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Discussion Starter · #223 ·
My welding has been rubbish, just couldn't see well enough to tig. So I stopped before I wrecked the tank. I still think I can do it so I bought a new helmet yesterday from Bunnings and might get a chance tomorrow to try again. If still no good I will buy a magnifying lens to go in the helmet, Bunnings didn't have one to fit.
 

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The question really is where does the air exit. There is no duct to the carb on this bike, and just to point it out his bikes ran a single carburettor. He was an advocate for a single carb. :cool:
There are extra holes at the rear of the fairing that were not on the previous versions, before that it would have been drawing air for intake and cooling at near 200 mph from where, the cockpit or around the front wheel
 

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My welding has been rubbish, just couldn't see well enough to tig. So I stopped before I wrecked the tank. I still think I can do it so I bought a new helmet yesterday from Bunnings and might get a chance tomorrow to try again. If still no good I will buy a magnifying lens to go in the helmet, Bunnings didn't have one to fit.
What you need is one of those shields that goes dark as soon as you spark up, for eye correction nothing beats single use contact lenses.
 

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Discussion Starter · #226 ·
There are extra holes at the rear of the fairing that were not on the previous versions, before that it would have been drawing air for intake and cooling at near 200 mph from where, the cockpit or around the front wheel
Hope that works its a picture of a Bert Munro display
 

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Discussion Starter · #227 ·
Been a while but long story short, My welding mask wasn't good enough for me to tig weld. My first attempt at putting the Divider panel in the tank "tanked" looked like bird droppings and blew a hole but it was tacked in. I wasn't brave enough to try again till I got a better mask.
I got a mask from Bunnings a mask I had looked at on line for about $70 from china but I really wanted the better $130 mask from China, but I didn't want to wait so I paid $150 for a $70 mask.
Then every time I went to use it, it rained so today was the first time things worked out for some welding time.

Wow what a difference I can see... now know I will be able to weld this tank leak free :D :D still learning but confident.

Also bit the bullet and got a more traditional fuel cap
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Discussion Starter · #228 ·
Getting there slowly I have welded in the piece dividing the airbox/fuel tank, and I am getting better, although far from picture book. It has caused shrinkage across the centre but it's not twisted.
I have made a flat bottom for the fuel part which is a really good slip in size but without the underside shape in it yet I can no longer sit it on the bike at this stage, and the support hoop has now been removed.
The tank does look a little less bulky than the pictures from the side with the hoop removed. And I am now planning on flattening the top a bit buy removing the lip from the old filler position.

Any other thoughts welcome to help my cafe racer look, now's the time for changes before its set in steel.
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Discussion Starter · #230 ·
Spent time today doing a final trim of the tank shape, so apart from changing the fuel filler area, that is the look..
That is the final shape no real changes now just need to get stuck in and finish it.
Plan is original hinge mount on the rear, standard petcock, Honda fuel sender compatible with the gauge cluster. Harley sportster fuel cap boss and my quick release pins at the front.
I have all the parts so its all a go.
Apart from that the paddock stand is sinking from all the wet weather and there are match box cars down the muffler I need fish out $%@$
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Discussion Starter · #231 ·
A little more progress. Handle bars in position to suit the fairing. Running my custom bent bars allowed me to rotate them to maintain ergonomics.
Smoothed some welds and massaging knee and bar dents, slapped some black primer on to just get better prospective.
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Discussion Starter · #232 ·
Never quick enough. Working on the hinge at the back of the tank, once done I will fit the filler bung and fittings for the petcock and sender.
Finish panel beating because last change with access before sealing up the rear part of the tank shaped for the seat.
Then I will leak test ad weld up leaks, then braze over all welds to destress welds and add material.

Then sort out the air box end (I don't even know how I'm doing that yet)

Then just because I want to be sure of no leak I will use a tank sealer.
then strip it back bog and paint fit the cap petcock and sender and it's done.

Then I have to finish fitting the fairing.
 

