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Goldstar rep build

Posted By: Goldiebenny

Goldstar rep build - 11/08/15 9:27 am

Hi guys, I'm new on this forum, I'm currently in the middle of building a 1955 Goldstar clubman rep out of my old b33, I'm only 32 years old so I'm still gaining knowledge of these old bikes! I'm reluctantly putting back in my mildly tuned 500 iron engine, has anyone on here got any Goldie big fin 500cc top end bits as I'm keen to build an alloy top for mine, any help will be greatly appriciated, Ta Ben(England)
Posted By: Andy Higham

Re: Goldstar rep build - 11/08/15 10:45 am

I am in the process of building a similar bike to you.
Mine is a 1955 B31 over bored to 400cc using a Triumph T140 piston, Pearson crank with bigger shafts and metric timing side bearing conversion, Modified gold star valves, ported head with unleaded exhaust seat, gold star cam followers, ABSAF 65-2442 and 65-1891 vernier cams and ABSAF high capacity oil pump. I am in the process of converting the head to take eccentric rocker spindles. My aim is to take it to Elvington next year and get a timing ticket with over 100MPH on it.
The chassis is pretty much gold star clubman look alike apart from alloy engine plates and Barleycorn comfort stainless clipons. I have fitted stainless mudgaurds, many stainless nuts and bolts, stainless spindles and needle roller swing arm bearings.
Where in East England are you? Phil Pearson the guru of all things gold star is in Great Yarmouth
Posted By: Goldiebenny

Re: Goldstar rep build - 11/08/15 1:09 pm

Hi thanks for the reply, I'm in suffolk, phil built my fathers old db500 engine, his a top bloke, always keen to give good advise, your doing some pretty interesting mods, that should go real well!!! I was thinking of trying that over bored b31 trick as a lot o people reckon it's a very sound conversion, I just love the big fin alloy engine, I might have to do a slow bench build and buy the bits off phil unless any second hand bits come along, thanks ben
Posted By: chaterlea25

Re: Goldstar rep build - 11/08/15 1:49 pm

Hi Andy & Ben
I am going down a similar path converting a B33
Clearly marked "THIS IS NOT A GOLD STAR" LOL!!

My intention is to build a mildly tuned big fin engine
Originally I thought about modifying the B33 engine but when I found a really nice set of BB cases I changed tack
These will need modifying same as Phil Pearson does to fit a DBD crank, I have had the crank rebuilt with new shafts and big end
I had spent a long time looking for secondhand top end components
Anything that could be bought was utter crap and ridiculously priced
I came to the conclusion it was better to buy new a replica head and cylinder !!!!
Luckily I got a very good rocker box and rockers secondhand
New scrambles cams and followers and a NOS BSA piston
Its getting a 36 mm Mikuni to feed it
In reality I am almost ready to start building, only a few smaller items needed
needle roller outrigger plate, new oil pump and sump plate plus some fasteners, I have a new headbolt set from Dave Flintoft

A STD gearbox will get a splined mainshaft for either a Norton or home built Suzuki clutch conversion

All I need now is to clear the backlog of work thats waiting for customers !!!

Posted By: Dave - NV

Re: Goldstar rep build - 11/08/15 2:40 pm

Gents ... Over the years I've accumulated a B33 engine and a B31 head. I've long had a (dreamy?) idea of building up a really go fast iron single like the gents race in OZ. Some time ago a racer from Australia sent me a large amount of data on his engine build, running on alky as they do down there. Sadly my hard drive puked and I lost his data and many other valued things.

I had thought about fitting a short rod GS crank, shortening the B33 barrel and fitting a much modified B31 head with the combustion chamber much smaller that the B33. Machine off the intake port and fit a tube insert. And of course fit a larger intake valve. The gent I've mentioned had bored out a B33 cylinder and fit a 90 mm sleeve oohh.

