Author Topic: What goes in this hole then?  (Read 18017 times)

Offline Mosin

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Re: What goes in this hole then?
« Reply #30 on: 17.08. 2009 22:34 »
Ok, it looks as though I am going to have to bite the bullet and take the head off.

This evening I was describing the symptoms in some detail to an elderly and knowledgeable friend of mine who also has an A7SS, and he seemed fairly sure that it sounded like a knackered piston ring. He suggested having a good look at the plugs and sure enough, the left hand one (the side that was smoking) was all oily but the right hand one appeared absolutely fine.

I am not looking forward to doing this.... Not one bit....

1960 A7 Shooting Star
1959 D3 Bantam
1994 Triumph Trident 900

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Offline LJ.

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Re: What goes in this hole then?
« Reply #31 on: 18.08. 2009 09:20 »
Quote
I am not looking forward to doing this.... Not one bit....

Sorry to hear of your problems Simon, but hey relax you'll be okay. Just take your time and report back here for further advice if need be. You obviously enjoy riding the A10 and will probably now be keeping the bike for a very long time to come, just put this all down to experience as in a few months you'll be wondering what all the fuss was about. You'll get there!
Ride Safely Lads! LJ.
**********************
1940 BSA M20 500cc Girder/Rigid- (SOLD)
1947 BSA M21 600cc Girder/Rigid-Green
1949 BSA A7   500cc Girder/Plunger Star Twin-(SOLD)
1953 BSA B33  500cc Teles/Plunger-Maroon
1961 BSA A10  650cc Golden Flash-Blue
1961 BSA A10  650cc Golden Flash-Red

Offline Mosin

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Re: What goes in this hole then?
« Reply #32 on: 18.08. 2009 11:06 »
Many thanks for the support and all the guidance guys, it is much appreciated.

This may sound like a supid question, but is it possible to remove the head with the valves in situ without disturbing them, or do I need to take them out as well?



Simon
1960 A7 Shooting Star
1959 D3 Bantam
1994 Triumph Trident 900

North West England

Offline a10gf

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Re: What goes in this hole then?
« Reply #33 on: 18.08. 2009 11:21 »
Your burden is getting lighter: the head goes of as one piece with all internals.

When your done and found your problem, reassembling top, just some fun aligning the 4 cam rods, you'll need the tool, tightening the bolts following the right procedure, then readjust tappets clearance. See the 'head' pages under tech and maintenance here. More info: here & here. Check\replace the cylinder top & base gaskets.

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Online RichardL

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Re: What goes in this hole then?
« Reply #34 on: 18.08. 2009 12:47 »
A few extra tips that I have learned along the way and/or the hard way:

1. Removing the rocker box will be easier if the rear center cover stud is removed, thus avoiding the top frame member.
2. Let the stickyness of your gasket sealer hold the rocker-box base gasket to the box during replacement. (The tool will still get a bit goopy on removal.)

3. The tool comes out by sliding it forward and there is just enough space between front and rear rockerbox sections to, then, pull it out sideways.
3. Slacken the tappet adjusters so there is no force on the valves as the rocker box is tightened down.
4. When you're done using the comb of the tool to align the rods, use the other end (placed between head fins) as a platform to support the hex nuts (one at a time) as you work on getting them started on the front studs. Otherwise, this is nut-dropping nightmare (humor there, but not really intended).

Richard L.
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Offline Mosin

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Re: What goes in this hole then?
« Reply #35 on: 20.08. 2009 20:19 »
OK guys, now I am flummoxed.

This evening I removed rockerbox, head and barrels. There was a lot of oil around the cylinder head, but the gasket appeared to be ok (see photo). When I got the barrels off, the piston rings all appeared to be intact. However, while the right hand piston is all clean and shiny, as you can see, the left hand one (the side that was smoking) is all streaky.

Any suggestions to what may have caused this or further diagnoses?

As always, many thanks.

