Author Topic: what could happened???  (Read 5921 times)

Online RichardL

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Re: what could happened???
« Reply #15 on: 22.09. 2009 18:48 »
Moto,

Thanks for adding your thoughts. Just to clarify, the bike is Emilios', in Cyprus. I have just been, cautiously, trying to help.

Richard L.
Plan on signing up for the world-wide 2017 DISTINGUISHED GENTLEMAN'S RIDE on September 30, 2018. Watch website at https://www.gentlemansride.com for details.

Offline beezalex

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Re: what could happened???
« Reply #16 on: 22.09. 2009 19:22 »
Before you start throwing money at this thing, you need to figure out why it died.  You said compression was the same...same as what?  It still had compression?  A head gasket leak will not make it die unless it's REALLY bad on BOTH cylinders.  So, that leaves fuel and spark.  Particularly sudden dying without any unusual noises means one of two things: 1) you ran out of fuel or 2) it stopped sparking.  Even when you run out of fuel, it usually sputters, so 2) best describes your symptoms.  This can easily happen when your point gap adjuster screw comes loose and finally backs off enough to hit the post.  Boom, it just stops.  Ask me how I know. *sad2*

Anyway, take your time and figure out what really happened before you tear it all apart.
Alex

Too many BSA's


Offline A10Boy

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Re: what could happened???
« Reply #17 on: 22.09. 2009 20:14 »
Don't worry Richard, he probably wont sue you...   ;)

I think you could have found your problem more easily before you took the head off. But since it is off now, you should take Richards advice and pull the barrels off and check pistons, bores etc and at least renew the rings. I think that's where your oily problem is coming from.

I don't think its a bad head gasket, oil is usually blown out not sucked in. When was the last time it had a de-coke? Whats the quality of petrol like in Cyprus ?

Only replace valve guides if they exceed the tolerance, then stick it back together and run it. If it stops again, check the usual, mag, carb etc.
Regards

Andy

1960 A10 - Black Golden Flash
Plus
1974 Kawasaki Z1a
Yam XJR 1300

Offline emilios

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Re: what could happened???
« Reply #18 on: 22.09. 2009 21:05 »
Thank you all guys for help..
Well petrol in Cyprus is unleaded 95..
I have my A10 for about 2 years...When i bought it from England it was in running condition..the only problem was points that i renew and head gasket too...
Since then i travel all the island with no problems..
The day that bike stoped was strange cause i had a 40miles trip at morning,i came back and after 8 hours i start bike to go somewhere,,after 200meters bike sudenly stoped...
The only thing that i can think is a loosen mag pilion and spark at wrong time...cause after engine stoped i was trying kickstarting her and sometimes almost start for a coople of turns..
Anyway i know now that i shouldnt pull head off but i did..and i saw that black piston on left..i think i will pull barrel off too and check piston rings and pistons..maybe its time for a rebore.
I checked before spark on plugs with a tester and looks fine on both sides..
Any other thoughts
1956 BSA A10 Plunger
1954 BSA B31 Goldstar Replica
1970 Honda cb750K0 project
Cyprus

Online RichardL

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Re: what could happened???
« Reply #19 on: 22.09. 2009 22:01 »
Emilios,

It's a brain teaser that probably has an obvious solution, but you insist spark is good, you are getting fuel and you have normal compression. Adding a few more possibilities, now for fun:

1. On your 40 mile trip, did you run low on gas and, maybe, suck in water that was there from a previous fillup or other event?
2. Did you refill on gas from an unknown and, maybe, questionable source?
3. Is your float stuck one way or the other?
4. Is your fuel filter in the carburetor clear.
5. Was your check of the spark recent enough to know it is not the mag condensor gone bad from the heat on your long ride? Maybe this hangs the spark only when trying to recharge faster than when you kick it.
6. Is your fiber magneto gear stripped of a few teeth?
7.
8.....
200.

If, somehow, one of these is the reason, I'll faint. Then I'll get up and stick my chest way out and strut around with plumage fully deployed. No, really, I'll claim it was dumb luck and that only through the exhaustive advice of our other members do I know anything at all, which would be mostly true.

Richard L.
 
