Slow start - no hot start

[wheatonFJR]

I bow to your dark wisdom and mystical sayings...

[John d]

Just got the AIMO meter MS2108A meter today and read up on how to use it.

Readings around 288 amps DC on hold. Started the bike around 10 times cold and the resting voltage dropped to 12.8V from 13.0V. I'd hate to see what it would draw when the bike is really hot.

I'll see how long I can hold off actually making the starter repair, while I look at the repair or replacement costs.

[NTXFJR]

What peak amps is the starter drawing during cold starts and hot starts?

[ionbeam]

John d wrote
...Readings around 288 amps DC on hold...I'll see how long I can hold off actually making the starter repair, while I look at the repair or replacement costs.

What peak amps is the starter drawing during cold starts and hot starts?

The HOLD on John's meter should hold the peak amp reading though the meter doesn't claim 'peak hold'. Once the meter has been zeroed on the amp scale it will show peak amps even though it isn't a steady reading; I believe what the meter shows is really the true peak amps.

I have the same meter (with a different name) and once it zeroed it does read read current with adequate accuracy. Hot or cold, 288 amps is about 210 amps too many.

John is in a race to see if his starter will die before it kills his battery

[John d]

Looks like I already killed my previous battery. I'm not in a hurry to test it really hot. I already know what I need to know. $$$ and time .

[John d]

The HOLD on John's meter should hold the peak amp reading though the meter doesn't claim 'peak hold'.

You have to press the hold button sometime while cranking, but before the bike starts. It will read hold whatever it is at the time of the press, results vary. It's not a perfect system.

[raYzerman]

Pics of the project bike's starter w/148k kms on it. Preventative inspection while I have it apart..... looks good to me, cleaned up the commutator and put it back together, good to go. BTW, this bike had a hot start problem too, but was due to low compression. To get the starter out, kinda looks like taking the throttle bodies off.

[John d]

^^^ I don't think mine is going to look that good. There is a starter/alternator shop in town. They will do mine no problem with one day sevice. Just have to get started.

[John d]

It took about 2 hours to get the starter out.

Here is what I found.









It doesn't look that bad to me. Commutator needs cleanup, etc.
What do you guys thinks?

[FJRoss]

Doesn't look bad. If the residue inside seems particularly oily, you may have a seal going. Seems to me that Yamaha doesn't list a replacement but someone (FJRay?) has restored these.

[raYzerman]

Clean 'er up and go... maybe go to the shop, they MIGHT take a lathe cut off the comm, then can run an abrasive stick on the comm once cleaned up and it will bed in the brushes perfectly... worth that IMHO if the comm is a little out of true. You can also buy a new brush set if you really want to (Partzilla U$23)..

[Harald]

Zooming in on the pics, I see oil all around the brushes. Mine was worse, but you will want to replace that oil seal that's not listed in the Yamaha parts list. The numbers on the seal are IIRC ID and OD in mm and a local bearing supply place can hook you up.

I also see the gaps between the commutator segments all clogged up with dust off the brushes. This shorts them together and leads to your high current draw. This is an easy fix with a Exacto saw blade (I hear that a cutoff hacksaw blade works also) to undercut the segments and clean out the oily carbon dust clogged in there. After that you can chuck it up in a drill press and take some emory cloth to clean up the contact surface.

I wouldn't change the brushes because they look plenty long enough. Beware of the screws that hold the brush holder plate in place. I had one head sheer off during removal (they are in there super tight) and this created extra work drilling and retapping the hole. Perhaps a torch flame on there will help before trying to loosen them?

[ionbeam]

The three primary reasons a starter will draw excess current are:

* The kerfs in the commutator fill with brush dust, this can be compounded by oil infiltration which makes a nice conductive paste of the brush dust. This causes current to leak between the adjacent lobes of the commutator, thereby shorting them together. A starter rebuild will include cutting the kerfs clean.

