Mapcycle long rods

Might as well consider Ti crankshafts too but google that to see what you'd be up against and why only ones so far are in economy low hp low rpm engines. About the only advantage of Ti rod is their low mass over steel or even Al but unless spinning into new age short stroke engine range its not much an advantage in Norton clunkers yet a whole lot of risk taking. Remember the Al rod caps of M.A.P. cycles require grinding room in bottom of cases so likely similar for all Ti rods. I now think the rod cap bolts are one of the weakest links in what ever rod installed and will cryogenic them as well as rod and caps in future. Don't know if Ti respondes to this or not. So what is the prefered rod/stroke ratio in Nortons? The main thing that may show up is the inhaling of mixture character on power delivery.

hobot said:

Might as well consider Ti crankshafts too but google that to see what you'd be up against and why only ones so far are in economy low hp low rpm engines. About the only advantage of Ti rod is their low mass over steel or even Al but unless spinning into new age short stroke engine range its not much an advantage in Norton clunkers yet a whole lot of risk taking. Remember the Al rod caps of M.A.P. cycles require grinding room in bottom of cases so likely similar for all Ti rods. I now think the rod cap bolts are one of the weakest links in what ever rod installed and will cryogenic them as well as rod and caps in future. Don't know if Ti respondes to this or not. So what is the prefered rod/stroke ratio in Nortons? The main thing that may show up is the inhaling of mixture character on power delivery.

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The early Crower Ti rods for Commandos required grinding the ends of the cap screw and nut to clear the crankcases, but the later Crower rods fit with no grinding of either case or rods. Don't know about other brands.

Some rod/stroke ratios:

Stock Commando - 1.68
Stock Short Stroke 750 - 1.96
Short Stroke 750 with JS lightweight (6.400" c-c) rods - 2.02
JS lightweight kit for stock 89 mm stroke - 1.83
Maney 1007 cc kit with stock rods - 1.60
Maney 1007 cc kit with JS lightweight (6.400" c-c) rods - 1.75
Maney Ultra Short Stoke 750 (7r mm stroke) with stock rods - 1.99

Ken

lcrken said:

The early Crower Ti rods for Commandos required grinding the ends of the cap screw and nut to clear the crankcases, but the later Crower rods fit with no grinding of either case or rods. Don't know about other brands.

Ken

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Exactly my experience with R&R alloy rods, which are remarkably similar to other alloy rods discussed recently. In fact, I gave up atlogether when the rods fouled the cases because I couldn't decide where to remove metal. in context, the motor I'm working on is a C.1970 with the timed breather, so a bit more metal available than combat cases, possibly?
Notwithstanding this, I'm now minded to grind the bolt heads, and as they're 3/8" 12 point I don't believe there will be much of an issue with the socket slipping on a shorter bolt head...
We'll see!

Oh cool Ken, thanx for the range r/s in Nortons. R/S ratio is a fairly subtle effect that mostly helps or hinders n/a engines breathing depending on the bore/stroke over or under squareness. With boost maybe higher R/S ratio might allow a bit more time at TDC dwell to pack in more mix but on the other hand also tends toward detonation states.

here a forum quote on another way to view think or wish for in R/S

Rod Stroke Ratio summed up real quick: higher the number the less wear and tear on the motor, also has less torque, but more revablity. the higher the number the more wear on the motor, more torque, peak power at lower RPMs...

thats not saying that a low RS motor will not last a long time, the B18A/B motors have a "shitty" RS of 1.54 and still will last a couple hundred thousand miles... and in our game your gonna ---- your motor up before the average life expectancy of the motor. so it doesnt matter...

so in closing: you want nice low end power run a low RS, you want all your power at topend and dont mind reving the ---- out of it you need to go with a higher RS. either way if your reading this you will need to rebuild that ---- in a couple years anyway...

