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madman
01-10-2007, 01:06 PM
Ducati 9oo ss wound out in top gear at the race track. Dropped a valve, Messed up badly. It had carillo rods in it and wiseco pistons. The valve head went straight through the piston and mucked it up. All repaired except the expensive(air flowed cylinder head) The combustion chamber is pretty chewed up as you can wwell imagine. Now after muchwelding its time to remachine the chamber HELP PLEASE any tips. ? Mastercam the shape and try to reproduce? Rotary table ? Any good ideas will be appreciated thanx Mike

Mark Hockett
01-10-2007, 01:48 PM
Madman,
If you have a good head (V-twin right?) take it to someone with a CMM. Have them probe it and generate a 3D drawing with a Mastercam file extension. Make sure they also probe a couple of good reference points. If you are not in a big hurry send the head this way and I'll cut the combustion chamber and send it back to you. Then you can finish cut all the details like the bores for the valve seats and spark plug holes.

Dawai
01-10-2007, 01:48 PM
Tracer arm, off the mill quill,, put a original head next to it with tracer probe same as profile as the end mill.. just follow it around in the head with the feed handles. All day to set up, half a day to machine.

OR cnc it, scan it take it into mastercam, verify it in a cheaper block of metal. Days work. Mucho setup.

Either way, the customer is not going to like the end price you will have to get.

Duckatti? ain't that a river bird?

John Stevenson
01-10-2007, 01:59 PM
Duckatti? ain't that a river bird?
No it's a proper motorcycle, probably quite rare in the States :D
Nice design and uses electronic ignition and not a flint and a rock.

.

pntrbl
01-10-2007, 02:25 PM
If there's such a thing as sex on 2 wheels ... it's a Ducati.

I never did more than lust after one tho. It was always Japanese inline 4's over Angeles Crest Highway when I was young and bold enough for that sort of thing .....

SP

Magic9r
01-10-2007, 03:22 PM
John,
I was given to believe that somewhere in every Ducatti is the timer which tells it when to have the engine eat itself.
Regards,
Nick

Dawai
01-11-2007, 08:59 AM
<quote>No it's a proper motorcycle, probably quite rare in the States
Nice design and uses electronic ignition and not a flint and a rock.
</quote>

Yeah it's italian.. HUH? WHoo hoo about that national pride there.
Ohh them sexy hairy armpits and legs some of them ladies have.
http://virtualindian.org/pixarch/dak2.jpg
Now that English Indian 4.. yeah baby.. got a volvo marine engine, a bmw transmission and runs like a dream. Way to go brits, if you can't make it, at least you can put a good one together huh? It's called the Dakota 4 here in the states because of that patented name.
http://virtualindian.org/dakota4.htm
Still a excellent motorcycle. Not quite as fast as any ducatti I have rode beside, but then you don't look like a monkey humping a football riding it either.

Them old flint-rock ignition systems went out with the flat leather drive belts me thinks. I could have had one of them silent grey boys.. I was too niave to know it's future worth.

motomoron
01-11-2007, 10:19 AM
About 6 years ago in the space of one week, I:

Proposed to my wife.

Settled on a 60 year old renovation project house.

Bought a very gently crashed 1994 Ducati 900SS from the motorcycle shop where I worked.

I may have done other things like "had coffee and a bagel" but they're not as memorable. Anyway, The house is 97% finished, my wife is excellent, and as for the mighty SS...

Like boat and airplane ownership the best days were when it showed up and when it left. It's a fabulous bike on a twisty bit of tarmac on a pleasant day. It's one of the best sounding bikes ever. It's SO red. It's not too bad to work on...

"Honey, hold the handlebars and keep the front end upright while I lift the chassis off the motor here...Yes, I know I just got it last week and there's a foot of water in the basement, but it broke a cylinder stud so now I need to take it completely apart..."

But the charging system is almost BMW aircooled-boxer bad, and in traffic it's very unhappy indeed. A snarling mess of driveline lash, basso-profundo exhaust, intake honk, and harsh suspension. The clutch pull will make you friends think you've "switched hands". I live a block from the city, and it did not like it one bit.

