1999 Honda VTR Firestorm struggling to start
 

Hi, we have been having starting issues in our Firestorm for quite some time now and in the past 2 days it has gotten worse. Getting the bike started has become very challenging. When we hold the push start button, the instrument cluster would dim and the starter motor makes a ‘wrring’ noise like its struggling to turn. In the past few months this would happen time to time, but it was possible to jump start the bike using jumper cables with the help from a car battery. Due to this, I even replaced the battery recently thinking it was the cause of the issue. However, even jump starts don’t work anymore. Not even with the old battery in. So my guess is that the battery in the end is not the what’s causing this problem.

We then thought the issue was with the starter motor, so we took that out and took it apart. We noticed some brushes had worn out and so we replaced them with new ones. The starter motor would spin without any problems when held to a battery outside the bike even before the brush replacement. However, when we put it back in the bike, it made no difference.

We did this small test where we removed the spark plugs in both cylinders and hit start to see if the engine would turn and it was able to turn the engine without any trouble. However, when we put the plugs back in and tried again, the starter makes the ‘wrring’ noise again like a huge load has been put on to it and it is struggling to turn the engine. We are unsure about what is going on. We were only able to start the bike once today. We even let it run for few minutes to warm up, however when we stopped the engine and try to start again, the same issue would happen. Has the starter motor gone bad, or is it something else?

Any help to troubleshoot this issue is greatly appreciated. Many Thanks.

Do you have or have access to a multimeter? If not you will want that before you can diagnose the issue

I've had personal experience using a jump cable when the on-vehicle battery was kaputt and had an internal short. More power went into heating that than turning the starter motor.

Certainly sounds like a low current supply problem to the starter motor. If you've confirmed that the motor itself is sound then, and you have replaced the battery, then maybe take a look at the starter solenoid and see if the contacts are dirty or burned. Also how is the battery-earth wire connection where it bolts to the frame?

I'm assuming when you removed the starter, that you disconnected the terminals on the motor; I have read that water leaking under the boot causes corrosion on the terminal and starting issues.

Yes we do have access to a multimeter.

We have already cleaned up and checked the earth connection and terminals on the motor. Also replaced the bolt that gets power to the starter motor with a new one and cleaned up any corrosions we saw in other parts of the motor. Couldn't check the starter solenoid, will do that today. I am no expert, however I have doubts if its a connection issue as the motor was able to turn without any problem when the plugs were out. Could it be something else?