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Which Gold Star Piston/Cams Combination? #22732
03/23/07 12:58 pm
03/23/07 12:58 pm
Joined: Aug 2006
Posts: 56
Colorado
rockitdoc Offline OP
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rockitdoc  Offline OP
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Joined: Aug 2006
Posts: 56
Colorado
Putting my GS back together and wondering about which piston/cams to put in. I'm at 6000 MSL outside Denver. I've been told 10.5:1 with Clubmans cams is a good combination. What do you think?


1960 DBD34
1974 Commando
1976 R90S
1985 RGS1000SFC
2012 ST1300
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Re: Which Gold Star Piston/Cams Combination? #22733
03/23/07 5:36 pm
03/23/07 5:36 pm
Joined: Aug 2001
Posts: 1,880
Elko, Nevada USA
dave - NV Offline
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dave - NV  Offline
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Posts: 1,880
Elko, Nevada USA
Rockit ... It's good to hear there will soon be another Goldie up and running!
I would suggest not using over 9 1/2:1 compresh pistons in your GS using today's gasoline. I agree that at your elevation which is much the same as mine here at home, det is much less a problem than at sea level. But .. 10 1/2 will surely be a problem especially when you ride the bike at lower altitude.

The OEM Clubman 42 and 46 cams work great on the road. That's the combo I and several friends use. But of course you can also fiddle around with other cams such as supplied by Kieth Johnson of Johnson Cams.

BTW, Harry's Motors on Santa Fe Blvd. used to be the BSA, Norton and Ducati dealer during The Era when I lived in Denver. This was my 'Shop', long ago and far away.

And speaking of riding Goldies ... Gee next week I'll be in among my NoCA GSr friends over the San Jose Clubman Show long weekend. You can bet we'll have some nice riding in the coastal mountain Twisties. There will be near endless chatter about Goldies while staying at GStarRon's for a couple days. With a supply of Boddington and Guiness in the fridge and ...
Ron will fill us in on the Daytona races and pal Peter Huber from Germany will have some racing stories about campaigning his Goldies on the Continent and ...
Fun Stuff to be sure. I like that.

bombomBAARROOM ... oh, sorry about the 'Music'.


dave - NV
Re: Which Gold Star Piston/Cams Combination? #22734
03/23/07 11:30 pm
03/23/07 11:30 pm
Joined: Mar 2005
Posts: 731
Asheville, North Carolina
C
ca7a Offline
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ca7a  Offline
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C
Joined: Mar 2005
Posts: 731
Asheville, North Carolina
I concur with Dave's recommendation. I'm running 8:1 w/ the same cams and 39 degrees advance on 93 octane in my '60 Goldie at
2200' altitude here. Fine, stress-free performance.
What's this Clubman Show all about, Dave? Is it time to resurrect the Club?

Re: Which Gold Star Piston/Cams Combination? #22735
03/24/07 8:05 pm
03/24/07 8:05 pm
Joined: Aug 2006
Posts: 56
Colorado
rockitdoc Offline OP
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rockitdoc  Offline OP
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Posts: 56
Colorado
Sorry to have to tell you this, but Harry's is gone. Sold. They helped me out with a V7 Sport I restored a couple years ago, then went belly up. Hope it wasn't my Sport. Turned out really nice, though.
Anyway, where is the best source for a 9 or 9.5:1 ish piston and ring set? Also, is forged the ticket or will a cast piston work? No racing in the future.
Thanks,
Scott


1960 DBD34
1974 Commando
1976 R90S
1985 RGS1000SFC
2012 ST1300
Re: Which Gold Star Piston/Cams Combination? #22736
03/24/07 9:33 pm
03/24/07 9:33 pm
Joined: Aug 2001
Posts: 1,880
Elko, Nevada USA
dave - NV Offline
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dave - NV  Offline
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Posts: 1,880
Elko, Nevada USA
Rockit ... Sad to hear 'Harry's' is no longer in business. I assume they were still selling Ducatis? hmmm. But it was prolly about time for 'young' Jim Tagaris to retire.

Anyhow ... I've gotten pistons for our Goldies from our pal Ron Halem aka GStarRon for some time. I also use 'Total Seal' rings but I'm sure the rings supplied by Venolia would be just fine.
Ron has modern forged Venolia pistons custom made to his specs. Again I suggest 9 or at the max 9 1/2 compresh. I have a 9:1 Venolia in my much modified kinda fast road GS and it works fine at sea level too. I have a dual plug ignition which prolly helps with the det a bit, but I wouldn't hesitate to reco 9:1 compression.

