César Santos wrote:I'm running out of solutions..
I did not perform any maintenance on the fuel system.
When I replaced the injectors I tested them out and everything seemed fine.
You are far from running out of solutions.
Everything
seemed fine at
idle and low speed until you tried to
ride the Brick at high speed. High speed
completed the test, showing everything
was
not fine. As Rick G implies, a partially blocked fuel filter will reduce engine performance at speed. That filter should have been replaced as soon as you bought your motorcycle. All the fuel tank's interior hoses should have been replaced, too.
You have written that your motorcycle was overhauled more than two years ago. It does not appear that the overhaul included cleaning electrical ground connections.
At this time, one point seems clear to me. Your mechanic should have located the problem by now. From your description of outcomes, your mechanic seems to be without sufficient experience, or time, to diagnose the trouble in your K100. That is not unusual and is one of the reasons why forums like this one have been created.
The problem many purchasers have when buying a used classic K-model motorcycle is their belief that the outcome will be the same as buying a used car. A used car's engine systems are somewhat protected by sheet metal or insulation. A used K100's components are much more exposed to harsh weather conditions and condensation. Because they have some protection, a used car's systems seem to degrade slower than a used K100's systems so if they are neglected under the same conditions for years, a neglected car has a somewhat greater chance of functioning sooner when reclaimed than a neglected K100 has. The K100's electrical components can function well bashing along on a potholed, rut-filled road but they are sensitive to neglect. Engine performance will almost certainly be negatively affected by oxidation created on their electrical connections while being neglected in storage.
The troubleshooting manual at this site and the other manuals I have for the K100/K75 series indicate that electrical ground failures and faulty electrical connections in general are one of the most common reasons for problems with engine performance. I have witnessed performance failures being eliminated simply by tightening ground connection screws or re-coupling electrical connectors. The attached photo shows me that you have much work to do reclaiming this old Brick. Right now, the easiest significant ground connection to clean is the battery ground cable connection circled in the photo. That means removing it from the transmission, then using a wire brush or wheel to remove oxidation from the attachment point on the transmission, the bolt, the washer and the terminal at the end of the cable. The assembly must be immovably tight when reconnected after cleaning. Also inspect the bolted components at the cable connections of the battery itself.
Once that has been completed and you've road-tested the Brick afterwards, you should remove the fuel tank and clean all the ground connections at the main ground connection plate on the backbone of the frame.
That work includes using a wire brush to clean the bolt, the plate and all the wire terminals that attached to the plate
. The frame connection to the transmission on the brake side of the motorcycle as should be cleaned. That is discussed
here. All electrical connectors of the wiring harness, including the ignition control unit plug and the fuel injection control unit plug connections, should be cleaned using electrical contact cleaner and verified to fit tightly together.
You
could have other problems that if corrected might restore full operation. You have not indicated that you have checked fuel pump delivery pressure, the function of the coolant temperature sensor, or the resistance of the coils yet. Maybe even divine remediation of faulty engine performance will occur; however in absence of that, there's no denying the following point, César: If it hasn't been done already,
you should complete all electrical component inspection and cleaning to have the
greatest chance of your motorcycle's performance being
reliably improved.
Be patient; your motorcycle has been malfunctioning for
only two years. Como se costuma dizer, o tempo voa.