I sold it (for 33% more than I paid for it) a year ago November. It was replaced with a Suzuki DRZ400 supermoto, which got a big pumper flatslide carb, titanium pipe from an Eastern Bloc Country, and various bits to make it more crashworthy and aggro. Other than than the fact that it's eye-wateringly loud, it goes through DC mayhem traffic like a waterjet through .
.040 6061, can be parked anywhere without fear of damage, since the bodywork is all molded polypropylene and costs about $50/set, wheelies very easily, and is essentially un-crashable. It's faster in tight twisties than about anything, and will go a tick over 100 screwed all the way open. I don't really ever go any faster anymore.

Then this fall I went crazy and got a KTM950 supermoto, which has all those advantages, plus about 100hp and an extra 100 pounds and a more comfortable perch. It does everything the SS did that was good (look cool, sound cool, go fast, be exotic) but without the quaint Italian "eccentricities" which some people also call "major glaring faults"

BTW as a gearhead fact that wasn't mentioned in prior posts, Ducatis still have Desmodromic valve actuation. This is a holdover from the days of valve float, so there's probably no valid reason for it anymore, but it and the distinctive welded steel trellis frame are Ducati signatures, so you get to live with 100% more valve train components than you really need.

There are 2 cam lobes and rockers for each valve; an opener which operates with a customary amount of clearance, and a closer which operates at essentially no clearance. Setting the valve clearance on a Ducati air cooled 2 valve engine isn't so bad, but the liquid cooled 4 valve engines require the removal and for the most part, disassembly of both heads, which are well and truly buried in a fully faired motorcycle covered with wiring harnesses and hoses. Uggh.

In the end I think it was that I liked the concept of being "someone who had a Ducati" more than actually living with one. The new 1098 is pretty nice looking though...



The SS right before it left.
http://img.photobucket.com/albums/v341/motomoron/900side.jpg



The KTM scaring passers-by in the alley out back.
http://img.photobucket.com/albums/v341/motomoron/ktmalley.jpg

pntrbl
01-11-2007, 10:49 AM
Yeah, I've heard Ducati's are more maintanence intensive than some. They sure come in my favorite color tho.

KTM's are off the beaten path but I've heard some raves. The 500cc Duke was the best kept secret in motorcycling ....

FWIW, Triumph is once again a viable machine. I saw what looked a 650 Bonneville one day that looked like an excellent resto, but then I spotted a front disc. It was a new bike.

Their sportbike line is gaining respect too.

As far as looking like a monkey riding a football ... I had an 87 FZ600 back in the day that had a seat you could have used for "cruel and unusual punishment!" In a straight line that thing'd wad yer shorts in no time. But when I was carvin' canyons I just about didn't use it.

SP

sidegrinder
01-11-2007, 11:24 AM
Yeah, she was an Italian PrimaDona. A bit high-maintenance, but oh what passion. It was a torrid affair that couldn't last. I knew she could never settle down, so we parted ways...Now seeing a minivan in the garage, I know things will never be the same...I miss her ;)

http://i89.photobucket.com/albums/k203/sidegrinder/P1010030.jpg

Dawai
01-11-2007, 12:58 PM
I parked the old cobbled together harley with the built engine at the plant I was working. (part 58, part 76,. part... homemade)

There, my supervisor, knowing I had just gotten a ticket for excess of 100 in a 45.. said to me..
Gee.. poor engineering.. I was *expecting to hear another anti-harley sermon I just smiled..

He said" it don't make good engineering sense to make something that will run 100mph and when you stop you have to prop it up"... (kick stand) <end quote David Wright>

I have been seen hanging around looking in at the Haybusas.. I got grey in my whiskers.. Should not think about things that can kill me in less than a three count. I don't have a bike at the moment. I can borrow one in five minutes.. but don't have one.

The Local police did have a drug dealers Haybusa, it had chrome nitrous tanks never been filled, a queer paintjob that cracked open like a crocodiles skin.. A girl I had tattooed was telling me about it and all the money he had in it. I was hoping to buy it at auction.. but no.. so back to the dealership to press my nose against the glass like a kid at the candy store.
Bobby even told me he'd buy it, let me keep it a month.. that'd be long enough to flush out the desires. (he wants all the good toys)
My wife screamed her head off for two hours when she heard of the plan. She could imagine wiping my stinky rear while in a body cast perhaps?

