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The Norton construction kit for Dominator twins

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Hello,

the construction kit of Norton allowed them to create models of different capacity while use as many parts as possible. Going through some books it came to my mind the I could convert a 88 slimline model while altering this and that part to a 650 slimline model.

Please note that I do not plan doing so it is more to know that it will work this way.

Going forward from a a 88 model with a 2 carb cylinder head one would need;

As the cylinder head of the 88SS is the same as the 99SS and the 650SS it can stay as it is

The 88 cylinder with 66 mm bore must be changed to an type with an type with 68 mm bore or can a 88 cylinder be bored out to 68 mm?  

The 88 crank must be changed to a type with 82 mm stroke for a 99 or with 89 mm stroke for having 650 capacity. Is the crank with 89 mm stroke the same for the 650 and the Atlas model?

I don’t have a good idea about the push rods and the camshaft which parts are identical or different. I only noticed that Andover only has one type of cam for all the Dominator twins.

Thank you in advance for your inputs this will help me to understand the Dominator construction kit more detailed.

cheers Daniel 

 

 

 

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I'd suggest you acquire a copy of Bacon's 'Norton Twins Restoration'  and also his small format hardback 'Norton Twins'. They should have most of the answers.

Also the Dommie parts list for your year of interest. That will tell you what parts are common to which models.

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The problem with both the likes of Bacon and Haynes is they hardly mention important data crucial to a rebuild. For example both show the tables below in one for or another

Dominator Pistons & Barrels

             CAPACITY            BORE            STROKE

                 497cc                 66mm             72.6mm

                 596cc                 68mm             82mm

                 646cc                 68mm             89mm

                 745cc                 73mm             89mm

But neither bother to mention clearly that the 88 barrel is shorter by nearly 10mm than a 99/650 barrel or that an 88 or 99 or 650 barrel will not fit 750 crankcases without bodging.

The 88 barrel can be bored out to take 99 pistons but will get most upset if plonked on top of a 99 crankshaft.

The 650 crankshaft is similar in dimensions to the 750 and Commando crankshafts but the centre web is machined and balanced differently.

Pushrods for post 1960 models are various lengths and types. Type pushrods into the searchbox (top right) to find a table of data about these.

daniel....if you can find somebody who knows all about Norton Dominators then ask them for advice.

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Hello  now has for early Norton dominator model 88 some engine parts are  different, to later models From September 1955-to-1962  model 99 barrels will not fit the 650  as the 650 was moved back  some  2mm  and the  750 moved back some 5mm  and crankcase studs moved back a 1 mm, Now early  Norton Manxman 650s  had finely balanced centre webs and the  early 750  Bracebridge  models were balanced to 60%  and had concaved low compression pistons 7:9:1,  made by BHB   part number 24279 RH and 24280 LH,  piston parts numbers for 650  are 23269 RH  and 23270 LH, these are 8:9:1  compression ratio,         please note that it states in the Norton owners Manuel   that it is not advisable  to Bore the barrels no more than 40 thousands oversize  with the models 99 and 650 and 750,  And after 40 thousands  you must resleeve  the barrel  at a good competent engineering company                                           yours    anna j  

 


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