The BSA A7-A10 Forum

Technical (topic titles must be descriptive) => A7 & A10 Engine => Topic started by: wardleybob on 27.06. 2013 15:42

Title: re build
Post by: wardleybob on 27.06. 2013 15:42
Hy every one I need advice (or a hammer) I have rebuilt a rocket goldy rep hole bick and engine. Every thing done mag carb ex.
Some times it starts second kick. It runs beautifully.  It will restart hot or cold.then it will not start if I take the plugs out dry them
It starts again. I have had the mag rechecked it is perfect. It has a alloy head and I have got ngk es6 plugs in. Any thoughts
Would be appreciated. Wardleybob.
Title: Re: re build
Post by: Motoanimal on 27.06. 2013 16:45
Wardlybob, You are not too clear on the temperature of the engine when it won't start? If hot starting is the issue and the plugs are wet then you need to suspect the float needle valve in the carb not seating properly. If it is running rich anyway this will further exacerbate the problem (hey that’s a good word anit it!! *smile* 'Exacerbate' I like that!) sorry where was I? Oh yeah, if she starts from cold with no ticking (my missus doesn’t!)  or choke if you have one, she is certainly too rich (Also unlike my missus unfortunately!) Try turning off the fuel when you expect not to be able to start her, if that makes sense?

Also make sure you don’t have resistor caps for the plugs.
Title: Re: re build
Post by: bsa-bill on 27.06. 2013 18:10
are any of you good chaps married to or know someone who works or hobbies in the dark art of pottery.
I'm wondering if there is a spray on glaze that I could spray up into the plugs nether region to give some degree of impervious  osity (my spelling checker baulked on that one) .
Your following my reasoning I hope, glaze should be up to the temps involved do you think and wet plugs would wipe dry or maybe not wet so much anyway
Title: Re: re build
Post by: gavinoz on 27.06. 2013 22:37
bsa-bill, my f-i-l is a potter, what temperature do you think it operates in there? gav
Title: Re: re build
Post by: muskrat on 28.06. 2013 08:18
About 2500 C  *eek*  http://wiki.answers.com/Q/What_is_the_average_temperature_inside_the_combustion_chamber_of_an_internal_combustion_gasoline_engine
The plugs would be around 500 degrees C.
Cheers
Title: Re: re build
Post by: gavinoz on 28.06. 2013 09:37
The f-I-l sais that he doesn't know of any "spray on" glazes. most glazes are fine powders that one mixes with water then paints on. (so possible with a very fine paintbrush?) the plugs would have to be 'fired' in oven before use, around 800 - 1000 degrees C. then they should be OK.
Not sure if I could be bothered! *dunno*
gav
Title: Re: re build
Post by: BSA_54A10 on 28.06. 2013 10:26
About 2500 C  *eek*  http://wiki.answers.com/Q/What_is_the_average_temperature_inside_the_combustion_chamber_of_an_internal_combustion_gasoline_engine
The plugs would be around 500 degrees C.
Cheers

Plugs well the outer electrode at least runs red hot so we arein the 700 deg C + range
Title: Re: re build
Post by: bikerboy on 29.06. 2013 03:00
If its any help what you do after a rebuild is kick it over forever and eventually cry a lot :)

Well that's what I did for a week anyway  *smile*
Title: Re: re build
Post by: wardleybob on 01.07. 2013 19:38
Hy I have been away for a few days I kicked it over and it started 3rd kick. It ran and ticked over lovely.I waited a few hours
And tryed again nothing..I cleaned the plugs and it eventually started. Dont know what to try next. Perhaps the carb.
Title: Re: re build
Post by: morris on 01.07. 2013 20:42
Had exactly the same symptoms on my A10.
sometimes it started first or second kick, then it needed 5 or 10 kicks, wet plugs etc.
I suspected the carb, so cleaned it several times, moved the needle up and down, got a new pilot jet etc...
All to no avail.
In the end, as it was the wrong type of carb anyway and I got fed up with it, I forked out for a new one.
Cost me about £170, but boy, did that make a change.
It has now become a first kick starter whether hot or cold.
Title: Re: re build
Post by: muskrat on 01.07. 2013 22:20
I'd say a carb issue, a B6ES is hot enough a 5 might be too hot once it starts and runs.
What carb have you got? Choke or no choke?
Common carb issues are Float/fuel height, float needle not seating, blocked pilot, worn slide and/or body, air leaks.
Cheers
Title: Re: re build
Post by: wardleybob on 02.07. 2013 16:17
Thanks lads I have cleaned the carb In a ultrasonic cleaner £20 00 from aldi hope to try it before the weekend. It is a 379
Monoblock 1 1/8 chock size whitch I think is big. Also the main jet is 400 would this effect starting. I hope to work out how to
Take a photo and I will post it. Cheers wardleybob.
Title: Re: re build
Post by: muskrat on 02.07. 2013 21:30
To post picture  http://www.a7a10.net/forum/index.php?topic=427.0 and  http://www.a7a10.net/forum/index.php?topic=2545.0
Main jet and venturi (choke) size won't affect starting. All items I posted will.
Cheers
Title: Re: re build
Post by: Topdad on 03.07. 2013 11:26
Hi Bob, this sounds sooo rememisant of mine following it's rebuild 8-9 yrs ago. I had an old 389 mono which had ,I think a 420 main ,it always started but never cleanly ,if you get my drift and was a pig to ride ,so much so after 35 yrs since riding anA10 I thought either my memory was at fault or they were simply to much for me. It only cleared once when I took a real fistful at about 45 mph ,it simply coughed and banged once then shot of like a completely different beast and then once slowed became the old cow it had been .I changed the carb for a concentric and bingo now and since 1 st kick starter even after the winter lay off . S o don't give up ,check everything as per Musky's advice then if still p*****g about try a new carb, best of luck Bob.
Title: Re: re build
Post by: wardleybob on 03.07. 2013 22:05
Hy lads I have got it going . I put the carb back on and it started relucktly. Then I was back to normal it would not start . My mate lent me his carb hey presto a different bike. So I striped my carb again it was then I noticed the difference . Some one has drilled the pilot jet out it looked huge . I replaced it with my mates
And it is spot on.thank you for your help and ideas especially musky cheers photo to follow I hope
Wardleybob
Title: Re: re build
Post by: muskrat on 04.07. 2013 09:11
Do you mean the fixed pilot jet ( at the bottom of the pilot screw hole?
If so you can use the screw in pilot jets in the float chamber. Either a 20 or 25.
Cheers
Doh, just saw you have a mono. Above is for a concentric. Sorry.