Ron's Email: GStarRon@aol.com

The GSR web page: http://members.aol.com/gstarron/Racer.htm

ca7a ... Check the 'Events' forum here on bb.com for more info on the San Jose Clubman Show and Swap I mentioned.
The Gold Star Owners Club in the UK is still going fine but sadly not much GS Club action here in the US. Our BSAOCNC has several of us Goldie enthusiasts who ride our bikes. Natch there are many more GSs that sadly just 'sit' (pose?) and of course there are more in baskets and boxes...


dave - NV
Re: Which Gold Star Piston/Cams Combination? #22737
03/24/07 10:54 pm
03/24/07 10:54 pm
Joined: Mar 2005
Posts: 731
Asheville, North Carolina
C
ca7a Offline
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ca7a  Offline
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C
Joined: Mar 2005
Posts: 731
Asheville, North Carolina
Thanks, dave. Appears we Goldie owners are not too clubby. Pity.

Re: Which Gold Star Piston/Cams Combination? #22738
03/25/07 2:12 am
03/25/07 2:12 am
Joined: Aug 2001
Posts: 1,880
Elko, Nevada USA
dave - NV Offline
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dave - NV  Offline
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Posts: 1,880
Elko, Nevada USA
ca7a .. "Not too clubby"??
It's by far different then that you may think, more like a cult group seems to me. With the magic of the Net many of us are endlessly jabbering 'GS this and GS that' with each other, trading stuff, etc. Kinda fun, I like that.

I was a member of the UK based Gold Star Club for a few years, but have drifted away it seems. I really must join up again. I certainly enjoyed meeting up with many of them in 2000 when we were on the IOM for the Manx GP and we US GSrs attended their 25th Club anniversary banquet, riding with all those guys on Goldies and the hoorah. It's interesting how a single model of motor bike can have such a world wide enthusiastic following.

You North Carolina GSrs should 'connect up' but perhaps you already have. I've met a couple of you and I'm sure there's more out and about.
dave - NV
One of the Gold Star Guys


dave - NV
Re: Which Gold Star Piston/Cams Combination? #22739
03/27/07 5:25 pm
03/27/07 5:25 pm
Joined: Aug 2006
Posts: 56
Colorado
rockitdoc Offline OP
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rockitdoc  Offline OP
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Joined: Aug 2006
Posts: 56
Colorado
I ordered an 8.75:1 piston from Ron. Thinking of getting the Pearson crank, but since I am not going to race the Goldie or even ride it that much (I know, I know...) on the street, I am reluctant to wait the 4-6 mos to get one, let alone the $1300. Magnaflux did not turn up any cracks in the crank or rod, so I dunno. What's your opinion(s)?


1960 DBD34
1974 Commando
1976 R90S
1985 RGS1000SFC
2012 ST1300
Re: Which Gold Star Piston/Cams Combination? #22740
03/27/07 6:01 pm
03/27/07 6:01 pm
Joined: Sep 2001
Posts: 2,796
Comox BC Canada
G
Gordo in Comox Offline
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Gordo in Comox  Offline
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Joined: Sep 2001
Posts: 2,796
Comox BC Canada
After seeing my ABSAF crank for my ZB34GS and comparing it to the original rivetted bits I am now a firm believer in up-dating to modern standards for any machine that will actually be ridden. Even the cranks in my B44 engines look a lot better than the early GS cranks.

Gordo


Without frequent roadside repairs there is no fun in riding!
Re: Which Gold Star Piston/Cams Combination? #22741
03/27/07 9:31 pm
03/27/07 9:31 pm
Joined: Aug 2001
Posts: 1,880
Elko, Nevada USA
dave - NV Offline
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dave - NV  Offline
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Posts: 1,880
Elko, Nevada USA
Rockit ... Gee, I've passed on my 'spiel' regards spending the 'insurance monies' for a modern Gold Star crank so many times, I'm sure many of the guys are tired of hearing it. But ... here's my spiel I posted on Morgan's 'BSA Pitstop' years ago. Perhaps you will find it interesting.

BTW, I only know of a very few guys who ride their Goldies without a modern crank. Most of us don't want to risk and can't afford destroying an engine due to a crank or connecting rod failure. And some of us have 'been there, done that and don't wanna go back'!

