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Of all the jobs I am crap at, this one ranks right up there.
First, can anyone recommend a bearing supplier ( I have bought oval ones in the past, I have had solid ones made all have gone within a few thousand miles).
Second, how do I make sure the bush is perfectly aligned. I have no confidence in adjustable line reamers as I cannot see how accuracy can be maintained to that sort of tolerance.
Third, how do I measure end float without having to pull off the drive side bearing and re-shim.
Fourth, I have had this job done by "professionals" in the past.
Fifth, I am tight and wont send the cases to SRM (the bike isn't worth a £3,000 bottom end).
Six, how can I bench test an oil pump (if that is possible).
Your thoughts would be most welcome.
Regards
Pat
email (option): sacombsashtrees@hotmail.com
The guys on the A10/7 forum really know their stuff and you will have no shortage of expert advice. You don't have to sign up to read and the forum is searchable.
https://www.a7a10.net/forum/index.php
Hi Dean
Thanks for this.
I had a trawl through this website.
It's very good. However, I couldn't find the tolerances for that bush. End float seems to be under 3 thou.
I will post something, but feel starting a thread on the timing side bush is a bit like starting a thread on what is the best oil to use. All the regulars will have seen it before and probably a bit bored of it.
Regards
Pat
email (option): sacombsashtrees@hotmail.com
Pat, I don't think you should worry, I've never found them to have that kind of attitude.
I hope you find your answer (says he somewhhat red faced as a long term multiple A10 owner!)
An alternative is to ask SRM, I have also found them pretty helpful and again have many years A10 engineering experience.
email (option): bsansw1@tpg.com.au
Thanks Trevor.
I think I will go for 1.5 thou between bush and crank and fit a spin on filter on the oil return line.
Regards
Pat
email (option): sacombsashtrees@hotmail.com
End float should be .003"...Shims should be fitted behind the bearing against the flywheel cheek...Check the end float with a DTI after the crank is fitted to the cases...
Years ago when I had many A7s and A10s I kept an old bearing the bore of which I opened out slightly with a flap wheel to ease the fit on the crank...That made the job easy and avoided the risk of damaging a new bearing.
SRM also supply good quality bushes as well as their more expensive end feed conversion but I guess they are not in the habit of offering that as a first option...Ian
email (option): ian@wright52.plus.com
Hi Ian
The cases and crank are at a local firm just now for accurate measuring.
From there, I will know what undersize I/D bush to get from SRM (I am going for a solid phosphor bronze bush). I will go for one that has plenty of material for the guy to work down to.
I want the minimum off the crank and bore the bush to fit.
He can use the old drive side bearing for the shimming (good idea of yours).
I have done this job twice (badly and without the correct measuring tools), must be in excess of 30 years ago now and the bike has been sitting on its bearings in the barn since then.
The problem with the conversion is that you end up persuading yourself that since you have spent so much you might has well go for the full monty e.g. buying one of their pumps.
Regards
Pat
email (option): sacombsashtrees@hotmail.com
The original 'end feed conversion' was developed by BSA for Chris Vincents factory sidecar bikes which as you can imagine worked under pretty extreme loads...
This was picked up by Devimead who offered the conversion to A65 owners as an upgrade to the oil supply for road use. There has always been some debate about the necessity of this conversion and one chap I knew who ran a business specialising in A65s wouldn't fit them. He argued that a correctly fitted bush made of the correct material and oil changes at the correct intervals was sufficient..His own daily bike was an 850cc Lightning which he ran thus equipped for years, which at least indicated he may have been right...
My own view is that the problem of exploding A65s is a fault in the con rod material/design...not the oil supply. Personal experience during the autopsy of the two I blew up indicated that was the problem....
Regarding A10s they didn't even have a problem, being renowned in their day as a high mileage bike..I knew an old boy in Plymouth who had a Gold Flash that had done over 200,000 miles from new and had never had the bottom end stripped down...I also did scores of thousands of miles on various A10s and A7s...The only timing side bush failure I had was with an RGS which had been built with odd crankcase halves and I ran two bushes before realising what the issue actually was...crank misalignment...
