it barely cranks- but starts anyway...
changed the battery. no difference.

shop manual isn't any help- what to check next? bad starter motor maybe?

 

bad compression release valve what year is your scooter

 

Is the motor stock? any mods?

Check and make sure negative cable where it is hooked to frame or engine is clean and tight.

What is the voltage at the battery while cranking?

 

2008 1200 c - V&H straight shots, Ness sucker and techlusion fuel management-

when I changed the battery, I did not remove the negative cable from the frame (as the shop manual says to do)- I just removed it from the battery. I inspected it but did not remove it. So that's one thing I see I should do.
and yes I should check the voltage at the battery.
will have to look up "compression release valve"--
good suggestions- thx for the input!

 

If your motor has stock compression you do not need compression release valves.

Knowing what the voltage is doing while cranking is the first step in finding what is going on.

Did the problem start after doing any type of work or changes on the Bike?

 

Does it make any difference if the bike is warmed up?

 

Outta town for a week... But nothing else different. Bike always on a trickle charger. Makes sense to check the crank voltage. Guessing it's down.

I rode it today for several hours. Parked on hills just in case! No diff cold or hot.

 

A trickle charger or a float charger (Battery Tender)? They are not the same, a trickle charger will cook the battery.

Battery cables have been known to corrode inside the connectors crimped on each end. Inspect and clean BOTH ends of BOTH battery cables.

You should disconnect the negative cable at the motor case. Remove the (ground) stud, clean the threads and reinstall stud and cable.

Also: try swapping the fuel pump and starter relays to see if that makes a difference. The starter relay might have worn/pitted contacts.

 

Yup, sorry... I use battery tenders on all my vehicles, not trickle chargers.
Cables and connections are clean since I just replaced the battery.
But I didn't remove the grounded cable at the bike. Will check it.
Thx !

 

Were you able to find out what is causing your issue ?
I have been having the same issue on my Nightster. Replaced the battery last year which helped for a little while, then it just went back to just barely turning over the motor. The first turnover would be slow almost like the battery was dead, then the bike would start.

I always have the battery tender on it and this morning after the bike sat for about 2 weeks, the battery wasn't strong enough to turn it over. Battery seems pretty much dead.

I'll have to put a meter on it and see what that is.

what else could it be ?
I only have the stage one kit on the bike.