23 Feb

Earlier motors


Some images and technical descriptions of my own earlier race motors can be found by reading on.

Malossi group 3/4

 The first one pictured is my old group 3/4 spec malossi barrel based motor. Its rotary valved conforming to the class rules. No welding to increase port area is allowed. Power was around 18hp. Pistons would require changing every 3 to 4 meetings to keep the motor in tolerance. It was the unit I raced on in 2000 winning the group 3 championship and also the most robust and reliable motor I built when I was tuning for myself. The main issue with these early motors of mine was clutch failure. Today as superior components are available its not such a problem Currently being rebuilt for a friend to race this year this engine will be using a carbon uprated xl2 type clutch which utilises multiple springs. A Drt top plate will help prevent the dreaded clutch drag that is common with 4 plate clutches. Carb will be the 30mm dellorto flatslide and exhaust is a one-off design made for me many years ago by Graham Best of Kegra Racing. Ignition will be the variable advance and retard unit from Vespatronic. Its the same as I use on my current Falc based Performance Tuning motor and has proved 100% reliable so far. Cylinder head is a one off  central plug design as you can see from the picture.

To gain extra performance with the Vespa its sometimes necessary to ‘jack the barrel’ up. Raising the barrel will increase port timings and therefore you’ll increase the effective area/time to get your charge in and out. The trade off can be a more peaky type of power delivery. Of course with a well designed pipe for the correct port areas and angles you can achieve the delivery that best suits you or your type of racing.. for example if you race small kart type tracks you be better off with a power delivery that begins fairly low and is spread out rather than a motor with a high rpm narrow power band. Pictured is the transfer area complete with its ‘packer’ from a group 3 motor. Note the gap on the left hand side half way down the port. As welding is not allowed you simply use the stator plate as part of the transfer on that side..a common trick used in the 80’s. As mentioned before clutches were a major problem with these early race motors. One trick was to ‘preload’ the malossi single spring with a seal retainer washer from a Lambretta. I personally didnt like it and felt it only added to the dragging issue of the 4plate clutch. With the introduction of the xl2 type clutch things got better. However this was a time before the amazing DRT ‘Parastrappi’ and so my alternative solution was to make this gear kit shown.

This Polini based kit has a welded billet basket enabling 4 steel  friction plates from the standard type clutch to be used with an xl2 spider and 12 springs. This solved the clutch problems but of course no cush drive is present. You have to be very smooth with gear changes to protect the crank and gear selector. Today with such racing firms like DRT and Falc the clutch and gear kit issues are fairly much a thing of the past.

Fabrizi Proto

The idea behind the Fabrizi barrel motor was to get max cc but still keep the bike legal within group 4. Group 4 rules allows certain homologated barrels within the rules. Welding to increase port area or use of reed valves is illegal in the class as is machining the spigot or moving the barrel studs. I planned to get the Fabrizi homologated at some point, or at least propose the barrel but first I had to have a running engine that was producing the power. The problem with the Fabrizi is that it required a spigot machine to fit the barrel. I got around this by the use of a longer conrod. This allowed me the use of a packer plate that I could machine to the standard spigot size of 61.5mm (approx) and then machine a step into that to accomodate the oversize neck of the Fabrizi barrel. I used a fairly short piston from Wiseco and calculated that the piston would use part of the original casing spigot and packer as the lower half of the barrel. With another bespoke pipe from Graham at Kegra the motor was run. The initial tests were good..again clutch issues didnt help but this was again resolved with the billet gearkit design and xl2 clutch setup you have seen above. Power was circa 20hp. However after long running tests it became apparent that vibration would cause me a major problem. I attempted to get the crank balanced by various companies before speaking to Steve at Vibration Free in Northampton. The motor was delivered, built and it was run on a dynamic balancing machine. With just a small weight added to one point on the flywheel the imbalance was cured . Power rose to circa 22.4 hp. I raced the bike competitively at Anglesey 2007 on the understanding that no points would be recorded due to the non-homologation of the barrel. It went well.  But Falc had just released the new kit barrel that was to reset the standards.. I had to be a part of that revolution and so the Fabrizi proto idea was shelved.

Fabrizi motor rev-up


Quattrini M1R

From Italian tuning house Quattrini the M1R is a barrel kit/crank/pipe package that is simply ready to race. I have built both old and new versions of this high specifiaction kit that has been raced by Steve Pollit on his ex Norrie Kerr 90SS in the Bsso series here in the Uk. The early version produces circa 24hp at the wheel. Its a beast to ride with a punchy power delivery. Clutch is also by Quattrini and is based on the single spring type setup. The later barrel shown uses ‘Boyesen’ type ducts from the reed to the transfers. Power delivery is less frantic and hp is lower.

Here you can see the exotic port configuration of the M1R barrel. Quite a difference from a standard Piaggio unit! Constructed of aluminium with a nicasil plate together with a central plug cylinder head the motor has proved its performance but basically its design was for 150m sprints so some re-work of the ports is due for this year.

6 Responses to “Earlier motors”

  1. Adam Romness says:

    I for one can’t wait for the supercross racing season to kick into full gear. Our bikes have been packed up and garaged for the offseason, but it’s time to get them out there. We have alot of work to do on some of the bikes, and its gonna take some time, but like we do each year, we upgrade several of the systems, and make our supercrosser bikes better than they were the season before. Ride hard – or go home…

  2. Super-Duper site! I am loving it!! Will come back again – taking you feeds also, Thanks.

  3. John Petersen says:

    This stuff is fascinating. I came across it whilst looking for info about “balancing” an older type VESPA motor, in particular an 86 PX 200…..not found the info as yet.

    Regards, John

  4. Adam Collier says:

    Absolutely top quality website…..
    very interesting reading, and the merchandise (stickers) are great too….

    i watched the Green Hornet Vespa 90 SS racing at Mallory Park earlier this year… UNBELIEVABLE.
    Keep up the good work

  5. chez smyth says:

    as adam collier said top site….. also have seen racing at malory (those mushroom things really got you airborn) was good to see a vespa looking like it could compete with charley cant wait for next year all the best chez..

  6. Tony says:

    Chez.. thanks mate.. pls come along and have a chat next year… the mushrooms got me for sure in that race! Just my bad riding.. 🙂 I’ll try harder next year 🙂

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