The BSA A7-A10 Forum

Technical => A7 & A10 Engine => Topic started by: Gerry on 16.09. 2015 11:52

Title: Ongoing saga of the a10 missing on one cylinder
Post by: Gerry on 16.09. 2015 11:52
OK guys, at last I have got the A10 Flash running like it should but only done a couple of hundred miles on her so far. I had removed the head as it was also blowing smoke from the left hand exhaust. Took the barrel off and found I had caused a piece of the oil ring to break off when reassembling. A friend with much more knowledge than I was visiting at the time and checked the side play of the conrods and said they have too much side play as in rocking side to side.....so out came the bottom end and let him have it to see if he could correct the problem. To cut a long story short he had to get the crank reground, new timing side bush, new three piece oil rings (machining of the pistons for this), new main shaft roller bearing and bigend shells. Apparently I had not managed to get all the media out from the vapour blasting and it had ruined all my hard work. He also chucked out one conrod and replaced it. Got the barrels honed and reassembled and hopefully now I can enjoy the bloody thing....Still have a small problem with starting when hot, got to give it a fistfull to start it so have ordered a smaller pilot jet size 15 to see if it will cure the problem as starting cold after tickling the carb and she starts usually first kick. Oh nearly forgot ...got an oil leak from the tee piece in the pipe that feeds the rockers, looks like a bad braze job. Will replace the feed pipe. Cheers all Gerry
Title: Re: Ongoing saga of the a10 missing on one cylinder
Post by: Greybeard on 16.09. 2015 12:35
It's good to hear that the old girl is coming back together. After reading recent posts, I have to ask; have you cleaned out the crankshaft sludge trap?  *contract* (this is a bloke pointing to the workshop manual)
Title: Re: Ongoing saga of the a10 missing on one cylinder
Post by: morris on 16.09. 2015 13:05
Still have a small problem with starting when hot, got to give it a fistfull to start it so have ordered a smaller pilot jet size 15 to see if it will cure the problem as starting cold after tickling the carb and she starts usually first kick.

If, apart from that the bike's running ok, I wouldn't mind. Both my plunger and SA need about 1/4 to 1/2 of throttle when hot, but start first kick on closed throttle when cold
Title: Re: Ongoing saga of the a10 missing on one cylinder
Post by: chaterlea25 on 16.09. 2015 13:13
Hi Gerry,
I hope you gave the oil tank a real good cleaning  before you ran the engine again *????*

Is there a heat insulation spacer between the carb and head? get a tufnol one, the soft ones are crap!!!

A 15 pilot ??  I am pretty sure this will cause problems? check the fuel level in the carb before doing anything else

HTH
John
Title: Re: Ongoing saga of the a10 missing on one cylinder
Post by: duTch on 16.09. 2015 23:22

 Nice one Gerry, happpy riding...I'll second GB re sludge trap.
 It's taken me a while to get the jetting right too (tried 15 20 & 30 pilots, but settled on 25), still not perfect but runs fine and starts easy hot or cold, don't generally even need to tickle it from 'cold'...maybe experiment a bit with plugs?
Title: Re: Ongoing saga of the a10 missing on one cylinder
Post by: Gerry on 17.09. 2015 02:17
Hi Guys, Yes the sludge trap was cleaned out as was the oil tank although I didn't split it like when I first got the bike (the oil tank had been grit blasted without sealing any of the orifices!!) Just washed it out with petrol a few times until it came out clean then with hot soapy water, then jet blasted it. I am still going to fit a oil filter to the return line as soon as I can get one. As for the pilot jet, I shall experiment with sizes until I can get it right, may also mean a different slide cutaway, who knows. BUT..all in all she LIVES AGAIN!!! Cheers. Gerry
Title: Re: Ongoing saga of the a10 missing on one cylinder
Post by: Triton Thrasher on 17.09. 2015 06:46
...when hot, got to give it a fistfull to start it so have ordered a smaller pilot jet size 15 to see if it will cure the problem as starting

That doesn't sound like a problem at all. Don't fix it.
Title: Re: Ongoing saga of the a10 missing on one cylinder
Post by: Gerry on 17.09. 2015 07:29
Nah, want it to start hot or cold first or second kick no handfull. lol
Title: Re: Ongoing saga of the a10 missing on one cylinder
Post by: Triton Thrasher on 17.09. 2015 18:01
I don't know what you mean.

Does it not start first kick?

Is it important to you that it starts with the throttle closed?
Title: Re: Ongoing saga of the a10 missing on one cylinder
Post by: Gerry on 18.09. 2015 00:28
I don't know what you mean.

Does it not start first kick?

Is it important to you that it starts with the throttle closed?

Hi Triton Thrasher,
Yes I would love it to just start without it reving like hell when I start it warm. Nothing more satisfying than just a kick (or maybe two) and have it gently burble into life, although when stationary it ticks over good with or without selecting neutral. Before this rebuild I had trouble selecting neutral as well, and found the clutch basket was dragging with the primary chain off. Found a few of the clutch basket roller bearings were a few thou' longer than others. Replaced them with ones a little shorter and all came good. So worth looking into if you have a neutral getting problem. Cheers. Gerry
Title: Re: Ongoing saga of the a10 missing on one cylinder
Post by: muskrat on 18.09. 2015 05:29
So, you want it to start like a modern fuel injected beast. You'll need a http://www.startyourbsa.com/  as well. Just kidding mate.
Most old bangers I know just need a little throttle when hot. The ones that rev are posers. *red*
Cheers
Title: Re: Ongoing saga of the a10 missing on one cylinder
Post by: Gerry on 18.09. 2015 08:31
Hi Muskrat, Nah, just want it to start like a BSA should.....I'll get there don't you worry. If I can put up with all the problems I've had so far then this is just a walk in the park. lol Cheers. Gerry