MK 3 airbox repair

[markdenny]

Good evening all

I have a MK 3 Commando Interstate that until a few hours ago had a Mikuni carb, im going back to twin amals, my question is how do i repair my airbox the previous owner appears to have cut out the centre part where the carbs fit so im left with only the outer parts of the 2 holes, has anybody been succesfull in the past. Or does anybody have a complete MK3 airbox for sale in the UK. I have looked in all the usual places and found nothing.

Regards

Mark

 

[cliffa]

Good evening all

I have a MK 3 Commando Interstate that until a few hours ago had a Mikuni carb, im going back to twin amals, my question is how do i repair my airbox the previous owner appears to have cut out the centre part where the carbs fit so im left with only the outer parts of the 2 holes, has anybody been succesfull in the past. Or does anybody have a complete MK3 airbox for sale in the UK. I have looked in all the usual places and found nothing.

Regards

Mark

Mk2a & III airboxes once trashed, now seem to go for really silly money. I sold one for £70 a couple of years ago and then saw one sold for 3 times that shortly afterwards. They seem to be made of the same kind of plastic as dustbins and petrol containers so cannot be glued. ( Polythene perhaps?) So my suggestion would be to make an alloy plate (for example) of the correct dimensions and then use a good quality silicone to glue it to the front of the airbox.

 

[mdt-son]

Mark,
These air boxes are rare nowadays. I would assume the air box is made of shape-blown Polyethylene. It is a weldable material also used for car bumpers etc., so if you can get a piece of flat PE in approximately the same thickness, a car body repair shop may be able to weld it in. Do the trimming beforehand, not to load the weld seam unnecessarily.

Polyethylene Sheet HDPE 2mm-3mm-4mm-5mm-6mm-8mm thick

Supplier of high density polyethylene, PE300, in rod, sheet and tube. Buy online from the UK's favourite place to buy high density polyethylene online.

www.theplasticshop.co.uk

How to bend HDPE sheets? - Tangyin Xinxing Plastic

Bending HDPE (high-density polyethylene) sheets is a common thermoforming method, suitable for manufacturing curved structures, baffles, box corners and other products. Because HDPE material has good flexibility and thermoplasticity, it can be bent by controlled heating. The following are...

uhmwpe-sheets.com

- Knut

 

[lazyeye6]

Mark,
These air boxes are rare nowadays. I would assume the air box is made of shape-blown Polyethylene. It is a weldable material also used for car bumpers etc., so if you can get a piece of flat PE in approximately the same thickness, a car body repair shop may be able to weld it in. Do the trimming beforehand, not to load the weld seam unnecessarily.

Polyethylene Sheet HDPE 2mm-3mm-4mm-5mm-6mm-8mm thick

Supplier of high density polyethylene, PE300, in rod, sheet and tube. Buy online from the UK's favourite place to buy high density polyethylene online.

www.theplasticshop.co.uk

How to bend HDPE sheets? - Tangyin Xinxing Plastic

Bending HDPE (high-density polyethylene) sheets is a common thermoforming method, suitable for manufacturing curved structures, baffles, box corners and other products. Because HDPE material has good flexibility and thermoplasticity, it can be bent by controlled heating. The following are...

uhmwpe-sheets.com

- Knut

View attachment 124442

Good evening all

I have a MK 3 Commando Interstate that until a few hours ago had a Mikuni carb, im going back to twin amals, my question is how do i repair my airbox the previous owner appears to have cut out the centre part where the carbs fit so im left with only the outer parts of the 2 holes, has anybody been succesfull in the past. Or does anybody have a complete MK3 airbox for sale in the UK. I have looked in all the usual places and found nothing.

Regards

Mark

I assume you a

Good evening all

I have a MK 3 Commando Interstate that until a few hours ago had a Mikuni carb, im going back to twin amals, my question is how do i repair my airbox the previous owner appears to have cut out the centre part where the carbs fit so im left with only the outer parts of the 2 holes, has anybody been succesfull in the past. Or does anybody have a complete MK3 airbox for sale in the UK. I have looked in all the usual places and found nothing.

Regards

Mark

 

[lazyeye6]

Mark,
These air boxes are rare nowadays. I would assume the air box is made of shape-blown Polyethylene. It is a weldable material also used for car bumpers etc., so if you can get a piece of flat PE in approximately the same thickness, a car body repair shop may be able to weld it in. Do the trimming beforehand, not to load the weld seam unnecessarily.

