650SS to Atlas conversion

Hi Ian, The crankcase, flywheel,barrell,pistons and head are different , like me you need a lot although the crank shaft halves and rods are the same. If only new 600/650 barrels were made (preferably in alloy with a liner or ceramic coating) then the 650's life would be assured as rods and pistons are made still. The 88/99 motors need their own rods and appart from the Thunder Rods they have had no new supply since 1963.

Previously ian_cordes wrote:

Robert Tuck's thread on a 99 to Atlas conversion has made me wonder about the viability of installing Atlas barrels and pistons to my 1964 650ss motor, which one might think should be more straightforward.....? It has a 3-start pump set-up at present. The bores are + 0.040", I think the piston fit is a bit sloppy, and it breaths hard. Thus, I either need to get the barrels re-lined; buy new; if they could be found; or go the Atlas route, which appeals to me.

Your thoughts would be appreciated.

Ian

Hello Ian Now if you feel you have loads of cash to throw about at trying to convert an engine to 750 cc then go for it you end up with a scrap motor has the barrel studs on a 750 atlas are set back as the Atlas barrels are set back into the crankcases, So they Made A new set of Cases and Barrels and cylinder head to producethe Atlas 750cc motor on April 20th, 1962, engine numbers start at 101xxx -20, I am rebuilding an Atlas motor for a freind, And I own a 650 Manxman export only, built December 1960 So this was built well before any 650ss were ever thought about, even the models 88ss and 99ss as well to the mix, And I Own a 1954 Featherbed Dominator model88 Built April 1954 how do I know well featherbed frame are date stamped on the top edge of the top lug in small stamp marks just like this D/4/54 D is for dominator the 4 is the month and 54 the year, So I have now said all this to save you time and money, hope this helps yours anna J Dixon

Hi Ian, Although its likely that you have some bore wear ,I would not rush into liners till your bores have been accurately measured and pistons/rings inspected. It may be your apparent poor ring sealing is down to something else and a light hone , new rings and an effective break in will put things right. It might be worth checking the actual finished size of alternative piston supplies as there can be differences which may allow you to get away with a hone and still result in acceptable clearances.Say 41/2 to 5 thou.

Hello When measuringthe bore you take 3 readings for the bore as the barrels bores are slightlytapered and you find the bore a be some thous of an inch bigger at the bottom of the bore than the top of the bore the thing is to find if the bore as ovulated to do this you need a set of inside micrometres some of the best are moors and wrights or Japanese Mitutoyo digital precision instruments you can buy online at www.Mitutoyo.co.uk now all the best yours anna j

I would be most surprised if your bores are ovulating... the biologist aspect of my mind boggles.

Anyway, you can sleeve 99 & 650 barrels. Been there and done that.

If your bores are ovulating be careful at which point in the cycle you check them.

I wonder if it would be possible to sleeve a 99 engine back to 88 bore and fit 88 pistons? .thinking that it would not be necessary to weaken them with the normal sleeving process.

Previously ian_cordes wrote:

Robert Tuck's thread on a 99 to Atlas conversion has made me wonder about the viability of installing Atlas barrels and pistons to my 1964 650ss motor, which one might think should be more straightforward.....? It has a 3-start pump set-up at present. The bores are + 0.040", I think the piston fit is a bit sloppy, and it breaths hard. Thus, I either need to get the barrels re-lined; buy new; if they could be found; or go the Atlas route, which appeals to me.

Your thoughts would be appreciated.

Ian

Had my 650SS re-sleeved by David Burton - https://www.yell.com/biz/david-burton-engineering-thornton-cleveleys-1233524/ for £150 just over a year ago. Great job.

Kevin

Previously ian_cordes wrote:

Thanks Anna. I am hoping my bores are not ovulating. Could that be a reason for sludge in the crankcase?

yes well it should be some ware from to of the stroke top to the bottom of the stroke, were the piston change direction this is called ovulationin the bore, in thousand of an inch yours anna j

Previously George Phillips wrote:

If your bores are ovulating be careful at which point in the cycle you check them.

yes, Georgewe well could be having some baby Norton Barrels!! wouldn't that be nice? your Anna J

When you speak of no rods being available since 196.. is that because there is no demand or a general allergy to the price? I have had rods made for many engines by Arrow and they make a very good product. the costs are often high for my orders because they are one off oddballs but I also know the price is much more reasonable when clubs have had a few sets made spreading the design and setup costs over the whole run. Is there enough demand to be worth following this up?