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Discussion Starter · #233 ·
Still going, ran the welds all the way, some need attention but I will get there.
Made up a hinge bracket for the back of the tank out of 2mm plate strong enough to check it works but thin enough to bend to get it sitting correctly and check the opening.
Now that the tank hinge is holding the tank in the correct place, opens and closes, and gaps to the seat and frame are good, I can go ahead and add bracing to strengthen the hinge.
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Discussion Starter · #235 ·
Just been cleaning up welds and cutting up the bits to weld in and make it a fuel tight vessel.
But as usual my mind wanders and I am thinking about the air box end.
Despite appearances of having ample volume and room for a better air filter no matter how I envisage the layout the Ram Air filter I am using is the perfect size to fit.

I wanted to run a sealed air box with a filter at the intake with the possibility of cold ram air induction.
One method and the easier, have the tank seal on the air filter flange of the fish carburettor and mount the air cleaner vertical facing forward at the front of this chamber.
Basically making a hat (not big volume maybe a liter) a bit like what's used on blow though turbo setups.

Another way would be encase the whole carb in a box that would be fitted to the manifold and then the carb holds it in place the tank would have a seal and create the lid of the box when the tank is down. The filter would be at the front facing forward as above.
Down side is keeping this sealed the throttle cable and fuel line will pass through the box not to mention the potential for leaks between the tank and the box.

A third option is leave under the tank open, leave the air filter where it is. Then to reduce the air temp fit a baffle from the radiator directing hot air past the intake manifold and try to duct cool air around the intake.

I am leaning towards no.3 KISS keep it simple stupid.
After Ideas so please tell me what comes to mind.
 

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If you want to improve this setup the first step would be to reduce the length of the intake manifolds and second step would be to stack the carburetor. Your current setup looks like it came straight off a 1930's farm tractor, so it probably has the throttle response of a 1930's farm tractor.
 

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Are you still using a vacuum powered fuel pump to feed that antique carburetor? That setup isn't likely to do you any favours, your fish carb was designed to operate off a constant gravity fuel feed, not a tiny pulse pump that robs intake vacuum pressure from that huge intake manifold.
 

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Discussion Starter · #238 ·
If you want to improve this setup the first step would be to reduce the length of the intake manifolds and second step would be to stack the carburetor. Your current setup looks like it came straight off a 1930's farm tractor, so it probably has the throttle response of a 1930's farm tractor.
I don't know what you mean stack the carb.


Well the carb was designed in 1929 but they did well motor sports, last banned from the European rally series in the 80s .
It was an experiment which has worked well although the first dyno run was 62Hp at the wheel and 44ft/lbs of torque, maybe 1-2 hp down but 4ft/lb more torque though the midrange but the weird thing was it was more hp than stock at the rev limiter.
I have since cleaned up the idle (was rich) and part throttle was lean and cleaned up the plenum transition which was purely prototype and still crude for the dyno test.

It will get another dyno tune once the tank is done and the cams are in.
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Discussion Starter · #239 ·
Are you still using a vacuum powered fuel pump to feed that antique carburetor? That setup isn't likely to do you any favours, your fish carb was designed to operate off a constant gravity fuel feed, not a tiny pulse pump that robs intake vacuum pressure from that huge intake manifold.
No, It worked ok on the dyno but would run out of fuel riding. Its electric now powered by what was the carb heater cct.
I don't know if the pump was faulty or if an issue because it was seeing vacuum from both cylinders or if something to do with it being more like a throttle body (no venturi)
 

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Your pulse pump wasn't faulty, it is simply not up to the task of providing a constant fuel pressure.

You mentioned Burt Munro using a single carburetor, but take a look at how short his intake manifolds are. The Indian cylinders are so close together there isn't even room for more then one carb. Also he was going for a world land speed record, his engines only needed to operate effectively at top speed wide open throttle, you are riding a street bike, it needs to operate well at all speeds.
 
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