HTRN
01-11-2007, 02:11 PM
Say what you will about Harley's, but just remember - finding parts for some of the "Superbikes" becomes one of the trials of Job once they get to be more than 10 years old.. Meanwhile, Harley's have off the shelf parts for 70 year old motors.:D

Hell, there's at least one company making NEW complete knucklehead engines.. :eek:


HTRN

aboard_epsilon
01-11-2007, 03:04 PM
is it a proper half hemisphere or is it some pent roof combustion chamber.

if its the hemisphere jobby you can do it on a Bridgeport.

with a boring head and a rotary table.

take note of LEvants first post ...2nd pic down

http://216.239.59.104/search?q=cache:tgo-LUopyLwJ:www.practicalmachinist.com/ubb/ultimatebb.php/topic/1/17436.html+sphere+bridgeport+boring-head&hl=en&ct=clnk&cd=2

all the best...mark

Dawai
01-11-2007, 03:17 PM
<quote>Hell, there's at least one company making NEW complete knucklehead engines..<end quote>

Ok.. mostly you are right.. where you are not? all the reproduction motors I have worked on lately are not harley, will not accept gaskets or some of the parts. You are searching or making gaskets and other parts.

There is a reason why original harley parts bring a premium.

Example.. the Revtech motor, yeah pretty, pretty castings.. I searched for about a hour trying to find out where they are actually made... The head gaskets, and several other parts I had on hand would not work.

The Ultima engines, yeah they are pretty good.. some differences..

S&S rocks... Last two engines I built was using thier parts.. problems? well they cost as much as factory harley.. you can buy a 80ci evo engine for $2495 with warranty. The cheapest and best way to build a custom bike these days? Although a evo is a twin cylinder it has little to do withe the older pans and shovels I grew up around. Mucho more reliable.. and tame to ride.. no preignition and carburetor problems as much as the older jobs. A good carburetor can make a harley last, a bad one (bendix) will wash out the cylinders and crap it out.. I have saw top ends put together right last only 2500 miles with a bendix carb.. of course, the bottom start getting loose and the top wears out quick too..

A factory evo engine, (e2 not twin cam) Korean 100,000 mile krusher six speed transmission, harley take off wheels and korean fenders and front end.
All the take offs are getting more scarce on ebay since the evos have not been made in a few years.. ya gotta look under the benches..I doubt being able to find brand new exhaust again for $25 off ebay..

Willy
01-11-2007, 03:24 PM
David I believe the Revtech is a Korean engine,lots of problems,I wouldn't want one on my lawnmower unless I had sheep in the yard.;)

speedsport
01-11-2007, 03:25 PM
REVTEC engines made in South Korea

ralphe
01-11-2007, 03:48 PM
I believe that a used head can be purchased on ebay for around $250

pntrbl
01-11-2007, 04:10 PM
I ran across a guy with souped up Hayabusa one night at a bar. Had an air shifter, polished frame, nitrous, and I don't remember what all. He was talkin' big so I stole around and had a look at his back tire. Just talk. He wasn't using that bike at all.

Now if ya see a guy with scrape marks on his pegs you'd better listen.

SP

Your Old Dog
01-11-2007, 04:49 PM
Say what you will about Harley's, but just remember - finding parts for some of the "Superbikes" becomes one of the trials of Job once they get to be more than 10 years old.. Meanwhile, Harley's have off the shelf parts for 70 year old motors.:D

Hell, there's at least one company making NEW complete knucklehead engines.. :eek:


HTRN

Ihave a friend near Sacramento who builds harley from parts he buys at yard sales and super flea markets! No kidding, been collecting harley parts of all sorts for ovr 30 years. Believe it or not, he ain't eBaying the parts! I thouht he could make a killing but he has no interest in computers at all. He has a 2 car garage with shelves all over it stocked with every harley part he can lay his hands on.

Dawai
01-11-2007, 05:43 PM
YOD:

one of the old round harley air cleaners with the zig-zag twist on mounts around the outside.. My drunk buddies had been using for a ash tray for 20 years.. the lil screw slots were perfect to hold a cigarette.. The whole inside was red where the ashes made it rust..

Brought $150.. on ebay,, I thought it would bring $5... My wife has gotten us some fancier ash trays..

I had two or three different women throw that thing at me.. I didn't mind seeing it go into a box..

I sold the old legend, the 12 over girder that was too narrow for a real tire,,, I had it in probably twenty rental house closets as I moved around over the years.. went place to place with me.. they are back in style.. spool hub.. insanity or macho.. bot the same.

