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Mocked up the intake today with the new manifold. There's enough of an area to clamp the copper elbow securely into the rubber intake. And then the SU float is at the perfect angle and the carb body clears the head.
That just means the copper elbow has to be soldered to the alloy SU flange.
Due to the weight of the SU I'll make up a decent support from the head. Fortunately there's a couple odd OEM brackets I can use - now redundant.
Just to give me a bit of encouragement !! I should have the frame jig [very basic ] next week so I can start positioning the various lumps to check packaging.
At the moment the plan in my head should work out !!!
We finalised the crude frame jig yesterday. crude but I think effective.
As the top box tube frame section will no longer double up for fuel, I've ordered the much lighter gauge 2" x 2" x 16swg. Hopefully collecting that today.
Once the jig is firmly attached to my bench, I can start the P.O.C. mock up of the main assemblies.
Much better, we'll have the 2" x 2" cut and fettled so that the Bantam headstock sits in the box half way so we can get a neat finish. The box will be fettled at the correct angle to self jig the headstock angle [ 64 degrees ].
The crude [ very ] frame jig mounted and 100% level. Crude but effective.
The POC box has been cut and fettled, and when we're happy with all the measurements and angles, we'll cut the finished 2" x 2" top tube.
The headstock just nestles in nicely and will make for a smooth welded finish.
We mocked the front end up today [ forks / wheel ] just to get P.O.C. fit for the headstock / top tube and it all looks good. I've settled on 26 degree headstock angle initially, but that will be double checked when the front is mocked up properly and I can check the trail.
The headstock will now be fettled into the full length 2" x 2" box tube then we can determine how long that needs to be to pick up the rear frame upper tubes.
BTW, the purpose of logging this build [ the frame bit especially ] is NOT to embarrass myself in front of seasoned frame builders, but to show what can be done by those of us with little facilities, skill or equipment.
If you have the vision and will - it will happen.
My first set of Tribsa engine plates were cut using my Nan's front garden gate with the plate wedged in between the gate post and the gate to hold it in place so I could cut the alloy into shape. I didn't have a shed or workshop at the time [ 18 ] and certainly not a vice ! Oh yes, and it rained while I was cutting the last plate !
The final shape was made by using a file with the plates squeezed between my knees to keep them steady - 'ish.
We've got all the various lumps to make up the frame jig and mount the wheels and forks in place - then we can start knitting it all together. The top tube / headstock has been fettled and as soon as we start the mock up, I can determine how long the tube needs to be and get it lopped off.
POC for the frame jig - it will work. Final mock up of the forks. Just need a few brackets and some welding and they will be done.
These are the set up forks, the modified forks [ 3 bushes per stanchion ] have all been refurbed. There's a couple of pieces I want to get nickel plated, but I'm unsure yet about powder coating or painting. The wheels will be powder coated. Depends on the final colourways. I've decided on Coffee and Cream [ Cafe Creme ], just which parts to paint what !!!
We will make a template for the rear engine plates - will be more of a box section by the time it's done.
Moved on to Hi-Tech now ............. gone from Cardboard Aided Design to Wood Aided Design !!!
However, while I'm waiting for the headstock and top tube to be tacked, I thought I'd just check my original sums.
Here's the headstock at 67 degrees, the rake is 3 1/2". It can't be finalised until I get the headstock assembly, but we're in the ballpark. I also need to get the rear engine plate ass'y sorted so I can position the engine - mainly from a cosmetic point. I started out with 5" ground clearance, but that will place the engine too low and look a bit stupid. 7" will still give me plenty of clearance between the carb [ tallest point ] and the underside of the 2" x 2" top box tube. I want to leave enough room behind the engine to mount the cut down 2 gallon vintage petrol can - which will be my fuel cell [ 1 3/4 galls - imperial ].
My pal who does all the tacking of parts has been very ill, but now back to rude health and called me this morning to say he has tacked the headstock in place into the 2" x 2" box section.
It's a 2 handed job [ at least ] to get the top yoke into the headstock so we can finalise the headstock angle.
Once we're happy with that we can attach the jig fixtures to hold everything in place so we can use the laser gizzmos to align everything before it's tacked up.