If anyone knows or has contact with the gent from OZ, I would sure like to get in touch with him.
Posted By: kevin roberts

Re: Goldstar rep build - 11/08/15 5:07 pm

Originally Posted by dave - NV
Sadly my hard drive puked and I lost his data and many other valued things.

i hate that.

i back everything up in the cloud now, automatically. still can get lost, but only when civilization finally crumbles
Posted By: Andy Higham

Re: Goldstar rep build - 11/08/15 5:15 pm

90mm sleeve!! even allowing only 3mm sleeve wall thickness would mean boring the barrel to 96mm, the barrel would be in danger of becoming a pile of big washers
Posted By: Goldiebenny

Re: Goldstar rep build - 11/08/15 7:08 pm

Iv only got as far as speaking to phil Pearson about my iron engine, I was going to run my
Standard crank (lightened/balanced) in my b33 cases,
Early b33 long con rod (7 3/8 between centres)
High comp Wiseco goldie piston (8.5:1)
Goldie cams 2448 & 2450
Standard head with Lightned rockers, maybe look at working on the valves?
Lightened timing gear
Amal 900 series mk2 carb
Untill I can afford an alloy engine I'll expirement with this and we what brakes first?

Posted By: Kerry W

Re: Goldstar rep build - 11/08/15 11:54 pm

If you plan to eventually go to an alloy top end, presumably on the same bottom end, you can have some simple fun with the B33 top end, without going to extremes (saving cost and effort for the alloy top end purchase) but set yourself up for the alloy bits later on.

If I was to add a bit of 'go' to a B33 I would start with compression and cams. The 2448/2450 options are good (they were early racing cams and became touring cams for the later engines) and are much nicer on the road than the 2442/2446 option, though these also work well. Leave the exhaust valve size alone, but try and squeeze a bigger inlet valve in if you plan to open the inlet out a bit. I ran a B33 years ago, as a road racer, with a 32mm inlet track (and 32mm MkI Concentric) and a valve that was as big as could be fitted (DBD size, as I recall), that was turned down from one that was intended for a Ford V8 Cleveland engine (stem size was correct and plenty of size to turn to fit). One secret to reliability was using aluminium-bronze valve guides (we had valve sticking issues initially - the al-bronze is used in BIG air-cooled aircraft engines..). Rocker were standard but lightened. Valve springs were standard B33, with lightened caps and set-up to be coil-bound about 1mm after full lift. That engine (as a short--rod) never valve bounced and ran hard to 7000+.(short rod)

If you bore a B33 barrel to more than about 60 thou oversize you will have problems with the bottom spigot breaking. At 80 (i.e. 87mm) thou over it is almost a certainty. In other words, to go beyond 86.5mm you will need a thicker liner and also a bigger hole in the crankcase mouth. (which I think Phil can do for you).

Then there's the bottom end. If you really want to set the bottom end up for later use of a big-fin alloy top end, you will need a short rod. If you are going to do that don't waste time and effort working with an old B33 crank, but save the shekels and buy a crank from Phil. The stock crank will work fine with a short rod mod, after turning to Db/DBD size, but unless the tapers for the crank pin are perfect and the rivets absolutely tight on the mainshafts, don't bother. If you put the taper of the crankpin in the hole in the flywheel and the shoulder on the pain goes straight up against the face of the flywheel, don't use the flywheel (pin fit not good enough). If you do get a crank from Phil, buy the oval one - they are a little more and Phil won't thank you for ordering one, but even he will tell you they are better. If you do use the stock crank and long rod, this will limit rpm to about 6200 and I'd prefer to use a rod that had been polished and shot-peened..

When thinking about the bottom end and later alloy top end use, put the big-fin tappets in and make pushrods to suit the rockers you use (pushrod tops are different). This and the crank will save stripping the bottom end when/iff you get an alloy top end. However, if you use a short rod (making later swaps easier) you will need to shorten the cylinder, pushrod tunnel and the hold-down bolts. This is a nuisance to do but easy enough. How is the Wiseco piston you have for height? I suspect that that piston on a long (B33 rod) won't come to the top of the bore on a stock length B33 cylinder...

You mentioned a 900 series MkII carb - I think the 900 series is a MkI, but no issue: the 32mm MkI I ran had a 330 main jet, standard needle, 106 needle jet, #3 slide and the usual fixed pilot jet and a 70mm long inlet stack.

