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Re: Building Gold Stars using Simulation Software [Re: Magnetoman] #778162 07/08/19 7:32 pm
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Originally Posted by Gordo in Comox
could the machining at the factory around the valve area have produced different heads for different uses?
Harking back to an earlier conversation, they produced the BB scramblers in parallel with the CB Clubmans during the period of that short-lived model. But, the dyno sheets show that scrambles and touring CBs were made as well, so they must have given in to demand for the latest models for those purposes. However, the dyno sheets reveal that the same valves were used for Clubmans, Scrambles, and Touring CBs (65-1844 and 65-1845) so it appears they slapped the same head on all the models and, other than the cams, didn't try to optimize them for any purpose other than Clubman racing.

Looking again at the dyno sheets, there is nothing about the valves for the ZB, BB or DBD, but for all versions of the CB they're 65-1844 IN and 65-1845 EX, and for the DB Clubmans & Scrambles they're both 65-2511 IN and 65-2512 EX.

Originally Posted by Motolab
Each inlet track “in the day” was different... man shaped end THE “part” wich did and does make the biggest difference regarding power output on these engines,
Yes, but the hand shaping didn't affect the diameter by much, only the Flow Efficiency. When I say 'only' I don't mean to minimize the importance; it didn't require moving much metal around to have a significant effect on the h.p.

Originally Posted by Motolab
Flow testing a rather standard and original head from each type , Will make sence to get a “standard” to work with,
I very much would like to flow test a DBD head. It's just that I don't want the information badly enough to be willing to disassemble my 'Competition' to make the measurements. However, if someone has a DBD (and/or ZB, BB, CB, or DB) head gathering dust, that they know has an unmolested inlet tract, and they're willing to part with it for a few weeks, by all means let me know.

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Re: Building Gold Stars using Simulation Software [Re: Magnetoman] #778166 07/08/19 7:58 pm
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Originally Posted by Magnetoman


Originally Posted by Motolab
Each inlet track “in the day” was different... man shaped THE “part” wich did and does make the biggest difference regarding power output on these engines,
Yes, but the hand shaping didn't affect the diameter by much, only the Flow Efficiency. When I say 'only' I don't mean to minimize the importance; it didn't require moving much metal around to have a significant effect on the h.p.


We do both mean the same..... it is the form of the inlet wich makes the big difference, more than increasing the diameter.


Harold
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Re: Building Gold Stars using Simulation Software [Re: Magnetoman] #778167 07/08/19 8:22 pm
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Sorry I came very late to this discussion.

You seem to have gone a long way already but can I suggest you have a look at this engine simulation software. It is called EngMod4T. The programmer is an engineer in South Africa. The programme is based on and matures the G Blair simulation software that used to be marketed by SAE.

https://vannik.co.za/EngMod4T.htm


The fully professional version costs many $10,000.

https://www.optimum-power.com/Virtual%204-Stroke.htm


About 12 years ago I spent considerable time modeling and developing my Norton 500 Dominator bike for classic racing in New Zealand. I would iterate between the computer model and the dyno. At that ime I was using the old SAE version of the software and following the Blair text four stroke simulation.

Results were mixed.

I found very good curve shape prediction between the computer at dyno for modelling inlet tract changes. Especially lenght changes and peaks and troughs matched almost exactly computer to dyno.

I found very good shape and absolute value prediction results for a friends single cylinder Jawa speedway type engine.

On the other hand the computer did not model at all well the lower part of the rpm curve for the 500 twin. Megaphonitis was never predicted by the computer.i assume this was because it always assumed the carb would operate perfectly.

So I would say I used the software more to teach me about engine dynamics and pressure wave behaviour than using it for design - build - result type outcomes. Except for inlet tract modeling where the bike had clearly read the same book as the computer. :-)

For anyone interesting in seeing how these programmes work Lotus actually have free single cylinder basic simulation software on their website.

http://www.lesoft.co/

Re: Building Gold Stars using Simulation Software [Re: Magnetoman] #778173 07/08/19 9:26 pm
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Originally Posted by johnm
You seem to have gone a long way already
Yes, it's too late to turn back now...

Originally Posted by johnm
I found very good curve shape prediction between the computer at dyno for modelling inlet tract changes.

I found very good shape and absolute value prediction results for a friends single cylinder Jawa speedway type engine.

