The BSA A7-A10 Forum
Technical (Descriptive Topic Titles - Stay on Topic) => A7 & A10 Engine => Topic started by: magicflem on 08.08. 2014 08:55
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I am sure this question must have been raised before, somewhere - but I can't find it!!
Just finished an engine rebuild on my 1963 A10 RGS, there is a head gasket leak on the primary side and a spray of oil from the breather under the bike.
Would the spray of oil and overheating all be related to the leaking head gasket - could gases leak thru the gasket and into the case via the push rod tunnel?
Would a retension of the head gasket (haven't done this yet) solve the problem?
Help!!!
Regards,
Kim
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g'day Kim.
Was it a composite or solid head gasket? Was it annealed properly?
If can leak into the tunnel and would pressurize the case but so would blow by the rings if their not bed in yet.
A proper re-torque of the head (rockerbox off) is only 5 minutes away from lifting the head to try a new annealed gasket.
You could re-torque the four outside bolts, but it's something I wouldn't make a habit of.
Cheers
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Ahhhh, beautiful Lake Conjola.....
Thanks Musky, I did cherry the solid copper gasket on the BBQ wok burner. Hopefully a re-tension will solve the problem.
What do you suggest lbs for bolts?
Also, do you run in hard or otherwise?
Regards,
Kim
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Hello, try a search for head torque, lots of info available, for both alu and iron.
And remember how the different search options works > http://www.a7a10.net/forum/index.php?topic=1352.0
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Kim,
Is there any possibility that your annealing method brought some area of the gasket to partial melting and, theferfore, surface deformation? If re-torquing the exposed four bolts does it, count yourself lucky, but I suspect a new gasket or, at least, re-annealing will be called for. Have you done a compression test? Maybe both sides are leaking. Before and after tests could tell you if the re-torquing did the trick.
Richard L.
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30Ft/Lb with oiled bolts. (I give my cafe 35)
I don't baby mine, keep under 4000rpm for 1st hundred miles and don't lug it up hills.
How many miles since rebuild?
Cheers
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Only 20 odd miles since rebuild - I will re-tension head and see how we go.
I will let you know if this is a fix.
Thanks all.
Kim
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Kim,
Did you check the head and barrel faces for flatness?
The head can tend to get a bit of a warp.
Trev.
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Checked all head bolts this morning - no movement from 30 ft lbs as originally set when the head went on during rebuild.
Will now have to take head off and fit new solid copper gasket.
This is the way I intend to go:
1. Anneal head gasket with "Mapp" Gas to cherry red then immediately quench in cold water.
2. Clean gasket with "Brilo" sponge.
3. Clean all surfaces with "Prepsol".
4. Check head for warp - what is the best way of checking?
5. Coat both sides of gasket with "Permatex Copper Spray-A-Gasket Hi Temp Adhesive" just before fixing in place.
6. Fix gasket, head, thick washers and "wasted" bolts.
7. Torque to 20 ft lbs then 25 ft lbs then final 30 ft lbs. Then leave overnight, tap each bolt head with brass drift then check ft lbs again.
Is there anything wrong with my method?
Kim
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Sounds just as I would do it. Fingers crossed.
To check for flatness chalk the surfaces and rub them together. look for shiny spots.
Cheers
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Just took the head off and guess what a found.....
The timing side barrel sleeve has dropped 2.77mm!!! not happy #$@$%@^#$$$$
How the hell can engineers get it so wrong?
Has any body had this happen before and would it be part of my head gasket problem?
Kim
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BUGGA *eek*.
If your really care full you could push it back in and use a really small scotch key in the top to hold it or two small pins at the bottom of the skirt (chamfered on the inside to be flush with the bore).
Or. Get a new one made 0.002" bigger on the OD. Pray the other one stays put.
Wish it was just a head gasket.
Cheers
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geez mate, that's a total bitch agree the gasket would've been preferred...
Regarding the:- 6. Fix gasket, head, thick washers and "wasted" bolts.
The bolts won't be 'wasted' unless you don't use them, it's usually best to use 'waisted' bolts in the head..!
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Thanks guys....
Looks like the sleeve just touched the crank but lucky no damage to it or my new con rods.
It will be a trip to my regular engineers at Winsor on Monday with barrel, head and pistons.
I will have them replace both sleeves just to be sure.
The old sleeves will end up with the bloke who originally put them in - he may look a little funny with them inserted where they shouldn't be inserted!!
Kim
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The last set I had done had a small step at the bottom of the skirt for the sleeve to but against so it couldn't drop.
Are you buying proper sleeves or having foreign ones machined?
Cheers
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Muskrat,
Aren't they all "foreign", depending on where you are? Do you mean Asian as opposed to Englandian?
Richard L.
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Hi Kim,
Shit luck about the liners, maybe lucky the result wasnt a lot worse
Make sure the head has not been damaged where the "thick washers " seat
all the heads I have come accross need spotfacing to ensure a flat surface for the washers
I make my own washers 3mm thick
HTH
John
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hi guys, Dutch are you going to correct this one? ( had a small step at the bottom of the skirt for the sleeve to but against so it couldn't drop)
go on give Musky an `English` lesson,cheers
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hi guys/ Magicflem, perhaps the original engineer will fix his cock-up for free,cheers
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I don't think I want to see that "engineer" again!!
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Can I please have your thoughts on liners....
Should liner have a step on outer surface at top and barrel machined to accept. This would prevent sleeve dropping - or am I totally up the wrong tree?
Also, where is a good supplier of quality liners?