Incidentally, the over-bored B31 was also popular where I was, using either the Triumph T140 piston or BSA B44 item, though the B44 piston (and the T140?) had a smaller pin, so the little end bush needed replacing. I got as far as boring a B31 cylinder for the high compression B44 piston I bought but never finished it off before things went in another direction. It would have been about 400cc.

I had always thought that using a ported B31 head on a B33 would be a good idea (common way of making a squish head in the Velocette world) but that it would take a degree of effort and know-how I didn't have access to at the time. The squish option would surely work and allow use of a flatter/flat-topped piston and less ignition advance. (incidentally, we ran 38* advance with the short-rod B33 on then-available 96 octane pump fuel). Te other 'good thing' is probably (though I never got around to using it on the BSA) wis twin-plug ignition, with a small plug slid in behind the pushrod tunnel. Firing the second plug is easy these days, with various options, even down to a simple double-ended external coil, driven by (guessing here, but I'm sure it could be made to work) a ubiquitous Lucas SR1 rotating magnet mag (use the external double-ended twin HT lead HT coil, fired by the mag, instead of the SR1's usual internal coil) or a nice new twin-plug mag from BT-H (my preferred option!).

Sparkling up a B33 would be fun, and is something I have been thinking about recently too. Keep us posted!
Posted By: Don P.

Re: Goldstar rep build - 11/09/15 1:55 am

Kerry Could you elaborate on what the advantages would be with
oval flywheels?Would it be smoother?
Posted By: Kerry W

Re: Goldstar rep build - 11/09/15 6:43 am


I've never ridden a bike with oval wheels, a la CB34, though I have been told more than once that the CB engines were the best. The oval wheels have been discussed elsewhere on here, with various thoughts regarding why they might perform better. I'm not sure they are smoother, but the engines apparently do seem more willing.

It has been suggested that the BSA machinists hated making them, because they were paid by the piece and the oval wheels take quite a lot longer to make. Phil Pearson reckons the same (perhaps a day extra for him to make) and charges a little more, though surely not commensurately more for the additional time.

Posted By: Dave - NV

Re: Goldstar rep build - 11/09/15 2:17 pm

Andy ... I too have wondered about the gent from OZ boring the B33 cylinder for a 90 bore liner. I sure would like to talk with him. However I've not followed up with any look/see/measure. I have 3 Goldie engines with OEM 88 mm stroke and 90 bore Pearson cylinders made with his unique muff castings, so I have some idea of what's involved. It makes a nice engine. I'm sure Phil Pearson could give some guidance on the iron engine issue.

Gents ... Some questions as I'm only familiar with GSs.
I've heard that the later B33s had larger fins on the cylinder. How do I identify the difference in early/late cylinders? Measurements? Engine numbers?

How large can a B31 head intake valve pocket and port be enlarged without striking oil/air?

How much compresh and power will a nicely built iron BSA tolerate on gasoline? I guess it may be possible to convince my bride to follow along behind in the truck with a can of alky when riding with my friends... sheeze.

What drive side main roller bearing that's sized for B33 cases will fit a DBD crank axle?

An alternate plan for me would possibly be to merely build up another Goldie engine as I have most of the pieces, but what's the challenge?
I am nearing the end of 'a nice long ride' so that surely enters into my issue.
Posted By: Andy Higham

Re: Goldstar rep build - 11/09/15 4:02 pm

I don't know what year the B31 changed to "big fin" but my 1955 is big fin.
Roy Shearwood did my head work, he enlarged the inlet port to 32mm, the area by the carb flange is only 38mm on the outside
Phil Pearson makes a special crank for B31 (and possibly small bearing gold star) cases, it is 30mm where it fits the drive side roller bearing and 25mm for the drive side ball race. The timing side shaft is 25mm instead of 7/8" and Phil sleeves the outside of a metric roller bearing to suit the cases
Posted By: chaterlea25

Re: Goldstar rep build - 11/09/15 6:14 pm

Hi All,
Regarding the 90 bore B33?
Recently I fitted a liner to an early small fin B33 cylinder, the liner o/d was 89.75mm and I did not wind up with a pile of washers grin
So I would think that the cylinder would work overbored to 90mm without a liner ??????

