Swapped a four-cylinder for a V-twin recently? Read this!

Posted June 13th, 2012 in Advice.

We remap a lot of KTM V-Twins, and the following small insight maybe useful to anybody that’s made the change from a high-revving inline four to a V-twin motor recently…

A customer – not one of our regulars – bought his 990 SMT for a full remap (we don’t have a pic of his bike because Gill was on holiday). It had open cans on board, with baffles in; we rode it as it came in, remapped the ECU and changed all the things that make a big difference to the rideability of these bikes, secondary butterfly valves, emissions variables, and ignition and fuelling maps. On the test ride after the bike came of the Dyno it felt much better with a smooth, ‘analogue’ style throttle control (much more like the old carb’d 950 motors). We were happy to give the bike back to its owner.

We told him to take it away, ride it, and let us know his thoughts (which is what we do with all of these remaps). He did just that, and agreed he could feel the difference, but confessed he wasn’t entirely sure and still had some small issues with it here and there. So we asked him a few more question, about his riding experience and history, and it turns out he’s only just come off of four-cylinder Japanese bikes, and he’d done the grand total of 200 miles on his KTM, 80 of which were to our workshop near Peterborough.

So his V-twin knowledge was limited, at best. So here’s what we explained to him, to help him get the best out of what is a great engine; the KTM has a 1,000cc engine V-twin motor (big pistons) with no real flywheel, so has a certain nature all of its own. You’ve got to accept that you can’t dance up and down on the gearbox (like you can on a four) because you will lock up the back wheel if you go down one too many; you have to match engine rpm to speed. You need to be far more fluid with a V-twin, and use the engine’s torque – go a gear higher everywhere (our customer was a gear too low to get the best drive). These engines are at their most potent between 4-7,000rpm; above seven and you’re revving the tits off it, below four and you’re dragging it.

The customer listened, thanked us for taking the time and said simply, “I need to go away, do some miles and re-calculate the way I ride…” We agreed, and told him to come back when he had to see what he’d learnt.

We thought we’d mention this because this is a conversation that’s happned more than once, recently. Here endeth the lesson!