Regards,
Kim
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genuine Hepolite still come up on Ebay now and then
http://www.ebay.co.uk/sch/i.html?_odkw=Hepolite&_osacat=14780&_from=R40&_trksid=p2045573.m570.l1313.TR0.TRC0.H0.XHepolite+liners&_nkw=Hepolite+liners&_sacat=14780 (http://www.ebay.co.uk/sch/i.html?_odkw=Hepolite&_osacat=14780&_from=R40&_trksid=p2045573.m570.l1313.TR0.TRC0.H0.XHepolite+liners&_nkw=Hepolite+liners&_sacat=14780)
I fitted liners in my Flash some 14 - 15 years back, cant recall if the had a step, some advertised above don't , most do, also they don't come with bottom cut out for con rod, the shop do this.
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Haha- why me... *eek* *beer*
hi guys, Dutch are you going to correct this one? ( had a small step at the bottom of the skirt for the sleeve to but against so it couldn't drop)
go on give Musky an `English` lesson,cheers
Weeell...I did see it earlier, but had stuff to do so thought I'd mull it over, or stay out of it..but then forgot... *conf*
Glad you spotted it though, takes the pressure off me.....I did think a step at the top might be better, and aren't they slightly tapered..?? Mine were sleeved, but that was a long time ago....??
*beer*
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Hi Kim,
A10 liners are not usually stepped at the top
However they must have less interference fit where the cylinders project below the base flange
If they are too tight there they will split the spigots
The theorie on liners is that they will always run hotter than the surrounding cylinder and should not come loose or move, however a too tight piston to liner clearance will cause the pistons to nip the liners and drag them south *eek*
HTH
John
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Have got another cylinder with liners that have a "top hat". I am going to re-use my STD sized 9:1 JP Pistons with new rings of course but I am now wondering if 0.005" piston to bore clearance is too little. Also, how do I check that the connecting rod alignment is correct???? HELP..
Kim
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wrong post bill.
this interesting thread is about oil leaks caused by a loose liner worming itself south into the warp drive.
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Hi Kim,
A length of 3/4in. silver steel (drill rod) should pass through both small end bushes simulatatiously
without binding, with the rod through the small ends the crank should rotate as much as the bar will allow
without any problem, and keep checking the 3/4 bar is free to rotate
HTH
John
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I wouldn't have used JP pistons to start with. They have a reputation for growing.
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Trev,
Can you recommend a good piston?
Regards,
Kim
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I've used JP pistons in several bikes including the Super Rocket with no problems for a few years now.
One was a dirt track T****ph which would get a good flogging, no problems.
Of course I like them as they are made in South Oz, so I look after the local blokes.
Don
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Don,
If I am using STD sized 9:1 JP Pistons I am now wondering if 0.005" piston to bore clearance is too little.
Regards,
Kim
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JP recommend 5thou unless running a sidecar, which requires a little more clearance.
I'm running 8:1 comp in the Super Rocket, plenty of power and smooth.
Crank , mains etc rebuilt by Martyn Adams of MDA eng, another South Oz company.
Some people say he is expensive , but it stays fixed.
Don
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Would it hurt to go 0.006 or 0.007thou?
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Going out another thou is basically "wearing" the bore.
It won't greatly affect the engine other than reducing the life of this bore.
I have never had a problem with JP pistons only the rings he fits to them which I never use.
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My rule of thumb is for road use 4 and track (racing) is 6 using cast pistons. Forged pistons require a thou or two more.
Cheers
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Kim, are there any signs that the pistons picked up the sleeve? Such as sieze marks.
I have had good results with GPM pistons in 2 Rocket engines and a Norton Atlas as have some of my mates.
There are some here who have not.
In my low compression engines, 7.25:, I have used pistons which came in a plain unbranded box, probably Taiwanese, but looked good and so far are performing well.
As to JP, I recently did some work on an A65 which has new JP pistons fitted. They looked very good compared to the old production heavy things of the past and I suppose that I am prejudiced against the new ones.
The rings don't seem to be up to the job as the engine seemed too smokey to me, maybe time and a few miles will improve it
Trev.
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This is one of the JP pistons
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Can I ask what rings you suggest please BSA_54A10?
Regards,
Kim
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Little bit of a "grab" there, Kim.
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As the subject of liners was discussed here I thought I would add a bit more.
I knew I had some A10 liners but it has taken me a couple of weeks to find them, I really must have a clean out oneday.
Anyway here are some pics of genuine Hepolite liners for a A10 plus a scan of the fitting instructions. You will see they are parrallel (no step at top) but they do have the relieved section at the bottom that John (Chaterlea25) referred to.
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Kabana only $1 each.... you've had that tucked away for awhile... *eek*
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WozzA,
Have I missed something: "Kabana"? "$1.00 each"?
Kim
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Have I missed something: "Kabana"? "$1.00 each"?
Maybe just a decade or two..... *smile*
But at least it says '$', not '£'......!
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Ahhhhh.....
Must be showing my age - I don't read newspapers, everything is online for me!!
Sorry guys.
Kim
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OK.
Since we last spoke I have been busy locating another barrel that has not been sleeved. Bingo, found one and now I have decided to also buy new pistons (+60thou 8.25:1 GPM's).
The new barrel and associated bibs and bobs are with my new engineer being treated to a bit of a bore and a bit of a hone.
Now, for my next question - how do I ensure that when running in I do not overheat the engine and nip up a piston. Is it a matter of raising the needle a notch or not overreving etc..... help, I need advice!!
Regards,
Kim
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I wouldn't worry about the carby settings.
Just ride the bike normally without lugging it on hills, revving won't hurt it.
Make sure that the bloke that bores it gives it enough clearance.
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Thanks Trev. The GPM pistons spec is 3 to 3.5thou piston to bore clearance. Is this too little?
Kim
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Kim,
I would give it another thou but it is up to you.
Trev.
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Service sheet 216 says .0011 to .0031
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That would be for split skirt pistons Morris. I agree with Trev, 4 - 4 1/2 thou is good.
Cheers