TY Mono Tuning

TY Mono Tuning

In standard form the TY Mono is perfect for entry level riders and anyone not that interested in higher level competition or riding competitively in modern events. Power output is very docile and nothing happens very quickly, making the Mono ideal for anyone wanting to concentrate on their actual riding rather than engaging in a fight to the death with their bike. Something which seems all too common if you are a beginner on a modern machine!

Mono and 175 at test venue

 However, for better riders competing at higher levels, lack of power is something which can be a problem for some TY-Mono owners. Over the years many alterations have been carried out to improve the Mono with some working much better than others. The cylinder with shortened intake tract pictured is reflective of the type of work commonly carried out in the past and seemingly still available today. The fact that this mod is quite costly and doesn’t work that well, has not altered the fact that it’s still being offered by some tuners.


In terms of function increasing the time area of the rather small TY exhaust port provides more blow-down time, a little extra power and a motor which will rev more freely. Making the exhaust port larger is relatively easy to do and is certainly something which can be carried out by anyone with a die grinder and the appropriate cutters. However, without also increasing the transfer time the larger exhaust port may well mean a higher revving motor with a distinct power-band that might not be very nice to ride!


Stock and alternative reed blocks for Mono

From cylinders we have seen, it appears that many were altered by enlarging the exhaust port and shortening the intake tract, but without any changes made to the transfers whatsoever. In terms of time taken a cylinder modified in this way takes maybe half the time it would take to do one with transfers properly altered as well. Gas speed in the intake tract is marginally increased by cutting and welding but its more effective to fit a reed block with less flow area and reshape the port using Devcon to help speed up the gas-flow.


Something that seems to drastically reduce the effectiveness of any porting alterations to the Mono though is the long and rather restrictive intake hose sucking in and reducing flow when the motor is being used hard. Back in the day Kato produced alternative air boxes which overcame this problem. Today anyone who has a modern rear unit, can fit an auxiliary air box (pictured) which serves pretty much the same purpose as the Kato boxes back in the day, but provides higher volume and are less restrictive than the Kato boxes.

Mono air boost chamber

Realistically with careful attention to the induction/exhaust, carb, ignition and porting there is no reason why Mono performance cannot be increased significantly. However, many people mistakenly believe that these types of modifications will work in isolation, which to be honest simply isn’t going to happen when you are dealing with exhaust systems which may well be clogged with 35 years’ worth of carbon/oil residue and ignition system parts which if they are original will almost certainly be providing a weak spark and timing curve totally different to that given by new parts. Original carbs are also likely to be well worn and will often mean poor throttle response and various running problems.


The Mono exhaust front pipe is quite long and in combination with excessive carbon build up is something which can restrict the free passage of exhaust gases considerably.   The front pipe on a Mono has to be clean for the motor to run properly, and as new parts are not available having the pipe professionally serviced is the best option. Back boxes are available new and we would suggest a re-packable type for anyone who chooses to use excessive amounts of 2T oil, as this will clog the back box quite quickly. Non-re-packable large volume back boxes are a good idea if you have a modified motor and are using the correct 2T oil at the right mix ratio.  


Finally, carburettor and ignition are 2 things which are very often ignored by trials riders. If you have a modified motor the effects of a worn carb or ignition system providing a weak spark will be magnified and will be far more noticeable than they would be on a stock motor. For best possible performance both of these parts MUST be renewed/refurbished and if they are not running problems which are very difficult to pin down may well occur.


Modified Mono cylinder