On the other hand the computer did not model at all well the lower part of the rpm curve for the 500 twin.
My findings so far mirror yours. Although BSA dyno curves don't go below 4000 rpm for ZBs, and 5000 by the time we get to DBDs, so I have nothing to compare the simulations to for rpms lower than these.

Originally Posted by johnm
So I would say I used the software more to teach me about engine dynamics and pressure wave behaviour than using it for design - build - result type outcomes. Except for inlet tract modeling where the bike had clearly read the same book as the computer.
Well, since all the power is only what passes through the inlet tract, that's not so bad.

The program has taught me a lot about what matters and what doesn't. Once I got close with the DBD simulation I went through the inputs and changed them one at a time to see what effect each one has. For example, changing the exhaust port efficiency from 60% ("racing heads") to 70% ("excellent racing heads") has a barely perceptible effect on h.p. over the full range of the simulation from 3000 to 7000 rpm. So, if I were building a bike to race that tells me where not to spend any of my time. Intake runner length has a big effect in the midrange, which tells me I would want to explore longer intakes if building a scrambler.

I'm pretty sure all of this will pay off when "designing" a Gold Star for some particular purpose, e.g. spirited trail riding. Once the parameters are determined for a stock configuration, then "what-if" scenarios can be explored a lot easier than if having to actually swap parts and measure outcomes. The results based on the simulations only will be approximations, and one likely could do better given a large budget of money and time, but it appears to me that the simulations will take one close enough to the "optimum" that it would make most people happy. Unless they were racing and need to squeeze every last ounce of h.p. from the engine.

As an aside, you said you did your work 12 years ago. I wonder if any significant progress was made with simulation software in the meantime, or if the modeling available today is only incrementally better than it was back then.

Re: Building Gold Stars using Simulation Software [Re: Magnetoman] #778179 07/08/19 10:30 pm
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Oh by the way MM, I think that I can speak for all the GS enthusiasts out there when I say how much we appreciate the work that you are doing. I have my cam collection lined up awaiting for the results of your work.

Gordo


The roadside repairs make for the best post ride stories.
Re: Building Gold Stars using Simulation Software [Re: Magnetoman] #778197 07/09/19 4:55 am
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Gordo,

Thanks very much for that sentiment.

Re: Building Gold Stars using Simulation Software [Re: Magnetoman] #778245 07/10/19 2:01 am
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I played hooky for a while today from what I should have been doing for long enough to fabricate a jig for testing the flow of various pipe and silencer (or not) combinations. I made it on a plate that I can either mount directly on the top of the flow bench, or at 90-degrees on the large plenum I use for testing carburetors. I only have the header pipe attached in the second photo but when the silencer is attached I may have to add a secondary support. That may determine that one orientation of the jig is better than the other.

I have two header pipes not currently attached to bikes (Clubman and aftermarket full-length Catalina) and five "silencers" (OEM twitter, short 'Competition'-type megaphone, aftermarket Burgess-type, aftermarket shorty, and 'none') so the flow of whatever I'm missing from these lists probably will be able to be estimated fairly well from the measurements of what I do have.

Attached Files SuperFlow_ExhaustJig_01.jpgSuperFlow_ExhaustJig_02.jpg
Re: Building Gold Stars using Simulation Software [Re: Magnetoman] #778248 07/10/19 2:38 am
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Quote "The program has taught me a lot about what matters and what doesn't. Once I got close with the DBD simulation I went through the inputs and changed them one at a time to see what effect each one has. For example, changing the exhaust port efficiency from 60% ("racing heads") to 70% ("excellent racing heads") has a barely perceptible effect on h.p. over the full range of the simulation from 3000 to 7000 rpm. So, if I were building a bike to race that tells me where not to spend any of my time. Intake runner length has a big effect in the midrange, which tells me I would want to explore longer intakes if building a scrambler.

I'm pretty sure all of this will pay off when "designing" a Gold Star for some particular purpose, e.g. spirited trail riding. Once the parameters are determined for a stock configuration, then "what-if" scenarios can be explored a lot easier than if having to actually swap parts and measure outcomes. The results based on the simulations only will be approximations, and one likely could do better given a large budget of money and time, but it appears to me that the simulations will take one close enough to the "optimum" that it would make most people happy. Unless they were racing and need to squeeze every last ounce of h.p. from the engine.

