POPULAR MODS - so you want the fastest Dragster on the street (or the drag strip)? The following guide outlines the basic stages of tuning your Dragster. After fitting these mods (and parting with your hard-earned cash) proceed to our Daddy Mods section for taking your Dragster to its limit.

Stage 1: Performance Exhausts

The majority of professional tuners believe that fitting a performance pipe should be the first thing you should do when tuning an automatic scoot like the Dragster. Upgrading your exhaust from standard should in most cases give you an increase in performance across the speed range. Some exhausts require that the carburettor needs re-jetting, some require that the variator rollers need changing.
 
For the purpose of example, let's look at PM Tuning's PM55 exhaust which can be bolted-on without having to change the variator rollers. There are two versions, the original PM55 MkI and the PM55 MkII. The PM55 MkII has been proven to give good power increases on 125/180 and 172 kitted engines. Power is up by approximately 2HP across the speed range, and 3HP at around 75mph. Roll on throttle tests from 20mph shows the PM55 MkII to reach (84mph) 77 yards earlier (2.61) seconds faster than standard. The PM55 MKII (particularly in chrome) is also a great looking piece of kit, and a great sounding one too - it's got some grunt! PM Tuning's latest offering is the PM59 X-Tech pipe often called the 'curly wurly' pipe since the muffler points to the reverse of the bike by way of a 360 pipe. Good results have been obtained on both road-going bikes and bikes tuned for the drag strip with the PM59. Back to back comparisons between the PM59 and the PM55 MkII shows the power of the X-Tech pipe to be up by an average of 1.5HP across the speed range with specific power increases aimed at mid to upper power levels over the PM55 MkII.
 
Of a a similar design to the PM55 is exhaust manufacturer Scorpion's offering for 50, 125 and 180 Dragsters. The Scorpion pipe that will fit the D125/180 is a reasonably priced pipe and a good performer. Breakages were reported with earlier versions of this pipe, but to be fair this has been the case with many exhausts on the market. Once you start tuning your machine the exhaust in particular is one part of the bike that becomes particularly prone to vibrations from the engine. So when buying an exhaust, if you can see one up close take a look at the pipe for any signs of weakness e.g. poor welding (since most of these pipes are hand-made) and areas that are prone to stress e.g. brackets and muffler straps. Scorpion pipes have since proved to be a very popular and reliable choice among Dragster owners and a popular choice of pipe for Gilera Runner owners too.
 
For 50cc Dragster owners, the Giannelli range of exhausts and also the Arrow 'Kompress' and 'Limited' series have been reported to have been very good in the past. These are again hand-made and a lot lighter than the standard Italjet exhaust and give a respectable increase in performance. Another cheap but effective alternative is from Tecnigas who produce a pipe which will fit 50cc Dragsters. Some 50cc owners may be enticed by the Ninja 'Twin' (as seen here in the Gallery) which looks pretty cool but has been reported to have offered very little power performance-wise when tested.

Pipe dreams... Italjet unveiled this nice looking piece of kit (above) at the International Motor Cycle & Scooter Show 2000. It was originally designed by Lotus and manufactured by the now defunct Janspeed. I'm sure you'll agree that the pipe certainly looks the business. It's angled at about 45 degrees, which gives a greater view of the rear wheel (unlike the orginal exhaust). Don't be fooled though that such an exhaust for the two-stroke Dragster will ever be available, it's clearly designed to fit four-stroke engines. If you want to see more pics though, check out the Gallery.

For those of you who want to retain the original exhaust, it's worth noting that you can replace the original downpipe (which is very prone to rust) with a brand new stainless steel one. These are available from German company SIP who claim the downpipe will increase your performance by about 1HP.

Stage 2: Carb Kits

The carburettor is the part which vaporizes and mixes petrol and air, upgrading to a bigger carb increases the air intake. Carbs come in different sizes, Malossi offer 25mm carb kits, these come with a manual choke and you will need a larger size inlet rubber. PM Tuning do a 25mm carb and manifold kit including optional carbon fibre reeds as used on their PM Equinox Gilera Runner. This carb kit will fit the standard Dragster air filter box.