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One advantage to a greater dwell around TDC as a result of a greater rod to stroke ratio is less ignition advance is necessary; always a good thing for making power and increasing efficiency.

bwolfie said:

http://www.ebay.co.uk/itm/NORTON-COMMANDO-750-850-BILLETED-ALLOY-CON-ROD-06-4896-NM25369-/121016727681?pt=UK_Motorcycle_Parts&hash=item1c2d28b881

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The Very Same - and if anyone wants some I can get them a shade cheaper than that!

I found quite a few Ti bolts in an aircraft wreckers years ago and they are all around my Seeley. A thin one is used to hold the rear exhaust hanger. The hole was a bit oversize, and it became a bit loose. The vibration caused a dramatic reduction in diameter of the bolt where the steel flat was vibrating against it - I don't know how Ti valves survive for long . It is really bad to machine - when we were recently making my gearbox top and bottom bolts, the threads were growing as they were being machined. Really difficult to get dimension.

acotrel said:

I found quite a few Ti bolts in an aircraft wreckers years ago and they are all around my Seeley. A thin one is used to hold the rear exhaust hanger. The hole was a bit oversize, and it became a bit loose. The vibration caused a dramatic reduction in diameter of the bolt where the steel flat was vibrating against it - I don't know how Ti valves survive for long . It is really bad to machine - when we were recently making my gearbox top and bottom bolts, the threads were growing as they were being machined. Really difficult to get dimension.

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Pretty much any Ti part that has to move against another part (valves, shafts, piston pins, etc.) only works because it is treated with with one of the thin film, low friction coatings. Titanium nitride, chromium nitride, molybdenum disulfide, zirconium nitride, DLC, etc.

Ken

I would have thought that a valve hammering the seat woud be too much for a film of anything to handle.

As trick as Ti sounds I tend to stay away from it. On my first Seeley I had a machinist friend make me a Ti rear axle. Very trick but now I recognize it is a liability if it galls and seizes when I try to remove it.

Someone on Access Norton pointed out that you can gain most of the reduce weight benefits by rifle drilling the axle or trans bolts. I think you can purchase the rifle drilled trans bolts from Minnovationracing.com. Either way, easy enough to have drilled.

I've run both intake and exhaust Ti valves in the race Nortons and now shy away from the Ti in the exhaust and stick with Ti intakes only where necessary. Durability of the Ti valves is good but I am told you need to change valve seat material to Aluminum-Bronze or Copper-Beryllium. I have run Ti valves with moly coated valve stems; the current set of valve do not appear to have the coating. The valve tips need to have steel winkler caps as the Norton rocker tip will destroy the end of a Ti valve.

Dances with Shrapnel said:

As trick as Ti sounds I tend to stay away from it. On my first Seeley I had a machinist friend make me a Ti rear axle. Very trick but now I recognize it is a liability if it galls and seizes when I try to remove it.

Someone on Access Norton pointed out that you can gain most of the reduce weight benefits by rifle drilling the axle or trans bolts. I think you can purchase the rifle drilled trans bolts from Minnovationracing.com. Either way, easy enough to have drilled.

I've run both intake and exhaust Ti valves in the race Nortons and now shy away from the Ti in the exhaust and stick with Ti intakes only where necessary. Durability of the Ti valves is good but I am told you need to change valve seat material to Aluminum-Bronze or Copper-Beryllium. I have run Ti valves with moly coated valve stems; the current set of valve do not appear to have the coating. The valve tips need to have steel winkler caps as the Norton rocker tip will destroy the end of a Ti valve.

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Ah, but think of the weight savings if you rifle drill the TI axles and fasteners! Just kidding. I tried drilling a Ti axle, and it's really difficult to drill such a long hole in Ti without overheating the drill bit, or work hardening the Ti, or both. I have been known to drill out some of the shorter Ti fasteners like the brake caliper bolts, which are unsprung weight, but that seems to be really reaching the point of diminishing returns. And I still end up spending a lot of time sharpening drill bits. Just compulsive, I guess. I have no problem turning and threading Ti with carbide insert tools, but drilling is more of a challenge. If I could afford carbide drills it would probably be a lot easier.