As an aside, you said you did your work 12 years ago. I wonder if any significant progress was made with simulation software in the meantime, or if the modeling available today is only incrementally better than it was back then.
[/quote]


That's what I was hoping to judge from your work actually. :-)

Intake runner length has a big effect in the midrange, which tells me I would want to explore longer intakes if building a scrambler.

Agree. That's what the computer told me and what happened in practice. In the specific case of Clubmans rules racing in NZ with mandated 4 speed gearboxes and tight circuits good midrange was exactly what won races.

Last edited by johnm; 07/10/19 2:40 am.
Re: Building Gold Stars using Simulation Software [Re: Magnetoman] #778294 07/10/19 8:30 pm
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Originally Posted by johnm
That's what I was hoping to judge from your work actually.
I haven't actively looked for it, but neither have I stumbled across it, but I don't know what the code is based on. Twenty years ago the cheap 'Desktype Dyno' program that came for free with a paperback book did a pretty good job.

To digress, many years ago at lunch one of my colleagues mentioned that custom golf clubs were a waste of money. I've never played golf but was interested in his comment. He pointed out that basically everyone's arms reach to the same point above ground so standard-length clubs fit everyone. That caused me to check this out and, it turns out, he was right. A tall person's shoulders are high above the ground, but their arms are long, so they reach down to a certain point. Similarly, short person, short arms, so they also reach to approximately the same point as the tall person's arms. The result is you could win a bet if you said you could predict how high above the ground the hands would be of the next person to walk into the room.

Back to engine simulations. Not knowing what's behind the code, I wonder if a similar principle to golf clubs is involved. That is, are all internal combustion engines basically the same so all you have to do is input a few simple factors (bore, stroke, valve configuration,...) in order for the program to use a look-up table to get an answer that is pretty close, after which it just tweaks that basic figure? Hmm....

Back to flow measurements. Take a look at the first photograph. Which pipe flows more air, the shorter 'Clubman' or the longer 'Catalina'? Well, you're wrong. The longer pipe actually flows 3.2% more air than the shorter one (I checked each pipe twice to be sure). Air typically doesn't behave the way you might think, and there's nothing like a flow bench to determine that the extra resistance due to the longer Catalina pipe is more than made up for by the sharper bends of the Clubman.

The simulation program uses exhaust flow rates measured at a pressure difference of 20.4" H20 so I've converted all my measurements to that value using conversion factors in the SuperFlow manual. In addition to the pipes I tested my OEM 'Twitter' silencer and two new aftermarket Burgess-type silencers whose internals are quite different. The results are:

Catalina pipe 201.6 CFM
Clubman header 195.4 CFM
Clubman + Twitter 165.4 CFM

Burgess-type #1 90.9 CFM
Burgess-type #2 184.4 CFM
OEM Twitter 186.5 CFM

These measurements are quite useful for the simulations since I now know the exhaust system is less restrictive than I had thought, which makes a significant difference in the calculations. The Twitter and #2 Burgess-type both allow the exhaust to pass straight through and only silence wayward sound waves that get lost and wander outside that straight path. The lower CFM of the Clubman + Twitter than the Catalina is largely due to the overall length being 11" longer and only somewhat due to the alleged silencing properties of the Twitter.

Attached Files SuperFlow_ExhaustJig_03.jpgSuperFlow_ExhaustJig_04.jpg
Re: Building Gold Stars using Simulation Software [Re: Magnetoman] #778315 07/11/19 12:17 am
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[quote

To digress, many years ago at lunch one of my colleagues mentioned that custom golf clubs were a waste of money. I've never played golf but was interested in his comment. He pointed out that basically everyone's arms reach to the same point above ground so standard-length clubs fit everyone. That caused me to check this out and, it turns out, he was right. A tall person's shoulders are high above the ground, but their arms are long, so they reach down to a certain point. Similarly, short person, short arms, so they also reach to approximately the same point as the tall person's arms. The result is you could win a bet if you said you could predict how high above the ground the hands would be of the next person to walk into the room.

Back to engine simulations. Not knowing what's behind the code, I wonder if a similar principle to golf clubs is involved. That is, are all internal combustion engines basically the same so all you have to do is input a few simple factors (bore, stroke, valve configuration,...) in order for the program to use a look-up table to get an answer that is pretty close, after which it just tweaks that basic figure? Hmm....

Hi

I understand your are a university physics professor and are therefore in a much better place than most of us to understand the maths.

