The next generation of KTM engines is said to feature a 990cc inline-twin. A patent has been filed for this engine and the designs revealed.
First appearing as the 790, with a displacement of 799cc and evolving into the current 889cc version, referred to as the 890, KTM's LC8c twin-cylinder engine has already received a notable displacement increase – and now another is on the way as the company prepares a new generation of 990.
This first increase came from the relatively simple job of expanding the engine bore from 88mm to 90,7mm while the 68,8mm stroke remained unchanged, but the next update will see a complete overhaul of the LC8c engine, with virtually all components modified to accommodate a displacement close to 1000cc. Also, the engine seems to have been completely redesigned according to the search for maximum integration with future chassis and with standards that are about to become more and more restrictive (Euro5+ will be in force from 2024).
KTM has already been spotted testing the new engine in a next-generation Duke and the highly anticipated RC990, but this is our first clear look at the changes thanks to the official patent filing for this powerplant for the redesign at come.
Viewed from the right side, the modifications include a new cylinder head, new cylinders, new crankcases. In fact, while the layout is generally similar to the old model, there's virtually nothing carried over aside from bolt-on parts like the water pump cover, ignition coils, and throttle bodies.
The updated design shares the same engine mounts as the old version, allowing it to slide into existing frames as a direct swap if KTM decides to do so, but it also gives the company more possibilities for other chassis layouts.
A close examination of the engine reveals the path taken by KTM to further increase its displacement: an elongated stroke obtained by increasing the height of the cylinders.
At the front engine mount bolt, on the old engine (top right) it is directly under the separation between the cylinder head and cylinder block, but on the new one (top left) there is clearly has a few extra millimeters of cylinder block rising above the bracket. This means there is room for a longer stroke crankshaft.
To compensate for the added height of the new cylinders, it appears that the new LC8c engine will have a more compact cylinder head, allowing the overall size to remain unchanged. From this side we can see that the transmission design is similar to the old engine, with matching gear linkage and output shaft positions, but again, the housings and parts castings of the new LC8c are all new.
Seen from the front, above, we get a good look at another key change: the oil pan. On the new engine, the sump is significantly offset to one side, freeing up much more space for a catalytic converter and exhaust system under the engine. The oil cooler is also enlarged, suggesting more performance, and it appears the exhaust ports are larger than before.
It's worth noting that the designs seen here come from KTM's Chinese joint venture with CFMoto, showing that, like the current LC8c engine, the new one will be manufactured in China and may well find its way into CFMoto products in the future , just like the old 799cc appeared on the CFMoto 800MT.
The rear view of the new engine (top left) shows another modification that appears to be aimed at improving the layout of the motorcycles it is fitted to. The transmission case castings have been cut away significantly at the top, so the starter is more visible (white on the new engine) compared to the old one (top right, where the starter is colored blue). The redesign may have been done to allow the rear shock absorber of motorcycles equipped with the new LC8c to be positioned lower.
It is not yet possible to make any hypothesis on performance: the 890 of the Duke R delivers 121 hp, for a 990 we imagine being able to reach 135 hp. Furthermore, nothing can be deduced about the possible presence of variable valve timing which was mentioned as a possible technical equipment.