Note: Ultima engines.. Midwest distributors are mostly STD.. some S&S.. pretty good, some are dyno tested before shipment.. THE std panheads thou have shovelhead ports and head gaskets. Shovel power.. pan looks. The prettiest harley engine ever made.. well I do like the knuckle too.. Oil leaker that it was..
All you young guys.. the old harleys, had a one way primary oiler.. it went into the primary.. then it went on you.... the newer ones, 1965 (pans then shovels) and up they recirculated.. Evo? you add the oil up to the mark and it stays there.. does not recirculate..
When you are building one of them $6k evos I laid out? (worth 12).. they make two kinds of breathers on the heads.. ya gotta pay attention.. and the 93 up does not have the breather in the cam cover.. ya gotta match them parts.. You can ride one like that for free for one or two years and sell it and still make money... free riding...

madman
01-23-2007, 10:54 AM
CMM ed the shape (friend generated it) mastercam tool path and cut cleaned up ;ppks like a new head. Amazing technology with computers.

Mark Hockett
01-23-2007, 11:29 AM
madman,
I'm glad to hear that worked out for you, Post some pictures of the part.

HTRN
01-23-2007, 06:23 PM
<quote>Hell, there's at least one company making NEW complete knucklehead engines..<end quote>

Ok.. mostly you are right.. where you are not? all the reproduction motors I have worked on lately are not harley, will not accept gaskets or some of the parts. You are searching or making gaskets and other parts.

David, the engine in question is being made by Accurate Engineering (http://www.accurate-engineering.com/custom_engines/knuckle.htm) I don't know who is doing the cases, but I strongly suspect S&S or STD.

There are a number of third party vendors, making everything from cases to taillights for motorcycles more than 50 years old. How many 10 year old foreign bikes(with the notable exception of Triumph and possibly Norton) can claim that? Not to mention the factory support Harley Davidson does - they have parts for bikes going back decades...


HTRN

A.K. Boomer
01-23-2007, 08:37 PM
BTW as a gearhead fact that wasn't mentioned in prior posts, Ducatis still have Desmodromic valve actuation. This is a holdover from the days of valve float, so there's probably no valid reason for it anymore, but it and the distinctive welded steel trellis frame are Ducati signatures, so you get to live with 100% more valve train components than you really need.




I beg to differ with that statement, Dukes desmo's have more advantage than just no "valve float", Its not a "holdover" for anything, its still a very intelligent way to go about producing more horsepower out of a normally aspirated engine than anyone else can for the same engine design, because they dont have to worry about returning the valve in time they can go totally radical with valve lift, this not only equates to extra power -- they also dont have to compress horsepower robbing valve springs --- this is huge, power saved is power earned...

Valve springs only return a fraction of what they take to compress (on the non-comp. side of the cam lobe) and at high RPM's this gets diminished real quick because most of the springs energy is then spent trying to return the valve in time.....

Ducatis Desmodramic system is still considerd a piece of fully functionable mechanical art, In my humble opinion the only one iv seen one up them is me, I utilized ports and didnt even have to recipricate anything:D

However -- I was also a Kid, didnt know a thing about metalurgy and mine ran and then "seen the ghost" (great siezures ghost):(
Sure was fun to find out I wasnt totally insane though;)

Gotta luv a duke, Id pull a motor to do a valve adjustment if it meant owning one of the newest desmos:p

and from what i hear there coming out with a desmo inline four - Now were gonna see some RPM's fella's...

A.K. Boomer
01-24-2007, 09:20 AM
CMM ed the shape (friend generated it) mastercam tool path and cut cleaned up ;ppks like a new head. Amazing technology with computers.



Just a word --- With all the trauma that you said this thing went through trying to compress its own valve head and such - I would keep a close eye on the relationship between the valve guide and the valve seat after a bunch of heating and cooling cycles and I would do this by means of a leak down test, (did you have to replace valve seats?) That head has got some parts that are very heavily compressed and others that are fluffy (im assuming you had to weld and build up material) This can make for a head thats going to move around for awhile before it settles in, in general this is not a problem except for one area, the relationship between the guide and the seat, because they have some distance -- if they squirm it can result in a valve that closes at an angle or worse yet offset even after its been properly machined, This is extra critical on a desmo because it relys on the combustion pressures to seal and does not have any aid from valve springs,,, By the way, how did the carillo rods hold up? them things are amazing but i dont know what happens to them when they try and compress a valve...:eek:

motomoron
01-24-2007, 05:39 PM
Nope.

Holdover technology.

