Ducati 350 Mk 3 and PBIR Track Day Report of 02/09/14 The Fast Ones

21 Jan 2015 | Author: | Comments Off on Ducati 350 Mk 3 and PBIR Track Day Report of 02/09/14 The Fast Ones
Ducati 350 Mark 3

Ducati 350 Mk 3 and PBIR Track Day Report of 02/09/14

The Fast Ones Ducati 350 On-Site at PBIR Track Day

Martin Weiss, aka Reptile Motos, on his Moto Guzzi V7 at PBIR Track Day on 02/09/14

Okay, honestly this is really an article about the Ducati 350 that Eric is racing now.  But it’s also a short track day report.  The Fast Ones and Reptile Motos recently made an appearance at the February 9 th track day at PBIR, formerly known as Moroso Motorsports Park, near West Palm Beach.

  The Sunday track day followed a vintage bike show which had been held in downtown West Palm Beach.

02/08/14 Vintage Show in West Palm Beach

Moto Guzzi specialist Martin Weiss, owner/operator of Reptile Motos in Orlando, Eric Watts (Ducati 350), yours truly (Eric’s father and the Ducati’s original owner), and Martin’s step son, Izzy, drove down from Orlando, representing The Fast Ones Vintage Racing at the track day.  We also did a quick walk through of the downtown show on Saturday afternoon before driving back out to the track for camping.

Saturday Night Camping and Drag Racing

It was great camping weather, though quite noisy at the track until the wee hours of the morning! Saturday night also offered the opportunity to watch drag racing, comprised of competition between all sorts of cars, from modified street legal cars to full alcohol motors in rail chassis, to junior dragsters piloted by kids.

Sunday 02/09/14 Track Day

Martin gets a ride on the PBIR Schleppwagen back to the paddock after a kill switch failure

Martin’s rode his well prepared V7 Sport Moto Guzzi, the bike being on track for only the second time since its arrival from its original home in Luzern Switzerland, Martin’s former homeland.  Other than missing a couple of sessions due to the failure of a cheap Chinese made kill switch on the Guzzi, Martin had a full and happy day of track riding.

Tim Gundlach on his loop frame Guzzi

We pitted next to Tim Gundlach and his brother, both Guzzi riders, and builders of the “Raven”.  The Raven is an interesting home-built classic look machine featuring a Guzzi engine turned sideways to create a classic looking V-twin configuration.  It is chain driven and has the appearance of a 1930s era bike.  They claim to be able to make it go quite quickly, so  I was disappointed that they didn’t ride the Raven on track.

It would have been really great to watch a good rider passing 600cc sport bikes.  Pitted on our other side was Martin’s good friend Bobby Summerville, aboard a Tonti framed Guzzi.

The video below is from Tim’s Ambassador 750 Guzzi.  You can see Martin exiting to the pits near the end.

And here is some action of Martin on the V7 recorded by Eric:

The Real Subject of this post, Our Ducati 350

Eric’s day was only a little bit disappointing, as we had all wanted to see the Ducati ridden again.  Since the Ducati got no track time this weekend, and because everything in my own little world was revolving around it, then I suppose this post is more about the Ducati and its history than it is about the track day. The backdrop of the track day and the camaraderie and good times spent with fellow motorcycling enthusiasts makes a great foundation for the story.

  History of Eric/Stirling Watts’ Ducati 350.

This Ducati has a fresh motor, just put back together about 15 years ago.  The bike itself had been disassembled since 1991 and scattered about my garage.  Martin spent the past couple of months getting the Ducati re-assembled, but it was not quite as ready as we had hoped.

   Let me take a step backwards 41 years to fill in the blanks.

The Initial Purchase

In the fall of 1973 I was a senior in high school.  I was riding a Ducati Mototrans 350 single (manufactured under license from Ducati in Barcelona) which I had purchased brand new earlier in the spring from the Columbus, Ohio Ducati/MotoGuzzi dealership.  I believe the price for the Mototrans was $943, and my mom got me a loan to help me buy it.  In October 1973 I found this Mk 3 350 for sale at a business called “Corvair’s” in Columbus.

  They were in the business of buying inventory cheap from businesses that were closing their doors, much like the Odd Lots of today.  Corvair’s of Columbus had purchased about a dozen brand new Ducati singles out of Canada from a dealership that had closed its doors. I got wind of the deal from the young fellow who worked as a mechanic for the Columbus Ducati dealer.