Professor Gordon Blair of QUB was one of the pioneers of engine simulation.

https://daro.qub.ac.uk/pages/2016-rebrand/news/obits---all/obits-professor-gordon-blair

https://www.amazon.com/Design-Simulation-Stroke-Engines-R-186/dp/0768004403

Constrained by my rather dismal math ability (my MSc is in geology) I understand he did develop his programmes from fundamental physics and engineering calculation supported by experiments in the QUB labs. However Blair died a few years back so things should have moved on from there. I did look at some of the US programmes available years ago and they did seem to sit more in the look up table camp - and the lookup tables were built from dyno results on American V8 engines.

However despite what Blair said, I was always a little suspicious that my best matches always occurred with engines similar to the Matchless G50 engine that he uses for an example in the chapter on empirical engine simulation. ie for all the maths he still used experiments with the G50 to build his fudge factors ;-) The exhaust discussion on long pipes in that chapter did seem to have been read by my Norton as well !!.

A University Professor of engineering who designed racing motorcycle engines and pit crewed for his students at the Isle of Man should always be listened to very carefully !!



Last edited by johnm; 07/11/19 12:30 am.
Re: Building Gold Stars using Simulation Software [Re: Magnetoman] #778364 07/11/19 1:48 pm
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Gordon Blair was a very genial man and quiet man who really loved racing, especially in Ireland. His first success on a bike called the QUB, which was a four stroke. I can't remember what it was based on, perhaps the G50. He then had huge success by designing expansion chambers on the ubiquitous Yamaha two-strokes of the day, the 250cc and 350cc. These flow-tested engines were really fast, ridden by Queens student, Ray McCullough, and were the basis for what became a long-lasting relationship with Yamaha, and Blair's work being hailed all over the world.

Several years later, MMan and I had the pleasure of knowing Nobby Clark, who worked on some of those Yamaha teams, and shared some of his technical insights regarding flowing the two-strokes, this time by raising the ports.

Fun stuff.


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Re: Building Gold Stars using Simulation Software [Re: Magnetoman] #778370 07/11/19 3:05 pm
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Originally Posted by johnm
Professor Gordon Blair of QUB was one of the pioneers of engine simulation.
Indeed he was. Most of his work was on 2-strokes but he did a lot of work on 4-strokes as well. And he wasn't just a pioneer in the sense of having done important work long ago. He continued until his death at a youthful 73 less than ten years ago.

Originally Posted by johnm
I did look at some of the US programmes available years ago and they did seem to sit more in the look up table camp - and the lookup tables were built from dyno results on American V8 engines.
No matter how sophisticated the underlying models might be, the capabilities of most PC-based programs have to be hobbled to work with the PCs available at the time they are released. Since the computing power has increased by at least 100x in the past decade, a state-of-the-art program written in 2009 would be significantly less powerful than one written today. However, that's a general statement. A given program may not have been all that advanced when it was released, and may not have been updated much or at all since then. Or, a program may have been able to take full advantage of the models that existed at the time and new modeling might not have added much since then.

Anyway, the manual for the Engine Analyzer Plus program I'm using has a 2010 copyright date. However, I don't know if there's a newer and more powerful program for a similar price. In any case, the program seems to have inputs for all the relevant factors that should go into a proper model and it is producing quite credible results that are only limited by estimates I have to make in the absence of certain specific data. However, that took a step forward yesterday with the flow data on exhaust systems, and shortly will take a leap forward when I make flow measurements on the Catalina head NYBSAGUY is about to send.

Originally Posted by johnm
A University Professor ... should always be listened to very carefully !!
I couldn't agree more...

Re: Building Gold Stars using Simulation Software [Re: Magnetoman] #778411 07/11/19 9:02 pm
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I've been keeping quiet, but by invoking the name of Gordon Blair you may have entered a rabbit hole from which you can never return.
Steady state gas flow is important, but as Walter Kaaden and Gordon Blair found, the pressure wave characteristics of the pipe have a significant effect on the engine's power peak and torque spread. They also found that once you're hooked, it's impossible to shake the addiction...

Re: Building Gold Stars using Simulation Software [Re: Magnetoman] #778482 07/12/19 4:43 pm
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I was thinking the exact same things the last few days, regarding the pressure wave effect. This effect is very significant on 4 stroke’s indeed...and within limits far more important than “more” flow. Phil irving did explain the effect and how you can use it (and what happens when wrong) in his master piece for the (home) tuner ,” tuning for speed” published in the ‘40’s, this book contains also some goldstar specific info on other subjects..