What drive side main roller bearing that's sized for B33 cases will fit a DBD crank axle?

Ok here's what I came up with (This was what Phil P suggested as well) as I have a DBD crank and BB32 cases (small roller main bearing)
The B31/33 and early 350 GS's have a 25mm drive side shaft
The drive side case bearing housing to suit this is 62mm
There are roller bearings available,
LLRJ1-1/8C3 Cylindrical Roller Bearing 1-1/8 x 2-1/2 x 5/8 inch
where the outer diamater is 2.5in. = 63.5mm

Phil P suggests fitting two of these bearings side by side.
To accomodate these the bearing housing will need to be bored from 62mm to 63.5mm
The 1.125 part of the mainshaft needs extending to accomodate the second bearing inner race
a sleeve 25mm x 1.125in can shrunk onto the mainshaft to accomplish this
Crank centering and bearing distance spacers will need to be calculated / measured and made to suit

This setup does not use the bearing retaining plate as on the DBD engines

If a needle roller bearing outrigger plate is used as well
the crank now is supported by five bearings !!! cool

Of course I discovered about the 30mm crank mainshaft option
(30 x 62mm bearing) after I had gotten the DBD crank rebuilt frown


Posted By: Goldiebenny

Re: Goldstar rep build - 11/10/15 4:52 pm

Kerry W.....question, where did you take the meat off of the rockers when you lightened them??? And roughly how much is deemed as safe? Don't suppose you know the weight after? I'm going slightly bact to the drawing board for my engine I think, time to get in the garage and finish the rolling chassis
Posted By: Kerry W

Re: Goldstar rep build - 11/11/15 12:20 am

Sorry - a long time ago, and some of the lightening work was done to the rockers we used before I had them, though the area around the pushrod 'cup' was reduced and the end of the arm where it presses on the end of the valve was thinned down. Some meat was taken off the 'barrel' section where the shaft runs though and the the arms were thinned down a little, but I left a lot of meat there - i have heard reports of rocker arms (in other engines) deflecting (sideways) because of too much ,metal being removed from the arms themselves.

Can't help with the weight sorry, though metal taken from the ends of the arms, where they move most (requiring the most effort to accelerate and stop) is worth more than the same weight off the centre area that hardly moves, I believe.
Posted By: Goldiebenny

Re: Goldstar rep build - 11/17/15 4:58 pm][Linked Image][/URL]
Posted By: Goldiebenny

Re: Goldstar rep build - 11/17/15 5:48 pm

[Linked Image]
Posted By: Goldiebenny

Re: Goldstar rep build - 11/17/15 5:51 pm

[Linked Image]
Posted By: Goldiebenny

Re: Goldstar rep build - 11/17/15 5:55 pm

Iv just worked out how to add pictures, here is a couple of pics of the project so far, the tank is a Indian alloy goldie tank, and is absolutely brilliant!!!! Considering Iv been in specialist fabrication and been alloy tig welding for the last 18 years it's superb and only 320 to the door!!
Posted By: Boomer

Re: Goldstar rep build - 11/18/15 1:14 am

Looking really nice. Just needs that big fin alloy engine stuffed in there.

Bill B...
Posted By: kommando

Re: Goldstar rep build - 11/18/15 5:39 am

GB, as most Indian sellers seem to sell junk with a couple of notable exceptions, it would be good to know who supplied your tank, hopefully a new addition to the list.
Posted By: Kerry W

Re: Goldstar rep build - 11/18/15 11:56 am

Nice to hear a positive result. Nothing like a bit of shininess to add a bit of motivation! Keep going!
Posted By: Goldiebenny

Re: Goldstar rep build - 11/18/15 11:56 am

The Tank is the only thing I have bought from overseas as I do not like or trust the cheap [***] they spew out, Autocycle engineering is my main go to for new bit as he knows his stuff and has quality gear.
I will post on here the eBay sellers ID for the tank though.
Definetly need that big fin engine!!!!! ...........dear Santa ......
Posted By: kommando