This is a desmo version similar to our bike when it was new. This bike was in the Saturday show in West Palm Beach.

I went out to Corvair’s on a cold rainy October Saturday morning and looked over the selection of Ducati singles they had purchased.  If I had had a few thousand bucks I would have bought them all, but I had to make a choice.  Besides Ducatis, there were also a couple of MZ two stroke MX bikes in the lot.

  In the Ducati department there was, as I recall, a blue 250 Mk3 with Desmo head, a couple of yellow 450 Scramblers, a variety of others that I don’t remember, and the one that caught my attention –  a red 350 Mk 3 with a springer head.  I think they also had a silver colored one.  No titles were available, and I bought the bike from them for just a little over $600.

  Dad had a lawyer friend who got me a title.

I kept both of these Ducati singles (the Mototrans and the Mk 3) for a while.  After I got back from Switzerland about a year later, I ended up selling the orange Mototrans Ducati for about $500.  I needed a car, and that money was applied towards the purchase of my first car, a 1967 Fiat 124 Sedan.

  I kept riding the Mk 3 in stock form on the street until about 1983.

Florida Road Racing in the 1980s

Jim Tribou GSXR 750, inside, and Henry DeGouw, TZ 750, in 1986 at Loudon

In the middle of the 1984 season I started road racing with American Association of Motorcycle Road Racers (AAMRR) at Moroso.  The Florida branch of AAMRR was the original group managed by TZ750 rider extraordinaire, Henry DeGouw.  Henry’s group later became AMA CCS, which still races at PBIR today, and is still under the management of Henry.

There was a very informal group of vintage Florida AAMRR riders who started to become organized around 1985.  After I ran my GS1000 and GS750 for a season at Moroso, I decided to transform the Mk 3 into a full race bike.  It went through several configurations of various home-made seats, rear set controls, gas tanks and megaphones.  During those years I also began to race more with the WERA vintage program in Savannah, and with a really informal and fun group called Florida Gran Prix Riders.

  I only ever raced with them at the old Sebring, but they also ran some at some other cheap makeshift racetracks in Florida, including Gainesville Raceway and the Tampa Fairgrounds parking lot.  It was a fun but sometimes slightly dangerous group to race with.

Does anyone know what became of Dwaine Williams?  He ran a little motorcycle speed shop in Lakeland.  Dwaine and Henry DeGouw never saw eye to eye, and the story was that Henry kicked Dwaine out of the track grounds at Moroso back in the AAMRR days for some blatant safety infraction, or for just being a dick, or something like that.

  Dwaine then decided to start his own informal and low budget racing club, which became FGPRA.  I stayed out of the politics.  I only know it was cheap to race in FGPRA and it was a lot of fun.  Dwaine rode a very modified 750 Norton quite quickly, which he trailered on a little open trailer behind a clapped out 70s era big Chevy or Oldsmobile sedan.

  I rather liked Dwaine, but a lot of people avoided FGPRA because of the personality clashes he had with other organizations which I chose to stay clear of.

Here is Syd Tunstall a few years back working on Malcolm’s bike at au unknown event.

The Tunstalls also came to those Sebring FGPRA events, and it was there that I became a little bit acquainted with Malcolme, the son who is roughly my age, and Syd Tunstall,  Malcome’s Dad. Syd was an Englishman who had immigrated to the US and later became Ducati’s original and sole US importer back in 1959.

When I bought my Ducati, Ducati was an unknown name.  I mean completely unknown.  Now Ducati is a big name, and nobody even knows of the Tunstall family and their contributions to the success of Ducati.  Syd never got much credit for putting them on the map here.

  You can read more about the Tunstall family in Mick Walker’s book “Ducati Singles”.

AHRMA Daytona 1986 and 1987

Eric was there!  He was three months old.  We ran the all three bikes at the Daytona during bike week in 1986 and 1987.  At that time the AMACCS modern bike cluib races races and the AHRMA vintage races both ran during bike week.

