BSA A Group Gear Side Main Bearing Bush

Fitting and boring of the phosphor bronze gear side main bearing bush on a BSA A7, also applies to the A10, A50, A65 etc and other engines with the same bearing arrangements. Look out for the post credits scenes...

[@user-mg5fe5ot2m]

Just about to rebuild an Ariel Huntmaster 650 engine with the help of some friends, people who know vastly more than me. Just came across this video and I'm in awe of such skill. What a cracking fella, so much care and time taken to get it spot on. I'm down in Kent, wish I lived closer. Thank you for making such a clear video, even if it was a while ago, timeless. Kindest regards. Richard

[@AGEngineering]

Glad you found it useful, thanks for the great comments.

[@thra5herxb12s]

Proper engineering using proper skills, and good old fashioned experience 👍

[@AGEngineering]

Many thanks for watching, appreciated, Ade

[@brittweir8844]

Great video 👍thank you for your time .I have recently inherited my father‘s 69, 650 lightning A65.He was always concerned about the oil pressure dropping at idle when warm , he told me, I would eventually have to replace this,bushing. again, oil pressure will come down when warm ..Appox. down below 30 pounds at idle ,he had recently installed high pressure oil pump with good oil, he told me that I should consider replacing this bush in the future due to low oil pressure , the other day I took it for a spin in the evening it was about 80° outside and when I got close to 5 miles of driving around my neighborhood (never got out of third ) stop and go basically ,oil pressure started to come down at idle. However, with engine off idol oil pressure would be high (30-40 psi)no problem .❤ this bike was my dad‘s baby. It is absolutely cherry. Low miles. Everything has been overhauled or updated. With the exception of the lower end. Thank you for your time.

[@AGEngineering]

Great to hear these stories and related history, many thanks for sharing.

[@petergbank9474]

This is a really excellent method..the factory required a special plate and reamer, which are obviously unobtainable. The alternative would be to bolt the cases together, turn a dummy beating for the drive side as a pilot , and then line-bore or line ream the timing side using that. Contrary to belief, the BSA TS bush was not a bad idea. You need to have either an original steel bush with soft bronze insert ( no longer available) or else use lead bronze ( softer) over phosphor bronze for a one piece bush. If The correct clearance is reached (max 1 thou) and the oil changed regularly, it will last a very long time!

[@AGEngineering]

Thank you for your supportive comments and thoughts. Best wishes and happy Christmas, Ade

[@Daithioyeah1]

Hi Ade, thanks for taking the time to share your time and knowledge. This is a job I need to do but don't have a milling machine, I am hoping to buy a reamer and open a lead bronze bush out by hand. Thanks again, Dave

[@AGEngineering]

There are other ways to do the same job, depends on budget, availability of machining services and other factors. Many years ago I hand scraped an A65 main bush to suit the crank, that was about 1987. It's still running today with the current owner and has not been rebuilt since. Thanks for watching and commenting, Ade

[@phv757]

Hi Ade. As you probably know the old Redditch built Royal Enfield Bullet Engines have a bush like that however the Indian made ones have upgraded to a Roller Bearing so the hole would obviously need machining out & i know the Man for the job. (Hint Hint :-) )

[@AGEngineering]

Honestly I've never tried this with an Enfield, I would have to 'consult' to see if it was doable, but I would think so if the castings had sufficient material to work with.

[@phv757]

@@AGEngineering I'm Game if you are Mate. I have a pair of cases to practice on. Where are you based Ade? I am in N/Essex. I bet you are miles away?

[@timothyharper3982]

Thank you for taking the time for this. I am in the USA and have an A65 I am restoring. I am contemplating the bearing conversion.

[@AGEngineering]

Hello Timothy, thank you for the comments. I presume you are referring to the roller/thrust bearing and crank end feed arrangement similar to an SRM conversion - www.srmclassicbikes.com/unit-a50-a65/bsa-unit-a50-a65-engines I have heard good things about this and would agree it is the way to go, let me know if you do this and what the results are like, thanks, Ade

[@dropkicker101]

Hey Tim howd your A65 turn out? im rebulding one too. im debating weather i should job out the timing side bush or tryn do it myself. lol

[@rayelliott4710]

Excellent. Thank you.