Last edited by Motolab; 07/12/19 10:15 pm. Reason: Damn iPad “corrector” changes unwanted my text... grrr

Harold
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Re: Building Gold Stars using Simulation Software [Re: Magnetoman] #778487 07/12/19 6:14 pm
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Originally Posted by Shane in Oz
, but as Walter Kaaden and Gordon Blair found, ...
Originally Posted by Motolab
Phil irving did explain the effect and how you can use it
OK, you guys, Irving's book was published 70 years ago(!), Kaaden's groundbreaking work on expansion chambers was done over 60 years ago, and Blair's further development of exhausts had pretty much ended as of 40 years ago. It seems like a reasonable assumption that simulation programs that have been around a long time, and periodically updated, have incorporated what's right with early work, weeded out what's wrong, and included developments of the most recent four decades.

Re: Building Gold Stars using Simulation Software [Re: Magnetoman] #778498 07/12/19 9:14 pm
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Originally Posted by Magnetoman
OK, you guys, Irving's book was published 70 years ago(!), Kaaden's groundbreaking work on expansion chambers was done over 60 years ago, and Blair's further development of exhausts had pretty much ended as of 40 years ago. It seems like a reasonable assumption that simulation programs that have been around a long time, and periodically updated, have incorporated what's right with early work, weeded out what's wrong, and included developments of the most recent four decades.
That will be the add-on exhaust tuning package.
What parameters are available in the simulation package(s) for exhaust systems?

Re: Building Gold Stars using Simulation Software [Re: Magnetoman] #778505 07/12/19 10:30 pm
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Originally Posted by Magnetoman
It seems like a reasonable assumption that simulation programs that have been around a long time, and periodically updated, have incorporated what's right with early work, weeded out what's wrong, and included developments of the most recent four decades.

I hope so, and is seems a reasonable assumption, ;-)
are 2 or 4 valves a variables in this program? What we see here on de dyno, for instance, that with the same engine layout, in stroke and engine displacement but with different head/valve layout (2 valve or 4 valve) an engine asks for different flow rates of the exhaust, (4 valve engines/heads are needing more flow) but ofcourse the engine/exhaust system needs the same pressure wave characteristics... to get a “flat” as possible torq curve.. (within the limits of what is possible with these variables and exhaust systems)

Last edited by Motolab; 07/12/19 10:34 pm.

Harold
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Re: Building Gold Stars using Simulation Software [Re: Magnetoman] #778513 07/13/19 12:26 am
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Originally Posted by Shane in Oz
]That will be the add-on exhaust tuning package.
Spoken like someone who understands commercial software... The company I bought from has four levels of packages, priced at $129, $199 (the version I bought), $499 and $749. Needless to say, the more expensive packages have a lot more inputs (although most of the additional capabilities of the most expensive one seem to be aimed at turbochargers and fuel injection).

Originally Posted by Shane in Oz
What parameters are available in the simulation package(s) for exhaust systems?
There are two headers that seem applicable to a single-cylinder engine: individual tubes that connect at a collector, or individual tubes. For a single-cylinder engine both should give the same results if the collector has the same dia. as the pipe and the overall lengths are the same. Beyond that choice, inputs are dia., pipe length, collector length (if any), and flow efficiency. If there is a silencer, another input is its CFM. In most cases (e.g. silencer CFM) the program suggests values to use if you don't have the measurements.

Originally Posted by Motolab
are 2 or 4 valves a variables in this program? ...
Yes, for the head there are ten chamber types (hemi, wedge, sidevalve, ...), and intake layouts of 1 valve or 2 valves, with the latter having combined or separate ports. Valve dia., average port dia., port length and flow efficiency are the other inputs for the inlet.

But, keep in mind I didn't buy this program to try to build an engine to win the IoM or set a land speed record. I bought it to try to accurately model the output of Gold Star engines as they left the factory 60 or so years ago in order to then run 'what-if' simulations with different cams, carburetors, etc. For this, the biggest limitation I can see thus far is the inability to enter something like the behavior of the Clubman's semi-reverse-cone megaphone. The program handles the effect of the length of a pipe, but the additional strength of the pulses due to the megaphone is an uncertainty. However, the Scrambles data with straight pipes allows me to gain confidence in the simulations.