Reed Valves & Petals - the Dragster's two-stroke engine uses what is known as a reed valve. Fitting a larger, thicker sized reed valve will alter the characteristics of the motor.

Air Filter - bigger carbs (i.e. over 25mm) such as the Dell'Orto carbs require a bigger air filter which will enhance the air flow allowing the carb to perform at its best. Malossi do a range of air filters to suit, there are two distinct shapes, straight or angled. Upgrading to a bigger air filter will require re-jetting. It's advisable to get a qualified dealer to do this. The standard Italjet air filter though has the advantage of being water-proof (due to the plastic casing), so by upgrading your air filter it's not really advisable to ride in wet weather.

Available from Doppler is their 'Air System' filter designed to reduce induction noise and offer improved carburetion. The Doppler 'Air System' filter is based on the principle of 'forced air' employed by motorcycles using 'Ventura tubes'. This principle accelerates the speed of the gas and as a consequence increases the air passage to the engine. This air filter can be used with the original carb (Dragster 125/180) or with carb's having larger diameters. In the case of the latter, it is simply a matter of adapting an additional Ventura tube (which comes supplied) to the air filter unit.

Stage 3: High Compression Cylinder Kit - the next stage after fitting a new exhaust and carb is to fit a high compression cylinder head kit. This will increase the power and torque of the engine. If you're not equipped or experienced enough to do the job, go to reputable dealer or tuner who will fit an appropriate cylinder kit of the correct specification for your Dragster. The usual case being a 70cc kit for Dragster 50s or a Malossi 172cc kit for Dragster 125s. Cylinder kits usually comprise of: cylinder head, piston with piston rings, clips and a top end gasket set. The new parts will require running in once fitted and you'll have to run your Dragster on super unleaded fuel. Cylinder kits will require changes to the carburation and some may need clutch, oil pump and transmission changes. In terms of reliability Malossi are Europe's biggest manufacturer of cylinder kits hence a good choice for reliable parts, contact your nearest Malossi Tech Centre or a reputable dealer.
 

Other parts to consider upgrading are:

Variator - upgrading your variator can give your Dragster slightly higher gearing but without the bottom end power. Or, they can help you eliminate some of the rev drop off by increasing the revs at lower/mid-range speeds.

Rollers - come in different weights and help to produce peak power where you want it, i.e. at the correct RPM. Fitting the correct rollers is pretty much trial and error, so it's worth buying sets of rollers of various weights in order to find out what works best.

Belts - the belt runs from the variator to the clutch, upgrading to a kevlar belt is more suited to upgraded motors where belt slip needs to be eliminated, kevlar belts are heavier and more durable than standard belts with less slippage. Malossi kevlar belt's (part no. 61 8739) are a popular choice as are Polini drive belts as a replacement to the original Piaggio belts.

If you're wanting to increase revs from stand still, upgrade your Clutch Springs . These are used in conjunction with other performance parts to allow you to harness the power better. A set of Malossi clutch springs consists of three different strengths in three different colours (red, blue and green). A common question is, how do you identify which springs to use and what do the different colours represent? Well, identifying the strengths of the springs by colour is irrelevant, due to continual changes in Malossi specification the colours now do not signify any particular point, other than as a means of being able to identify the three unique sets. To identify the strongest springs then, you have to measure/compare the thickness of the actual wire. This combined with the LEAST number of spirals will denote the strongest spring. At the other end of the scale the weakest springs will have the thinnest wire and the most spirals (not in all cases though). Fitting the weakest strength springs would be advisable with standard motors and you'll improve your set off speed. Hence the middle selection would be the closest to standard.

PM Tuning's Engine Pivot Bush Kit will eliminate a large amount of engine side flexing, allowing for better stability and tracking during mid- to high-speed cornering.

Ultimately, fit a performance exhaust, a 172cc kit and PM Tuning Pro Street Billet Head (see Daddy Mods) and you'll get a 10HP power increase across the speed range with wheelie credentials.