[@AGEngineering]

Thanks for watching Ray, and for the kind comments, Ade

[@9traktor]

This man knows what he`s doing - fine!

[@AGEngineering]

Thanks for watching and commenting

[@linuxacc7366]

Wow very nice!

[@AGEngineering]

Many thanks for supporting the channel

[@white-wy6dg]

I always pick up used bronze bushes at jumbles.I get the crank ground to the minimum to clean it the guy does not even need to measure it .Then I select a bush with a just smaller undersize fit that,and using an expanding (adjustable ) reamer with aground guide spigot ,and ream in conjunction with the roller bearing in the left casing (fully bolted together) Just ream till the crank fits.You may get away with twice many regrinds as you are not having to take off a full 010 thou .I`ve had a `58 Huntmaster since 1971, I have used it A LOT and done a rebush three times ,but this has never failed on me and was only ever done as a part of general rebuild, KEEP YOUR OIL CLEAN! One very important thing ! what ever type of bush you use ,check the radial (1/8"?) oil holes, they should be angled slightly in towards the centre of the engine to line up with the grouve in the crank

[@white-wy6dg]

I`m sorry I hadn`t finished! some "pattern" bushes have been made with the oil holes at 90 degrees and they do not line up with the grove in the crank,or are partially obscured. This can be put right with a round needle file ,slotting the holes is fine. Please check this ,one of my friends seized his A10 up in five minutes of first startup!

[@AGEngineering]

I would agree with that, I have said to people only grind to clean up, ignore the std and o/s figures that were recommended, keep that material on the crank! I've seen some pretty awful bushes over the years, please have a look through the other comments to this video, i think it has been discussed with other viewers. Thanks for watching and commenting, best wishes, Ade.

[@barrynash2046]

Brilliant! really enjoyed your piece very informative.

[@pm270100]

well done i say very nice

[@AGEngineering]

Thank you, thanks for subscribing

[@Rugbyman269]

SRM used to do a needle roller conversion for A50/65s ,don,t know if they do it for A7/10s ,but it does away with the bush

[@AGEngineering]

Hi Graham, I looked at this a while ago, it is something I would like to try and do, I have a NKIB5906 bearing sitting on the shelf ready, but finding cheap A10 cases to experiment with, well that's a different story....

[@gavind9487]

I am not a precision engineer so apologies if this is a dumb question. Why does the bush need to be bored out in-situ? Isn't it easier to do that first then fit it into the crankcase?

[@AGEngineering]

No problem, the clearance needs to be very precise to ensure good oil pressure and oil feed to the crank, and needs to be accurate to be in line with the bearing opposite. The crank grinding also has a tolerance which needs to be accounted for. Many thanks for the question and viewing.

[@frankkemble2103]

That's funny. I've always just heated the case with a tiger torch and the bearing simply drops in!

[@AGEngineering]

Absolutely, hate to see bearings in engines hammered in or even pressed, much prefer heating the cases. Thanks for watching

[@johnorchard9164]

Easier to turn down the shoulder of the crank shaft to suit the bush Have just done one on my tiger 100ss regards john

[@AGEngineering]

Absolutely, fit the bush, take the case to the crank grinders and have them grind to suit. Many ways to skin the moggie! Best wishes, happy new year, regards, Ade.

[@petefletcher]

Those BSA plain bushings where a daft penny pinching idea. I know a plan bush can be more accurate than a ball bearing but on an engine with hardly any oil filtration it was always asking for trouble. Even a small amount of wear put the oil pressure at risk.

[@AGEngineering]

Couldn't agree more, I'd love to experiment with a roller bearing/end feed set up one day. thanks for the comment and support.

[@neil1150]

A G Engineering Back in the 70's I had a local firm do just that to my Ariel Huntmaster, basically an A10 engine with minor differences to casting shape, they used a caged roller bearing, forced oil direct from a drilled port down the end of the crank. I added a remote old filter the return line, engine was fairly well breathed on, porting big valves, cam, lumpy pistons and ridden hard, last ed very well after the work, before the bearing conversion 2.5 to 3 thousand miles was the most it ever did without losing oil pressure from the worn main bush. But before you say how good yours are, I rode it hard and fast, my mate all road later triumphs and nortons, I never got left behind.