  Accordingly I rode the Ducati in the vintage events and the big Suzukis in the AMACCS full track configuration.  These were the only AHRMA events I ever ran, as the organization did not really appeal to me.  First, the AHRMA of that era was comprised mostly of riders who had little or no track experience.  Secondly they were quite adamant about their rather unreasonable rules which in my opinion left no room for imagination and creativity.

  That was why I always favored riding with WERA, FGPRA, and the sometimes non-existent vintage group within CCS and AAMRR.  These groups always had more of a “run what you brung” mentality, and let you go out and race and have fun.  That’s really the only point.

  I felt that AHRMA represented a snobbish element with which I did not care to associate.

Engine Modifications

For the first two seasons, we ran the engine stock. When it came time for a complete tear down which included splitting the cases, we decided to just go all the way.

The Bottom End

Ducati single engines utilize a pressed together roller bearing crankshaft.  This means that the big end bearing is fit to extremely tight tolerances, has an extremely long life, is well lubricated and thus offers much less rotational friction than does the more common setup of plain split bearing inserts.  This also means that replacing the connecting rod and ensuring that bearing tolerances are correct is no simple task.

I chose to have the crankshaft lightened and rebalanced by a crankshaft specialist, Falicon, located in Tampa.   That work would be a wasted effort without also lightening and strengthening the connecting rod.  The rod was purchased from Carillo, a reputable competition connecting rod manufacturer.

  I got my hands on the connecting rod, then purchased the appropriate roller bearings from a bearing specialist in England, checked and rechecked tolerances, and had Falicon press it all together again.

The ends of the crankshaft, as well as the transmission shafts ride in ball bearing assemblies which are pressed into the case castings.  When they get worn out, you split the cases and press them out.  We pressed them out and obtained the required replacements.

  Putting new ball bearing assemblies into this type of engine requires heating the cases in an oven to expand the size of the openings, and freezing the ball bearing assemblies to make them smaller, and then swiftly and efficiently pressing them back in. On two occasions this was accomplished in my own kitchen using the oven and the freezer, and a press.

The piston is a tried and tested piece supplied by Malcome Tunstall.  The manufacturer is Arias. The Tunstalls have had great success with this piston.

  I didn’t measure the compression ratio, but it is advertised as roughly 10.5 to 1.  We did, however, measure the piston to valve tolerance, just to be sure there would be no unexpected internal collisions.

The Head

This is not our bike again. This picture shows a Dell’Orto 29mm with remote float.

We are currently running a stock head with standard valves and the square slide 29 mm DellOrto carb that came on the bike.  We plan to fit our more modified head sometime soon, but we elected not to install it this time due to some oiling difficulties.

 Fitted with that head the engine burned oil only after getting significantly hot, and the only conclusion we could come to is that the wall between the valve box and the ported out intake tract is so thin that oil is getting sucked in when it gets thin enough to be sucked in.  Perhaps the ported tract need to be thickened and reshaped.

For what it’s worth, in my modifed head I installed a 42 mm intake valve from a Chrysler engine, and the exhaust valve was increased to 36 mm.  I had the valve seat work done by someone more experienced than myself.  Cams are stock grind, and you can’t get much more radical with cam timing really.

  The Mk 3 valve spring head cam timing is virtually identical with the cam timing in the desmodromic head.

In the hogged out intake tract, we ran a 36 mm round slide DellOrto from a Ducati 750 Sport.   I built my own intake “manifold” to match the big carb to the hogged out intake port.  (It’s not really a manifold, but simply an adaptor, on a single cylinder engine).

We never tested this engine, but I have read that Ducati engines with similar modifications have delivered dynamometer results over 40 bhp.  Of course, we are going to have to fix this modified head again before we ever see those numbers.  But according to Mick Walker, Ducati 350 singles in such a state of tune have reached over 120 mph on the Isle of Man.

Modifications by the late Gregg Woodruff

Maybe I’m getting off track again.  But this is a good point at which to introduce the contributions of my late good friend Gregg Woodruff.  Gregg and I became friends when we were both employed by the contractor for technical services for the USAF Eastern Test Range.  The ETR supports all USAF funded launch activities originating from facilities on Cape Canaveral AFS.

  Our activities included launch and tracking related work both at the Cape and at downrange tracking and communications stations which were located in The Bahamas, Antigua, and Ascension Island in the South Atlantic.

