Time for a rebuild

[RichardL]

Sorry, I couldn't resist the challenge. You can ship 45 kilo (edit: probably more than you have)  from Tonbridge to Aberystwyth for about 60 GBP, round trip (myHermes). Seems you would still be better off by about 120 GBP. Otherwise, look up Andy at Leigh Classics in Leigh-On-Sea. Minimally, he can mic your bores, but could do the work, as well (he might farm out machining). Tell him Richard from Chicago said hello. I'm still waiting for my free RGS replica for recommending his shop.

Richard L.

[BSA500]

Sorry, I couldn't resist the challenge. You can ship 45 kilo (edit: probably more than you have)  from Tonbridge to Aberystwyth for about 60 GBP, round trip (myHermes). Seems you would still be better off by about 120 GBP. Otherwise, look up Andy at Leigh Classics in Leigh-On-Sea. Minimally, he can mic your bores, but could do the work, as well (he might farm out machining). Tell him Richard from Chicago said hello. I'm still waiting for my free RGS replica for recommending his shop.

Richard L.

Richard if I use Andy I will be sure to tell him to ship your RGS directly.

[morris]

I will get a quote from SRM but even though I am in the UK the postage costs there and back will still be steep. Them old crankshafts and barrels are bloody heavy old things :)

  This is how I do it; take the wife on a trip to the (Welsh) coast, and when arriving, well I'll be damned, by accident you have the engine in the back of the car... bit stupid then not to have a quick drop by at SRM, no?

[BSA500]

Hmmm nice idea, but my chances of survival would not be good I think 

[Topdad]

Do it over a weekend , get there friday have alook round the workshops (and be impressed ) even your better half will be surprised and then you're free to look at the wonderful countryside around there combined with great pubs and restaurants so I'm told . Also have you considered the end feed conversion for the bike , well worth thinking regards Bob

[Duncan R]

Not sure if you have 4 wheeled transport but I got all my work done at T&L Engineering in Bedford,only a 90 min trip from North Kent. The work was excellent ,on time and a fair price.

[BSA500]

I have a few irons in the fire so to speak. I remembered that where I first had her rebuilt is still open in a roundabout way. I first used Vic Millers in Hastings to have the bottom end rebuilt and a little later the cylinders were resleeved(20 years and 50,000 miles ago). The shop is still there doing classic bike rebuilds they are called Cosmo Motorcycles.
More investigation of the big ends shows more wear/movement in the timing side which is a little strange seeing it gets the oil first hey ho

[terryg]

Another satisfied customer of T&L (Elstow, nr Bedford) here. Good communication and they did what they said they would at the price quoted. They also pointed out what did NOT need doing.

[BSA500]

So took the crank out so more pics...



Damaged shims



Timing bush



Big end shells note hardly any wear so good news and from rough measurement no wear to the crank





But the timing side of the crank looks like it may need attention. That looks to be some timing bush shavings

[BSA500]

Ok did some measuring,big ends are fine. Checked the timing side journal and it measures 1.366 inch so what timing bush size would be suitable -10?

[beezermacc]

Standard size is 1.375 so logically -010 is 1.365. If yours measures 1.366 that suggests it has been ground down once and there is little or no wear. You need to check for ovality i.e. that the up/down measurement is the same as the front / back measurement. Also make sure there isn't a lip on the outside of the journal. If everything meausures OK a -010 bush should do the trick. Obviously it will need reaming to ensure roundness and fit. As an aside I usually have the timing side journal ground round, regardless of size and have a bush made to suit; this prolongs the life of the crankshaft because each cut is usually about 3 or 4 thou rather than the 10 thou required to suit a commercially produced bush.

[RichardL]

Well, Beezermacc was typing at the same time with some good advice beyond what I have here, but since I'm not contradicting in any significant way, I'll go ahead and post (having completed the thumb typing).


Since it costs no more, I would go with a -0.020" new bushing. I think this will put less stress on the machinist rather than starting with a sparce 0.007" to work with. This is how I see the numbers:

1.366" (timing-side OD) + .001" (bearing clearance)= 1.367"

If -0.010" bearing: 1.367" - 1.36" = 0.007" (to remove to match the crank journal)

If -0.020" bearing, then 0.017" to machine down. Of course, the machinist should know or be told to clean-up the journal (it seems grinding may not be needed, or, at least, not much), then ream the bushing for 0.001" clearance with respect to the journal, not according to the bearing's undersize rating (with no more than 0.0015" clearance, but you know that).

As always, and for good reason, I stand to be corrected and wear the dunce hat if this is proved to be spurious advice.

Richard L.
 
(I made a small edit, in light of Beezermac's advice.)

[beezermacc]

The journal measures 1.366, not the bush, so the journal is oversize which is good. If the journal does not need machining, as the initial measurements suggest a new bush at 1.365 will be 0.001" too tight, again which is good. If the journal is round (i.e. less than 0.001" oval - some people might expect it to be even better than that but I reckon 0.001" is the limit) there is no need to have it machined which would shorten the life of the crank. When the bush is fitted it will shrink a bit more so, after reaming about 0.002" the crank can go straight back in. No point in taking another 010 off the crank if it is not required. All this assumes further measurements confirm the journal is OK.

[RichardL]

I'm certainly not debating with you, Andrew, but just to be certain I was not misunderstood, I would like to expand on what I said. I noted that the timing side (journal) OD is 1.366". The specs I was reading gave the standard bush ID as 1.375" in some models, then, 1.37" for others. I just quoted the latter, figuring it didn't much matter based on my logic of removing more material. In my own awkward way, I was trying to say that the crank should not be reduced in diameter beyond establishing roundness and smoothness, after which the new undersized bush would be machined (reamed or bored, I'm not positive which). The last time I had a new bush fit I handed the machinist the new one that I had on hand, which was maximum undersized. I forget how much he had to remove, but it wasn't billed by the thousandth, so I figure why bother cutting it close with meat to remove.

Much respect,

Richard L.

(Man I make a lot of typos!)

[Triton Thrasher]

The straight scratches on the pistons look like what you get when the honing grit isn't all removed from the bores.

Use soap, hot water and a sponge, until the bores no loger put a black mark on a paper tissue.

Your rings may never have bedded in properly. Is it safe to say "dry assembly" and "cheapest oil" and "make the engine pull hard" for running in, around this forum?