The BSA A7-A10 Forum
Technical (Descriptive Topic Titles - Stay on Topic) => A7 & A10 Engine => Topic started by: Pecon on 30.05. 2012 17:43
-
Hi
As a new member I am hoping for some advice on an engine noise I have. I recently bought a 1955 A10 plunger from a friend (My first BSA) and it is in almost daily use. I fitted a handlebar fairing but had to remove it due to a huge increase in noise from the engine. (it was so loud that I had to wear ear plugs..!!). The noise is a rumble and seems low in the engine. It does not increase greatly in volume when the revs are increased. I know that it would probably take an engine strip down to find the source of the problem but if there are any known faults that might be a starting point.
The bike is running well when warm and without the fairing the noise is not too noticeable. The engine number is BA10-12065. (Forgive my ignorance but am I correct in thinking that this is a long stroke engine?) the frame number is BA7S-16217 (Could the bike have started life as an A7?)
The noise is still there when the clutch is engaged and I have re-greased the wheel bearings as part of routine maintainance.
Any advice would be greatfully accepted,
Peter
-
One of the problems which gives that type of noise is a worn timing side bush. The crankshaft has a bearing on the drive side, but a plain bronze bush on the timing side. If you remove the outer timing side cover, you will see the end of the crankshaft passing through the timing side bush to the oil pump drive. If there is any appreciable wear you will be able to lift the crankshaft with a pinch bar. You need to build something up at the side (stack of bricks or timber etc) to the same level to bar against. I know it works because I have done it, as you lever up you will see any movement within the bush. all the best Goldy
-
G'day Pete, I think all frames were stamped 'A7', up until the later A10 swing arm frames. A7 'S' denotes spring frame, as option to rigid.Good luck with the mains. Cheers, duTch
-
Hello Peter and welcome to our friendly forum.
In answer to the second part of your question. All A7's and A10's shared the same frame and all the frame numbers started with *A7 as a prefix so your A10 would have been in an A7 numbered frame when it left the factory.
There are a couple of exceptions to this rule and there were a couple of A10 models that used an A10 frame number. The * would be a different letter and would denote the year that the frame was made. For example:-
XA7 1947
YA7 1948
ZA7 1949 to 1952
BA7 1953 to 1957
The "S" after A7 signifies a plunger (sprung) frame.
Beezageezauk.
-
Thanks for the information on the frames guys, it is a relief to know that the frame and engine probably started life as one unit.
Goldie, I had some worries when I saw that SRM do a modified bearing assembly, never a good sign *sad2*. Is this a job for the home mechanic or will it need an engineering works to sort. How much of a strip down would be required to replace the bush if this is indeed the problem.
Any thoughts on the engine itself, long or short stroke?.
Cheers,
Peter
-
If you do a search on the forum for timing side bush you will find lots about it. It's a complete engine strip and a new undersized bush needs to be fitted which is then inline bored by a machine shop. But see if there's any movement in it first.
-
Peter,
All A10 engines have the same stroke so there is no long or short.
Long stroke only applies to the early A7 engines, Xa7,Ya7,Za7.
Rumbling could also be the drive side main.
Any idea how long since the engine was overhauled?
Trev.
-
Goldie
I was afraid of that, I'm not sure what the engineering situation is here in Ireland as it is 40 years since I had cause to use their services. I suspect that few will have any experience in classic machinery. If there is a problem it may mean shipping the bits off to the UK which is going to get expensive. I'll wait to see if there is any play before going off half cocked.
Trev.
The Bike came to Ireland in 2009 and while I have receipts for work done before that it is all cosmetic stuff like electrical, wheels etc. No Idea of what, if anything, was done to the engine. I will try to trace the previous owners and see if I can get any information.
Thanks again,
Peter
-
Peter, re the engineering companies over there , one of the most knowledgeable guys on this forum is based over there , john , aka chaterlea I think, very clued up about A10's and where to get things done ,I'm sure He'll respond to this post but you can find him in many old posts particularly concerning engines, i'll try and PM him for you best of luck BoBH ps he's around cork .
-
Hi again it's charterlea25 and I've pm'edhim for you Bob.
-
Bob
Thanks for mentioning John, in fact I had thought of him as I met him at a show here in Dublin and have his card. I tried to ring him but from the ring tone he is out of the country at present. I'll try again next week.
