Hi Guys.

I have decided to build an exact replica of Scott Ellis's last works BSA C15 F. I have several photos of the bike with Scott riding it, but only one picture of the bike from a side view, in Don Morley's book.
Has any one out there got any side view shots of the bike, or does any one know where the bike BOK228C is. It is still registered at the DVLA as a BSA 250. ( this is the frame that the copy is now reffered to as an Otter).
Regards Charlie.

Hi Charlie,

Last I heard, my friend, Colin Dommett had BOK228C, the ex-Scott Ellis BSA.

Big John

Hi Guys.
Hi Big "J" thanks for the information, I must have Colin's number somewhere. is this the bike that I
remember Scott riding somewhere I should have took more notice then. Would still Like loads of pictures and any information on the bike that I can get ,to build it as near to it was in 1965-66.

Regards Charlie.

Hi Guys,
I am still looking for any info on Scott's last BSA, ( the so called Otter).

I have found out that the frame was a bit of a bodge, and probably had the front and top frame tubes from an Ariel HT. I think that they may have come from a Bsa Gp scrambles frame. But i'm sure the sub frame and S/Arm was Tiger Cub widened by one inch. I'll leave it to you Guys to put me right.

Regards Charlie.

going to be h**l of a project charlie, sounds like your going to have to cut up half a dozen bikes to make one!!

Hi Guys,
I thought I would update you on progress of the Scott bike,

Have got most of the frame parts ready (In T 45) to bronze weld up. I have bought a Tiger cub frame for the swinging arm and sub frame . which I have widened both by one inch without cutting.
I have also managed to sorce a C15 F type engine, less crank and some other parts , will fit forged crank and Alpha rod and bearings have sorced a new clutch from Trials Bits and have a head and barrel from a B25 of which I am considering changing there shape. PVL Igniton is sat in a box waiting for my head to get round it. Bantam rear hub is also here waiting for me to stretch it by One inch. Still have an open mind on which forks to use. Will keep you posted and post photos as work progreses.

Regards Charlie.

Charlie, please let me have your email address and I will send you photos of my frame/bike.

regards,

Pat Slinn.

Hi Guys.
For some reason I clicked into “classic trials� last week just to see if there was any thing interesting. Only to find a new post by new member “Slinny�,
I started to read the post, and within a couple of lines was amazed at what I was reading. I have this year steadily worked on the Scott Ellis bike when I have managed to find the parts needed on e-Bay, and not been working on other bikes or doing proper work. The frame was finished by last Easter, the back hub widened by one inch and skimmed along with the front Bantam hub, and I even skimmed the oversize brake shoes that I got from Mick Ash.
The swinging arm was sorted with the help of nearly a bottle of gas. And even fitted with the chain guard that I made. Thought hard and long and disided to fit a oil filter while I had the chance as this will be covered by Scott Ellis type plastic(vinyl car roof covering from the right period has I have a roll left over) cover when the bike is finished.
The stumbling block as been the bits for the engine and gear box, the trouble being there was not many of the type “Fâ€� engines made, but have three parts of the bits for both now. I had bought a alloy loaf type BSA tank for the bike, but looking at more pic’s of Scott’s bike proved to myself that I needed a “Victorâ€� type tank for it to be right. I have cheated a bit as I have a pair of Yamaha forks which I have modified the damping and are now ready to dive into a pair of BSA steel sliders. I’m sure someone else has done this mod.
Any way to cut the story short. The name Slinn somehow rang a bell, but I was in a hurry for once, (as I usually don’t do quick), I had got to the gate and the name Pat came into my head, I could remember him taking my seat on the Dan Shorey Ariel outfit for the DK Mansell, I think 1965, Mick Bowers was the pilot, he had borrowed the plot from Dan. I still can’t believe he let him borrow it. Anyway typed in the name in Google and it took me straight back to “Trials Centralâ€�. I contacted Pat and he has sent me pictures of his frame and bike, What a Brilliant tool it is, and all age related. My frame is not that far out, but I am trying to copy Scott’s, of the two I would say that Pat’s is the better design, and uses the better later type Swinging arm as used on the batch of 1963 C15T’s. He says I can put the picture of the bike on this site. But I need one of my son’s to accomplish the task as I have failed. Fingers crossed.

Regards Charlie.

Is that the bike thats pictured in this months Classic Dirt Bike, its very nice and nice to see a genuine old Trials bike.

