WAS PAUL DUNSTALL MAD ?

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nortonfan

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Go back to the 60s-early 70s !!

Did everyone think that Paul Dunstall was mad putting an 810 kit onto a 750 bottom end ?

Does anyone care to answer now that it is history?
 
You certainly don't hear much about that stuff anymore. It must be *impossible* to find replacement pistons/rings for those kits.

I did have a set of Dunstall mufflers on my 850. The stock peashooters rusted out in short order and I bought the Dunstalls because they were cheaper than stock. They looked great, sounded great, and were very durable. Much higher quality than stock.

Debby
 
Dunstall 810's

I remember seeing a few fully equipped dunstall Commando's back in the day, you could'nt miss 'em. I've never ridden an 810, but I've seen 'em go. They are quick. I bet most of them went to Norton heaven quick too! I remember a Cycle magazine test where they pulled the mufflers and air cleaners I think and ran an 11.9 quarter! Can you imagine that ride!? If you think Dunstall was nuts, how about the guys that fitted the Drouin superchargers for a cool 100 HP! I've seen a few of these also and always wondered how long that bottom end was good for.-Rob
 
nortonfan,
My personal belief is Dunstall was a great market man, like Bill Gates. He did well in the early days when Norton pulled out of racing and he "took over" the factory racers with help out the back door of the Norton shop. With this reputation he started his "cafe racer" business.

He was pretty successful and the designs looked good. Quality was another thing altogether. I have a Dunstall double disc front end on my cafe racer that looks sharp. Functionally it's crap. It is a poor casting full of air holes and the machine work is crude. The clearance between the aluminum pistons and the aluminum caliper/leg is great enough that the piston will cock in the bore.

The 810 cylinders are noted for pulling the head studs out of the aluminum. It's standard procedure before trying to use one to helicoil these threads and then torque very carefully. I doubt many kept the cylinder head on long enough to worry about the bottom end. Besides, the 810 didn't make a lot more HP than a Combat. The best part of the kit was the cylinder head work.
I have a friend that bought a Dunstall commando in the early 70's and went to England to pick it up. He was amazed to find the shop in what was no more than a garage down and alley. After two or three years of ownership and four broken seats, and numerous cracks in the fibreglass fairing, he sold it to buy a Kawa***i.
 
810 Dunstall

By "mad" do you mean too much displacement/force for the bottom end or moving the displacement out of a race class?

My own opinion of Dunstall equipment has already been expressed...poor quality. Norton factory equipment was much better made.
 
Thanks for all your replies.

David, I am just trying to get some clues from anyones experience with the Dunstall Equipment, having never used anything but his rearsets, tank & seat.

Ron L, You have mentioned the head work as being the most beneficial. Also you have noted that the 810 displacement did not do much.

No one has commented on the cam or exhaust setup yet.
Has anyone got any thoughts on these parts ?

I like the look of the 2 into 1 into 2 exhaust myself & have had a quote to have one made up. Trouble is, the standard "peashooter" exhaust looks good to me also.

I dropped my second frame off at the powder coaters yesterday, so I am busy with the mechanicals right now. My intention is to put a 1972 crankshaft into 1973 850 cases with a 3S camshaft. The 850 bore is standard & the head is the 32mm RH4 type. A mikuni carby is going on this engine, I haven't tried one as yet.

The front end will have a brembo caliper & master cylinder but standard norton rotor for now.

All parts have been acquired, so I am busy, busy, busy.

Basically, as I have stated b4, I am copying CNW's build 36 commando.