[@logotrikes]

As I found out....

[@jerryhansler2197]

Thank you. We have an A50 to do and no machinist local wants to try the alignment. I think I have one but he is 3 hours away. We also need to line bore the cam bushings and one is a blind hole. Can you advise or demonstrate that procedure? Thankyou again. jerry

[@AGEngineering]

Thanks for your message, cam bushes are covered in a couple of my videos, check out the bearing conversion ones. I promise everyone I will get back to the bearing conversion at some point 🤞

[@MILITARY1231]

Hi pal, nice tools and knowledge. How come you can just use a lathe bear

[@AGEngineering]

The bush really needs to be bored after fitting to achieve the tolerances needed for good oil pressure, hope this helps, Ade.

[@MILITARY1231]

A G Engineering thanks ade

[@kilosalamanca]

I thought you were meant to line ream using the other casing?

[@AGEngineering]

As with most jobs there is more than one way to do it, this is the method I use with the tools available to me, not saying it's 'right' , just one of the ways. If line reaming facilities are available then that would work as well, but a reamed finish is not as good as a bored one. I have improved the tooling since this example and now use indexable carbide inserts for non- ferrous applications, then hone to final size on a Delapena Speedhone. The BSA factory service method was a plate which bolted to the timing chest and reamed through a guide sleeve. In all honesty given the choice and money I would go for a needle roller and thrust conversion with centre oil feed like SRM. Thanks for the observation, thanks for watching, hope you are enjoying the channel. Ade.

[@geoffgreenhalgh3553]

@@AGEngineering Hi, I am a Recently retired turner of 49 years. When I was an apprentice I used to make the phozy bronze bushes for our local motorcycle repair shop. He used the method you mentioned (BSA) and I also had the reamers ground to various sizes for him. Keep up the good work. Geoff.

[@campbellstevens6288]

Hello.....your services are like hens' teeth these days. Are you able to perform virtually the same task on an Ariel SQ4 crankcase.....pretty much identical but 2 off. Looking forward to hearing from you. Campbell

[@AGEngineering]

Send me an email [e-mail] and I'll get back to you.

[@davidsketchley5458]

Hi are, brilliant video thanks, I need the same doing on a 71 a65,could you do theirs for me please,thanks,David.

[@AGEngineering]

Hi David, hopefully you got the email reply, many thanks for supporting the channel

[@swatts9301]

Hi, I need some work done and was wondering if you'd be able to help me? Is there anyway I can contact you? Thanks

[@AGEngineering]

I can be contacted at [e-mail]. However please be aware this is a hobby channel only where I do work for my own machines and that of some very close friends occasionally. I may be able to guide you in the right direction however. Thanks for your support.

[@MILITARY1231]

Do you do crank balancing and grinds

[@AGEngineering]

Unfortunately not, I've been asked about crank grinds many times but the grinder is expensive secondhand and I would not have the room to put one. As I'm only doing this as a hobby, I could not justify it, but trust me, I've looked.....you can never have too many tools! Thanks for watching, Ade.

[@MILITARY1231]

A G Engineering thanks pal. Great work.

[@1mikechung]

Hi, I need this bush looking at and lots of parts need replacing, checking etc . What are your contact details?

[@AGEngineering]

Sorry Mike but I am not able to assist you at this time. Many thanks for your support and following the channel.

[@davidsundquist1845]

I am a 50 yr pro (continuous) It is better to grind the crank to fit the proper new unadulterated FITTED bush size.

[@AGEngineering]

Thanks for the comments. The present thinking is to grind the minimal amount off the crank to preserve the crank and bore the bush to suit, however both ways will work, personal choices. Best wishes, Ade

[@carlosgooglemaps94]

Wow, lot of fine tools and can’t afford a heat gun?

[@AGEngineering]

Takes too long to get the heat in, my choice is the propane torch but I have also used hot plates, heat guns, the oven etc. Thanks for watching Ade

[@MrPeterbennett]

There many problems with these engines

[@AGEngineering]

Looking at sorting some of them out hopefully..