'ScottT', Hi, Yes it is, Regards, Pat.

http://i272.photobucket.com/albums/jj170/l...tt/IMG_0036.jpg

Hi Guys.
Thought I would try and post a Picture of the "Scott Ellis" replica frame before it goes off to the powder coaters.
I now have most of the bits to assemble the bike after a year trawling through e-Bay to get all the parts that were needed to build the bike.
If you can open the link you will see that the photo is not that brilliant , but it was taken with the eldest's new camara that cost over a grand, so you can't expect a lot can you.
Will update you with progress of the build as it happens.

Regards.Charlie.

Nice to see some progress Charlie. Take care if your going to machine that barrel round though. The temptation is to hold it from the inside with a 3 jaw chuck. If your not very careful you can break the spigot off the top of the liner-like i did!

Hi Guy's
Hi "Tricky Mick".
No fear of doing that mate, I have machined the spigot and crank case mouth so that it is a nice fit , and we have the Ex Brian Hyatt C15t that has had the fins rounded by grinding, and you know how nice them thin little four inch cutting blades are now a days, hope you did not throw the barrel away, as i think there is some good old stock liners about that I have seen somwhere.
Cheers for the warning though.

Regards Charlie.

Hi Charlie,

Thanks for posting the photo. I lightened it up a bit to show more detail:



cheers,
Michael

Hi Guy's
Hi Michael,
Thanks for that ,that shows a much better light on the project.

Just a note on the alloy barrel. Patt Slinn who worked in the BSA comp shop at the time,told me that most of the works riders bikes had alloy barrels fitted.
They were imported from the USA along with a batch of alloy clutches.
The barrels were used, but had to be painted black, so that they looked like the cast iron ones fitted to the customer bikes.
The clutches were less usefull as they were made of to soft a grade of alloy and when tested by Pat wore out in one days use on a prototype army bike, so were left on a shelf untill the factory closed.
So the nearest I can find is the one from a B25 which is fitted with a spacer under the barrel to make up the length of a standard C15 cast one.
hope this is of intrest.

Regards Charlie.

Hi Guy's .
Just found the timing side bearing we made some time ago for the S/E bike, so juring this cold snap I thought I better get on with the project, the finished frame as been on the bench in my "little Shid" for too long , and all the rest of the bits that were in one place, seemed to have taken a stroll to other parts of the house and shed while I was not watching them. Just checked on this referance site to check were I had got to so to speak. then found this pic of Pats bike, and that has spured me on again, loking at that.

Regards Charlie.

Just a thought, but which side should he front brake be on. (or would have been on originally)

Hi Guy's
Hi B40rt.
Well the front on Scott's bike and most of the others using Bantam hubs at the time would have been on the right as you sat on the bike.
It Is only over the past few years that, shall we say engineers, have worked out that you get a better cable run when the brake is on the other side. Some works riders did swop from side to side to get even brake ware, and seemed to think some trials suited the brake on one side or the other. Also BSA works riders did try other available brakes. I.E. 7inch BSA as on Pat's bike and the Ariel Leader alloy brake Etc.

One other little hint on the new Alloy replica Cub/Bantam hubs is, be carefull which way you fit them because the good ones are designed to be fitted only on the side you spec , and some of the copies of these the braking surface comes away from the alloy hub, because there design is not quite right..

Regards Charlie.

uhhhhhmmm
i can only imagine that you are referring to hubs with threaded braking surface inserts ???
even then wouldn't there be a risk of the insert un-screwing as you roll backwards down the hill with the brake on.

aren't the more expensive hubs metal sprayed so you can fit them either way (i note they use a circlip as a bearing retainer for the same reason, when you fit a cub hub backwards there is a possiblity of unscrewing the lefthanded bearing retaining ring.)

as a side note... i understand that apart from a better cable run, the brake plate is orientated so that the leading edge of the shoe acts on the weight bearing side of the drum for a more positive action..

Hi Charlie
That makes sense regarding the cable run.
I was told that some of the replica hubs had a groove to encourage water to exit the hub, and that would be specific to which side the brake plate was on.
I thought that the steel/iron insert was shrunk into the hub, and therefore not effected by direction ?
Ross

Hi Guy's
Hi B40rt.
Alans said it all realy. but you can see you need to check out which hubs you use and it is not a matter of just fitting them. Locktite stops the bearing retainer from moving !!!

Regards Charlie.

Hi Charlie,

Did you ever find out where BOK 228C is?.

Happy christmas to everybody.

Pat Slinn.

Of course, Colin Dommett has it!

Big John

Hi Guy's.

Hi Pat.
Happy Christmas, mate, and every one on here.
Well I think Colin still has the log book , but I don't know about the bike, I think the frame has been scraped? I would like to know?

Regards Charlie.

Hi Charlie,

Yes it would be nice to know what happened to that frame.

