Author Topic: engine wont run  (Read 2517 times)

Offline Tumbleweed

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engine wont run
« on: 15.05. 2013 15:30 »
hello everybody, i dont know wether you can help on this one, after a top end overall , rebore, new pistons/ rings ,valve grind ,clean carb, timing spot on new plugs,caps , leads,mag  pick ups,clean slip ring , ive been trying to get the ******* thing going for days now , all of a sudden (after a lot of kicking over) it will fire up and run rough for about 15 secs and then stop, and wont start again at all  i take out the plugs check the spark , clean the slip ring reset the points gap , and try again for ages the same thing all the time , i did have it running for about 30 secs once but i could not take my hand off the throttle to grab a screwdriver,        i think my leg is about to fall off *problem*  p/s i have searched the posts but cant get any info
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Offline TT John

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Re: engine wont run
« Reply #1 on: 15.05. 2013 15:38 »
Hi There

What bike is this we are talking about?  Have you checked valve timing?

TTJohn

Online bsa-bill

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Re: engine wont run
« Reply #2 on: 15.05. 2013 16:00 »
Quote
timing spot on new plugs
Quote
take out the plugs check the spark

Can be a torturous path working through what could be wrong. DAMHIK
These bikes should start after three kicks often less, if it doesn't your time is better spent working back through the things you've replaced, new stuff does fail unfortunately
Could do with a bit more info though - model and so forth
Some suggestions - no offense intended if you've already been through them  

timing can be spot on but on the wrong spot however if it has fired up and run for a short while the timing cannot be far out, unless it's moving - check magneto pinion AA unit points plate and cam ring are fixed.

all being well there, change back to your old plugs, a spark with the plug sitting on the crankcase does not necessarily mean there will be a spark in the combustion chamber and new plugs are notorious for giving up the ghost in the dark  or damp.

 the carb, are the plugs wet after kicking over, valve timing (easy to move the engine with the idler off again DAMHIK)

My stab in the dark would be plugs followed by carb - anyway best of luck with it and remember rest your leg after three kicks and exercise eyes and little grey cells

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 Tumbleweed

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Re: engine wont run
« Reply #3 on: 15.05. 2013 16:19 »
thanks, i will look at those things , there must be something i am doing wrong,  BSA A10 1954 , and the plugs are dry  mainly , sometimes damp.  cheers      TW
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Offline a101960

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Re: engine wont run
« Reply #4 on: 15.05. 2013 16:26 »
Given what you said, that the engine has run but only for short bursts, and that you have cleaned up the carburettor my inclination would be to make sure the pilot screw is set in the right position. Turn the screw in until it is fully closed, and then turn it back out one and a half turns.

John

Offline mayes

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Re: engine wont run
« Reply #5 on: 15.05. 2013 17:11 »
Hi back to basics check fuel carb is a good start check needle setting start on 3rd check pilot jet ensure carb is clean and clear
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Offline Tumbleweed

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Re: engine wont run
« Reply #6 on: 15.05. 2013 19:11 »
thanks,   i will start again  in the morning , i  never had old plugs with the bike, i dont know if both new plugs would pack up at the same time *sad2*      bill whats DAMHIK ?
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Online bsa-bill

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Re: engine wont run
« Reply #7 on: 15.05. 2013 20:50 »
Quote
, i dont know if both new plugs would pack up at the same time

If they both get wet at the same time they'll pack up at the same time, it has been known.
But carb seem the first suspect
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 muskrat

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Re: engine wont run
« Reply #8 on: 15.05. 2013 20:57 »
DAMHIK = don't ask me how I know = Doh I made that mistake.
Sounds like she's not getting enough fuel. Tank taps or filters blocked. Fuel hose restricted/melting from ethanol fuel. Needle and seat blocked. Float sticking up.
Cheers
'51 A7 plunger, '57 A7SS now A10CR,  '83 CB1100F, 88 FXST .
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Offline morris

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Re: engine wont run
« Reply #9 on: 15.05. 2013 22:25 »
Noticed you put on new caps. They are not by chance suppressor type? I made that mistake, and after going back to regular caps, the spark was noticeably fatter. A DAMHIK would not be out of place here.
How did it run before the overhaul?
My A10 was getting more and more starting and rough running problems, and in spite of cleaning the carb twice, and changing all the carbs gaskets, it kept on getting worse.
As it was worn, and not the correct type anyway, I bit the bullet, and ordered a new one. At first I had to fiddle a bit with different pilot jets and needle settings, but since getting that right, it never ran any sweeter as it is now.
Just remember; there's a solution to everything wink2
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Offline orabanda

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Re: engine wont run
« Reply #10 on: 15.05. 2013 23:50 »
I would try changing both plugs, having also fouled two new plugs at start-up before.

Richard

Offline wilko

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Re: engine wont run
« Reply #11 on: 16.05. 2013 00:40 »
What carb. Blocked pilot jet.

Online Topdad

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Re: engine wont run
« Reply #12 on: 16.05. 2013 13:18 »
I'd noticed the caps mentioned like Morris so that may need looking at however if all the associated info given above doesnt work it will be back to basics. whizz the tappet covers off  and whilst checking Ing timing make sure the valves are closed . If that checks out can you borrow a spare carb ?, by then you'll have checked fuel flow from tank as per Muskys thoughts and another carb would at least take the carb out of the equation. A bit drastic but if you can't borrow a spare  how about a squessy bottle of fuel and squirt some direct through the carb only have an extinguisher handy just incase. As already said there is a solution ,  it can only be a) mechanical :- valve timing ,lack of comp.
                                    B) electrical :- mag leads plugs
                                    c) fuel   :- carb fuel taps
                                    d) restricted exhaust.
 just thought of another problem I saw once ;the bolt holding the points to the mag also hows the keyway and just by chance the bolts not dirty at the contacpoint or have a fibre washer fitted to it .I once saw a bike kicked for ever which a kind sole had fitted a fibre washer on that bolt and isolated the points from the mag ,may be completely wrong but have a look   
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Offline A10 JWO

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Re: engine wont run
« Reply #13 on: 16.05. 2013 17:51 »
Does sound like those drilled out pilot jets are blocked, see the thread I started on this, loads of good input from the lads.

Regards Colin

Offline Tumbleweed

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Re: engine wont run
« Reply #14 on: 17.05. 2013 08:49 »
just put a new pilot jet in the other day colin , i am going to get some more plugs to day and start again from the beginning as suggested, the springs on the aa unit dont seem very strong to me i suppose that could be another prob , i dont know anything about the engines history, just getting it running long enough to listen to it would be a bonus  ,   cheers and thanks everybody for your help as well
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