BMW K1/K100 RS 4V

Once again, not a before/after report, but passing on some info given to me by Duane at FIM.

We had a K1 in recently with an odd running problem that had existed for all of the time the current owner had owned it. Its intermittence had recently gotten a little worse though. We spent some time going through everything as you do, wary that others had tried before and not found the problem.

We had pretty much come to the end with the only variable I hadn’t ruled out being the ECU. I don’t usually suspect ECUs of this kind of problem, as the bike was just running very lean. Would start and idle fine, but die when the throttle was opened. ECU problems are usually a bit more dramatic, but all the usual suspects had passed examination so it needed to be cleared. The only problem was getting an ECU to try. If it was a 996 then no problem, but we didn’t have a 4V K100 around. I eventually found a wrecker with the required part who, for a modest fee, would let me try out the ECU. So we got the ECU, fitted it and problem solved. Swapping the original and the secondhand a few times did confirm that it was the ECU, so I was convinced.

At this point I contacted the owner who mentioned the bike had an aftermarket chip fitted, and could this be the problem. I remembered him telling me this earlier, but that the chip had made no difference. Anyway, we pulled the chips and swapped them, with no change. Definitely the ECU. At this stage the owner flipped out a little at the cost to date and the cost to fix, but for once I knew 100% what was wrong and could charge accordingly. Believe me, this is pretty rare. These jobs usually end with us taking a very cold bath on lots of labour time.

Anyway, getting to the point of this story. The aftermarket chip fitted to the bike was from FIM. I rang Duane and said " I didn’t know you made chips for these" and he replied that this particular chip was a ripper. Originally for a K1 or K100 RS 4V with a STAINTUNE, Duane had almost forgotten he sold them too until someone put a post on the internet somewhere about how well it worked in an otherwise standard bike. Duane has had quite a few faxes with dyno curves showing 10 to 12 Hp increases just by changing the chip alone, with the standard exhaust still fitted. I told him that was pretty surprising, and he replied it had surprised the shit out of him too, but he wasn’t complaining as everyone seemed to love them.

This sort of increase is pretty rare these days given that the factories know how to get it right. Often performance chips work by advancing the timing as well, which changes fuel requirements to get the result. This chip changes the fuel map alone, so someone at BMW obviously got something wrong.

If we get to tinker with this K1 some more, I may even end up with a graph yet.

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