Do I upgrade parts for more reliability?

[the chippy]

Quick one about me.
Never been a biker or a mechanic, a carpenter by trade. Now retired. Direct access and full A licence last summer.
In 2023 I started looking for my late fathers 1950 B31 to pass on documents to the current keeper. You will see I posted on this forum in 2023 when trying to who had the bike. With help from the BSAOC I did locate the keeper and although it was not my intention to buy the bike, last year the keeper said he was planning on selling it and I got first option to buy it, thus a new A licence followed and I have been riding a Kowasaki Versys for a year.
I picked up the B31 in August last year and I want to use it, not just look at it. 
Now the long story.
Its an older May 2004 restoration, and restored very well I believe, I have receipts totalling £1889.59 for parts and images of the bike in bits going through resto. But it has not been used since, just taken to shows in a van, started up, then back in the van to come home and put away until the next show and dry stored.
Externally its in great condition and as the clutch, gearbox and magneto are all new or refurbed it should be good. But after riding it a few times it was obvious I had a few issues. Popping when slowing down, float chamber flooding, lacking power when climbing hills.
I also found the 2004 resto had included a fuel tank re-line, but that has failed with lining material hanging in the tank like curtains. So I now have the tank off and am stripping internally for re-lining.
I also have a couple of really small oil leaks come to light after I had completed a couple of 50 mile trips and everything got warm, maybe gaskets here and there are not good, probably as the bikes has not been ridden since the 2004 resto job.
I removed the carb, ultra sonic cleaned everything, and fitted a service kit. But that made things worse. Carb flooding more and backfire more frequent. So I am thinking the carb may just be worn out as the throttle slide does feel a bit loose.
I am not necessarily going to be taking the bike to classic shows for winning prices, I want a bike that's really reliable. In fact I want a bike where I can tour the UK.
A trip to Ireland from Kent is planned in May. I was going on the 650 kowaski, but hey I would rather do it on the B31 even if it means mainly staying off motorways.
I trust a 2004 restoration but I don't trust the bike is good and reliable.
Therefore, should I put the 276 pre monoblock in a box, send away to be restored, or just upgrade to a newer carb? What other mods if any should I do if I want a bike that needs to be reliable for long trips?
I can do certain maintenance but will be relying on the maintenance sheets and help.
Thanks Steve.

[rhyatt]

Popping and banging on the overun is usually nothing more than an airleak in the exhaust.
1, where the ex pipe pokes into the head must be airtight
2, where the pipe joins the silencer must be airtight.

Usually these coke up as machine is used , but yours has not had much use.

Remove , reseal and see how it makes an improvement

[the chippy]

Popping and banging on the overun is usually nothing more than an airleak in the exhaust.
1, where the ex pipe pokes into the head must be airtight
2, where the pipe joins the silencer must be airtight.

Usually these coke up as machine is used , but yours has not had much use.

Remove , reseal and see how it makes an improvement

Thanks, but I still need to address the carb flooding. I don't need choke to start, just a little tickle and I get fuel, and starts fine. But when I stop turn off and short time later, as soon as fuel switched on the carb just floods all over the place, worrying as the engine is hot. I have to turn off fuel off instantly and start with fuel off, and after it's going for a moment slowly turn fuel on. Indicates stuck float. But I see no reason it should be stuck as all clean.

[rhyatt]

Have you spoken to Burlen in Salisbury,  they make all the Amal parts and sell all the service parts

[limeyrob]

The float has a needle valve and these don't aways seal when dirt gets in or wear. You can get a rubber tipped valve for about £15 that stops this.  Popping and banging is quite common on old bikes, air leaks, lean or rich mix on the over run, ignition timing off.  Most people live with it and find the culprit when fixing something else.
B31s are lovely reliable bikes, they do leak a bit but I commuted on one for many years and it never let me down (but lots of tinkering...) .  Many years ago I met a guy who had ridden a standard B31 from England to Helsinki and back via France, Holland Germany and Sweden so it will certainly make it to Ireland. Last year I was at an event and there was a guy I a German registered un-restored B31, he'd ridden from Germany and was riding home.
Why not post a travelogue

[neil1964]

I am not sure that I can add very much to the sound advice you have received thus far, the exhaust pipe fits into a tube like recess in the head, sometimes it is not a good fit and can be flared slightly but a bit of exhaust sealer around the (cleaned) gap will help, then some more before you slide the cooling ring along the pipe back to the head, but as said with use this will coke up!

The flooding issue can be a number of things from poorly seated float, incorrectly set fuel level, sticking float (bent needle) or, more likely from your description contaminated fuel from delaminating sealer causing the float needle to stick open.

I suggest that you first try starting/running it, after cleaning the float chamber out, with a remote fuel tank (Ebay for £10-15 inc eg https://www.ebay.co.uk/itm/397468148860) and see if that is better, then you know that once your tank is repaired you should be ok.  I would also make sure your taps have decent filters (the inlets to the taps can sludge up with silt) or install a couple of in-line filters in each fuel line.
Regarding the carburettor itself there are people that can restore them or you can repair it yourself (new brass sleeve/plastic float kit, new jets and needles will set you back about £120 from someone like Burlens or Hitchcocks which, unless the body is very worn, will fix most things - unlike Mk1 concentrics which wear badly due to metallurgical no-nos!).

