PDA

View Full Version : Etek motor seizing or binding



chef
21 June 2012, 1259
This motor has developed a cold-start problem. When the motor turns over in the morning, it shutters and jerks during acceleration and makes a low pitched rubbing sound. The frequency correlates directly with motor RPM. It feels like at a certain point in the rotation the motor 'sticks'. After running it for 10-20 seconds it mostly goes away though I can hear (but not feel) a slight irregularity at high RPMs. If I let go of the throttle, the binding ceases immediately and it coasts freely.

Some history on the bike: The chain developed an affinity for jumping off the sprocket during hard turns. Lots of chain adjustment & tinkering eventually led to a loose front sprocket (*facepalm*). The nuts holding the sprocket in place had worked their way loose, allowing it to wobble. Could this unevenness lead to premature motor wear?

My first guess is a bad bearing. Another suspect may be the bushings. I haven't taken the cover off again so totally speculating here. Does anyone service Etek motors with this type of problem?

EVcycle
21 June 2012, 1414
Have you tried listening to it without the chain? - or - Take off the chain and roll the motor by hand.
That will give you a good idea if it feels "rough" that it may have a bad bearing.

There are few that have the original ETEK (Ted comes to mind) that may be able to help.

teddillard
21 June 2012, 1501
Is this an authentic ETEK or one of the Mantas? The ETEK will have a stamp that has a Briggs and Stratten serial number.

Here's my information on the ETEK (Manta, actually) doing much the same thing, but I can make it a lot more concise if I know which one it is.
http://evmc2.wordpress.com/category/the-etek-thread/

Allen_okc
22 June 2012, 0600
:O what ever the problem is, you are definitely gonna have to take the motor apart, before does even more damage to itself...

a question - does it smoke???

chef
22 June 2012, 0925
Ted - thanks for the helpful pics & vids with the writeup. I'll have some time this weekend to open her up and check for the make.

Allen - No smoke visible or smellable. The binding has been getting progressively worse :(

Allen_okc
22 June 2012, 1001
Ted - thanks for the helpful pics & vids with the writeup. I'll have some time this weekend to open her up and check for the make.

Allen - No smoke visible or smellable. The binding has been getting progressively worse :(

Thats a good sign then - you may just have a bearing problem - i've had the commentator fall apart from excessive heat, it pretty much destroyed the whole motor...

teddillard
22 June 2012, 1427
What's happening is that the rotor is migrating to one side. On the Manta motors that is actually why they were rejected by B&S in the first place. They overheat, (or have overheated), and the rotor gets warped to one side and rubs against the magnet. A B&S shouldn't do that, but a Manta basically already has.

One of the strategies is to try to push the rotor back to center and, while holding it, use high-temp epoxy to basically glue it back to center. You don't have to disassemble the rotor and shaft to do that, you simply have to have some way to put pressure on the outer rim of the rotor and hold it there.

Clear as mud?

If it's a Briggs, I'd say it's worth the effort. If it's a Manta, then you're going to be giving it another bandaid treatment, at best.

The Manta guys on Ebay do offer some degree of warranty support, in that they'll replace a motor within a certain time frame, but you pay shipping to and from. That said, they just ship you another unknown quantity, and there's nothing to guarantee the new motor won't do the same thing.

The Briggs logo is on the outside, BTW, plainly visible without taking it apart. If you don't see it, it's a Manta.

chef
25 June 2012, 0359
Took off the cover, snapped some pics and spent the evening trying to recover my YouTube password :mad:

Attached is a shot of the sprocket side motor. Speaking of sprocket, does this one look overly worn? I hope there's enough detail in the picture. I wiped off as much grease as possible. The remaining stuff wouldn't come off easily.
Upon closer inspection of the motor, this might be a Mars ME0709 (http://www.evdrives.com/mars_motor_me0709_etek-rt.html) (wiping egg off my face). The motor has some sort of unevenness going on even with the chain removed. I'll post a video of it as soon as I can. I happened upon a post by chdfarl who had a ME0709 serviced by northernelectricmotors.com (http://www.elmoto.net/showthread.php?961-Mars-ME-0709). The ebay ad states "the commutator was uneven so the brushes were jumping". Maybe this is similar to the problem with Ted's Etek?

Turns out that the rear brake seems to be main the binding culprit (more egg to wipe off). The disc rubs against the pad and makes the characteristic groaning sound approximating an A440. The disc shifts ever so slightly at the spot where it complains. Man I hope it's not warped.

Richard230
25 June 2012, 0747
Chef, I can't comment on your motor problem, but the counter-shaft sprocket looks just fine to me. A dragging brake pad will overheat the disc and cause it to warp. That has happened to me more than once, but you can usually feel it quite noticeably when braking as a pulsing through the brake pedal when coming to a stop. To check the disc you will need to spin the rear wheel, place a fixed wire marker against the brake disc and see if wobbles, compared to the wire tip.

Allen_okc
25 June 2012, 0922
by the way - a very clean motor mounting - did you do that???

teddillard
25 June 2012, 0931
this might be a Mars ME0709 (http://www.evdrives.com/mars_motor_me0709_etek-rt.html) (wiping egg off my face).

