sam000lee
Forum Mentor
Hey there, on a trip (see other thread) and the 550 lost a lot of its power in southwest Colorado. Bike runs fine at low speed and idles fine but can't really get above 45 mph and starts lurching once it gets going. So far we have a couple of thoughts: my friend thinks there's a chance he put 85 octane gas when we last filled up and the issue started shortly after that, normally we put 87 in (MA minimum octane rating is 87) so we were wondering if anyone has any experience running 85 and if that could account for the loss of power. We checked the points and the 1-4 point looked worn. At first thought the spark plugs were fouled and after checking them the 1-4 plugs were really corroded and the 2-3 plugs looked white, but we changed them and the problem persisted. After about 30 miles we checked the plugs again and the 2-3 plugs were white (getting there the throttle was wide open the whole way to keep it around 50). Took pictures of both sets of plugs see below. Let me know if you have any thoughts, thanks!