Suzuki is working on making its 250 cc parallel-twin engine comply with the stricter Euro 5 emission norms. Patent images of the updated engine reveal the changes that Suzuki plans to implement.
Suzuki’s quarter-litre SOHC mill already has a catalytic converter located underneath the engine. However, to meet the Euro 5 emission regulations, Suzuki would add another catalytic converter which sits closer to the exhaust ports and the cylinder head of the engine. The placement of the new cat-con is optimum as the unit will reach its operating temperatures faster, which is a key requirement to meet the Euro 5 norms.
Since the new cat-con sits closer to the exhaust ports, Suzuki has to merge the two exhaust header pipes much earlier so that they enter the new catalytic converter. At the exit of this cat-con, the pipes unmerge and then make their way into the old cat-con. It can be seen in the patented images that the new catalytic converter has two oxygen sensors. They keep a check on the exhaust gases before they enter and after they leave the unit.
A different approach to this whole process is to add two separate cat-cons to each of the header pipes. In this case, there’s no need to merge the header pipes as they have their own cat-con units. However, this method is on the expensive side because it increases the usage of the catalyst materials which are pretty costly. Consequently, Suzuki will most likely not use this procedure.
At present, Suzuki uses its 250 cc parallel-twin engine in the GSX250R, V-Strom 250, as well as in the GW250 Inazuma. To ensure these motorcycles continue to be on sale post the implementation of the Euro 5 emission norms, Suzuki has to fit them with the updated Euro 5-compliant engine.