Devimead sold out to Steve Mc.Farlane and SRM came into being (his initials)..After some years he sold out to the current SRM management who retained the name....
Business is business and under their control the conversion was also offered for unit Triumph engines fitted with a bush as standard...Another engine that didn't really have a problem with the bush in the first place...
Like wise with upgraded oil pumps...There was no deficiency in the oil supply of an A10 that indicated a pump fault...
What you have to remember is that SRM (and any other business selling 'upgrades') are looking for business, so any opportunity taken to play on peoples worries will produce beneficial results for them...
I'm not a member of the flat earth society and have upgraded certain aspects of many, if not most, of the bikes I have owned both with my own mods. and bought in products. However, the first consideration before buying should be is there actually a problem that needs solving?...
It shouldn't be assumed that all such upgrades are needed just because they are being offered.....
Personally I think the classic bike media are also complicit in this possible deceit...In the back of the classic bike guide for example, I remember reading the comment...'BSA A7/A10. One of BSAs best sellers from the 50s, benefits from bottom end conversion'....If you read that again it is actually a contradictory statement.. It's suggesting one of BSAs best sellers had a basic fault....Hmmm....
Personally I would argue that is not the case....People are assuming it is, based on various magazine articles, a lack of experience of the particular engine and chatter at the clubhouse...
If as stated, the timing side bush is really so problematic and the end feed conversion is really so necessary why, as a supposedly honest supplier, are SRM still selling them?..
It's actually because they know that the bush will work and that not everyone is prepared to pay for their conversion...and at the end of the day they still want that customer...Ian:laughing:
email (option): ian@wright52.plus.com
Gees Ian,
You and I are in agreement again.
Interesting that you had bottom end failures as all I have known about were from the USA .
I put most of these & the A65 ones down to ring flutter allowing oil to litterally blow out the exhaust when running WFO for long periods as is the want of Americans, particularly on the West Coast with single straits longer than the UK is wide.
I never thought about this till talking to Prof Falco and his analogy between riding positions & saddles on horses makes perfect sense to me as I do some thing similar depending upon which side of the hill I am riding .
The one & only case of left rod exitus I know of down here was on a bike owned by a very fast rider and when he pulled down the engine there was almost no oil in the tank ,but it was dripping out of the pipes.
He had been "dragging" some one on a rice burner for miles of expressway when it happened when he backed off to enter the fuel station.
And yes a plain Tin-lead babbit slippers was not a good idea in a short stroke high compression engine and I always recommend not using NOS slippers when people rebuild bottom ends.
Never seen an A10 throw a rod.
Have seen a few A 7's fitted to go-carts do this but the 9000 rpm probably had more to do with that.
Too much oil and too much oil pressure can be just as destructive as not enough .
And double ditto on the business that fuel the hype of the ignorant encouraging them to print misinformation to the uninformed.
Valve seat replacements for unleaded fuels is the perfect example.
Something that only happened in aircraft under lean burn conditions at high altitude being extrapolated to rich running engines at sea level.
email (option): bsansw1@tpg.com.au
A quote on the A10 from Classic Bike Guide Feb 2018:
"SRM main bearing and uprated oil pump conversion are plusses when looking to buy".
A quote on the A65:
"Specialist engineering sorts suspect bottom end oiling, as in all BSA twins".
Regards
Pat
email (option): sacombsashtrees@hotmail.com
Quotes from journalists...and from journalists who may well never have ridden or owned either bike or really examined and thought about anything regarding the design and construction of the engines mentioned...
What journalists do generally is talk to a few people in the trade and an 'expert' or two and then sift through the answers they get to create an article...
The resulting article is therefore constructed largely from the knowledge, opinion, experience and crucially, bias and possible vested interest of others...That makes checking the facts a bit hard for the writer...
It has to be said that it's a system that works OK generally but has the inbuilt weakness that the accuracy, truth and logic received by the writer depends entirely on those they choose to talk to...Additionally, I feel information provided by experts who have something to sell should, logically, be treated with caution and thoroughly checked...
I tend to read old copies of the Blue 'un and Green 'un when seeking enlightenment...Back in those days the journos were often ex industry men or were keen clubmen and riders who knew the practice and theory of their subject and crucially, were passing on 'first hand' information based on their own experience...