Other option is a new 276 https://accessories.hitchcocksmotorcycles.com/Amal-Carburettors/276-Pre-Monobloc/12539 £400+ ( ouch! but quick, simple and reliable) a new Monoblock https://accessories.hitchcocksmotorcycles.com/30020 £250+ or a Concentric https://accessories.hitchcocksmotorcycles.com/Amal-Carburettors/600-Mk1-Concentric-4-Stroke/13616 probably need to spec the Premier variety on a concentric https://amalcarb.co.uk/mk-i-concentric-series/600-series/base-line-specifications/24mm-bore/aluminium-premier-lh-24mm-4-stroke-carburettor.html as the premier has the modified pilot system, suitably coated slide, stay up float and viton tipped lightweight alloy float needle.
Always ask for it to be supplied to the correct spec (the seller should set this up for you for your bike).

I'm sure that I don't need to tell you that for a longish trip like you are planning I would tape or tiewrap a prelubed spare clutch cable, front brake cable and throttle cable and couple of litres of oil (same will do for engine/gearbox and clutch) and a spare inner tube and a simple tool roll to be able to replace the above.

A B31 will not set the world on fire but will take you anywhere and back once running properly.

[the chippy]

Have you spoken to Burlen in Salisbury,  they make all the Amal parts and sell all the service parts

I was on their website last night. I'll need to call them. I could see the component parts listed for my pre monoblock but not a full replacement. I'm sure it's there, just couldn't see it. I'm thinking of going concentric type as may be more reliable.

[the chippy]

Have you spoken to Burlen in Salisbury,  they make all the Amal parts and sell all the service parts

Not spoken to them yet, but I will. I was on their website last night to see whats available. Thanks.

[DAVE BRADY]

Hi,

No amount of new parts can restore a worn out carb.  The small fuel and air passages wear over time and even if clean will skew any settings.  You may get your bike running OK but if you want to use it regularly and for longer trips then a new carb. is probably the best option.
Many riders have fitted an Amal Concentric to a B31 so there will be plenty of ideas re jetting but as already mentioned, ask Hitchcocks for the best jetting options.
Unless you really enjoy fettling, a new carb. properly set up is a fit and (almost) forget item.

For the exhaust pipe sealing I use a high temp. silicon sealant.  Works well and is easily pulled out when needed.

Dave.

[scifi]

If it is flooding when the tap is turned on, that means your float is not closing the valve correctly.
It should be an easy fix.   First make sure the float is floating and is not filled with petrol.

Then by using a length of new hose, check the action of the valve by raising the float, whilst blowing into the tube.  The float should have some travel remaining when the air stops going through the valve.

If you have the carb off the engine, the air should stop just with the weight of the float, when the carb is held upside down.

As it is a pre monobloc carb, with the separate float bowl.   Is the float bowl vertical when the leaks occur?   You might have it leaning on the side stand, or worse, it could have a wrongly installed 'tilted' float bowl....  They are available with 0 10 30 or more degrees of tilt, to suite different installations.

[the chippy]

Hi,

No amount of new parts can restore a worn out carb.  The small fuel and air passages wear over time and even if clean will skew any settings.  You may get your bike running OK but if you want to use it regularly and for longer trips then a new carb. is probably the best option.
Many riders have fitted an Amal Concentric to a B31 so there will be plenty of ideas re jetting but as already mentioned, ask Hitchcocks for the best jetting options.
Unless you really enjoy fettling, a new carb. properly set up is a fit and (almost) forget item.

For the exhaust pipe sealing I use a high temp. silicon sealant.  Works well and is easily pulled out when needed.

Dave.

Thanks Dave. I am of the mindset its a new carb, I just needed the push.
I was planing on touring on the Kowasaki, but I only started riding in the first place because I was ably to get my Dads old bike. And if I don't use it properly, it will just sit in a shed, one day the roof will leak un-noticed and will get rusty etc etc. So I want it to be my go to bike.
All the best. Steve

[ducati2242]

if you are getting the tank re lined make sure the material used to line in is ethanol resistant .mine came off after years of working one the new fuels arrived . 

[ducati2242]

why not use an Amal 376/2 Monobloc carb . I had one on my gold star for a while and it ran perfect . Started good and ticked over good . I wanted the gp carb on mine which is now running good with it but takes a lot of work . If i were going touring i would refit the monobloc 376 .

[Derek996]

Have you spoken to Burlen in Salisbury,  they make all the Amal parts and sell all the service parts

I was on their website last night. I'll need to call them. I could see the component parts listed for my pre monoblock but not a full replacement. I'm sure it's there, just couldn't see it. I'm thinking of going concentric type as may be more reliable.

I have a Monobloc on my 1948 B32 it works perfectly, no issues at all. The Monobloc is a more robust carb than the Concentric and is preferred by many riders. It also has a replaceable pilot jet whereas the Concentic is fixed with a "one size fits all". And it's cheaper.

[rhyatt]

By chance, you don't have a fibre washer UNDER the banjo union where it screws into the float chamber ?
Burlens are very helpful lot.
They bought all the Amal factory tooling and records etc.

Things to carry with you ---
As you use the bike and it settles and evolves , you will generate your own list of tools and bits to carry.
Personally , pliers , pertinent screwdrivers , a few relevant spanners , chain adjusting spanners taped together , spare chain link , magneto spanners.
Are you 12v or original 6v ? If you're 6v then a few light bulbs or consider changing to 12v and led bulbs and easier life for the dynamo .