Ducati's in the fashion accessory business now. They've had 2 "product launch parties" in the DC area in the past year, and they're full-on euro disco nightmares with air-kissing narrow wannabe models and greasy guys in shiny suits.

Trellis frames? desmo actuation? Ha.

If there was a compelling case for either they'd be on every manufacturer's bike in MotoGP, rather than the aluminum sheet and casting weldments and springs that everyone except Suzuki uses, who have adopted the pneumatic valve springs that are on all F1 cars.

Trellis frames and desmo valves are like the twin-kidney grilles on a BMW car, or the leaping cat on a Jaguar. Quaint holdover styling touches that the marketing division deems necessary.

I managed the parts department of a large multi-line motorcycler dealership in the 90's when Ducati was rapidly building a customer base on the strength of 9000SS and 916 sales, and the release of the first 900 Monster. The dodgy charging systems, breaking cylinder studs, exploding coolant overflow bottles, crappy generic Italian switchgear. All "european charm".

My 900SS was a hoot on the right road on thr right day, but in the main was shiny red turd.

It's been replaced by a KTM 950 Supermoto which does everything it did better, and is worlds more practical to boot.

If I get anymore Ducatis they'll be proper bevel drives.

Michael Moore
01-24-2007, 09:04 PM
While the frame and desmo are being used to differentiate the Ducati product, there's a lot to be said for a triangulated steel tube space frame.

They are fairly easy to make/modify/repair, pretty crashable and steel doesn't have the fatigue issues that aluminum does.

Plus, a space frame can offer less access problems than having some big frame spars in the way.

It isn't like the desmoseidici GP bike needs a lot of frame bits since the engine is doubling as a significant portion of the chassis. I'd be surprised if they have more than about 8 lbf of steel, if that much, in the frame.

Here's one I built for a Laverda 750:

http://www.eurospares.com/lavmk3sh.jpg

I'm not going to argue with you about desmo though. :) It can work just fine, but it doesn't seem to be the ultimate method for valve acutation.

cheers,
Michael

pntrbl
01-24-2007, 09:36 PM
Wow. That's nice work Michael. Triangualtion to the max .....

SP

A.K. Boomer
01-24-2007, 10:01 PM
Nope.

Holdover technology.

Ducati's in the fashion accessory business now. They've had 2 "product launch parties" in the DC area in the past year, and they're full-on euro disco nightmares with air-kissing narrow wannabe models and greasy guys in shiny suits.

Trellis frames? desmo actuation? Ha.

If there was a compelling case for either they'd be on every manufacturer's bike in MotoGP, rather than the aluminum sheet and casting weldments and springs that everyone except Suzuki uses, who have adopted the pneumatic valve springs that are on all F1 cars.

Trellis frames and desmo valves are like the twin-kidney grilles on a BMW car, or the leaping cat on a Jaguar. Quaint holdover styling touches that the marketing division deems necessary.

I managed the parts department of a large multi-line motorcycler dealership in the 90's when Ducati was rapidly building a customer base on the strength of 9000SS and 916 sales, and the release of the first 900 Monster. The dodgy charging systems, breaking cylinder studs, exploding coolant overflow bottles, crappy generic Italian switchgear. All "european charm".

My 900SS was a hoot on the right road on thr right day, but in the main was shiny red turd.

It's been replaced by a KTM 950 Supermoto which does everything it did better, and is worlds more practical to boot.

If I get anymore Ducatis they'll be proper bevel drives.

Here we go again, It has nothing to do with "holdover technology" Its an amazing way of getting things done -- Ducati only wastes energy in the form of reciprication to open and close the valve --- nobody, not formula one or suzuki can make that claim, pneumatics eat power as well as valve springs, the only real upgrade over a desmo would be a port system..

