been keeping my self busy

[chicago]

hi folks, not been on here for a while, just thought i'd keep you all updated on what ive been upto.
well first was the clutch basket. after i took off the chaincase to have a poke around i noticed a bit of play in the clutch basket (clutch center solid as a rock with no play) so pulled off the clutch and found that instead of having the standard roller bearings somebody had decided to mix an match them, so off to lightning spares (just down the road from me) and a quick word with brian who owns the shop and knows all there is to know about bsa, and i come back with a nice new set of roller bearings, fitted them in and hey presto far less movement in the clutch basket, still a little but nothing to write home about. well the fun really began when it came time to tension the clutch springs, i would leave the chaincase off and run the engine and try the clutch and the bike would go in gear fine with no crunch and no clutch drag, but when i put the chaincase back on and put oil in it and try it' it  would then crunch into gear and pull forward ??. well the fun went on for a couple of days with me taking off and putting on the chaincase (five times in total) but due to trial and error with the tension of the clutch springs i am pleased to say ive now got it spot on. well that was fun.

the next job on my list was to have a poke round on the timming case side. and when i took the case off i noticed that the dynamo drive chain was catching on the casing due to half an inch slack instead of a quarter of an inch. re adjusted the chain and put the case back on and resulted in a less rattley engine. i think the chain and sprockets could prob do with changing soon though.

i also changed the oil, cleaned out the oil tank, cleaned out the presure relife valve which had the wrong spring and ball fitted, new ones now fitted. and cleaned the sump filter.

and finally the oil leek from the front of the head gasket. well to cut a long story short i took the rockers off and the 3 head bolts under the front rocker box were finger tight, so a bit of a miracle the bike ran at all. i was going to re-tighten the bolts but as i'd already bought the gasket set ive gone for the head off option. ive now taken off the head and had a quick look at the pistons which are +060 and as i understand it from looking on the forum the barrels have had their last safe re-bore before the walls become to thin ???. ive also had a quick look at the condition of the barrel bores and they look very good with no scoreing and no lip at the top but with the piston in situ and the piston rings in place there does seem to be a little free play backwards and forwards, its not much but how much can there be to get away with ????.
anyway all the best folks and take it easy. chicago

[duTch]

Chicagogo,
  I'm impressed that you've made those discoveries, I'm personally rough-as-guts, and if the pistons aren't rattling/slapping too much I'd use them under duress, but others will be more qualified to give good info.
  Just make a note of how much you've adjusted in the clutch springs, so you have a reference point.
 As has been discussed elsewhere, do a few revolutions of the timing chain, to ensure there are no tight spots.
Re- leeks growing in the rocker box?  o..k.., and I like the 'relife' valve fix too.
 Won't be long before you have a full blown race motor I reckon>

  No serious, good to see you in touch with the goings on, and it keeps you off the streets till you're again licensed

Cheers duTch

[chicago]

hi there dutch, cheers fella. its going to have to go back together anyway as no money for replacement barrle or new pistons so fingers crossed it will be ok for the foreseable future, there is a slight rattle when the bike is just bearly ticking over but stops when you increase the revs, i thought it was the dynamo chain as it did get better with the chain adjusted. the bike dosnt seem to be burning any oil or loseing any from the oil tank, although ive not yet ridden ridden the bike. there also dosnt seem to be any oil burning smoke coming from the exauste. so maybe not that bad ?.

i did just go and measure the gap between the barrel and the top of the piston with the piston roughly three quarters of an inch from the top of its stroke and there was 0.25mm gap between piston and barrel. it says in the haynes manual that anything over 0.010 and it needs rebore, if google is right 0.25mm =  0.00984251969 inches, which confused me even more (never been good with mm or inches).

"Just make a note of how much you've adjusted in the clutch springs"
 already done fella 7 an 3quarter turns on each spring which doesnt seem a lot when haynes manual tells you to screw in the springs untill you can just start to see the thread come thru the top of the nut ?.
"do a few revolutions of the timing chain, to ensure there are no tight spots"
didnt think to do but will do now when i take the case back off,
" Won't be long before you have a full blown race motor I reckon>"
or maybe just a full blown engine  .
all the best dutch, chicago
p.s. is 0.25mm acceptable wear ??

[Brian]

Hi Chicago,
               the gap between the top of the piston and the bore doesnt matter. Pistons are a smaller diameter at the top where the rings go than lower down on the "skirt". The only way to measure the clearance where it matters is to remove the barrels and pistons which in your case there is no indication that there is a problem.

If the motor was not using oil and there is no or almost no lip at the top then I would leave it alone. Dont fix it if it aint broke.

If by chance you replace the generater drive chain at any time be sure to ask for a chain for a longstroke motor, they are different to the later ones.

[duTch]

Chicargogo,
                One metre = 39.37..+..inches.Therefore, 1 mm=0.03937...." (that's 39.37thou, close enough to 40thou) which means 10thou is close enough to a quarter(.25) mm (0.00984251969 inches-what you said), so seems you're close to the money!!
  Also with the clutch springs, check number of coils(winds) and the free lengths and wear on the sides , and if there is a considerable variation in length, try and distribute/balance them evenly? (new springs'd be better if extreme- not sure of stock length).  There's more to springs than we usually think!!
 There's been a fair bit of chitchat about the dynamo hum chain, on here, and worth researching, and also worth keeping in mind a belt conversion.
    Ciao for now duTch

[chicago]

sorry for the late replie dutch but been really busy with one thing or another. cheers for the help though, the clutch now seems to be really good after a lot of trial and error. ive now had the barrels and pistons down to lightning spares and brian had a look at them he he thinks in an ideal world i should change the pistons and rings and i should be ok, but i got a price for +60 pistons and they were £300  i think im going to go down the re-sleeve to standard size and standard size pistons route as it might work out better. i had a qute for a re-sleeve from a place in birmingham and they quoeted £175 and if i could pickup some new standard size pistons for around £100-£125 it still works out at the same money but i would have a machine with a virtually new top end. and i would then be able to have it re-bored when needed in the future.  but im affraid the old girls going to have to wait a while before anything happens as i'm skint at the moment. all the best dutch, chicago

[chicago]

hi there brian, barrels now off, will check but thinking of re-sleveing now though. but if there isnt that much play/gap at the bottom of the bore/piston then maybe i can save myself a bit of dosh  . i will keep you all updated when i get time to check the gap. all the best fella's and thank you to everybody for the advice, it certainly make's owning a bsa a lot less worrying for a novice mechanic like me, chicago