I expect when the Catalina head arrives from NYBSAGUY the flow bench data from it will significantly reduce remaining uncertainties, even for the Clubman. Rather than me having to guess at the inlet "Flow Efficiency" based on descriptions like "Racing Head," "Good Racing Head," etc. the program lets me enter flow measurements at a minimum of four, and max. of eight, valve lifts from which it calculates the Flow Efficiency. This parameter has a large effect on both the slope and max. h.p. so I'm very much looking forward to having the data to enter since it then will reduce the remaining uncertainty in cam/lifter parameters. At that point, whatever parameters I have to enter to fit the dyno data shouldn't have much uncertainty in them.



Re: Building Gold Stars using Simulation Software [Re: Magnetoman] #778516 07/13/19 12:53 am
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MM: I have been going through your old thread on 'part numbers for heads' and I am a bit confused about the Catalina. For clarification were there both DB and DBD Catalina engines? The thread implies there were both types. How are the Catalina engines stamped?

Gordo


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Re: Building Gold Stars using Simulation Software [Re: Gordo in Comox] #778517 07/13/19 1:15 am
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Magnetoman Online Content OP
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Gordo,

Yes, there were both DB and DBD Catalinas. An undated (but obviously 1957) supplement from BSA East Coast lists two heads for 1955-56 DB Models: 65-2467 for the 'Cylinder head' and 65-2467 for the 'Cylinder head (Catalina Scrambler)'. The next page of the same supplement for 1956-57 DBD Models only shows one head: 65-640. I don't remember now where I got the information (or misinformation), but I recall that Catalinas continued with DB heads for some time even though they where stamped 'DBD'.(*) Catalina engines had the extra code 'S' under the engine number. A possible source of confusion is that if an engine is stamped with a 'C' it's a Competition, not a Catalina.

(*)I've now found despatch information that confirms all DBD34 Catalinas were in Catalina CB32C frames (first of which was despatched 12 November 1958), whereas DB34 Catalinas were in CB32 frames . However, this doesn't address whether or not early DBD Catalinas might have had DB heads despite the DBD stamped on the engine.

Last edited by Magnetoman; 07/13/19 1:24 am. Reason: (*)
Re: Building Gold Stars using Simulation Software [Re: Magnetoman] #778523 07/13/19 2:47 am
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Gordo in Comox Offline
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For sure specifics are hard to come by some 60 plus years after the fact. The BMS book chart shows the first Catalina in 1959 (model year?) as a DBD in a CB32C frame. Of course what would the UK researcher know about a US model?

Thanks

Gordo


The roadside repairs make for the best post ride stories.
Re: Building Gold Stars using Simulation Software [Re: Gordo in Comox] #778525 07/13/19 3:44 am
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Originally Posted by Gordo in Comox
The BMS book chart shows the first Catalina in 1959 (model year?) as a DBD in a CB32C frame.
The 1956 East Coast sales catalog has a Catalina in it, three years before BMS was aware. Not for the only time was a British author oblivious of export-only models like the Catalina or Spitfire.

Attached Files Catalina1956_East.jpg
Re: Building Gold Stars using Simulation Software [Re: Magnetoman] #778530 07/13/19 5:26 am
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Gordo in Comox Offline
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I should have looked at my copy of 'The Gold Star Buyer's Companion' before I commented. It seems to have better info.

Gordo


The roadside repairs make for the best post ride stories.
Re: Building Gold Stars using Simulation Software [Re: Gordo in Comox] #778554 07/13/19 3:11 pm
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Originally Posted by Gordo in Comox
'The Gold Star Buyer's Companion' ... seems to have better info.
I'd say that much more so than any other motorcycle book, information was carefully vetted before it went into the 'Buyer's Companion'. Even if certain information is "common knowledge," but if it couldn't be verified, it's not in the book. It's always possible mistakes or errors have still managed to slip through, but they should be rare exceptions.

Re: Building Gold Stars using Simulation Software [Re: Magnetoman] #778557 07/13/19 3:28 pm
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MM: I think the real issue is what left the factory and what was actually sold in the US dealerships. Did the dealers make standard Scramblers into Catalinas by sticking on a decal and using the name in the adverts even before the factory recognized the unique model? The BMS type list could be what the factory thought they were shipping to the Colonies.

I will search through the Goldie magazines to see what Ian has published about the Catalina and the CB32C frames according to his records. It could be the factory catching up to reality.

Gordo


The roadside repairs make for the best post ride stories.
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