And of course not everybodys doing it, ever see a desmo head all torn down, nobody else is willing to put in that kind of machine time, and the finicky valve adjustments and on and on, they are a pain in the butt, but there is a reason for it, I ran a motorcycle service department on and off for close to a decade, Iv worked on everything from around the globe, I love the japs, but there is one machine that is just as exciting in the way its built, The japs have practical perfomance down to an art, But ducati throws a unique spin into the mix --- practical? God no, but for the most part attention to detail is second to none, I used to get annoyed with the dry clutch pack rattle that most of the dukes had, Id think - wut the hell, these guys are putting out some really fine stuff and then they drop the ball on this,, but then all the other stuff like the fit of the levers and foot pegs and shifter feeling like it was on roller bearings, I have allot of respect for a company who has shown the world for decades now that things can not only be done different, you can do it and pick up a few extra ponnies too...
Name a valve train that can accomplish what they can, You cant... everything you bring up will take much more horse to push it around be it electric, pneumatic, hydraulic or whatever,,,, unless of course its another Desmo design, and there have been many, but none as sucsessful as the dukes... Holdover? yeah -- right...
Want a real simple comparison --- take a look at a dukes timing belt, as much as they never want to break a belt the ducati's belt is about one third the thickness, its so wimpy looking it scares the crap out of you -- but its so wimpy because it doesnt take any effort to run a duke cam drive, in fact --- with light enough oil you can whip the cam sprocket and the valves will open and close until the cam gear runs out of momentum, try that on your KTM and get back to me.... Holdover ---- Get real.

A.K. Boomer
01-24-2007, 10:07 PM
That frame does look very strong Mike, I remember when the Japs first started using the engine as part of the frame, We had to put signs on them when we pulled an engine out "DO NOT SIT ON BIKE" thats all it would take to bend a frame sometimes...

Michael Moore
01-24-2007, 10:49 PM
That was 1" x .032" wall tube, which was very likely significant overkill for the application. But tubing is CHEAP, and in that size it doesn't weigh much and it has a pretty good second moment of area. Strong isn't a big issue, but stiffness is. If it is stiff enough, strength shouldn't be a problem.

Frames that depend on the engine should have "do not sit" notices on them when the engine is out. The person who got me started building frames made that a standard feature (when appropriate) on his race frames, as they'd definitely end up bent if someone hopped on them with the engine out.

Desmo can work (I had a 650 Allazzurra I raced) but it really was a solution to the poor valve spring technology of the late 1940s/early 1950s. Ducati has the tech down, so they can continue to use it and get good results. But it isn't anything that someone else (including F1 cars) couldn't use. Modern spring tech is sooooooo much better than in the old days, and if desmo was significantly better we'd see it being used on lots of F1 cars. Those guys seem to think nothing of spending $500K if they think it will give them an extra 1-3% performance boost.

I'd be really surprised if someone just starting out in F1/Moto GP (still can't get used to calling 500GP that) decided to use desmo valve actuation.

cheers,
Michael

speedsport
01-24-2007, 10:54 PM
Boomer where did you hear that Ducati was working on a inline 4?, it will be a cold day in hell before Ducati builds a inline four, they are as wedded to v engines as they are to Desmo valves. I have 3 Ducs sitting my garage right now, and 2 Honda VFR's, wanna know which one I ride?

Michael Moore
01-25-2007, 12:02 AM
He's probably thinking of the L4 replica of the GP bike they are saying they will produce in street trim.

cheers,
Michael

pntrbl
01-25-2007, 12:29 AM
My 83 Honda XR500 has an unusual valve setup. Honda called it RFVC for "radial four valve combustion" and what it means is the valves are all canted towards the center of the cylinder. It takes an extra set of sub-rockers to accomplish this, but it's been dead reliable for over 20 years.

The silly thing has 2 carbs too! One's a secondary that mechanically opens at about a third throttle. If it's making noise it's in the powerband .....

Good old bike tho. The Baja 1000 was dominated by derivatives of this machine for years.

SP

speedsport
01-25-2007, 09:36 AM
As the race for more power via higher revs continues Ducati has a problem with the desmo system, frictional losses goes through the roof and the added heat produced means even bigger radiators.

A.K. Boomer
01-25-2007, 10:44 AM
Frictional losses? Please enlighten all of us on how there is more frictional losses in a system that all but eliminates it,,, Like i stated before all the Ducati is dealing with is the recipricating weight of the valve itself, the valve spring system has to compress a spring that is strong enough to return the recipricating valve in time, so it not only has to get the valve open in time and is also dealing with recipricative force, its has to do it under the load of a heavy spring and retainer, because the valve spring is unable to give back all but a fraction of the power it took to compress it most of this power is a lost cause and is directly related to friction, Here's where things get interesting with your statement -------

"As the race for more power via higher revs continues Ducati has a problem with the desmo system,frictional losses goes through the roof and the added heat produced means even bigger radiators"

First off this made me laugh ----- but to put it in laymans terms, only the Ducati desmo engine will use enough power to get the job of reciprication done and it does take more but reciprication is the only thing its up against...

a standard engine will either float its valves or will have to run very stiff valve springs ---------- as the rpm's increase to the point of the valve springs limits (a little over redline) you can kiss just about all of your return energies that the springs would be giving back to the cam, not only does friction take its toll, but because the spring has reached its "time frame limit" in the amount of time it takes to return the valve back to its seat --- all of its energy is now dedicated to valve return ---- all the return energy is now dealing with the return reciprication, this means that the back side of the cam lobe that was returning a little at lower rpms is not even being loaded at all, this means that all the power that it takes to compress a valve spring is lost, and im sorry to inform you but this also means that your statement is ass backwards.