So, I will let you all know if it blows up or not.
 
dunstall

as ron has said the dunstall stuff was mostly CRAP. I tryed just about every part in the book that he sold. the 810 cyl was IMPOSSABLE to keep a headgasket on. the head was ok but not for the money. the 2-1-2 exhaust helped the midrange torque and had a diferent sound. BUT it also broke welds at the head joint and wanted to FALL APART at the frount where the two headpipes went in to the single bottem pipe :evil: . if you are going to replecate the exh. I would STRONGLY recomend changing the frount three parts to two parts ( ie one head pipe& bottem pipe as one part and a second head pipe to slip into the first pipe ) than use the later style 850 collett's and nuts to the head joint. as for the body work the fairing was poorly mounted and the headlight was not mounted good. the tank was ok with the gas of the time but I would question it on todays petrol. the seat was JUNK. it was hard to keep it on the bike so I adapted a kaw######ki h2 seat and tail on mine and mounted the stock taillight in to it. hope this helps :D .

bill
 
If you really want a Dunstall "Dr. Blair" 2-1-2 exhaust system, Tom Epperson (EPCO) (http://www.epcostainless.com/) has copied Kurt Monroe's original in stainless steel. Last I heard from Kurt, they were still adjusting the fit, but it might be better than starting from scratch.

Keep in mind you will lose the ability for a center stand or will need to cut the center brace out of one and have a U-shaped one welded back.
 
Thanks for the info Ron, I think I will stick with the "standard" exhaust. If it scrapes these days, it is by accident.

I still have a Paul Dunstall catalogue (1973) showing the modified centre stand for the "Dr. Blair" system. I would be able to make one up, no problem, if I do go the dunstall way one day. That catalogue has been in my possession for quite some time now & I have seen them go for big bucks on ebay nowadays.

Would like to know what your "special" is made of. Maybe you could let us all know ?
 
Does any one has the specs for Dunstall Timing settings for a 850 engine.. is there such a setting? Is it applicable to a standard motor..

The reason i ask is that a 'Classic dealer' recently suggested 'we' should look at Dunstall recommended for a Commando !??
:?:
 
Stuart-SS,
Are you speaking of cam timing specs? Dynodave has nice comparison of cam profiles, including some of the Dunstall cams on his website. These are not specific to 850's, although depending on other engine modifications would work as well as in a 750. If you are thinking of installing a hotter cam, check out Dynodave's comparison. Personally, I find the 2S plenty for a street motor.
 
Having reformatted my computer a lil while back, I lost an email from "Jerry someone". It was about the plates for the Dunstall Centre Stand. It may have been Jerry "Doe", whoever it was could u please email me again maybe with the pattern/diagram of the mounting plates.

I have had a quote of $600 AUS to make a set of the 2 into 1 into 2 headers up as Bill/Ron suggested.
That is with less joins to "come apart/maintain"

With Thanks,
Reg.
 
Re:

Stuart -SS said:
Does any one has the specs for Dunstall Timing settings for a 850 engine.. is there such a setting? Is it applicable to a standard motor..

The reason i ask is that a 'Classic dealer' recently suggested 'we' should look at Dunstall recommended for a Commando !??
:?:
Click to expand...


If you are thinking of purchasing an original Dunstall cam, if my experience is anything to go by, beware.
I purchased one from his shop in the early 1970s and eventually found most of the cam lobes timing nothing like what was in his manuals.
Pure junk.
 
I have a copy of an original road test on an 810 Dustall. I believe it's from Cycle World but I don't remember, I'm not at home in Mexico where the test resides. I will be on Fri evening. Anyway, the test results as far as acceleration were quite disappointing - low 13's sticks in my mind though I could be wrong. In any case, it was considerably slower than the much-publicized 12.6 that appeared in a test/Norton ads of the time.

When I had my '71 Commando back then, I always wanted some Dunstall stuff but couldn't afford any of it. I was not aware of the 810 road test at the time, so I wanted Dunstall add-ons through the ages until I read that 810 road test in 2008! OTOH, I do find Dunstall's Norton performance book to be interesting, informative, and useful.
 
I owned a Dunstall 810 as my first road bike almost 40 years ago. It did indeed blow a head gasket and when torn down it looked like the cause was poorly designed head stud into aluminum problem. It had a lot of power and would pull the front wheel up shifting into second on the gas. The exhaust started to rust out and was replaced. The seat fiberglass would crack at the area just above the shock mount. The riding position put a lot of weight on your wrists and even at 18yo. I could not ride for more than an hour without stopping for a break.
I loved that bike even with all its faults.
 