I hope everybody has a really good Christmas, and all the best to everybody who is trials riding on Boxing day.

Pat.

Hi Pat,

I've just sent you an e-mail with the details you requested!

Best wishes,

Big John

HI
I’m confused? I know two people that are manufacturing replica cub hubs and neither have stated that the brake has to be on a particular side. Could someone please explain? I’m thick

Hi Guy's

Hi TBoy.

OK I will make it simple ?.
Now the proper way to cast a steel liner into alloy is to sit it in the casting sand in the right position then cast the alloy around it. but because this is complicated, it makes the hubs expensive to produce. So you can either shrink a liner into the machined cast alloy hub, and hope it does not get to hot while you are using it, or you can machine the liner and hub with a fast screw thread, so when you apply the brake the force applied tends to screw the liner further into the hub, so it does not come loose. this is why the hubs need to be fitted the correct way, otherwise when the brake was applied it would tend to loosen the liner, just think of it as a nut and bolt? The other way is to have the machined hub chrome plated onto the braking surface, has were some Bultaco hubs I seem to remember, and these soon went oval and the chrome peeled off. Fascinating brakes you know.
Regards Charlie.

I take it that the aluminium of the hub expand faster than the liner. If they expand at the same rate, or the steel faster, presumabley not a problem, or can that make the hubs oval.
Genuinly interested.
Do Grimeca hubs have a thread or are they shrunk. Anybody know ?

Ross

Alloy will expand much faster than steel/iron.

With shrunk in liners it's about getting the fit correct. I must of relined over 100 Bultaco hubs throughout the 90's as far as I know none of the liners slipped or came loose and that was a thin insert (1.5mm Wall). The interference fit I used was severe though.

Wayne.....

quite agree, the heat rise on a trials bike will not cause significant expansion,
However, being further away from the heat source ,exposed to the air and a good conductor, the aluminium hub will be cooler than the steel liner so the differential expansion will have little impact if the correct fit was used to start with.

Thanks Wayne

Never had any problems with my original cub hub which was on the "wrong" side. Mind you the brake was so bad excess heat was never an issue !

Hi Guy's
Hi B40rt.

Cub /Bantam hubs were never round when they left the factory, and never matched to any shoes, But they do become a good brake as I have stated before. If you skim the braking surface of the hub and then centralise the pivots on the brake plate through the central spindle hole, then fit oversize brake shoes to the plate and skim this on the lathe until it is a good fit in the hub. A better brake arm with more serrations for adjustment also helps. Don't forget to widen the back hub an inch or so for better spoke adjustment, and also Bantam hubs are slightly wider than Cub hubs. PS, always fit double rubber sealed bearings now they are available, seems silly not too?

Regards Charlie

Possibly they were knocking em out so fast the raw castings were not aged properly? A local firm to me does disc brake rotors for the automotive industry, the castings sit outside in all weathers for years it seems.

Wayne....

I think that is like seasoning?

I have heard of this technique before

Big John

Always been known to me as aging. Interesting was the BMW F1 engines in the 80's based on the 1500cc car engine, it was said they used blocks from cars that had already done high milages as the basis for each F1 engine. Said to be stronger and more stable than fresh blocks.

Metals can be artificially aged and stress relieved through heat treatments, but probably the slow natural process gives better results in some cases.

Wayne...

Hi

Thanks for the reply I must still be thick. I have been riding my bike with shrunk in liners for 18 months and they are still tight in the drum. If aluminium expands like you say, why does the liner in an aluminium barrel and valve seats in a head not come loose. With most replica hubs I would say it does not mater which way round you mount them.
Jack

Jack

The real point is they should not come loose if all working parameters are evaluated properly when the parts were toleranced. Al-alloy has about twice the coefficient of thermal expansion as steel/iron, so some correctly applied math should give ideal fits for a proposed working temperature range.

As for brakes on a trials bike, well I doubt they would be even significantly warm in the average section.

Hell of a tangent this threads become!

Happy New year all!

Wayne....

Hi Guy's
Happy New Year.

Talking of the Liners in alloy barrels not coming loose, Well the first BSA B25 barrels did not have a lip at the top and were very prone to slipping down into the crankcase. So they were soon changed to ones with a lip. Why BSA did not do this in the first place amazes me. I bet the ones used in the Comp shop always had lips fitted to the top? Pat!! But then these were made in the USA. and not in the cheapest foundry BSA group could source? Probably their own.
Ah the good old British Motorcycle Industry. They always built down to a price,and not up to a standard.

Regards Charlie.

At the risk of a complete thread hijack, i think this shows how the term "engineer" has been cheapened in this country. In Germany, for instance, you need to be qualified to at least degree standard before before being accepted as an engineer.