I believe that's why the older magazines contained much more hard technical information as opposed to the 'riding impressions' so prevalent in todays publications..
I read an article in one well known magazine written by a so called 'tech' (how I hate that expression) on the use of measuring equipment. It was memorable only for its inaccuracies (ironic or what?) and was plainly written by someone who didn't fully understand the subject...
Sadly, whilst someone well versed in a subject will soon see through a 'fake' expert, those less familiar will simply absorb the information provided as fact...
Eventually the whole thing becomes part of 'folk lore' knowledge, is enshrined as fact and the person that disagrees with the accepted wisdom is written off as an eccentric (at best)........
That brings us neatly back to timing side bushes..:laughing: ...Ian
email (option): ian@wright52.plus.com
Bloody hell Ian,
Agreeing with you twice in the same thread, unheard of.
I stopped buying all modern "Classic Bike Mags" back in the 90's for just that reason.
All eye candy and no brain food.
Even worse was an article that requoted some lines from an 80's motorcycle magazine.
"BSA was doomed to failure, there is no way they could make modern motorcycles to close tollerances using all of that worn out machinery that was so old all of the calibration marks had worn off "
Who ever wrote that story has never worked a capstain lathe like the one in the accompaning photo clearing showing no markings.
In the 80's I was an occasional contributor to all 3 local motorcycle magazines.
AMCN was written by full time motorcyclists, usually racers.
The others were written by by people many of who could not ride.
The editor of Two Wheels ( which has just closed down ) was also a sub editor of Surfing Aust, Cricket Aust & Ski Slopes.
There was no full time motorcycle staff, apart from the testers ( and some of them did both cars & bikes ) every one else contributed to 2 , 3 ,4, or 5 other titles.
email (option): bsansw1@tpg.com.au
['Bloody hell Ian, Agreeing with you twice in the same thread, unheard of...']
:laughing: :laughing: ...Maybe you're mellowing out in your old age...I wouldn't worry though, it's probably a passing phase and normal service will be resumed on the next topic of discussion...Ian:volcano:
email (option): ian@wright52.plus.com
Ian,
I cancelled my subscriptions to Classic Bike and Classic Motorcycle many years go for reasons you mentioned.
You have a writer who was not even born when the bike was made he is writing about. Almost all who worked at the factory are dead so the only option is to read previous articles that have incorrect information. And is gets repeated as the truth.
I also don't need to read about the 1959 Triumph Bonneville for the 100th time! They have run out of bikes to write about so keep recycling the same articles.
As for A65's breaking rods, yes have seen it many times. Even on a perfectly assembled motor, they will one day break a rod for no apparent reason?
Never seen a A7 or A10 break a rod.
I'm glad this thread came up again...I quite enjoyed the re read....I find the best people to talk to these days to glean new information are the ones who have ridden a lot of miles and gained real experience of the practicalities, people who tune engines, who tend to have a grasp of quite a lot of theory, anyone with an engineering background and an interest or anyone who has received formal training in a motorcycle shop....
Fortunately there are also a number of contributors to this forum who are pretty knowledgeable in their chosen areas of expertise and I get many of the answers I want, new information and ideas, right here....Ian
email (option): ian@wright52.plus.com
I rebuilt my A10 several years ago because the timing side main was worn. Iam in West Australia and there are limited suppliers here so I searched the internet for considerable time until I found a supplier in the UK that could supply an original type of steel backed main bearing, which was an MCA Made in England. I have always believed the solid bronze type bearing will go oval much quicker due to the thicker, soft bearing material. I got an undersized bearing that would allow it to be machined to the main bearing. A local reconditioner had an ex-UK fellow that specialized in motorcycles, and he ground the crank until true and then lined bored the main bearing to suit. The finished job was perfection. I also fitted an SRM oil pump which was of a high-quality standard as the oil pump is the heart of an engine and the original die cast type pump was 55 years old at the time. With new ball and spring for the relief valve and non-return valve I had good oil flow and never wet sumps. Probably as good as one could ever get one.
email (option): kimbo5205@gmail.com