Carburetter after fire

[AdrianJ]

A couple of weeks ago my carb - 276 on a plunger A10 caught fire.
I was running the engine periodically over the winter as I don't want to get the bike covered in s**t, so I'm not taking it out.
Being a plunger I have no air filter and when kicking it, it spat back and ignited the overflow from tickling.
Major panic, but I had an extinguisher and used it. There is no fire damage to the bike.
However it was covered in powder (ABC40 - ammonium phosphate with hydrophobic additives). I have washed most of it off but it has started to rust on every surface the powder touched, and oxide alloy corrosion.
More importantly, it got into the carb and one cylinder. I'm not too worried about the cylinder - taken the head off and cleaned it.
The carb is now seized solid - releasing fluid didn't help - now trying hot water, or should I write it off (carb not bike)? It was on its last legs anyway, I think.
All the rest of the damage is cosmetic.
Any thoughts or ideas would be appreciated.
Adrian

[RDfella]

Can't help with your present problem I'm afraid, but I'd just re-iterate what I said in a recent post. For dealing with small vehicle-related fires you can't beat CO2 extinguishers. Very effective, never fail to go off (in my experience), stop as soon as you release the trigger and also leave no mess / residue. The only type I have in my workshop.

[AdrianJ]

That is useful to know. You won’t be surprised to learn that I’m getting a replacement and reluctant to use powder.
I’ve got the carb apart now. Hot water and a rubber mallet did it. The powder has made a right mess. Going to clean and polish and see where that gets me.

[chaterlea25]

Hi Adrian,
I think you have answered your own question ??
Knackered carb leaking caused the fire,
Why persist with it?
I would be tempted to wreak revenge on it with a BFH 
What ever you do fit an air filter or a gauze on the trumpet
A couple of years ago on a rally here a plunger  A7 did the same as yours, it was  badly damaged , and written off by the insurance company

John

[mikeb]

following on from John's advice, if you want to do better than a gauze on your plunger then have a look at the pic below - spotted on someone's b33 plunger with monobloc at a rally a few weeks back, i've googled the brand (Uni) and there are a range of shapes and sizes and i assume one that will fit your 276. there are threaded cone filters around for 289's but not sure re a 276.

i struggled to fit a filter to my b33 plunger (with a monobloc) tho managed recently with an adapter (see in the 'just a pic' page somewhere) but if my adapter fails from all the back-firing i'll next try one of those Uni filters

[muskrat]

G'day Fellas.
The problem with the plungers is the room behind the carb (doesn't matter which model Amal). Even the original rubber is hard to fit. Using a short bell mouth with wire needs the carb mounts to be bolts not studs.
There are tiny cone filters used on mini moto's that can be shoe horned in. https://tinyurl.com/y3vyh4s4
Cheers

ps: re fire extinguishers, Had two fires put out with powder, what a mess. I have another powder now but will be getting a CO2. The powder one cost $30 a CO2 the same size is $180. But with 4 bikes and all my tools it's worth it. Also installing sprinklers in case I'm not home 

[AdrianJ]

Dead right Musky! It’s a pain getting anything in there. The original air filter was missing when I got the bike and I am reluctant to pay what the rare items cost.
I can (and will) get a CO2 extinguisher the same size as the one I had for £30 or £33 with a fire blanket.
Bolts sounds a good idea. Whitworth I assume.
Adrian.

[Rex]

Nope BSCy.

[AdrianJ]

Good! I don’t like using Whitworth on things that get unfastened frequently.
Adrian

[AdrianJ]

I have to ask though , if they are not going into alloy, why did they use studs in such an awkward place?
Not really expecting a sensible,answer 🙂

[Greybeard]

... Bolts sounds a good idea. Whitworth I assume.

I changed to bolts for my carb. I don't know how I'd get the rubber onto the carb with studs.

[Swarfcut]

Adrian The original fixing is bolt 2-129.  It's cycle thread into the manifold stub but with a reduced hex head, same as gearbox outer nuts, to aid fitment against the carb body.

 A fella with your skills should be able to knock up an airbox, the rubber elbows are available and the element can be adapted from a modern item, as GB did. Here safe and efficient operation is more important than a highly priced quest for original parts.

 Swarfy.

[AdrianJ]

Thanks very much Swarfy.
I’ve just ordered a new carb. I take your point about originality, but the sheet metal skills are beyond me, so I’m going to fit one of the small conical filters.
Still wonder why anyone would fit studs, it’s just making life difficult. I assumed it was in order to reduce thread wear.
Adrian.

[Greybeard]

... Still wonder why anyone would fit studs, it’s just making life difficult. I assumed it was in order to reduce thread wear.
Adrian.

Before I changed to bolts it was easier to leave the carb on the head when stripping the top end.

Back in the day it may have been more common to have the head off than just the carb. Factory fitted carburettors wouldn't need to be meddled with.

[AdrianJ]

Just ordered stainless set screws.
Adrian