KTM’s next-gen LC8c twin breaks cover in design registrations
By Ben Purvis
Has written for dozens of magazines and websites, including most of the world’s biggest bike titles, as well as dabbling in car and technology journalism.
03.01.2023
New LC8c engine, left, is completely redesigned compared to the current version, right
Having first appeared as the 799cc ‘790’ and evolved into the current 889cc ‘890’ version KTM’s LC8c parallel twin engine has already been given one notable capacity boost – and now another is on the way as the firm prepares a new generation of ‘990’ models.
That first increase came via the relatively simple job of expanding the engine’s bore, which rose from 88mm to 90.7mm while the 68.8mm stroke went unchanged, but the next update will see a complete revamp of the LC8c parallel twin, with virtually every component changed to accommodate a near-1000cc capacity.
KTM has already been spotted testing the new engine in a next-generation Duke and the highly anticipated ‘RC990’ sports bike, but this is our first clear look at the changes thanks to the firm’s official design registration for the upcoming revamp.
Seen from the right-hand side, the revisions include a new cylinder head, new cylinders, new cases, a new sump and new engine covers. In fact, while the layout is generally similar to the old model, there’s virtually nothing carried over apart from bolt-on parts like the water pump cover, ignition coils and throttle bodies.
The updated design does share the same engine mounts as the old version, allowing it to slide into existing frames as a straight swap if KTM decides to do so, but it also gives the firm more scope for alternate chassis layouts.
New KTM engine (left) has a taller cylinder and more compact head than the old one (right)
A close look at the engine hints at the route KTM is taking to increase its capacity further: a lengthened stroke achieved by raising the deck height of the cylinders.
Look at the front engine mount bolt hole. On the old engine (above right), it’s directly below the split between the cylinder head and the cylinder block, but on the new one (above left) there’s clearly a few extra millimetres of cylinder block rising above the mount. A taller deck means there’s scope for a longer-throw crankshaft and more stroke.
To compensate for the additional height of the new cylinders, it looks like the new LC8c engine has 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 the gear linkage and output shaft positions matching, but again the cases and castings of the new LC8c are all new.
New engine is on the left, old one on the right
Viewed from the front, above, we get a good look at another key change – the oil sump. On the new engine, the sump is shifted substantially across to one side, clearing much more space for an under-engine catalytic converter and exhaust system. The oil cooler is also enlarged, hinting at more performance, and it appears that the exhaust ports are bigger than before.
It's notable that the designs seen here come via KTM’s Chinese joint venture with CFMoto, showing that like the current LC8c engine, the new one will be manufactured in China and could well find its way into CFMoto products in the future, just as the old 799cc version has appeared in the CFMoto 800MT.
New engine is on the left, old one on the right
The rear view of the new engine (above left) shows another alteration that appears to be aimed at improving the layout of the bikes it’s fitted to. The castings for the transmission housing have been substantially cut away at the top, so you can see much more of the starter motor (in white on the new engine) compared to the old one (above right, where the starter is coloured blue. The redesign may have been made to allow the rear shock of the bikes fitted with the new LC8c to be positioned lower, with the shock sitting in the dip that’s been made in the top of the transmission of the updated engine. That will give scope for KTM to shuffle other components like the airbox and fuel tank to help keep bikes using the new engine to be compact and light.
Like the current ‘890’ version of the LC8c, the planned ‘990’ version will end up being used across a range of bikes. It’s expected to debut in the 990 Duke, probably for the 2024 model year, before appearing in a new ‘990 Adventure’ and the RC990 sports bike, which has also been spied on test in recent months.
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