* Mechanical problems caused by bad bearings or displaced magnets which obstruct armature rotation. Bearings can be replaced. Repairing the magnets seems simple but without the means for exact placement it never turns out good.

* Heat, vibrations and oil infiltration breaks down the armature wire insulation allowing the windings to short together. The armature needs to be stripped of wire and rewound.

A good rebuild will clean the commutator kerfs as mentioned previously. The commutator will be turned to true and smooth the surface. If there are brush issues like wear, scored faces, contaminated brush faces or lateral movement in the brush holder the brushes should be replaced. If there is any trace of oil vapor or oil film the seals must be changed.

The picture below shows the commutator kerfs that must be cleaned and rough, oxidized commutator lobe surfaces which should be cleaned up.



The picture below shows the beginnings of oil infiltration. This needs to be thoroughly cleaned and the seals replaced to stop the oil incursion. If this continues, the oil film will foul with conducive brush dust and short the commutator lobes together as it fills the commutator kerfs.



Edit: I see that Harald said all this in an overlapping post while I was typing. At least we agree

[John d]

I just came back from the starter/alternator shop.

One of the guys there took one look at it and said the starter looked okay and shouldn't be my problem. He then put my starter back together and tested it, came back and said that yes, there is a problem with the starter but there is nothing he would do to fix it. He said there is something funky going on and suggested that the armature is probably breaking down.

He then checked if he could get me a new one, but none of his suppliers list one.

I asked if I owed him anything. Nope not this time. So I took the starter back, it was hot.

It's probably a good thing I went to the shop. It saved me from doing the cleanup and all, and putting it all back together to no avail.

Time to order a new starter.

[John d]

Just ordered a new one "1MC-81890-01-00" from Yamaha PartsHouse.
$192.50 + $49.80 shipping, all USDs.

[fjray]

I'll take the old one off your hands and pay the freight. I rebuild them and have them for member when needed. I haven't seen a bad comutator yet.

[John d]

I'll take the old one off your hands and pay the freight. I rebuild them and have them for member when needed. I haven't seen a bad comutator yet.

The starter/alternator shop didn't think there was anything wrong with the commutator either, but seemed to think the armature was the problem.

Pm me your address and I'll find out how much the $$$shipping from Canada is.

[ionbeam]

I'll take the old one off your hands and pay the freight. I rebuild them and have them for member when needed. I haven't seen a bad comutator yet.

The starter/alternator shop didn't think there was anything wrong with the commutator either, but seemed to think the armature was the problem...

I agree with the armature being the likely cause of excess current draw. When the insulation of the armature windings overheats and sees mechanical stress and vibration it breaks down and shorts windings together. This reduces motor torque and sucks major amps. A good shop should have been able to test the windings, even if they can't do rewinding themselves.

[John d]

^^^ It could be they didn't want to get that technical with me. On the other hand they may felt their labour to rewind the armature would compete with new. The place looked like they have been in business for a very long time.

[FJRoss]

I'll take the old one off your hands and pay the freight. I rebuild them and have them for member when needed. I haven't seen a bad comutator yet.

The starter/alternator shop didn't think there was anything wrong with the commutator either, but seemed to think the armature was the problem...

I agree with the armature being the likely cause of excess current draw. When the insulation of the armature windings overheats and sees mechanical stress and vibration it breaks down and shorts windings together. This reduces motor torque and sucks major amps. A good shop should have been able to test the windings, even if they can't do rewinding themselves.

Can they even test the armature windings with a semi-hard short across the comutator from conductive brush dust/oil/comutator dust paste? I would think that would have to be cleaned up first. From the photo, it doesn't LOOK like there was major overheating in the windings but we can only see a bit of it. Before tossing it, I would clean up the comutator and check things out - are ohm specifications available for the armature? (Or would you measure inductance to determine whether windings were shorted?) "Open" is easy to determine but won't cause excessive current draw.

Does FJRay do armature rewind?