Simon
1960 A7 Shooting Star
1959 D3 Bantam
1994 Triumph Trident 900

North West England

Offline a10gf

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Re: What goes in this hole then?
« Reply #36 on: 20.08. 2009 20:43 »
Elimination method? Gap checking: when contracted, do you have a correct gap on all rings ? And are they moving freely or is anyone stuck. Remove rings (read a little about 'how to' before breaking one!) and insert into respective cylinder using a piston to push them in, and measure gap in different parts in the cylinder. If all seems ok, then move on. What's your piston to cylinder clearing?

The marks on the piston may be signs of oil starving, do you have the conrod with the extra oil hole near the bottom, pointing inwards towards the centre of the crankshaft. Is sludge trap clean. Piston, may be just a polish job to salvage, if the cylinder bore otherwise looks ok.

At least some ideas to start with. Next suggestions, please.

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Online RichardL

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Re: What goes in this hole then?
« Reply #37 on: 20.08. 2009 21:37 »
Maybe the gasket leaks, but can't tell very well. Guides must be considered a possible source as well, having found no broken rings.

Don't forget, anneal the new head gasket (or, maybe, the used one, but better new) before putting it back together. It's a bit hard to see the scoring of the piston and excessive oil in the combustion chamber as related, assuming the ring gaps, as A10gf has mentioned, are correct.

Repeating - Next suggestions, please.

Richard L.

IN THE PICTURE, I MEAN "OTHER SIDE OF THE GASKET."
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Offline chaterlea25

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Re: What goes in this hole then?
« Reply #38 on: 20.08. 2009 22:59 »
Hi Simon,
A couple of things to check, as others have said re oil starvation,
Is the trough under the camshaft full of oil?
are there any scores on the cams or followers?
Have you removed the sump filter plate and gauze  yet?
Are there scores on the LH bore?

in one of the photos there is a lot of excess gasket goo on the primary case!
Is this the same goo that was used on the engine?
Excess goo can easily block oilways /gauzes etc

Look in the ports on the head and see if there is oil on the inlet valves/guides
also the same on the exhaust sides
Regards
John O R
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Offline trevinoz

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Re: What goes in this hole then?
« Reply #39 on: 21.08. 2009 03:40 »
Looks to me like seize marks.
Trev.

Offline cus

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Re: What goes in this hole then?
« Reply #40 on: 21.08. 2009 05:43 »
Mosin,
I'd agree with that, looks like it's been nipping up, you mentioned in earlier posts that it was getting hot,
you might want to have a good look at your timing, do you have a manual or auto R/Advance?
I just re-built a bike & had 3 peice oil rings made, if you can access them where you are, it might be
worth doing,

regards, Cus
56 G/Flash project

Online RichardL

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Re: What goes in this hole then?
« Reply #41 on: 21.08. 2009 06:03 »
Gents,

Everyone is talking about the siezing up, but the observed running problem was white smoke, which is normally diagnosed as burning oil. Of course, whatever is causing the siezing needs to be fixed, but, it seems to me, the oil burning might be a separate issue. The siezing may have been one isolated occurance in the past.  However, we are not seeing the bores. Perhaps the left bore is scored enough to prevent the oil scraper from doing its job. Ipso-facto, burning oil.

Richard L.
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Offline cus

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Re: What goes in this hole then?
« Reply #42 on: 21.08. 2009 07:23 »
Yeah, I think it probably wouldn't be bad advise, that now its apart to get those barrells looked at, maybe new pistons, rings, guides etc.


Cus
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Offline a10gf

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Re: What goes in this hole then?
« Reply #43 on: 21.08. 2009 07:38 »
Quote
problem was white smoke
A little off topic, my experience with engines: black smoke = fuel, blue smoke = oil, white smoke = ...water !

ps: has become quite a topic. I mentioned seizing in the 1st reply, which I believe usually has to do with an oil supply problem. Difficult job sorting it out, but to be positive, Simon, maybe look at it this way: it's not a problem, but an opportunity  ;) Lot's of insight will come out of this, and a well running bike.

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Online RichardL

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Re: What goes in this hole then?
« Reply #44 on: 21.08. 2009 08:09 »
E,

You are correct. I was wrong to refer to white as oil, but I just assumed Simon was using "white" loosely.

Richard L.
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