As for shrink fitting components together that have different co-efficients of thermal expansion, as Wayne says "an engineer" would consider the temperature rise in each component, calculate the likely expansion based on its size and cross-section. The cold interference required would then be determined. The engineer would then calculate the realease temperature, ie the temperature at which the interference is lost and then build in a safety factor.

In the good old days this would have been done with a slide rule, and a rule of thumb would have been devised (such as 2 thou interference for every inch of diameter.. or similar)

These days, the parts are designed on computer and then modelled to see what will happen in service. As a result parts are trimmed down to reduce costs and improve efficiency.. hence single cylinder engines happily running to 14,000 rpm and more, producing in excess of 150 hp/litre

Hi Guy's
Hi Alan.
You Are right "An Engineer"!!! should be someone who is also a good mathematician, Know materials he is working with inside out ,have a vast amount of common sense, and the ability to put into practice the task in hand, and the most important ability is to be a perfectionist, and only turn out the very best item that you can create.
So I fail in some of these counts, but do my best. But I have a guy at my shoulder who has all of these abilities, so am very lucky.
I also have a son who is quite talented (so he says) at doing all the CAD modelling ETC, and has a program that can show all the weak points,etc on a model , to the forces of destruction, material thickness etc, so it would be foolish not to use this facility as well don't you think? Sixty odd years, of progress, I know!!!

Long live British Engineers. OLD and New.

Regards Charlie.

Wellsaid Charlie, happy new year.

Pat.

Hi Charlie,

I guess i am am saying that in the good old days, the guy that could do the sums to design something that worked as it should was "an engineer"

over the years the technician/mechanic/ fitter that could manufacture/assemble these bits (often using a degree of feel and common sense) has become known as an engineer

now any Tom, Dick or Harry that can only swap entire units proudly call themselves engineers.


I have seen some fantastic developments made that would not have been possible without CAD, but i have also seen some tremendous cock ups that have been corrected by the old boys on the bench..
sometimes , you can't bet human experience.......

Hi Guy's.

Just a Update, on progress,with the project.

Well the Bottom end of the motor now seems fine.But with all this talk this week about casting alloy,shrinkage, ETC. I am sat here with the TR 25 barrel and a 1/4 inch spacer, thinking shall I proceed to cut the fins round and fit this,or go another route. Then I looked at the Triumph piston, 69mm, and checked the bottom of the liner, It is going to be too thin if I bore it out,I thought I will need another liner. Well I have found just the one on the Westwood site, and have used them before.
So do I now go the whole hog and either hand make, a wooden casting pattern. or go the fast CAD prototyping route for a alloy barrel, or use the TR25, and make half a job of it?
Well you know what I have said earlier about an "Engineer". So it looks like I have got to create a new one. And have checked the web and cant find a BSA C15 alloy barrel. So looks like the woodworking tools are coming out this week. PS,I think I will incorporate the pushrod tunnel into the design like the B44.

Regards Charlie.

hey up charlie

why not go the whole hog.. rather than fitting a steel liner, why not have the alumuminium bore nikasil coated ?

Nikasil is a trademarked electrodeposited lipophilic nickel matrix silicon carbide coating for engine components, mainly piston engine cylinder liners. It was introduced by Mahle in 1967, initially developed to allow rotary engine apex seals (NSU Ro80 and C111) to work directly against the aluminum housing. This coating allowed aluminum cylinders and pistons to work directly against each other with low wear and friction. Unlike other methods, including cast iron cylinder liners, Nikasil allowed very large cylinder bores with tight tolerances and thus allowed existing engine designs to be expanded easily, the aluminium cylinders also gave a much better heat conductivity than cast iron liners, which is an important factor for a high output engine. The coating was further developed by US Chrome Corporation in the USA in the early 1990s (under the trade name of "Nicom"), as a replacement for hard-chrome plated cylinder bores for Mecury Marine Racing, Kohler Engines, and as a repair replacement for factory-chromed snowmobiles, dirt bikes, ATVs, watercraft and automotive V8 liners/bores.

Porsche started using this on the 1970 917 race car, and later on the 1973 911 RS. Porsche also used it on production cars, but for a short time switched to Alusil due to cost savings for their base 911. Nikasil cylinders were always used for the 911 Turbo and RS models. Nikasil coated aluminum cylinders allowed Porsche to build air-cooled engines that had the highest specific output of any engine of their time. Nikasil is still used in today's 911s with great success.

Nikasil was very popular in the 1990s. It was used by companies such as BMW, Ferrari and Jaguar Cars in their new engine families. However, the sulfur found in much of the world's low quality gasoline caused some Nikasil cylinders to break down over time [1], causing costly engine failures.

