NSR250 Exhaust Tuning NSR250 Expansion Chambers

MC21 Jha Expansion Chambers

The exhaust system is usually the first major item on any owners shopping list. Purely on aesthetics alone, shiny new expansion chambers rank as the number one upgrade! Just their presence is bound to invoke the "What else have you done to it mate?" and "How fast does it go now?" type questions from onlookers!

It is impractical to tune the standard exhaust system. However, the stock MC18 and MC21 exhaust systems will actually perform rather well on a lightly modified bike. If tuning to a high degree or racing though, a complete replacement system is required. If your finances won't allow it, at least a pair of less restrictive silencers should be fitted. High quality carbon fibre and alloy silencers can be purchased through the NSR-WORLD Marketplace.

Choosing the parts.

First decide on how much performance you require, if you are just looking for a modest increase in speed, a basic speed delimiter (or better yet, a free wiresplice!) and a pair of end cans will be more than adequate. However, if you are trying to extract the last nth degree of performance out of your bike you will want a race system.

MC21 Ethos Design Titanium Chambers

The immediate benefit of a race system is its weight saving. An aftermarket exhaust is also tuned to assist shifting peak power higher than stock, assisting conventional engine tuning.


Note: Although each system can look very similar in design, each will require the jetting optimised to suit. Even swapping pipes from the same manufacturer, say from Jha's 500V to their SP type or vice versa, the jetting must always be reassessed!


Fitting the system.

Most aftermarket systems now come with separate manifolds and spring clips to hold the various sections together. Bear this in mind if you are modifying your bike in steps, for example, if you intend to buy end cans only, with a view to fitting a system at a later date, check that the system you are buying can be used with your bolt on cans! Below is a diagram of a typical aftermarket manifold and its associated components.

NSR250 Race Manifolds

When fitting the new manifolds always use new gaskets and remember that the rubber O-rings, if used, will need replacing regularly, as they rapidly deteriorate with the heat generated by the exhaust gases.

When racing, the sections should be lockwired together. This provides added security just in case those springs work loose! (Lockwiring also stops some bright spark running off with your end cans when you're not looking!)


 Original product images reproduced by kind permission of Jha and Ethos.

Ignition Tuning.250 Tuning Index.Carburation Tuning.