Topic: starter woes-motor won't crank

[Jerry E.]

 I have two used starters, both of which bench test good and came from running bikes. Neither will crank my new motor for more than a couple seconds. I have a kick starter, but there are rearset clearance issues, so I would like to use the electric start. I know new starters are available, but does anyone know if anyone sells a high-torque starter for higher compression motors? Is there another way to increase starter output? Will it work after I put some miles on the bike? Is this normal on these bikes  with high compression? thanks

[calj737]

What bike? How "high" is the compression? Several of the guys on the HiPo section run the stock starter with 12+ compression.

Is it perhaps your battery...? Resting voltage reads? Brand and model of the battery?

[Jerry E.]

had the battery load tested first thing, tested good. My K3 has 10.25-1 compression. Don't know the brand of battery, but is a full size bike battery.

[PeWe]

Ground wire from battery has good contact with engine/frame bolt? I had mine connected to frame closer to battery that made a weak starter.
My std K6 starter worked well, but nothing compared with the latest mod, CB900 DOHC starter motor that has stronger gearing too. 800W instaed of 600W.

[hoodellyhoo]

Clean contacts on the starter solenoid? Had a K6 with an old battery that stopped cranking one day. I cleaned the contacts in the solenoid and she turned over fine again. Was able to finish out the season on that same old battery.

[DaveBarbier]

I don't think the starter solenoid is the issue, but you can open them up and flip the bar around to get clean copper if you're so inclined.

[PeWe]

Check with a wire you connect direct from battery plus to starter motor connection on the solenoid (lift the rubber) and feed the motor direct.
Still problem, another thick wire from battery - to crank case, a good clean bolt that can fasten it.

Still problem... it must be the starter motor of engine that is heavy to crank, check without plugs.

[Bodi]

Testing the battery is good, I would still try with a big battery as high comp means higher starter current than normal.
Eliminate mechanical issues. The starter gear could be jamming somehow, if the clutch has a bad roller the unbalanced force can cock it a weird angle under load. Removing a plug or two will reduce the torque needed to spin the engine and let you tell if the electric start is working smoothly.
No experience with starter adequacy on built 750s but we had to source a stronger starter for a GS1100 that had been hotrodded.
Tests to try...
While trying to start (means with starter motor powered, only do this for a few seconds then let it cool off for several minutes or the starter will be destroyed):
Measure the voltage from engine case (starter motor housing is best) to battery "-" ... this should be close to zero volts. More means there is a problem with the ground connection from battery-frame-engine.
Measure from battery "+" to the solenoid stud with the wire to the starter motor. Lower voltage is better. I dont know an ideal reading but I would want less than 1V. High means problems with either the cable from the battery or with the solenoid contacts.