They're two completely different motors. Should be pretty easy to figure out which one it is. (More photos plz?)



The ebay ad states "the commutator was uneven so the brushes were jumping". Maybe this is similar to the problem with Ted's Etek?

Again, totally depends on which motor you have. I can't imagine an ME0709 doing the same thing the Manta did.




Turns out that the rear brake seems to be main the binding culprit .

d'OH!

chef
25 June 2012, 1113
Chef, I can't comment on your motor problem, but the counter-shaft sprocket looks just fine to me. A dragging brake pad will overheat the disc and cause it to warp. That has happened to me more than once, but you can usually feel it quite noticeably when braking as a pulsing through the brake pedal when coming to a stop. To check the disc you will need to spin the rear wheel, place a fixed wire marker against the brake disc and see if wobbles, compared to the wire tip.Thanks for your feedback on the sprocket. The rear brake has never pulsed when I've used it (probably 10% of the time). A friend recommends bleeding the brake line which I might eventually try. Oddly this morning it stopped binding, and this is after 2-3 weeks straight of it acting up.


by the way - a very clean motor mounting - did you do that???
I can't take credit for that. Jeff K, the original owner, did all the work. I did clean the grease off for the photo :D


I've sorted out my YouTube account and will upload the video tonight. The other side of the motor has a ventilated black cap that looks just like the Mars.

chef
25 June 2012, 1822
Video of it free spinning (the high pitched squeak at the end is a bird in the background)

http://www.youtube.com/watch?v=Y6ToxhWY3WY

Ted - Here's a shot of the opposite side with the black cap attached.

The rear brake is binding again :( Not unexpected but I was hoping it would magically disappear.

harlan
25 June 2012, 2209
The rear brake is binding again :( Not unexpected but I was hoping it would magically disappear.

It should be pretty easy to tell if it is the rotor or the motor. I would suggest putting the chain back on and lifting the rear wheel off the ground. Spin the motor up and try and identify where the sound is coming from. Then remove the caliper bolts and hang the caliber to the side and spin it up again. If it is the rotor, there shouldn't be any issues with the caliper off.

teddillard
26 June 2012, 0146
Video of it free spinning (the high pitched squeak at the end is a bird in the background)

Ted - Here's a shot of the opposite side with the black cap attached.


Def. a Motenergy, (not a Mars, anymore, and certainly not an ETEK or Manta) and it sounds fine to me. If the brushes are new, they need to be broken in... if not, maybe they need to be checked, or the motor just run for a while. Ed has WAY more experience with these motors than I do, though, so I defer to him.

None of the disassembly I posted earlier applies to the Motenergy, it's a completely different design.

EVcycle
26 June 2012, 0250
Watched the video

Looks and sounds normal to me. Hard to tell if any of the small noises are a potential issue from here anyway. Make sure the
sprocket on the end is on good and tight.
IF you have new brushes you need to keep off the amps and let it brake in for a good 20 miles.

chef
26 June 2012, 0944
This set of brushes have seen over a thousand miles and hopefully are worn in by now. They looked ok inspecting them from the outside. All of them make contact evenly. If you look closely at the video, the edge of the commutator isn't completely even when rotating. It seems to spin the shaft fine in spite of that but the warbling concerns me.

The sprocket nuts have a habit of working their way loose which seemed to be the main contributor to the chain jumping. I've tightened them down twice already and they work loose after a few hundred miles. Need to put some loctite on them.

The rear brake pads don't want to retract fully, or are very slow to do so. If I mash on the rear brake, it binds pretty badly. It clears up after a quarter mile and is usually ok for the rest of the ride. It binds again after it cools down if I've used the rear brakes during the previous ride.

Richard230
26 June 2012, 1154
Brake pistons sticking in the bores of the calipers is a pretty common thing with motorcycles. I recommend that you remove the caliper and pads, put a piece of cardboard between the pads and gently push on the brake pedal very easily so that the pistons extend slightly past their usual position when contacting the disc. Then spray the exposed portions of the piston(s) with brake cleaner and wipe them with a rag. Then push the pistons back into the calipers and reinstall the caliper and pads. Squirting a little dry Teflon lube around the pistons before reinstalling the pads might also help them retract into the caliper.That should prevent the pads from dragging on the disc and help them retract properly.

EVcycle
26 June 2012, 1536
This set of brushes have seen over a thousand miles and hopefully are worn in by now. They looked ok inspecting them from the outside. All of them make contact evenly. If you look closely at the video, the edge of the commutator isn't completely even when rotating. It seems to spin the shaft fine in spite of that but the warbling concerns me.




The commutator looking uneven is normal for this motor. All of mine do that, but they are cut smooth and even on the part that counts.

chef
07 July 2012, 0809
Thanks again guys. I've been meaning to make time to clean out the rear brake pistons but have had to diagnose another problem on the bike. The throttle wire got pinched between the seat & crossbar :( Diagnosed it to the throttle and have the part en route via the slow boat from China.