 
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Offline emilios

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Re: what could happened???
« Reply #20 on: 04.10. 2009 10:18 »
Hi
I removed today cylinder and pistons
Engine was fitted with +40 pistons so im going to +60..
Im wondering how much the total side play of connecting rod should be?
Mine is 3mm
Do i have problem?
thanks
1956 BSA A10 Plunger
1954 BSA B31 Goldstar Replica
1970 Honda cb750K0 project
Cyprus

Online bsa-bill

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Re: what could happened???
« Reply #21 on: 04.10. 2009 12:06 »
more knowledgable members than I will probably comment but having stripped and rebuilt two A10 engines I'm not sure 3 mm is that much out, I'm assuming you mean 3mm sliding the conrod across at the big end, rocking the conrod 3mm at the little end is more of an issue probably
There has to be some movement when you think about it, things like shimming on crank, wear on bush side/bearing sides and tolerance for casing machining all add up to needing some sideways allowance if the con rod is going to push the piston up free of any side pressure.
Will be interesting to hear from anyone who knows what the limmits are ( but I'm not stripping my engine down again as it's running fine )

All the best - Bill
All the best - Bill
1961 Flash - stock, reliable, steady, fantastic for shopping
1959 Rocket Gold Flash - blinged and tarted up  would have seizure if taken to  Tesco

Offline Josh Cox

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Re: what could happened???
« Reply #22 on: 04.10. 2009 12:34 »
3mm on the gudgeon pin or big end on the crank ?, I would not imagine that would cause the engine to stop ?.

I believe the piston is supposed to be able to move laterally on the gudgeon pin, if you have a big end or little end problem, that would be evident with knocking or metal in the oil.

If the pistons are sucking and pumping, the valves are opening and closing when they are supposed too, you've got fuel and spark at the correct time, the engine should run.

The piston gaps are unlikely to cause a unexpected engine stoppage unless they seize.
Black 1953 Golden Flash Plunger

Offline emilios

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Re: what could happened???
« Reply #23 on: 04.10. 2009 13:17 »
My problem should be 99% spark at wrong time cause magneto sprocket pinion loose..
But i striped engine anyway.
So im just asking if 3mm total sideplay of conrod to crank without piston on should be problem.
   





 
1956 BSA A10 Plunger
1954 BSA B31 Goldstar Replica
1970 Honda cb750K0 project
Cyprus

Offline Josh Cox

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Re: what could happened???
« Reply #24 on: 04.10. 2009 14:03 »
I believe a black piston on the left is not unusual, perhaps a bias problem, i.e. the amount of fuel making it to the cylinders is not equal.

If the LH piston is black, I'd hazard a guess at the LH side running rich or bad spark on that side.
Black 1953 Golden Flash Plunger

Offline a10gf

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Re: what could happened???
« Reply #25 on: 04.10. 2009 14:08 »
Quote
magneto sprocket pinion loose..
welcome to the club  *smile* see this.

Conrods, afaik some sideplay is permissible, don't know how much is too much.
Look for up and down play, after cleaning away all oil.

A10 GF '53 My A10 website
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Online RichardL

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Re: what could happened???
« Reply #26 on: 04.10. 2009 14:22 »
Emilios,

Take a look at these two videos I posted a while back. The first shows excessive wobble at the piston end of the rod. (Ignore where I say they Plasitigage to 0.001"-0.0015", because I think I messed up the Plastigage process.) In the second video you see the correction using new rods. There is a video between these in the "series," but that was a mistep. In these videos you can see the  conrods moving side-to-side on large diameter big ends and it is quite a bit less than 3mm, which, I think, is too much. I can imagine that there could be excessive side-to-side play if the ends of the crank pins are not radiused where they meet the body of the crank.  The radius is necessary to avoid stress fracture in the crankshaft. My experience is with large diameter A10 crank only. Others might comment if other cranks allow more play.

Richard L.


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Offline emilios

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Re: what could happened???
« Reply #27 on: 04.10. 2009 16:43 »
Sorry again.My rods total sideplay is 3mm on top side(gudgeon pin)
Is that regular?
1956 BSA A10 Plunger
1954 BSA B31 Goldstar Replica
1970 Honda cb750K0 project
Cyprus

Offline muskrat

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Re: what could happened???
« Reply #28 on: 04.10. 2009 17:19 »
G'day Emilios, 3mm rocking at the little end is good, side play at big end should be about 0.010". Throw the pistons,rings & guides in and triple check timing. If you can get your hands on a colourtune check for induction bias.
Cheers
'51 A7 plunger, '57 A7SS now A10CR,  '83 CB1100F, 88 FXST .
Australia
Muskys Plunger A7

Offline rocket man

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Re: what could happened???
« Reply #29 on: 04.10. 2009 19:10 »
i would think side play is ok
its up and down thats important
because thats where the most stress is



dave