Dunstall 850 overhaul

850commando

850commando

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Nov 1, 2014
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My 1974 roadster converted to Dunstall came home last year. i owned it from new until 1978 and traded it for a 750 Suzuki. the Suzuki was reliable enough to take me across Canada on a NFLD trip. over the time i owned the Norton originally, it fried every electrical component. i knew most of the succession of individuals who owned it after me. and as i discovered , i was the only person who had ridden it any miles. a Dunstall fitted Norton is not really a bike you would take out for anything more than short trips. i however have covered long distances with it, because i had arranged the luggage to suit the riding position.

when i traded it in it had about 11,000mi, it came home with just over 13,000mi.

it shows some neglect and requires some TLC. so that's where we are starting from.
Dunstall 850 overhaul
 
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at this point the plan is to exercise every lucas component except the alternator and rotor. i plan to remove the low bars and sell of the dunstall body kit complete
 
I did the same conversion to a 73 850 back in 1995. After the conversion I was convinced that Dunstall was the Lucas of seats. Too wide and no cush. Plenty of support, though, as in sitting on a slab of granite support. Rode it around for about a year then sold the body work off for a profit. Looking at your photos brought back memories, none of them very good. My wife chuckled when I showed her the pics. She remembered how many miles my truck racked up after putting on these implements of torture. No rear sets so I was kind of practicing human origami. Good luck
 
the rearset pegs and a lower bar was all i really needed, but never had the chance to try them so ended up going wholehog with the dunstall kit, unique yes; practical no, i built my own seat back then so will do it again , but with more padding etc. i'm also contemplating bashing a dunstall tank in alu.... after which i will sell off the entire dunstall kit... i'm to old to be hunched over for any long periods of time. i had a brief fling with a suzuki TL1000s but 350mi convinced me (18 yrs ago) i couldn't the hunch anymore but that TL had an engine...
 
it was so cold in Jan and feb that no work happened. i finally has some time after the early spring yard work was well attended to get back into action. I had done a strip down last year to just the frame and engine, the GB was leaking between the case/intermediate and outer covers, so a resealing was in order and good time to swap out the layshaft brg.
Dunstall 850 overhaul


the KS pawl was worn so i ordered a new one, well it didn't want to move see attached pictures of the fix. just wish the AN parts would be right to begin with
Dunstall 850 overhaul

Dunstall 850 overhaul
 
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rear iso's cleaned up and reinstalled cradle mounted to engine
Dunstall 850 overhaul

Dunstall 850 overhaul

Dunstall 850 overhaul

and last little job today primary main seal
Dunstall 850 overhaul
 
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Hopefully you're able to keep your momentum going. Thanks for posting. I look forward to seeing your build as it progresses.
 
I love the Dunstall look, though I know my old carcass won't tolerate riding in that position. Good luck with your redo.
 
Got the new front iso installed. though it would be a good time to check the cam lift, so pulled the timing cover and proceeded to hand rotate the crank with a dial gauge on the spring retainers. during the rotation i could hear an audible click from the left cylinder, so now i need to redo this to determine what it might be coming from, my worst fear is valve contact

anybody have any ideas? which might help diagnose this before i have to pull the head? i'll try and get it on camera...
 
850commando said:
Got the new front iso installed. though it would be a good time to check the cam lift, so pulled the timing cover and proceeded to hand rotate the crank with a dial gauge on the spring retainers. during the rotation i could hear an audible click from the left cylinder, so now i need to redo this to determine what it might be coming from, my worst fear is valve contact

anybody have any ideas? which might help diagnose this before i have to pull the head? i'll try and get it on camera...
Click to expand...

I hope it’s not a Stellite tip on the cam follower that’s broken off!
 
hold for video location

some more background. the engine is sitting in the chassis, and i am using a wrench on the timings side to rotate the crank as the primary is not installed. the tick seems to occur just after the left intake valve opens. because ALL the adjusters looks normal with approximately normal lash, its not likely to be a missing stellite pad on any of the valves.
 
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I slept in a Holiday Inn once...Is one of the valves sticking and then closing after the lobe has passed?
 
since the action is spring driven, i don't think a valve could hangup. i suppose a bent valve might unload the keepers under the right cicumstances. i was thinking i might have to pull the head but maybe i should do a compression / leakdown test first..
 
I have had a valve stick before, although it was not a motorcycle engine, or I'd not have mentioned it. I thought it was witchcraft until I actually caught the momentary hang up. Hopefully something else.
 
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