Nikasil or similar coatings under other trademarks are also still widely used in racing engines, including those used in Formula One and ChampCar. Suzuki currently uses a race-proven nickel phosphorus-silicon-carbide proprietary coating trademarked SCEM (Suzuki Composite Electro-chemical Material) to maximize cylinder size and improve heat dissipation, e.g., on the engine of the Suzuki_TL1000S and Suzuki DL650 V-Strom and Hayabusa motorcycles [1].

Engines using Nikasil:

Aprilia RS125 And Aprilia SX/RX 125
Armstrong MT500 - Rotax engine cylinder lining
Chevrolet LT5 engine, designed by Lotus and used exclusively in the Corvette ZR-1
Chevrolet Vega 2.3l, and 2.0l Cosworth fours
Citroën Visa twin
Citroën GS birotor ****el engine made by Comotor
BMW M52 I6, except exports to North America
BMW M60 V8
BMW R80GS, as measure to reduce weight over cast-iron lined cylinders
BMW S1000RR, scheduled for early 2010 release.
Ferrari F50 V12
Ford RS200
Honda RS125R [2] - cylinder lining
Honda RS250R [3] - cylinder lining
Honda NSR 150SP
Honda XR650R
Jaguar AJ-V8, 1997 - 2000 (XK series VIN range 001036-042775, XJ V8 series VIN 812256-878717) [2]
KTM LC4
Kreidler Florett,Flory
Lambretta TS1
Lotus Esprit Turbo 2.2
Maserati Biturbo 2.0 V6 Engines
Moto Guzzi 850 T3 and derived engines
NSU Ro80
Porsche 912 engine ( engine in 917 car, not to be confused with the Porsche 912 car )
Porsche 911 1973+ (excluding some 1975-1978 911S)
Suzuki LTR450
Suzuki RGV250
Vespa T5
Sonex AeroVee Aircraft Engine
Ford Puma

Hi Charlie & Alan,

I saw a C15 barrel during the 60's that had the pushrod tunnel cast in. It was from the states. Cant remember if it had a liner or a Nikasil bore. The 441cc Victor GP had a Nikasil bore and that was in the early 60's. The F1 & F2 Ducati engines that I built for Tony Rutter in the 80's had NiKasil bores and were trouble free. I never had to change a barrel on the 600 or 750 in 3 years, and that they were used in the TT and all the F1 & F2 championship races in the UK & Europe. There is something really satisfiying about making your own patterns, and casting something. Go for it Charlie.

Pat.

Hi Charlie & Alan,

I saw a C15 barrel during the 60's that had the pushrod tunnel cast in. It was from the states. Cant remember if it had a liner or a chromel bore. The 441cc Victor GP had a Nikasil bore and that was in the early 60's. The F1 & F2 Ducati engines that I built for Tony Rutter in the 80's had NiKasil bores and were trouble free. I never had to change a barrel on the 600 or 750 in 3 years, and that they were used in the TT and all the F1 & F2 championship races in the UK & Europe. There is something really satisfiying about making your own patterns, and casting something. Go for it Charlie.

Pat.

hi Pat,

were the Ducati bores plated localy.. somewhere like Stalybridge for instance.. or were they shipped from Italy?

Charlie,

At the risk of nearly going back on thread.. When i had my Serco ally barrel rebored, the liner had gone oval. The ovality was blamed on the uneven shrink due to the irregular shape of the barrel especially in the region of the push rod tube cut out..

nikasil bores might kill two birds with one stone...... and maybe open up a commercial opportunity...

this time next year, me, you and Pat could all be millionaires...........

Alan, Ducati had there barrels plated in Italy. I believe that there is a company called Motrac from Ellesmere Port that are specialists in Nikosiling cylinder barrels. Remember the early air cooled 250 TD Yamaha racers, they had a piston siezure problem because of cylinder distortion, water cooling sloved the problems. PS. Just looked up Motrac on the internet, I Googled Niksil plating.

Pat.

Hi Guy's ,

Alan Pat,
Thanks guy's for the encouragement, yes I will go for it, get the castings done and then decide ,Liner, Nikisil ,Or even Ceramic bore as I have a company in cheltenham that will process the latter.

Pat, have you heard of a foundry with the name SIRMAL, as I have a B44 barrel with that name on it in front of me,bore is 85mm, Is it from the USA? as it was one used by Arthur Lampkin,I am told, and has a cast liner built in,Not the norm hey, as you guys say they were Nikisil plated. Do you think we may be on to a gap filler then?

Regards Charlie.