Re:

Ron L said:
If you really want a Dunstall "Dr. Blair" 2-1-2 exhaust system, Tom Epperson (EPCO) (http://www.epcostainless.com/) has copied Kurt Monroe's original in stainless steel. Last I heard from Kurt, they were still adjusting the fit, but it might be better than starting from scratch.

Keep in mind you will lose the ability for a center stand or will need to cut the center brace out of one and have a U-shaped one welded back.
Click to expand...

As for putting a U-shaped brace on a stock center stand...I've thought of that but suspect the stand will remain too far back and the feet will interfere with the rear pipes. With the Dunstall stand, the stand mounts forward. Hence the rear wheel doesn't come off the ground when on the stand. That's another story altogether..
 
Viking has those 2-1-2 exhausts. I was going to buy one but the speed bumps in Mexico make that a non-starter. The pipe wouldn't survive the first mile outbound from our house. ;)
 
mike996 said:
Viking has those 2-1-2 exhausts. I was going to buy one but the speed bumps in Mexico make that a non-starter. The pipe wouldn't survive the first mile outbound from our house. ;)
Click to expand...

He was also going to make an attempt at the center stand. I sent him mine some time back so he might copy it. I see no mention of it on his site but who knows?..
 
I ran my 750 with many of the Dunstall external bits on my bike in the 70's and 80's. The fairing lasted until a nasty crash broke it up in 5 or 6 places. I repaired it with fiberglass and ran it again for 4-5 years, no other problems. The seat pan was reinforced with a 10" light alu panel that ran across between the shocks and bent down to include the mounts. The 2-1-2 exhaust never gave me any grief what so ever although I changed the last section to a single tube and ran only one muffler for a number of years for a significant weight reduction with no noticeable performance loss. On really rough roads with bad pot holes you have to watch ground clearance but with clip ons and rear sets you pretty much avoid those kinds of roads anyway.

I bought an 810 kit and cam back in the day but things changed in a big way for me back then and I never got a chance to install them. There were 2 types of cams offered, drop in cams and race cams with forced pressure lube to each lobe and grinds requiring radiused lifters. The lifters in the 810 kit were lighter than stock. There have been mixed reviews on the quality of the cams but I have seen some reputable reports where the hardness levels were top shelf.

Was he mad
nortonfan said:
Go back to the 60s-early 70s !!

Did everyone think that Paul Dunstall was mad putting an 810 kit onto a 750 bottom end ?

Does anyone care to answer now that it is history?
Click to expand...

People ask the same thing about Norton going to 750cc's. He was just pushing the envelope. He wasn't from a wealthy family so had a limited budget and a passion for racing. He followed the path of least resistance, marketing his innovations became his livelihood a means to support his family. 40 years later if you look at other racers who market their products,i.e.: Steve Maney, did he blow up engines to get to the cases that can take the 1000 kits? 40 years later they're getting it right but it's tricky, real tricky, they aren't just bolt on kits today, they require extreme care and custom tooling to install.
 
Are you claiming that Paul Dunstall was mad because he attempted to improve the 750 commando, or because he had a backyard business where his livelihood depended on getting money from motorcyclists ? I suggest you are looking at him through American eyes. Colin Seeley also operated out of a factory down a lane. A friend of mine worked for him, and lived in a van outside the factory while also racing at weekends. Perhaps we were all mad back then ? I don't think people today recognize how it was back then, the whole of the British motorcycle industry was run on a shoe string. The Dunstall aluminium barrels were a good attempt, probably better than the Alfin Wellworthy barrels which some of us fitted to Triumph 650s ? With anything like that, you have to be prepared to do the re-engineering if there is a problem. My Alfin barrels cracked through the cast iron which was part of the liner around the stud holes - that's when I gave up.
 
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