norton dunstall 810

Classic Norton Commando Motorcycles.

norton dunstall 810

Postby valdemar » Sun Jan 29, 2012 11:44 pm

im new to this forum
im in the tail end of finishing the 810 motor and what a project its been.but worth it as i was able to improve the reliability of the 810 barrel.resleeving it to 750+.60 thou for a thicker sleeve that wont break, to using loctite 635 to lock in the threaded inserts so they dont work loose(i dont understand why the inserts werent helicoil).loctite 635 is permanent it wont work loose,can only be drilled out,this was used in conjunction with spray primer (hardener).more data available if required

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Re: norton dunstall 810

Postby grandpaul » Mon Jan 30, 2012 7:03 am

Welcome to the forum.

I'm sure there are others besides me that would like to see pictures...
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Re: norton dunstall 810

Postby rotorwrinch » Mon Jan 30, 2012 7:35 pm

I believe you are on the right track in working around the weaknesses of the 810 cylinder. They are porous and frail. I have pushed using a Dunstall Cylinder to the right on my project list. I wanted to include studs that fully engaged the threads of the cylinder before any torque is applied. The thin sleeve of the 810 kit are a disaster. BTW, the OD of the 810 liner and an Hepolte liner for a 750 cylinder are the same. 76 mm in a liner that was designed for 73mm. Any wonder!
All the best on your project. Send photos. Inquiring minds want to know.
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Re: norton dunstall 810

Postby madass140 » Mon Jan 30, 2012 7:46 pm

I will follow this thread becoz I'm seriously considering manufacturing the Dunstall cylinder. I know I know , there are heaps of people making these so dont bother telling me that.
If the problems cant be sorted with the 76mm bore then I was thinking maybe leaving them at 73mm, I know it kind a defeats the purpose, but if I had a choice of either stock iron 750 cylinders or Dunstall alloy 750 cylinders I know which I would prefer, I think this thread has a long way to go , I'll be watching.
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Re: norton dunstall 810

Postby valdemar » Fri Feb 03, 2012 1:38 am

i put a 750 +60 thou sleeve which gave the sleeve an extra .75mm thickness
i was also advised by the engineer that made the sleeve metal technolgy has come a long way since 1970
ive taken photos of the comparision of old sleeve and new sleeve and theres heaps of difference
i also found when i removed the threaded inserts for the head bolts they are different length reach sizes
and that brass shims are fitted to compensate

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Re: norton dunstall 810

Postby valdemar » Fri Feb 03, 2012 1:43 am

ps how do i submit photos
i taken heaps of photos have tried but unsuccessful
can someone help val

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Re: norton dunstall 810

Postby valdemar » Fri Feb 03, 2012 1:58 am

its val again
by using +60 over sleeves which wont break it gives it 74.5 mils
i think this is approx = 775 to 780 cc
so its still bigger than standard 750 and give a throatier sound .i had stainless steel studs made to bolt to the cases
im using a brass base gasket,ive hade allen head bolts made in stainless
and when more financial redo the header pipes to 1 3/4 to breath better thus hopefully reduce
engine heatup

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Re: norton dunstall 810

Postby Matt Spencer » Fri Feb 03, 2012 2:08 am

Image

Im sure this one suggested 1 7/8 o.d. , screw in bored inserts , plug in pipes , m-x type spring & hook retainers .
The old 1 3/4 is ok on a 650 Triumph . 3 in Cooper Ex pipe for 36 Buicks . :D
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Re: norton dunstall 810

Postby SteveA » Fri Feb 03, 2012 5:46 am

madass140 wrote:I will follow this thread becoz I'm seriously considering manufacturing the Dunstall cylinder. I know I know , there are heaps of people making these so dont bother telling me that.
If the problems cant be sorted with the 76mm bore then I was thinking maybe leaving them at 73mm, I know it kind a defeats the purpose, but if I had a choice of either stock iron 750 cylinders or Dunstall alloy 750 cylinders I know which I would prefer, I think this thread has a long way to go , I'll be watching.


The most popular alloy race barrels are surely Steve Maney's..... http://stevemaney.com/products.html

750, 850 and 920.....and like you say there are other choices....will you be able to do a quality product cheaper?

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Re: norton dunstall 810

Postby SteveA » Fri Feb 03, 2012 5:57 am

valdemar wrote:its val again
by using +60 over sleeves which wont break it gives it 74.5 mils
i think this is approx = 775 to 780 cc
so its still bigger than standard 750 and give a throatier sound .i had stainless steel studs made to bolt to the cases
im using a brass base gasket,ive hade allen head bolts made in stainless
and when more financial redo the header pipes to 1 3/4 to breath better thus hopefully reduce
engine heatup



From what has been said on exhaust ports I am not sure larger diameter pipes, beyond say 1 1/2 ID are going to make a lot of difference, particularly for road use, but whatever diameter remember that it is pipe volume that is important...larger dia pipes need to be shorter, and you may then have problems with mounting silencers if using conventional routing.......

1 1/2" ID by 28" worked on 850s! and smaller diameter (1 3/8") 32" pipes worked on 750s....way back when............

