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T5 ENGINE IMPROVEMENTS
The standard 125 motor gives impressive top end performance, but as standard the T5 suffers from lack of low speed torque. This results in difficulty in holding speed up hills and against head winds, especially when two-up or heavily loaded.
Cylinder Kits
One of the best ways to overcome this lack of pulling power is the use of a big bore cylinder kit.There are two on the market at present: Polini and Malossi.
The Polini is a cast iron cylinder (152cc). The Malossi (172cc) is an aluminium cylinder with a plated cylinder bore, like the original 125cc cylinder.
Our personal preference is for the Malossi cylinder. Although the more expensive of the two, it has proved the more reliable kit, even though it gives more power and torque. It gives a startling improvement in power when compared to the Polini cylinder. If all that is required is extra pulling power and approximately 75mph, then either of the above kits will give this as a bolt on, but the Malossi will normally give another 5mph and better acceleration. When further modifications are carried out the performance more than justifies the extra cost. Although it is not essential when used as a bolted on kit, it is desirable to modify the standard 125 cylinder head. Modification of the cylinder head for diameter and volume is essential when expansion chambers and/or reed type motors are used. Seek advice or send your cylinder head to us for modification.
Exhausts
Of the less expensive exhausts our personal preference is for the SITO-PLUS. We have found that this works very well whether the engine is standard or has a kit fitted. A further increase in performance can be obtained by using our Taffspeed Mk4 Goldline exhaust.
Note: When an engine is highly modified we can only recommend our Mk4 Goldline.
Gearing
It is possible to use 100/90 x 10 Pirelli or Michelin tyres from the Cosa model range to up-gear but you need to be careful and check the tyre/crankcase clearance. The clutch is basically of P200E type with different drive gear fitted (20t). The addition of stronger clutch springs or 4 plate competition clutch will usefully extend clutch life on a tuned motor. It is possible to up-gear 5% by changing the clutch drive gear to 21 tooth from 20. This gives a useful gearing improvement without stripping the motor beyond taking the clutch out. It is an extremely useful modification when used for long distance work with a bolt-on cylinder kit and exhaust.
The standard 125 motor gives impressive top end performance, but as standard the T5 suffers from lack of low speed torque. This results in difficulty in holding speed up hills and against head winds, especially when two-
Cylinder Kits
One of the best ways to overcome this lack of pulling power is the use of a big bore cylinder kit.There are two on the market at present: Polini and Malossi.
The Polini is a cast iron cylinder (152cc). The Malossi (172cc) is an aluminium cylinder with a plated cylinder bore, like the original 125cc cylinder.
Our personal preference is for the Malossi cylinder. Although the more expensive of the two, it has proved the more reliable kit, even though it gives more power and torque. It gives a startling improvement in power when compared to the Polini cylinder. If all that is required is extra pulling power and approximately 75mph, then either of the above kits will give this as a bolt on, but the Malossi will normally give another 5mph and better acceleration. When further modifications are carried out the performance more than justifies the extra cost. Although it is not essential when used as a bolted on kit, it is desirable to modify the standard 125 cylinder head. Modification of the cylinder head for diameter and volume is essential when expansion chambers and/or reed type motors are used. Seek advice or send your cylinder head to us for modification.
Exhausts
Of the less expensive exhausts our personal preference is for the SITO-
Note: When an engine is highly modified we can only recommend our Mk4 Goldline.
Gearing
It is possible to use 100/90 x 10 Pirelli or Michelin tyres from the Cosa model range to up-