Gregg worked as a machinist and fabricator in the metal shops at Patrick AFB, and I was in the Communications engineering group on the same base.  We both came from sports car and motorcycle racing families. It was perfect match.

  I could create work orders for “antenna parts” and Gregg could manufacture them!  The US Air Force never had any idea that they were actually sponsoring a vintage racing bike.  Besides, those guys in the shops had nothing to do most of the time.

Aluminum Alloy Swingarm and Rearset Brake

One of the most beautiful pieces of work on this bike is the cast aluminum alloy swingarm adapted from a Kawasaki KX-80.  On a manual milling machine, Gregg fabricated two beautiful shock mounting lugs from forged aluminum which were then heli-arced to the swingarm.  The swingarm rides in needle bearings as opposed to the standard bronze bushings about which the more flexible steel tubing swingarm rotated.

  There is a little bit of a tire clearance issue, so it’s preferable to use a 100/80 rather than a 100/90 sized rear tire.  The rear wheel could also come back a bit more in the swingarm to provide more tire clearance if we would go up a few teeth on the rear sprocket and compensate by using a smaller drive sprocket up front.

This swingarm is, or was at the time we built it, unacceptable to AHRMA, and technically it was not even allowed under the WERA rules.  But in WERA and especially in FGRPRA, nobody really cares.  Besides, I used to also run the 350 in the F3 class against real 125 two stroke road racers, and in F3, modifications are unlimited.

  We wanted to build a special modernized and improved Ducati, and not just a nice looking relic restored to factory specs.

Ducati 350 Mark 3
Ducati 350 Mark 3

You can see a little of the modified Kawasaki KX 80 aluminum swingarm in this picture

We elected not to use any rearset control on the shift lever.  This bike, like all Italian bikes built before the federal mandate for left side shift levers, shifts on the right side in a one up four down pattern in stock form.  The factory shift lever was a heel and toe design which was operated from forward and centrally positioned rider/operator footpegs.  The rider/operator footpegs are too far forward for roadracing work and have been removed.

The rearset footpegs are simply the factory passenger footpegs.  From the rear passenger position, the transmission can be easily shifted  by simply pushing and pulling the back arm of the double shift lever, the back art being initially designed to be operated by the heel.  The front arm of the shift lever has been cut off.

  Thus, since shifting is done from the passenger peg, the shift pattern is inverted, making it a one down and four up pattern.

The rear brake lever is a beautifully crafted forged aluminum allow piece which actuates the brake via a rod. These parts were also fabricated in the PAFB shops.

BSA 650 Triple Clamps and Tapered Roller Steering Head Bearings

This was a pretty easy conversion.  Ball bearing steering heads wear a lot, always require adjustment, and always seem to have a little bit of slop and play in them.  The stock forks which utilized short external springs mounted up top were initially replaced by used Triumph forks which measured about 34mm in diameter.

  That has been updated since the current forks are 35mm units from a Guzzi, adapted for the purpose of the eventual disc brake conversion.

The Front Brake

Back in the day, when I was trying to mores strictly follow vintage class rules, I elected to install a real drum brake.  I bought a 4 leading shoe front drum brake from a Suzuki 750 water buffalo, drilled it full of holes for cooling and to help lighten the whole assembly, and adapted it to the above referenced Triumph forks.  It worked pretty well, in fact much better than did the wimpy little stock 2 shoe brake, but it was heavy.

This time the decision was made to build a special, not just a replica.  It was to have real brakes.  Several years back I had purchased a Guzzi front hub which would carry a disc.  Martin purchased a new Akront style rim (I think the rim is actually a Borrani) and laced it to the Guzzi hub.  Guzzi forks replaced the worn out Triumph tubes, which were too long anyway.

  Some material had to be removed from the triple clamps to accommodate the larger diameter fork tubes.  The result is what you see.  It has real brakes now!

Technically the disc brake should be permitted under vintage rules, even though I am sure AHRMA and WERA rules still prohibit it, as the 1974 Ducati 350 Sport did offer a single front disc as an option.

The Fairing and Tank and Seat

Fitting the fairing in Reptile Motos Shop

I used a variety of gas tanks on this bike.  At first I used the stock Mk 3 tank and a home made fiberglass single seat, with no fairing.  As time went on I fitted a Yamaha TZ 125 fairing and windscreen, and built a replacement fiberglass seat that I never liked.  At one point in the 80s I bought a 250SCR narrow case Ducati for parts, and I think that’s where I got the bigger steel tank, which looked pretty good.