I had the same problem with the Ti axles I've made. I found that coating them with a spray-on moly-based dry film lube solved that problem for me.

I ran Ti valves in my Wood Rotax road racer, with beryllium-copper seats. The interesting bit was that the valves and seats never seemed to wear. The tuner that did the head for me later switched to aluminum-bronze for seats, after he started to worry about health hazards from machining and grinding beryllium alloys.

Ken
Ken

Yes, machining ok, grinding bad.

One of the many neat things about Beryllium Copper is it's ability to sap away heat. I figure that's a nice compliment with the thermal conductivity of the Ti.

Back to the bit about corrsosion fracturing when Ti contacts certain compounds and solvents; I seem to recall it being more of a factor on high heat applications like exhaust valves and SR-71 skin. May not be such a factor for axles and connecting rods; maybe someone else can chime in on this.

Someone else on this thread asked about roller race Ti rods; a machinist friend of mine was turning out Ti rods for Goldstars several years back. Construstion included shrink fitting a steel race on the big end and plasma applied hard surface on the thrusts sides of the rod big end. Pretty trick. I think they were being made for Ted Hubbard (RIP) or Ed Veliketh (sp).

Dances with Shrapnel said:

Yes, machining ok, grinding bad.

One of the many neat things about Beryllium Copper is it's ability to sap away heat. I figure that's a nice compliment with the thermal conductivity of the Ti.

Back to the bit about corrsosion fracturing when Ti contacts certain compounds and solvents; I seem to recall it being more of a factor on high heat applications like exhaust valves and SR-71 skin. May not be such a factor for axles and connecting rods; maybe someone else can chime in on this.

Someone else on this thread asked about roller race Ti rods; a machinist friend of mine was turning out Ti rods for Goldstars several years back. Construstion included shrink fitting a steel race on the big end and plasma applied hard surface on the thrusts sides of the rod big end. Pretty trick. I think they were being made for Ted Hubbard (RIP) or Ed Veliketh (sp).

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I had some one piece Ti rods made for Yamaha four stroke singles some years ago, and that's how they were constructed, hardened steel race for the big end, bronze bush in the small end, and plasma coated moly for the sides. I used to have a Ti rod for a Manx Norton that was made back in the late '60s or early '70s by an outfit in SoCal, and it had a similar construction, although I'm not sure now what the treatment on the sides was.

Ken

Thanks for the Ti roller rod info, I recall that BSA also used Ti for a number of items [including frames] on their factory MX racers back in the `60s, & not without certain practical difficulties.

ZFD said:

Here is what we think of rods machined from solid:

http://www.andover-norton.co.uk/Pirate Parts.htm

Not something I would willingly put into one of my engines. For that reason fitted my shortstroke 750 with standard production Commando rods, even though geometrically that is not ideal, and it meant shortening the barrel and worrying about valve gear geometry.

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There's a huge difference between rods machined from solid, and rods made from cold extruded billet alloy bar, supplied by Kaiser in the U.S. which is upwards of 90,000 psi tensile strength.
http://rrconnectingrods.com

The extruded alloy used by R&R is used in top fuel engines producing in excess of 8000 horsepower, and their rods are used by Monster Trucks, NASCAR and by the Drag Racing teams. In 2012, you will be hard pressed to find any forged connecting rods in any serious racing engine, used within the Drag Racing community.

Plus, the ARP rod bolts they use are basically 'bullet proof'.

The forged rods that were fitted to the nostalgic British Motorcycles were a good choice for a stock engine, but will not handle the abuse of a modified engine imo. If forged crankshafts were fine to use in top fuel engines, they wouldn't be using a billet piece now, and the same goes for a connecting rod.

It's 21st century technology v old cottage industry technology. To use the term 'machined from solid' can be very misleading, and certainly shouldn't be used to describe the US made R&R Con Rods!