BSA Owners' Club Workshop Discussions

The BSA Workshop => Twins => Topic started by: Willie Dee on 30 Aug, 2019, 16:58

Title: A65L Engine noise.
Post by: Willie Dee on 30 Aug, 2019, 16:58
Hi all, my Lightning has a dry,scraping bearing noise from the engine. Tracked it down to the front of the primary cover where the alternator lives. Before I dig in any clues to what the possible issue is? Cheers.
Title: Re: A65L Engine noise.
Post by: A10 JWO on 30 Aug, 2019, 17:59
Could the chain be stretched ?
Title: Re: A65L Engine noise.
Post by: JulianS on 30 Aug, 2019, 18:12
Rotor rubbing on stator?
Title: Re: A65L Engine noise.
Post by: Willie Dee on 30 Aug, 2019, 18:22
Yeh it sounds like something rubbing on something,what's the crack with this possible?
Title: Re: A65L Engine noise.
Post by: Splodger on 31 Aug, 2019, 09:39
Could be that the friction pad on the chain tensioner is worn through? Whatever is scraping away in there will probably contaminate the oil within so you might as well nip the cover off and have a look-see. Check 'noises' when you take your plugs out and spin her over a few times. Tensioner replacement is a two- minute job (plus £20). Have good cleanout of all the gunk in the chaincase whilst it's off. Don't over tighten the chain tension when/if you replace it. Use the recommended grade and quantity of oil when you've reassembled everything.
Title: Re: A65L Engine noise.
Post by: bikerbob on 31 Aug, 2019, 12:43
Whenever you here noises like that you should investigate straight away. Last year I had peculiar noise coming from the primary on my 1963 A65 I left it for only a week doing only about another 30-40 miles. On strip down I found that the Stator had been catching the rotor which resulted in heat which melted some of the green insulating material in the stator coating the inside of the primary with large amounts of burnt material, this ended with having to purchase a new stator and rotor and a complete strip of the primary and thorough clean out. What made this happen I am not sure as the stator and rotor had been running OK for about 4 years the only thing that I did notice was on the undamaged parts of the stator insulation it had some quite large cracks I assume these cracks allowed the stator to move slightly thus causing the problem.
Title: Re: A65L Engine noise.
Post by: berniej on 31 Aug, 2019, 18:06
In case it helps - the nut securing the LH rider's footpeg is a left hand thread.

Cheers,
Bernie
Title: Re: A65L Engine noise.
Post by: Willie Dee on 01 Sep, 2019, 15:13
Stripped off the casing and no debris inside,dug in further and found this scoring on the rotor. One of the stator mounting studs was bent and loose so reckon they have been making contact.
Title: Re: A65L Engine noise.
Post by: Willie Dee on 15 Sep, 2019, 15:53
Just an update on this,fitted the new studs and built everything back up but the rotor was still contacting the stator,slight adjust with a block of wood and a 2 pound ball pein adjuster and all is good,clearance all round. Finished off the rebuild, started it up and.......pause for effect......no scraping noise,so happy at that as it was annoying the sh&t out of me.