Similarly for my Cirrus aircraft engine we had 4 new barrels cast at Harlings Foundry near Hastings. I can't remember the cost now but it was not the most expensive part of the rebuild by an means.

At some point I suppose there has to be a mental adjustment from the old school model of rooting out old stock spares through accepting that they are gone to a new approach of how can we make these and how many should we make at a time.

With the high value of the classics its beginning to make more sense to get new spares made. The old AMC storeman tells me that no 88/99 rods came accross from Norton in 63 , if they had he might have "re-homed" them!. The only NOS was in the dealers. These Rods are forgedalloy so no easy solution other than Thunder Rods. I wonder if they were forged at Shellys?/Birco?.I understand they were the same forging as a BSA rod. New steel rods would be good if not too heavy.The old alloy rods are not particularly weak for classic use ,failure usually follows some other issue.

Previously robert_tuck wrote:

With the high value of the classics its beginning to make more sense to get new spares made. The old AMC storeman tells me that no 88/99 rods came accross from Norton in 63 , if they had he might have "re-homed" them!. The only NOS was in the dealers. These Rods are forgedalloy so no easy solution other than Thunder Rods. I wonder if they were forged at Shellys?/Birco?.I understand they were the same forging as a BSA rod. New steel rods would be good if not too heavy.The old alloy rods are not particularly weak for classic use ,failure usually follows some other issue.

Hello there were No Model 88 or model (99) built after October 1962 has by then Bracebridgehad closed and was moving plant to Plumstead to be up and runningby the first of 1963,the only 500cc twin but after the move to Plumstead was the model 88ss it was made up to late 1965 and had stopped by 1966 has AMC had collapsedby then and was boughtby denis poor and MBH All now history, yours anna j

I wonder where AMC got the rods for the last runs 63-66 88SS, must have ordered a batch or bought back from dealers.How many DD head 88SS were made?.

Previously robert_tuck wrote:

I wonder where AMC got the rods for the last runs 63-66 88SS, must have ordered a batch or bought back from dealers.How many DD head 88SS were made?.

hi Robert - They probably bought up some new old stock A7 rods ???? I have a 1965 genuine 88SS and the rods are subtly different from some earlier offerings from a 99 etc. These late 500 SSs with downdraught heads, stronger crankshafts, magnetos and 12V electrics are some of the finest Dominators ever built. I've never had a bigger twin spin up to 8K revs. They are smoother and more than a match to most 650/750's. The only reason one needs more torque from an Atlas is because the vibrations when they rev high is unbearable. If you do get them revving they fly apart. Far better to downsize your 650SS to a 500SS than go larger to Atlas.... Oh hum ! Howard

Thats interesting about the rods, Yes I would happily swop a later 650/750 for an 88SS. A fantastic balance of power,handling, braking etc. An expert on all things Norton in the mid 1960,s Harold Daniel no less told an unbelieving lad(me!) that my 88 was the best bike Norton ever made. Who is this silly scruffy old duffer I thought!.

The Atlas vibration isn't as bad as is claimed. One of the best things I did was to extract the blown up remains of my 99 engine - the snapped rod had cut the engine clean in half - and fit an Atlas engine. It is now a fast and reliable bike. The 88 is a good motor (as is the BSA A7) but there are times when the extra 250ccs are appreciated.

Previously Gordon Johnston wrote:

The Atlas vibration isn't as bad as is claimed. One of the best things I did was to extract the blown up remains of my 99 engine - the snapped rod had cut the engine clean in half - and fit an Atlas engine. It is now a fast and reliable bike. The 88 is a good motor (as is the BSA A7) but there are times when the extra 250ccs are appreciated.

Hello No it just knocks yourjaws out if the engine is not set up right, and For One Why would want to go 750 in the first place for little more gained at the low end of the rev scale, and the 650 is a smoother and a better power plant, the best power out of a 750 was on the desert race bikes, where the power was more useful, But anything i possiblewith cash and the right engineering aptitude, Yours Anna J

Hello, I love a good discussion. I have seen new rods advertised in the States. I believe they were forged. Have a look on the Access Norton website. In reply to Atlas power, I had a New N15 CS in dec. 1969 which I accidently saw 8000 revs on the clock twice, and still going. It never broke, but did worry me at the time. The Matchless frame absorbs the vibration a bit better. I have a lot of Atlas parts lying around, if you have the dimensions of the early rods I could have a look and see if I have anything in my 50 year collect that fits. They need to be in Hiduminium alloy, and are a stamping, there is a company in the States will make to order, I forget the name, they also list Triumph rods. Best regards, Paul