I also made a cardboard template for the rear engine plates, they'll be transferred onto ply so that the pattern can be finalised.
I managed to get the top tube / headstock onto the fork yokes on my own - not sure why there wasn't a big disaster, but all OK. Again, this is POC stage and I'm doing this to check out what was in my head - is in reality !
Chuffed - trail and headstock angle as I planned. Scope for adjustment when we have a proper check when my pal brings his laser gizzmos round. I also have scope to alter the wheelbase from 55" - 60" [ if required ] without changing the jig.
Couldn't resist cutting and fitting the tank and dropping in place as a "whatif"...... happy with it, but when the engine is in it's final position [ maybe 5" higher than the attached pix ] the tank might not be cosmetically deep enough. Mainly because I want to hide all the modern squitter under there - coils, ECU, fuel pump, etc.
I also made the final [ CAD ] rear engine plate patterns .............. just before the engine decided to leap off the bench and crash nearly 3 feet to the concrete floor. I feared the worst, but damage was confined to one top fin, which I was able to Araldite back .... good as new. While I had the Araldite out I decided to attache the SU flange [ alloy ] to the copper bend [ house plumbing ! ] ready for it to be silver soldered. Success - all fitted in the correct orientation with the float bowl level and the carb vertical ............ until you go round corners of course !
My pal is coming round to give me a hand to raise the engine into it's postion - he's bringing my scissors engine jack which is currently under the KZ750 Caff Racer [ yes, that's still going ].
Once that's at the correct ride height [ aiming for 7" ground clearance ] we can check out the position for the front downtube and the rear diamond.
More CAD today - sorted out the support mount for the SU carb, hoping to make that out of brass - if it's not ridiculously expensive [ in my world ]. I also decided that the proportions of the "tank" [ cover ] weren't right - so more CAD to lower the sides to see "whatif" ..........works for me.
Rear engine plate pattern finalised. I have a cunning plan for the front and rear downtubes ......... wait and see.
The headstock is now located by 25mm x 25mm x 3mm angle .... going nowhere. I'm using some more 2" x 2" box [ as per the top tube ] to locate the top tube relative to the base jig [ also 2" x 2" ] so that everything is locked into position prior to tacking.
Unfortunately the cut down Shell Mex vintage petrol can can't be used - it's far too big enough .... going to look silly. So it's a 1.2 gall [ imperial ] fuel cell under the top tube and hidden by the "tank". I know a bloke that's shit hot with fuel cells !
That's a bummer as I wanted to hide all the modern squitter under there - ECU, coils, Regulator, fuel pump etc., etc. Not many little nooks and crannies on a Boardtracker.
And the bonus .................... it's been pissing down today - but my garage is bone dry for the first time in 15 years !!!!
I had the 2 x 2" box section supports pre-mitred by the suppliers [ 9 degrees ] which puts the headsock / top tube in the right orientation.
Getting closer to being ready for tacking up.
And the cunning plan for the front and rear downtubes ??? I was quoted £95 for a split downtube with weld bungs and clevises ....................................... £10 for a hevy duty BMX fork !!!!! AND it's spot on dimensionally. the one in the pix is for the rear. The front one should be here at the weekend.
Starting to resemble a bike now ! Rear diamond mocked up to check lower chain run clears etc. and also finalise the rear wheel spacers.
I'm happy with the proportions now, the only point to finalise is the wheelbase, which I can easily alter without changing the jig. That will depend on how much room I need for the Valor paraffin can which will be my fuel cell.
Now you see it, now you don't !! How to disguise a 1950's Valor paraffin can as my new fuel cell.
The metal plaque will be trimmed so it fits in the radius at the top ........ the bottom won't be seen, but the can will be painted same coulour as the "tank". The plaques [ one each side ] will face outwards just behind the engine. The spout will become a breather exiting to one of my 1900's brass accessories.
I found matching headstock badges, so once I have removed any referrence to Yamaha on the engine ........ it's an Edoardo Bianchi bike !!!!! The Blue and Gold one will go on the Bantam headstock and the Black one .... not sure yet.
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