A B31 to go with the Golden Flash

[KiwiGF]

It's finally ready to go through the NZ re registering process. I'm embarrassed to say this has taken 4 years, mainly because the budget was limited and lots of parts were made. Finding a rear wheel took a very long time as well. The wheels turned out to be scarce in NZ.

https://youtu.be/9whHB58SKdc

[orabanda]

Ripper tune, Boris!!

I have added a B31, to the A10 fleet.

They are a lot of fun!

[duTch]

 And all held together with ticky-tacky but still looks just the same... still reckon nuts an bolts work better...

[KiwiGF]

Ripper tune, Boris!!

I have added a B31, to the A10 fleet.

They are a lot of fun!

Thanks, tick over is slow isn't it! I've only ridden it a short distance but yes it will be fun, especially on the NZ gravel/dirt roads, your b31 is overly complicated and heavy, having rear suspension and all 

[RoyC]

Well done, I love it.

[Sluggo]

Well done.   IMHO there SHOULD be a Singles section on this forum (Not for dating or hookups, I mean single cylinder bikes) because as my reasoning goes, these bikes have a lot of cross over and similar issues.
I have a number of BSA preunit singles as well and project for this winter is narrow the field of projects I might actually get to vs those that are a pipe dream.  Same with my unit singles too.

I am having some issues currently sorting these projects and ID'ing the parts as parts books are helpful but often it is unclear.  I suppose I should sign up over on BritBike, I see many of you folks are already there.

I have another BSA single I am anxious to get cracking on, a 1932 Blue Star I made a deal on and sitting in the UK for last couple years.  With any luck it will be shipped this winter.  Finding people with actual real knowledge of preunit BSAs is a real challenge, why not include singles in the mix?

[orabanda]

The B31 is enjoyable; you make a lot of (beautiful) noise.
Third gear is the one where the engine performs best; it pulls like a 14 year old, and will climb all of our local hills.

The engine likes to rev. I have warmed the donk over a bit; 9:1 piston, 65-2446 cams (GS Scrambler), GS valves & springs, and a Suzuki clutch (very sweet to use).

Agree about the tickover; must be around 600 rpm fully retarded.

Richard

[KiwiGF]

Hi Richard, yep I'm looking forward to riding it, I'm still going through the lengthy re registering process, which involves paperwork disappearing into a "black hole" in the Vintage car club offices in Christchurch for many weeks, but hopefully they will produce the bit of paper I need before Xmas!

I'm also waiting for burlen in the UK to get some new concentric in, they have been out of stock for months so I've not placed an order yet. The 930 concentric I have seems to be a mismatch of old and new parts in the needle jet area, and the bike cuts out above 1/4 throttle but (sort of) goes at full throttle. It seemed to be a better option to get a new carb rather than buying new parts to fix the carb I have.

Do you think I should get the 932? That's slightly bigger diameter than the inlet has been bored out too, but I intend to keep "warming" the engine up, it's only got standard valves at the moment but that's likely to change  . It's got GS touring cams and a bit more than 7:1 compression, its 390cc with an Yamaha xs650 piston.

It's a shame this is out of my budget range !

https://www.trademe.co.nz/Browse/Listing.aspx?id=1434627519

[Black Sheep]

 932 is rather big for a B31. A 928 would be more than big enough.

[KiwiGF]

I finally got a 930 (30mm) carb from burlen.

It’s got a number plate and is all legal now (a right paper chase, but not that hard in the end)....it had no history in the form of old rego docs etc. I also forgot to get a receipt from the PO of 35 years 

It’s done 300 Miles now and gained some stick on pin stripes 

That’s my brother in the photo, he rode his recently bought seventies CB750 sohc dunstalll cafe racer over to my place, I then made him ride the b31, he returned quite puzzled 

[jachenbach]

Only 3 years, KiwiGF? Now I really feel like a slacker! Just saw one of my old posts and found I've been working on my A10 for 3 years. Same as you, there are limited funds. Then there are the other projects ('71 Commando, '59 Venom) that came up and seemed so much closer (and cheaper) to completion so I switched over to them. Both are running, though not quite road ready, so I should be back on the A10 in the not too distant future. Looking forward to a ride report when you get her fully sorted.

[Greybeard]

That’s my brother in the photo, he rode his recently bought seventies CB750 sohc dunstalll cafe racer over to myplace, I then made him ride the b31, he returned quite puzzled

That's a really good looking bike!

[mikeb]

looks very nice kiwi.
why did you go for a non-standard 930 concentric? are you happy with it?
i ask as I'm contemplating a new burlen 376 to replace the worn-out 289 on my (xb) b33

[KiwiGF]

looks very nice kiwi.
why did you go for a non-standard 930 concentric? are you happy with it?
i ask as I'm contemplating a new burlen 376 to replace the worn-out 289 on my (xb) b33

I’m Simon remember? Anyway, the only reason for the concentric is that’s it’s cheaper than a monobloc for a new one. As far as I know performance wise there is little to choose between the two, and again as far as I know they are pretty much same design wise other than the float bowl, so the jetting would be the same for same size carb. The equivalent carb to the 930 is the 389 1 3/16”.

I’ve had the cylinder head bored out  to suit the bigger carb.

[KiwiGF]

That’s my brother in the photo, he rode his recently bought seventies CB750 sohc dunstalll cafe racer over to myplace, I then made him ride the b31, he returned quite puzzled

That's a really good looking bike!

Thanks, they are (sort of) the original bobber I guess?