Not going to argue with you about riding the Honda's instead of the Duke's -- like i stated before i love the japs, the only thing i would question there is why do you have so many expensive bikes that you dont even like???

A.K. Boomer
01-25-2007, 11:55 AM
He's probably thinking of the L4 replica of the GP bike they are saying they will produce in street trim.

cheers,
Michael


That was half my bad, its a V not an inline, http://en.wikipedia.org/wiki/Ducati_Desmosedici

speedsport
01-25-2007, 11:57 AM
friction occurs when metal surfaces rub together, maybe you should take apart a demso system and count the places where surfaces meet.

A.K. Boomer
01-25-2007, 12:03 PM
"Further testing of the GP7 in Motegi, Japan, revealed that the 800cc machine could run faster laps than higher-end 990cc bikes, and held nearly a second advantage over the next fastest 800cc (Pedrosa's Honda)"


Must be that damn "holdover technology" again huh...

speedsport
01-25-2007, 12:12 PM
Boomer,
Why do I have them?
1. Because I can
2.investments- 1973 Sport, 1992 Superlight, 1975 450 Scrambler
3. What makes you think I don't like them?, I really do.
4. The best riding bike I ever owned was a 1973 GT
5. Bought my first Ducati 41 years ago, New black and silver 250 scrambler
6. I wish I knew half as much as you think you do.

A.K. Boomer
01-25-2007, 12:18 PM
friction occurs when metal surfaces rub together, maybe you should take apart a demso system and count the places where surfaces meet.


Hello, The other part of the equation is there needs to be "resistance" where the metal parts rub together, maybe you should try spinning over a valve spring engine and let me know the results... Then try a Duke...

Valve springs are nothing more than a wound up torsion bar, this means that metal is actually bending back and forth, there are losses in all the area's iv previously stated AND add the fact that spring material has its own internal losses in the form of friction that results in more heat, dont think its a factor, start thinking 133 times a second at 16,000 RPM's --- now start thinking about the poor cam lobe that has to make it all happen.......

A.K. Boomer
01-25-2007, 12:26 PM
Boomer,
Why do I have them?
1. Because I can
2.investments- 1973 Sport, 1992 Superlight, 1975 450 Scrambler
3. What makes you think I don't like them?, I really do.
4. The best riding bike I ever owned was a 1973 GT
5. Bought my first Ducati 41 years ago, New black and silver 250 scrambler
6. I wish I knew half as much as you think you do.



Speedy, I got nothing against you or anyone else but im passionate about this subject because i built my own system when i was a kid, I do know allot about valve trains and cant stand when bogus facts are thrown around, this is where my brain lived about 20 years ago, how much do i think i know? Im not afraid to but heads with anybody in the world on this subject, at the very least i stand to learn something but for the most part i like to help others understand, and no -- modesty is not one of my best qualities:p

Willy
01-25-2007, 12:30 PM
Valve spring design is a very sophisticated science because of the demands placed upon the metal of the spring,not only must the spring exert the required force to control the inertia of the valve train,it must also contol the inherent harmonics associated in doing so.The biggest obstacle that the metal of the valve spring must overcome is heat,because in doing all of the other tasks which it is required to do, it generates an enormous amount of heat.This is one of the reasons that ultra high performance vlave springs are so expensive,the metalurgy and R&D are not cheap.

A.K. Boomer
01-25-2007, 12:36 PM
Well said Willy, They amaze me, take off on a vacation across the country with metal bending back and forth 20 or 25 times a second and never have them break (almost never) unbelievably dependable and to date the best cost effective answer weve got...

speedsport
01-25-2007, 02:47 PM
1. It's not me you are arguing with, it's the guy who heads up Ducati Corse, the guy who designs the GP engines.
2. I guess we don't need to discuss the valve springs that are in the Ducati Desmo head.
3. A closed mind leaves no entry for learning.