Re: Goldstar rep build - 11/18/15 1:54 pm

The ebay seller who has not had any negative said on this forum is
pummy.8081 , can't remember who the second one was.
Posted By: resingled

Re: Goldstar rep build - 11/20/15 11:17 am

Goldiebenny, I have a lightened rocker arm that I have taken out of a bb34 engine( not a GS) that you can have if you want. There are pictures on a post by Resingled titled exhaust valve lifter dated around 6th March 15. There is nothing wrong with it but when I aquired the bike the exhaust valve lifter was blanked off and to fit one I needed a standard rocker arm. I suspect it will fit your iron engine.
Regards. Dave.
Posted By: Tim Lynch

Re: Goldstar rep build - 11/20/15 2:56 pm

I went through the modifying B31/33 engine thing several years ago with great results.
My final set up was as follows.
GB31 crankcases, 94mm M20 crank, lightened and balanced to 90.5mm piston giving 605cc in small fin B33 barrel.
Bespoke needle roller big end bearing in long B33 conrod.
M20 crank drive side shaft machined back to give oil seal end feed.
3mm spacer under barrel to accommodate 94mm stroke, also pushrod extenders.
Barrel and crankcase mouth machined to accept a thin centering ring between them.
Big fin B31 head with modified Jaguar valves (bigger than standard but can't remember exact size).
Inlet stub removed and 38mm bore stub inserted, 38mm Mk 2 Concentric carb.
This can't be done with B33 head which also gave pinking problems.
B31 head with squish/decompression plate solved this.
Compression ratio with squish plate about 9.5:1
Various combinations of cams used but ended up with 2442/2446.
Used this engine on the road/track days/sprints for about 6000 miles of hard thrashing and it all held together.
Top end was scary at about 110 mph with great acceleration.
Fantastic fun.

Posted By: chaterlea25

Re: Goldstar rep build - 11/20/15 4:30 pm

Hi Tim,
I have seen your JABSA build pics online, very nice work indeed beerchug

I really like the TLS conversion you did on the standard alloy brake plate,
Did you make any drawings of the parts you made to do the conversion?
I have a couple of these brakes that I would like to modify

Posted By: Goldiebenny

Re: Goldstar rep build - 11/23/15 5:17 pm

Resingled, thanks kindly for the offer but I'm completely rethinking my engine situation at the mo, I'm trying to blag my fathers ZB34 goldie lump as it need running in, so I'll try and use that untill Iv build the big fin, got abit more font this weekend, swingarm, rear guard and forks build on Saturday, should be a rolling chassis by next Sunday
Posted By: Goldiebenny

Re: Goldstar rep build - 11/23/15 5:31 pm
Posted By: Goldiebenny

Re: Goldstar rep build - 11/23/15 5:33 pm

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Posted By: Goldiebenny

Re: Goldstar rep build - 11/23/15 5:35 pm

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Posted By: Kerry W

Re: Goldstar rep build - 11/23/15 11:38 pm

Do yourself a favour and convert an old B31 timing cover to rotary breather'll be a much happier engine..
Posted By: Magnetoman

Re: Goldstar rep build - 11/24/15 10:43 am

Although recent travels kept me from responding until now, I've been enjoying your progress with this bike.

Earlier Kerry wrote:

Originally Posted by Kerry W
If I was to add a bit of 'go' to a B33 I would start with compression and cams. The 2448/2450 options are good (they were early racing cams and became touring cams for the later engines) and are much nicer on the road than the 2442/2446 option, though these also work well.

I have no direct experience with the first set of cams Kerry recommended, but it turns out the guy who built my BB also built a ZB34-based "Gold Star" that a friend recently bought from the widow. I volunteered to rebuild the Magdyno and get it properly wired (it only has a brake light powered by a dry cell) before shipping it to him on the east coast. I've only ridden it a short distance so far, all in town, but the cams in it are quite acceptable.

Anyway, along with the bike was the builder's notebook. Quoting from his notebook, he put 2446/2446 cams in it because it "turns the bike into 3 times the machine." Later in the notebook he writes "love those 2446 cams. Damn do they work good." For what it's worth, he had roughly a dozen BSA singles, half of which were Gold Stars, all of which he built himself and regularly rode so his opinion was based on quite a bit of experience.