  And I even tried to fold up sheet aluminum and build an alloy tank, which was hideously ugly.  I did show up at the track in that configuration once, and it didn’t look so bad because the fairing was hiding it.

I apologize for not having any pictures from the old days.  I never thought about pictures, and it seems to me that people in general thought about pictures far less in the days of analog film only.  Somewhere I do have a stack of photos, in an old box somewhere – one of those boxes that’s been moved from house to house over the years.

The folded aluminum seat was built by the metal shops at Patrick AFB.  It was designed to go with the angular looking folded and heli arced tank that looked so bad.  But the seat came out nicely, and for the sake of a unique look, we decided to keep it when we purchased the factory replica racing tank and fairing from Tunstall’s.

  They also sell a couple of very attractive fiberglass seats for Ducati singles, but we felt that this seat adds some personality to the bike.

The red white and green paint scheme currently in use was Martin’s idea.  It resembles the 750 Hailwood replica fairing, but it is still unique.  I had painted my old TZ 125 fairing in a similar red white and green scheme because it was supposed to resemble an Italian flag.  I had not even thought about the Hailwood replica.

  Martin fabricated the fairing mounts which allow the fairing to be quickly removed using eight quarter turn Dzus fasteners.

Exhaust Megaphone

With the smaller stock 29mm Dell’Orto installed, martin wisely chose to use the smaller megaphone which I had initially used in the Ducatis earlier racing days.  It’s a straight through megaphone.  I have also a larger output megaphone which I had used with the ported head and 36mm carb.

  It tends to make power at higher revs, while the smaller opening tends to spread power more evenly through the usable rpm range.  Both of them sound good, and are not annoyingly loud at all.


In Martin’s shop we weighed in using an electronic scale at 251 pounds wet with the bike race ready.  That’s quite an improvement over the initial 280 pounds dry  in street trim, which means that a Mk 3 on the street weighed somewhere around 295 pounds wet as a street bike.

We reduced weight to the extreme is a number of ways that most people don’t even bother with.  Most important is the reduction of reciprocating weight, especially in the drive train.  That’s the biggest reason that flywheels are removed and crankshafts are lightened in competitive racing motors.  We drilled holes in every reciprocating as well as in other non reciprocating parts.  We even hollowed out the centers of a number of the heavier bolts.

 Some would find this a bit absurd, and, admittedly, maybe it is!

Troubles at PBIR and Future Plans

We basically had trouble with three items.  First off, starting this bike with the higher compression piston installed has never been easy.  Combined with the fact that the oil bath clutch was not fresh, we experienced some starting difficulties.

 We were using standard Castrol, which is kind of slippery stuff, and found that when the clutch was dropped in second gear when push starting, the clutch was just slipping.  That behavior combined with the fact that the idle jetting is not right on, gave us some huge starting problems.  We also failed to start with a fresh set of points, and did not have the timing precisely set.

Eric and Martin discussing what to do next

We had successfully started the bike and run it up and down the street the day before, but on track day it just refused to light up.  We fiddled with fresh plugs, cleaned the points repeatedly, moved the timing around, and even took the clutch apart and dried to plates off to give it some extra grip to get it started.  After accidentally losing some clutch linkage parts through the clutch actuating tube, we decided we should go do some work before the next event.

To remedy these problems, three modifications are planned for the near future.  Electronic pointless ignitions with a choice of programmed advance curves are now available.  Dry clutch kits are also readily available off the shelf for Ducati singles.

 Those changes, supplemented by a set of starting rollers, will cure the starting blues, and once we get it warmed up with a selection of the right idle jets, we will be enabled to make this thing more reliable.

The other future plan is the addition of an electronic tach.  We were not able to locate the mechanical drive parts which drive the tach from the bevel gears, but after some consultation with the Tunstall family, Malcome suggested going the electronic route on account of tach drive failures in the past that head caused some bevel gear damage.

Thank You, Reptile Motos!

All of the work that went into resurrecting the Ducati was due to the intelligent and diligent work or Martin Weiss, aka Reptile Motos.  We thank Martin for his time and interest and we look forward to a long racing relationship.

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