A very interesting read on the subject is covered by Roland Pike in his unpublished auto bio "My Years at BSA". Pike was very instrumental in designing the DBD 'big fin' engine and did much developmental work. He tried to convince the BSA management to update the Goldie with many features he and the other engineers Knew needed improvement, but they weren't interested. hmmm
.................................................
Posted by David Kath Nevada on January 15, 2001

Everyone has a story eh? In '97 I broke a crank pin in my DBD road bike. Naturally the break was across the timing side oil feed holes. And as someone has already mentioned in this thread, It was prolly due to the pin loosening in the tapers and allowing excessive flex in the assembly. But has anyone ever taken a set of GS wheels apart
without noticing fret marks in the pin tapers from wheel flex?
What I find a bit interesting is that the near new rod/pin assembly had very low time on it. But in it's "previous life", many years before it
was in my dirt tracker for 5-6 race meets and I'm sure it was abused a bit due to over rev. I dunno.
BTW, I was only turning about 4k revs breaking in
a new piston when it let go. Luckily I was able to shut down quickly and not damage the rest of the motor, ie the timing side main bearing web.
whew..

I luckily found a NOS pin and this time hand lapped the pin tapers into another set of wheels I had. A long mournful project indeed. Of course during the lapping the flywheel cheeks needed to be milled down for proper pin shoulder/pin taper fit into the wheels. To give you an idea of how deep the pin tapers were lapped into the wheels before a perfect fit was reached, the rod needed to be ground - narrowed ~ 15 thou for proper side clearance.

The fact that the shoulder on the crank pin could easily bottom out before the pin tapers seat in the wheels is I'm sure a contributor to some of these pin problems. I'm thinking that other GS builders would agree? It could be easily overlooked seems to me.

But, "The Fix", was when I installed a Pearson crank the next winter. oohh nice, let that baby rev!

Something we can not overlook is the real cause of OEM Gold Star crank failures is that the motor breathes well, revs and makes serious
power, unlike any other production 500 motor of it's era and many much more modern engines. Because of this BSA recommended crank/rod assembly replacement every 50 racing hours.

Actually the rods breaking due to over rev was prolly the most common serious failure. Yup I've BTDT in the dirt with the tacko way over 8k. With wheel spin on slimy wet clay. sheeze.. When the rod broke the piston was jammed into the head with such force it split the head into two pieces and the barrel was badly broken. The cases were amazingly unscathed. huh? Anyhow, junk city top end....

But luckily for us GSrs now, nice rigid dead accurate pressed up chrome molly cranks with Carrillo or GM speedway rods are available from
Phil Pearson. The NEB crank is also used successfully by many. It's also a pressed up unit but they use a different rod of their own and IMHO not nearly as nice as a Pearson unit. I've also seen and heard good reports on the ABSAF cranks from Holland.
dave - NV

a reply from Steve Matz ............................................

In Reply to: A GS crank pin story posted by David Kath

Very Interesting Dave, I know years back when we sent stuff to TOM SIFTON, he would actually knurl the tapers on the Crankpin w/a tool post grinding knurling tool similair in appearance to what you knurled valve guides with. I guarantee you those flywheels will never move. In fact when you put the Rod Assembly back together you wanted it in the Crankshaft Jig w/ Dial indicators to get the runout as close as humanly possibly before you cranked down the Nuts. You then needed a hydraulic
press to twist/turn the flywheels to get your 0 runout.
Goldstars that were run at ASCOT every Friday during Race Season during the mid 60's that had Sifton Bottom Ends could get through a whole season w/o ever touching the Bottom End. My other Racing Pal that use to let Axtell do his Bottom end said that C.R. was basically doing a similair procedure to his Crank Assemblies. Obviously the tapered pin concept has its disadvantages especially in extreme racing applications.Had the Goldstar continued on w/ production threw the end of the 60's and longer, I think the Engineers would have realized that a straight interference fit pressed pin would have been the way to go. When H.D's alloy XR750 came out in 1972,Its Crankpin setup utilized the straight pressed pin design over the previously tapered pin design that H.D. incorporated into the Iron XR and the KR before that and has had basically close to 30 years of as close to a bullet proof bottom end as
your going to find....I really think BSA screwed up by discontinuing the Goldstar in late 63. The 500cc A50 series never even closely attained
the popularity of the big single....

Stete Matz


dave - NV

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