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Re: norton dunstall 810

Postby madass140 » Fri Feb 03, 2012 6:15 am

"The most popular alloy race barrels are surely Steve Maney's..... http://stevemaney.com/products.html

750, 850 and 920.....and like you say there are other choices....will you be able to do a quality product cheaper?"

I'm not looking at race barrels, my intention is to produce barrels for road use , Dunstall replicas supplied with the same Dunstall cam followers , stellite faced BSA style, Actually the cam followers will be the single biggest costly part to produce.
Do Maney barrels come with cam followers?
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Re: norton dunstall 810

Postby SteveA » Fri Feb 03, 2012 8:30 am

madass140 wrote:"The most popular alloy race barrels are surely Steve Maney's..... http://stevemaney.com/products.html

750, 850 and 920.....and like you say there are other choices....will you be able to do a quality product cheaper?"

I'm not looking at race barrels, my intention is to produce barrels for road use , Dunstall replicas supplied with the same Dunstall cam followers , stellite faced BSA style, Actually the cam followers will be the single biggest costly part to produce.
Do Maney barrels come with cam followers?


I only refer to the fact these are race barrels because that is Steve's business, and I don't go to events where many road bikes go. I see no reason why Maney barrels cannot be used on road bikes. Certainly Steve will supply them honed to the size and clearance you want, cast or forged pistons or whatever.

I don't see why cast iron is not the most appropriate solution for road bikes either,but then again I never really understood why Dunstall bothered!, but that really is just me. For me, black iron looks right, especially with closed through bolts, and I don't thenk the weight and heat dissipation are real issues for stock bikes. As far as I know some racers prefer cast iron anyway!

I guess if I think about it I see little need for a capacity of around 780 to 810 either, when there is an easy 828 solution available, Dunstalls product disappeared quickly when Norton launched the '850'. But maybe its just the technical challenge of casting barrels and inserting liners you are after, I am sure it will be fun to do if you can. :D

Concerning cam followers, the answer is no, Maney's don't come with the barrels, but I don't think they come with anyone elses barrels either!

Standard Norton Cam followers are stellite faced and I know that from experience when that 'friction welded' stellite comes off, it causes a mess.... Of course they are flat not curved like BSA style followers, and from Jim Schmitt and Steve Maney practice, surely you will need to look at your cam profile if you go for curved followers? Maney needs follwers that are to be used with his cams to be reprofiled, so again the follwer needs to suit cam profile.

Andover Norton standard followers are pretty pricey, so you don't really want to grind new ones.....and I don't think they come with that 'high performance sand' they used to contain when Norton made them.....clean internally and externally before use!

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Re: norton dunstall 810

Postby SteveA » Fri Feb 03, 2012 9:27 am

SteveA wrote:
valdemar wrote:its val again
by using +60 over sleeves which wont break it gives it 74.5 mils
i think this is approx = 775 to 780 cc
so its still bigger than standard 750 and give a throatier sound .i had stainless steel studs made to bolt to the cases
im using a brass base gasket,ive hade allen head bolts made in stainless
and when more financial redo the header pipes to 1 3/4 to breath better thus hopefully reduce
engine heatup



From what has been said on exhaust ports I am not sure larger diameter pipes, beyond say 1 1/2 ID are going to make a lot of difference, particularly for road use, but whatever diameter remember that it is pipe volume that is important...larger dia pipes need to be shorter, and you may then have problems with mounting silencers if using conventional routing.......

1 1/2" ID by 28" worked on 850s! and smaller diameter (1 3/8") 32" pipes worked on 750s....way back when............


BUT....after having those pipe dimensions in my head since late '75....I have just read them in Paul Dunstalls tuning manual....but since there was no 850 when he wrote it, he actually says for 650 and 750 sizes are the same but that the bigger ID shorter length is race cam, and the longer pipe smaller ID is for street cams....so maybe you need to look at your cam choice first?

I chatted exhaust dimension with Peter Williams in '78 and he said the 1 1/2 ID, 28 that I had been using was right for my 850 with it's ex Thruxton cam....so it seems to still stack up...except that Maney, from eyeballing his system, uses a longer and bigger ID pipe, but I have yet to measure one of his exhausts, and anyway they are 2 into 1 and a bit more 'sound concious'....

I have ridden a 750 PR copy Commando at Cadwell Park with one fitted and, a guy with lots of Seeley Norton experience changed to one last year and recorded an improvement over his previous system...

But for road use, do you need even 1 1/2 ID?

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Re: norton dunstall 810

Postby hobot » Fri Feb 03, 2012 9:55 am

Might want to read this Harley based article to decide on exhaust tubes and muffler sizing for intended use per engine configuration.
http://www.rbracing-rsr.com/exhausttech.htm

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Re: norton dunstall 810

Postby madass140 » Fri Feb 03, 2012 9:30 pm

"Standard Norton Cam followers are stellite faced and I know that from experience when that 'friction welded' stellite comes off, it causes a mess.... Of course they are flat not curved like BSA style followers,

the stellite faced Dunstall followers are flat not curved
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