings, as well as the condensor were professionally replaced:




So long,
Andreas


grumbern

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Reply #55 on: November 18, 2019, 09:35:47 PM
Next I needed an adaptor for the timing chest. I used a piece of aluminium that was roughly cut and turned:






Fitting the magdyno:




Drilling the taps:




Some spare parts:




Finishing the adaptor:




The rest was done with my highly sophisticated CNC centre - Completely Non Computerized (flat file):




With the shaft seal in place:




And with the pinion. You can clearly see there's still some missalignment:




That's why I put the engine on the mill once more:






Took off another 2mm in width:




As well as 1/10mm in hight, so I could use a 3mm shim, instead of several ones combined to 2.9mm:




The three bores were counter sunk:




After that the positioning holes for the magdyno had to be made. There are two in the right case and the shim:




The magdyno has two coresponding pins locating it on the crank cases:






this gives perfect alignment of the pinions:




The timing chest cover is in bad shape. Some idiot drilled a 1/4" tap, breaking through the pump housing:




But I found a nice small headlamp, that will look gorgeous on there:






So long,
Andreas
« Last Edit: November 18, 2019, 09:56:23 PM by grumbern »


Adrian II

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Reply #56 on: November 19, 2019, 11:24:53 AM
It's very appealing to see a special build that needs (and gets) some engineering. I do have vague plans to get a set of Electra-X crankcases modified for a magneto* (the Electra STILL has the cut outs for the magneto straps), your work on the Laubfrosch is the beginnings of a "how to".

My specials (bitsas) tend to rely on choice of components to minimize the need for serious machining, with a view to everything either being able to fit or being made to fit without too much effort for my limited skills/facilities. Some jobs I still have to pay someone else to do, though.

What are your plans for the damaged oil pump chamber? Repair or just replace the timing cover? I think I can guess the answer.

Also notice the rack of Bullet engines lurking nonchalantly in the background, guys...

A.

* one of these would be nice...


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


grumbern

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Reply #57 on: November 20, 2019, 06:39:17 PM
Hi Adrian,
yeah, it's one of the advantages of a professional trainer in the m+e industry to be able to use some of the equippment, but this could have been done on one of these small hobbyist mills as well. The earlier housings are better to use, as they still have that cast in provision on the oiltank, that was used as a platform for the magdyno and you wouldn't need an adaptor plate/shim. If you're planing to use just a magneto without a generator, you could use one of the later mags like the K1F, that just bolt to the timing chest as the distributor does. This wouldn't even need any machining. With the lean burn engines though, and some Electras, where they don't have the machined flange, you might run in some problems and still need to modify it to fit a mag to.

Your suspicions about the timing cover are right: I'll try to repair it. If it doesn't work I haven't lost anything and the cover itself has a very nice engraving job done to by the previous owner that I'd like to preserve.

The BTH is a nice unit and would shurely suit a vintage trials single!

So long,
Andreas


Adrian II

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Reply #58 on: November 20, 2019, 09:49:13 PM
Yes, that's the KD1TT magneto also used on some Manx Nortons and JAP speedway bikes. As with the Lucas competition magnetos, people tend to know what they're worth!

Fitting a magneto to an Electra-X crankcase also involves re-instating the two idler gears as well as either machining for a flange-mounted magneto or doing the same as you have for a platform-mounted magneto.

The K1F and its BT-H equivalent, the KC1, are not a straight fit, though they can be MADE to fit!  ;) I shall post something about this in a while. The Lucas SR1 magneto however DOES bolt straight onto the crankcase of any pre-electronic ignition Indian Bullet, though the automatic advance/retard units built into the drive gear can be hard to find.

I have a couple of projects on the go at the moment but have had trouble getting my picture hosting website's links spat out by this forum's dreaded database error. Maybe it's time for another attempt.

A.
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Adrian II

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Reply #59 on: November 22, 2019, 08:13:36 PM
Meanwhile this would be even more appropriate for your trials Bullet, only 480 GBP!

BSA Goldstar Lucas wader competition M01 magneto - ISDT Magdyno, ebay UK item 123984943206

A.

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