Peter
-
Whoa, slow down mate, 15years ago I bought a Super Rocket with a rumble coming from the bottom of the engine, I too had heard of the timing side bushing problem, so long story short, and $2000 later the problem turned out to be worn splines on the drive side of the crankshaft, the drive gear on the primary side rides on a sleeve that meshes with the crank on splines. So before you do anything rash and spendy, check to see if there is much play in that sleeve to the crank. I fixed mine by taking some 6 thou shim stock, cutting it into strips and sliding them in between the splines, no noise now or the subsequent 22,000 miles since. However "Goldy has a good suggestion on checking the up and down play on the crank. I'm not putting down the SRM conversion, I did it and now glad I did, but it wasn't necessary in my case, a regular plain bushing works just fine as long as you change oil regularly, and are not racing the bike. Good luck with your motor.
-
Hi Peter, Bob and All
Peter is correct recognising the out of country ring on the phone
I'm just back from a much needed sunshine break in Portugal, *smile*
Usual complaints of too much sunshine , beer and food LOL *smile* *smile* *smile*
Peter , phone me when you read this message or early next week, I met so many people at the Dublin event you will have to re introduce yourself ????
If I can help or advise no problem
Regards
John O R
-
Well it looks as though Goldy has called it. I tried the shaft and there is indeed a lot of play. I did manage to make contact with John and hopefully I will get something sorted soon. Thanks to everybody who replied.
Peter
-
Hello Peter,
I wish you all the best with your BSA A10.The AJS from you is still under construction. I have it completely dismantled,I think it will be ready by january.
Peter
-
Hi Peter
I'm glad to hear that you are making progress on the model 18. I look forward to seeing some more photos of your progress soon.
The A10 is now starting to look like a giant construction set. I have pulled off the barrels and found that in addition to the play in the crankshaft bush I found two deep scores in the left cylinder caused by a circlip becoming detatched from the piston but remaining in place in the pin. There is some damage to the circlip slot in the piston also so it looks as though a rebore is also on the cards. The strange thing is that there was no sign of smoke from the cylinder although there was some oil being blown from the breather onto the rear chain which I suspect might be caused by blow past the rings?. I also notice that the rivets on the plate over the oil seal behind the clutch have worn away leaving the seal cover loose. At least the head seems OK *conf*
-
Hi Peter,
by my BSA comes oil of the breather too,It has some threads about this breatherproblem in this forum.I think it`s not the rings.I do not write English well,you should read the treads on the breather problems.
In my case I have a Oil line valve installed and mounted below the motor a small oil-collecting tank, in tis tank leads the breathertube.I wish you success in your repairs. *beer*
Peter
-
While continuing with my strip down I noticed something odd when I checked the head gasket. The one I removed seemed very thick and on further examination it turned out that somebody had fitted two copper gaskets..!!. I have yet to check the head for warping but with an iron head I would think it unlikely that this would be a problem. For the life of me I cannot think why a previous owner might think it a good idea to do this. Does anybody have any thoughts on the subject?.
Peter
-
Peter ,the only thing this feeble mind could come up with is that the previous owner felt that reducing the compression ratio would be desirable ,can't think why ,unless of course the engine hasn't been down for over 40 yrs and at that time it was poor quality fuel then and the engine needed some help. cheers BobH
-
Well Bob, the same thought occured to me but how much difference would the thickness of a gasket make and I can see indications of work being done in the past, although some of this was done with a basic tool kit, lump hammer and vice grips. *conf*
-
Maybe just lost count after the first one?
I have a set of barrels from my first effort ('70's)that have the same circlip gouge, it's about 3mm deep!! A good thing to double check.
Cheers and good luck with it, can't offer any other ideas 'bout the head but does sound familiar- except have you checked that the head hasn't been shaved at some stage??
cheers
-
Just an update on my engine woes.
I did as John suggested and removed the engine and started doing some of the stripping myself. When I got as far as removing the head and barrels and discovered that the bore was badly scored along with the play in the bush I decided that the best course was a trip to SRM in Wales for a full check. Unfortunately the news was not good. in addition to the casing being damaged in transit I have a crankshaft which had been cut down from a large journal one to small presumably to match the existing con rods. So its a replacement crankshaft, (unfortunately the only one available is a small journal one) con rods, pistons, rebore and new bushes and bearings. The estimates are starting to turn my hair gray *sad2* but from the telephone discussions I have had with Geoff Dewhurst these guys do seem to know their stuff and I feel confident that I will have an engine which will outlast me..!!.
-
Hi Peter
That sounds very like the "tales of woe" that I find seemingly with every rebuild I take on *eek* *eek* *eek*
With the exchange rate between the Euro and Sterling at the moment and for the what looks like for some time to come *sad2* *sad2* this adds considerably to the costs
It may be worth asking here to see if any usable big lumps are available which might help reduce the costs??
or keep checking OBM and similar even Ebay??
Regards
John
-
Hi John
You're right about the weak Euro, it's adding about 26% to the cost. I did think about a replacement but I'm afraid I might end up with somebody else?s reject and be back to square one so I bit the bullet and paid the deposit.
Peter