The Honda X8R scooter are restricted by a rev limiter in the CDI, a washer in the exhaust system and a restricted variator that limits gearing. The washer in the exhaust front pipe is easily dealt with - just grind out the spot welds and remove it.
The original CDI has two rev limiters built in, one at 7,500rpm and one at 9,250rpm. The standard motor runs at 7,000rpm at peak power.
The CDI can be modified to remove the 7,500 rev limiter. If the cylinder and exhaust remain standard then this is okay, as by the time the motor hits the 9,250 rev limit power output is more than halved compared to power at 7,000.
The front pulley variator has restricted movement. The easiest way to fix this is to replace the variator assembly. Either a cheaper replacement unit or, if further tuning is envisaged, a Malossi or Polini unit.
The variator, CDI and exhaust modifications will give an increase in speed from 30 to 33mph up to 42 to 45mph. The power of the motor from the exhaust modifications rise from 3.5 to 5bhp, giving enough power at 50cc to go to 50mph. There is a modified Bali gear kit we do that is a 15% raise in gearing that gears the 50 to the right level to achieve this.
If a 70cc kit is to be used the higher gearing from Malossi or Polini is more sensible and increases the top speed potential to over 60mph on the standard exhaust and 70mph on aftermarket exhausts.
If a higher revving exhaust or cylinder kit is to be used aftermarket CDI are available that have programmable rev limiters to set to the RPM you wish or bypass it completely.
With aftermarket exhausts (LeoVinci or Giannelli) that will give power above the Honda 9250 rev limit. It is desirable to fit a CDI that will allow engine operation above 10,000rpm to obtain full performance.
There are Malossi cast-iron and aluminium MHR 70cc cylinders available. The road cast-iron cylinder with a suitable exhaust and carb kit will give over 8.5bhp at the rear wheel. The MHR kit will give over 10bhp. Both will work with the standard exhaust, but an aftermarket exhaust gives best results.
In order to achieve maximum increase in performance with the 70 kit - a larger carburettor is necessary. Malossi do a 19mm carb.
In order to maximise acceleration the transmission can be improved by the use of a torque driver rear pulley half, which minimises engine RPM changes.
When high gearing and higher revving cylinders and exhausts are used acceleration from standstill can be improved by use of clutches that can generate more slip. The Malossi fly clutch is the road version. The Delta clutch is the full race unit that has adjustable springs and weight positions as well as a choice of springs.
For most road engines stronger springs for the standard clutch or the fly clutch are adequate.
For the ultimate road tune a full circle crankshaft with race spec conrod and big end bearing is available. This allows modification to be made that allows 13,000rpm to be used reliably for race work.
Derestrict or change exhaust
Derestrict or change CDI
Change front variator
Fit raised gearing to suit 50 or 70cc
Fit 70cc kit, cast-iron or aluminium
Fit larger carb kit
Fit torque driver rear pulley to improve transmission
quality on high revving tuned motors
Fit race crankshaft
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