However, even before he put those cams in that bike he wrote about being on the Interstate followed by his brother in a car where "she did just under a hundred miles an hour. Talk about vibration." Also "The torque she has, you would think it would snap the chain."

Whether or not the 2446/2446 makes it into anything like "3 times the machine" is something I can't judge, and which others might comment on (Kerry?, Boomer?, DaveNV?, others?), but it's clear from the performance of this ZB34 that you should have no trouble getting more than enough speed out of your bike when it's done to risk serious jail time for speeding. Keep up the good work.
Posted By: Kerry W

Re: Goldstar rep build - 11/24/15 1:06 pm

Indeed, I'm keen to see how this progresses too - something different is always entertaining!

I found the 2442/2446 cams, in my hot B33, to always 'hunt' after more throttle and be not so 'stable' in part throttle operation than the 2448/2450 (or equivalent earlier versions), which we ran a old in our DB32. The 350 went well enough, sounded the part but had AMAZING fuel economy, even with both my parents aboard - 87 mpg (highway)/ 65-ish / miles per US gallon on a big Monobloc.

The 2442/2446 cams really did make the B33 fly though - pulled hard to 7000 on an open megaphone, with a 32mm MkI Concentric.

As an aside, the 2446/2446 big-fin scrambler setup is also a pokey street combination, with a surprising step up onto the power - I road-raced a friend's scrambler, on a straight pipe and small-port DBD head, 21" front wheel, scrambles bars and pegs and all - great fun!
Posted By: Boomer

Re: Goldstar rep build - 11/24/15 2:01 pm

As Kerry said the I relate the 2446/2446 set up as the "scrsmbler cams" and as such have a tremendous amount of torque through the mid range. I've really only experienced the 2442/2446 in my road racer with Gp carb and open megaphone. In that case once the revs hit about 4500 rpm it was like a rocket ship, as they say, coming onto the pipe. Would rev right up past 7K in a hurry and would want to keep right on going. Better have that Carillo rod in there if you let it run up to 8K.

I've been running the 2438/2436 combo in my BB GS because that's what the books called for and I only had half of the 2448/2450 combo available. These cams seem to be not as peaky as the 2442/2446, not quite as torquee as the 2446/2446 but powerful and smooth through the range. But then it is a long rod BB with big flywheels and not the short rod, quicker revving big fin.

Bill B...
Posted By: Rich B

Re: Goldstar rep build - 11/24/15 7:58 pm

I put 2446/2446 cams in my 56 DB with a DBD head, Amal 1038 equipped GS. I have posted a few pics on this board of the bike.

Got to say, I am very satisfied with the cam choice. Gives the engine an incredibly flexible power band. It does have a definite bump in power around 3500 RPM, but it isn't an obnoxious bump. More like, it pulls below 3500, but it REALLY pulls above 3500. But it is surprisingly linear power delivery.

Other people have ridden it and compared the linear power band to a modern bike. Never thought of the GS that way, but compared to my A65's, yea, the power band is more like my modern Brit appliance than the twins.

Maybe that is why the GS has become my favorite vintage ride.
Posted By: Magnetoman

Re: Goldstar rep build - 11/25/15 12:47 am

Originally Posted by Rich B
I put 2446/2446 cams in my 56 DB with a DBD head,...
I wanted to check to be sure before posting it but now that I have I'm pretty sure the 2446/2446 combination is what is in my Special Competition Model as well. My shop notes say 65-2446 is stamped on the inlet cam. The middle two digits of the exhaust cam were too lightly stamped for me to make out so are recorded in my notes as 65-2??6. However, although I don't know right now where I got the information, my notes say this model should have a 2442 inlet.
Posted By: Boomer

Re: Goldstar rep build - 11/25/15 1:07 am

I would think that since the Competition had a GP carb and head and the 1 7/8" pipe and megaphone a 2442 inlet would fill that prescription.

Bill B...
Posted By: Goldiebenny

Re: Goldstar rep build - 01/05/16 4:16 pm

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