Bike runs but starter issues

[gmac]

Hello,
I apologize for the long post but I'm new (had the bike for less than a month) and I don't know what might be relevant so I'm including everything. The bike is a '81 650L.

The bike used to start and run fine. On cold days it would take a few tries with the starter spinning and the engine catching momentarily before finally starting. One cold day the starter spun and spun but the engine didn't even come close to starting. I was able to bump start the bike easily rolling down the hill. During that ride I made a few brief stops and stopped/restarted the engine warm with no trouble. Later I pulled over and stopped the engine briefly to answer a call and when I tried to start it the starter motor wouldn't turn at all. I could hear it trying but there sounded like no movement. I thought the engine might be seized because when I tried to bump start it the bike came to an quick stop when I engaged the clutch without the engine cranking at all.

The next day I hooked the battery to a car and charged it but the starter still wouldn't turn. When I tried to bump start it cold I was able to do so with great difficulty. When it finally started I had to give it throttle even with the choke on to keep it idling. After about a minute there was a kind of pop and the revs shot way up so that it idled perfectly without throttle input. I rode it home without issues and as soon as as I cut the engine and tried to restart the starter wouldn't turn, just like before. One more note, after the failure to restart on the side of the road, it's been very difficult to walk the bike in second gear, even with the clutch disengaged.

Any suggestions would be appreciated.

 

[jbs80106]

Welcome with your 650! How many miles on it? What have you done to it so far?

Could be a couple of things.

First, when cold they can be very tough to start. You didn't mention it, but when you are starting it cold, are you opening the choke at all? Will help a lot if you aren't (mine's probably impossible to start without some choke).

Along with hard starts, it can take a lot of juice out of your battery to crank the bike too. So before going into too much trouble shooting, be a good idea to start with a fully charged battery.

Assuming you're getting good power to starter, the symptoms sound like it could be either a dirty starter motor and/or worn brushes in the starter.

Luckily both are easy to resolve.

You'll need to move the carbs out of the way to get the starter out. It sits on top of the motor underneath a plate. Don't have to take the carbs off the bike, but I do have to pop them out of the boots, take gas tank off and move carbs up as high as they'll go....

There's a hex head bolt that holds the starter in place, that you'll need a sock extender to reach.

Try searching the forum for cleaning starter motor or starter motor brushes....

 

[ChicagoBob]

Well, it sounds like a lack of voltage to the coils, in which the starter's current draw taxes the system enough to affect coil function. This would be especially evident in the first attempt to start the bike on a cold morning, whe oil is at its thickest, and the battery has sat uncharged for a time.

Low voltage, as well as excessive running on the choke, could could cause fouled plugs, which could lead to the idling issue you describe. I can't think of a fuel issue that would cause these type of problems, unless there is an intermittant vacuum leak.

The first thing I'd do is check the battery, or start the bike cold while it is actually jumped to a good car battery. If the battery is low, you should trickle charge it (less than 2 amps) for 12 hours or so before trying again.

If you still have problems once you have a battery providing full voltage, I would then check the spark strength, voltage at the coils and plug condition. You may need to clean the connections to the coils, and maybe add a coil circuit relay to ensure that the coils are getting a full 12V, even when the starter is cranking. Also, if you see that the plugs are fouled, clean or replace them.

I don't think the second gear dragging is part of your starting problem. This can occur when the oil is cold, and is normal. You are starting the bike in neutral, right? A dragging clutch could affect starter function, if you were starting the bike in gear with the clutch pulled, but i don't think the starter would "spin and spin" if this were the case.

There's probably a simple solution that you will hit upon after a few simple tests and some thought. Good luck!

 

[Big T]

One thing at a time

1. Where are you and how cold is "cold"
2. As you've only had the bike one month, when were the valve clearances checked? This issue is problematic of hard starting
3. Since the starter spins most of the time, I'd leave that for last
4. Charge the battery, start the bike and test voltage at the battery at idle and 3,000 RPM - it should be about 13 V and 14V. See the Stator Papers
5. Your bike has the clutch safety switch, disconnect that.
6 How old is your battery?

It is more likely your culprit is electrical rather than mechanical. You mention "hearing" the starter - do you mean the solenoid is clicking?

Your problems sound like either a bad charging system or dying battery coupled with some connection issues. Except for the clutch, which is a nonissue

 

[tom203]

One thing at a time

1. Where are you and how cold is "cold"
2. As you've only had the bike one month, when were the valve clearances checked? This issue is problematic of hard starting
3. Since the starter spins most of the time, I'd leave that for last
4. Charge the battery, start the bike and test voltage at the battery at idle and 3,000 RPM - it should be about 13 V and 14V. See the Stator Papers
5. Your bike has the clutch safety switch, disconnect that.
6 How old is your battery?

It is more likely your culprit is electrical rather than mechanical. You mention "hearing" the starter - do you mean the solenoid is clicking?

Your problems sound like either a bad charging system or dying battery coupled with some connection issues. Except for the clutch, which is a nonissue

Answers to these questions would be nice ! Also this bike had a stator leg thru headlight switch which causes poor charging output especially at low rpms. My bike starts quick with about 10.5 volts to coils - but needs full "choke" ( actually an enrichment device) . Remember to NOT turn throttle when you use "choke".