Polyethylene Sheet HDPE 2mm-3mm-4mm-5mm-6mm-8mm thick

Supplier of high density polyethylene, PE300, in rod, sheet and tube. Buy online from the UK's favourite place to buy high density polyethylene online.

www.theplasticshop.co.uk

How to bend HDPE sheets? - Tangyin Xinxing Plastic

Bending HDPE (high-density polyethylene) sheets is a common thermoforming method, suitable for manufacturing curved structures, baffles, box corners and other products. Because HDPE material has good flexibility and thermoplasticity, it can be bent by controlled heating. The following are...

uhmwpe-sheets.com

- Knut

View attachment 124442

Good luck! Gluing a replica back together and assembling all of the fitment bits will be difficult and costly. There was a reason that
Folks discarded these things. But I totally respect originality. Watch out for the airbox on the usual sales sites. They occasionally show up.

 

[nortonmargie]

I have one in reasonably good shape, but I am NOT in the UK!

 

[mdt-son]

Good luck! Gluing a replica back together and assembling all of the fitment bits will be difficult and costly. There was a reason that
Folks discarded these things. But I totally respect originality. Watch out for the airbox on the usual sales sites. They occasionally show up.

This isn't about a replica - where did you get that idea from? And I didn't propose to glue the damaged air box. Please read the thread more carefully.
What do you mean by "costly"? Nothing is free, but the repair should be considerably less expensive than the $350 bill I have seen these airboxes advertised for.

I don't know if brackets are missing or not - the OP didn't mention. If they are missing, replacements are available from AN for little money, so no issue at all.

- Knut

 

[markdenny]

My airbox is complete and original apart from the cut out bit in-between to two holes, I just wanted to know if its possible to repair somehow, or if somebody had managed to how did they do it.

 

[concours]

As mentioned above, fabricate an aluminum plate (14ga) and use pop rivets with backer washers, neoprene sponge gasket in between.
I've done it on other airbox applications.

Edit: be sure to use ALUMINUM pop rivits, that also have ALUMINUM mandrels. It will provide the correct crush, and not too much.
REAL hardware stores will have them.

 

[L.A.B.]

fabricate an aluminum plate (14ga)

I assume you mean 14 AWG (actually US sheet metal gauge which seems to be different) which generally means nothing in the UK, so probably nearest is 2.0mm as British SWG is no longer used.

 

[concours]

I assume you mean 14 AWG which generally means nothing in the UK, so probably nearest is 2.0mm as British SWG is no longer used.

Translate as needed.

But, for future reference, I made no mention of American Wire Gage, different altogether from metal gage.

For curiosity, what did you use there to define sheet metal before the metric system?

 

[Fast Eddie]

For a tenner you could get one of these to use as raw material, easy to cut and once you’ve painted over the rivets, practically invisible …

Water Storage Tank

WRAS approved. Made to BS4213 : 2004.Lid available separately (code 67700).

www.toolstation.com

 

[kommando]

Take a carb to black box rubber and measure the width of the slot for the black box. Use either black plastic or alloy of the same thickness as the width of the slot.

 

[markdenny]

For a tenner you could get one of these to use as raw material, easy to cut and once you’ve painted over the rivets, practically invisible …

Water Storage Tank

WRAS approved. Made to BS4213 : 2004.Lid available separately (code 67700).

www.toolstation.com

That sounds like a plan to me

 

[daveforty]

I have one of those which is surplus to requirements, you're welcome to it for the cost of the P&P and a donation to a suitable charity.

 

[markdenny]

I have one of those which is surplus to requirements, you're welcome to it for the cost of the P&P and a donation to a suitable charity.

What a complete MK3 airbox or the water storage tank ?

 

[daveforty]

Airbox. I took it out of my bike sometime last century in order to change to a ham can air filter and use metal roadster side panels and battery tray etc etc. It is covered in spider scheiss etc, but it will be usable.

 

[markdenny]

Airbox. I took it out of my bike sometime last century in order to change to a ham can air filter and use metal roadster side panels and battery tray etc etc. It is covered in spider scheiss etc, but it will be usable.

Daveforty, you could be a life saver what's the P and P to LN1 2DF what would be a suitable donation ? as long as there is no damage to the box I've got all the other bits attached to mine

 

[L.A.B.]

For curiosity, what did you use there to define sheet metal before the metric system?

SWG as far as I'm aware.

Standard wire gauge - Wikipedia

en.wikipedia.org

Standard Wire Gauge (SWG) conversion to metric

SWG wire sizes, imperial to metric conversion

www.clag.org.uk

"Inch and millimetre dimensions for Imperial Standard Wire Gauge (SWG) sizes, as used for sheet metal and wire."

 

[L.A.B.]

But, for future reference, I made no mention of American Wire Gage, different altogether from metal gage.

Yes alright US sheet metal is not AWG corrected above.