Need help diagnosing problem

BootScootin'FireFighter · Sun Jul 29, 2012 3:22 am

I've been significantly bogging down the past few weeks at WOT. I thought it was the locked up clutch, which was replaced. The clutch spring nut had backd off when the new NCY clutch came in, but we tightened it down with loctite red the second time. I haven't been able to check it again, not having access to the impact wrench to get the clutch bell off.

Anyway, this bogging down is very unique. It seems to be more severe when it's hotter and higher humidity. Day before yesterday, when I recorded this video, it was over 100F heat index. It was running very choppy, as you can hear. This morning was a pleasant low 80s and it barely hesitated, but it did very mildly. I am unable to get above 60bmph, or 53 GPS MPH.

Other then the new clutch, I ran seafoam through, adjusted the valves (which barely needed adjustment), oil was changed, replaced the spark plug. That picture is of the plug which is only in for a few days.

My question is where to go next? It sounds like a dying chainsaw. Is the carb running too rich or too lean? Or could it possibly be much bigger, like a stator going bad. How does the heat/humidity effect the performance? I've been riding year round and in some wicked heat, but never had any issue like this before.

What should the carb be set to for near sea level altitude? I was told all the way right, then 2 1/2 turns counterclockwise.

You can hear the bogging at
:10 to :15
:55 to 1:06
1:49 to 1:57
2:05 to 2:10
2:34 to 2:37

<iframe width="640" height="480" src="http://www.youtube.com/embed/U1zgwTdvYZU" frameborder="0" allowfullscreen></iframe>

Skootz Kabootz · Post by **Skootz Kabootz** » Sun Jul 29, 2012 3:34 am

Have you checked your airbox, air filter and the hoses leading to the carb? An air leak/ bad airbox caused the bogging down on my scooter. Does your scooter bog down if you rev it on the kickstand? Or does it only bog down under load?

Also, did you know Harbor Freight Tools has a great 12V emergency impact wrench for just $30. I love mine. There is no electric outlet in my garage so I just clip it to the Buddy's battery and pretso, I have impact. It is designed for cars to plug into the cigarette lighter incase of a flat tire. (But don't plug it into the Buddy charger or you'll blow the fuze)

spr0k3t · Post by **spr0k3t** » Sun Jul 29, 2012 3:41 am

From the look of the plug you may be a little too lean. Get a new plug and install it. Let it warm up from cold without running/revving. Go for a good hot lap topping out very briefly. After topping out, kill the ignition and pull the plug when it cools down. Essentially a plug chop. That plug looks like it's lean... but not by much. If you do a 1/4 turn to half turn out, that may be dead on for what you need.

Here's the plug chart I like to use: http://www.4secondsflat.com/plug_chart.html

Skootz Kabootz · Post by **Skootz Kabootz** » Sun Jul 29, 2012 4:05 am

A lean plug would also point to my airbox comment. If air is leaking in, scooter goes lean, bogs down under load. The exact problem that took me two frustrating weeks to diagnose on my scooter! I replaced the airbox, and tightened down the carb, hoses leading to/from the carb, etc and the problem was gone. Happy happy ever since.

Post by **Lostmycage** » Sun Jul 29, 2012 6:51 am

Check the exhaust header gasket as well as the air box. Something doesn't sound right, that's for sure.

Keep us posted.

easy · Post by **easy** » Sun Jul 29, 2012 7:01 am

sparkplug wire / boot is bad somewhere

BootScootin'FireFighter · Sun Jul 29, 2012 2:04 pm

It sounds that bad when it's hot and humid, but when it's dry and cool, it bogs less and is much quieter when it does. How do I find an air leak, will it be noisy or do I have to feel for it? And what direction do I turn the carberater screw, to the right?

On a recent trip out to a rally 150 miles away, it started acting up on the way there, as it was getting later in the morning and hotter. While there, it was rainy and humid, acting up severely on the group ride. On the way home, it was very humid, bogging down all the way home.

One other point, I've been getting higher than usual fuel economy, which leads me to agree that it's probably running lean.

BuddyRaton · Post by **BuddyRaton** » Sun Jul 29, 2012 5:06 pm

Looks lean to me but it is sounding like electrical

Post by **Lostmycage** » Sun Jul 29, 2012 5:15 pm

The CDI can fail in the heat and will cause similar problems. Is there another buddy you can borrow one from to test out? Leave the carb alone for the time being, you can cause a lot of gremlins to come out uninvited.

tortoise · Post by **tortoise** » Sun Jul 29, 2012 5:35 pm

Ignition troubleshooting guidelines . . parts resource.

BootScootin'FireFighter · Sun Jul 29, 2012 5:47 pm

spr0k3t wrote:From the look of the plug you may be a little too lean. Get a new plug and install it. Let it warm up from cold without running/revving. Go for a good hot lap topping out very briefly. After topping out, kill the ignition and pull the plug when it cools down. Essentially a plug chop. That plug looks like it's lean... but not by much. If you do a 1/4 turn to half turn out, that may be dead on for what you need.

Here's the plug chart I like to use: http://www.4secondsflat.com/plug_chart.html

I just finished doing a plug chop, the picture is below. Looks clean as far as I can tell. Compared to the first plug, I've seen them come out looking far worse then that, but without these symptoms.

BuddyRaton wrote:Looks lean to me but it is sounding like electrical

I'm thinking the same thing. It brings back nightmares from the first layover of Cannonball when Rich, Jess, countless other faces and I were up until nearly midnight trying to troubleshoot what ended up being a bad stator and coil. Both were replaced in Mississippi, however the components came off of a shop loaner, not brand new. If it were something simple, I'd feel confident trying to repair or replace myself. However, I'm limited on electrical diagnostic equipment and expertise.

Lostmycage wrote:The CDI can fail in the heat and will cause similar problems. Is there another buddy you can borrow one from to test out? Leave the carb alone for the time being, you can cause a lot of gremlins to come out uninvited.

I'm convinced this is a problem beyond my capability, so I'm going to solicit help from my favorite shop. It's 100 miles away, but I can't be dealing with this for a month long wait if I take it to MC, and I won't take it to Vespa Arlington anymore. I'll copy this thread to Ed over at Scoot Richmond, hopefully he can help me out or at least give me a day this week where I can ride down there and hopefully be heading home the same day. Otherwise I'll have to leave it overnight and take the megabus back home, then pick it up later in the week. I have rallys coming up, several ride ambitions, and I'd hate to be sidelined during the summer. Stand by for updates.

And to SkootzKabootz.... I don't hear anything unusual as far as I can tell from what may sound like air leaking, and the air filter is pretty new/clean.

As always, thanks for everyones input.

k1dude · Post by **k1dude** » Sun Jul 29, 2012 6:32 pm

I would just replace your stator and cdi one at a time and see if that fixes the problem. With high miles and after running the Cannonball, it wouldn't surprise me if they need to be replaced anyway. Fortunately, those components are pretty cheap.

charlie55 · Post by **charlie55** » Sun Jul 29, 2012 10:50 pm

The extreme whiteness of the spark plug insulator in both pictures tells me that you're running way too lean:

Should be a cocoa/tan color.

Could be an air leak (which you can test by shpritzing some WD40 around all the joints in your air intake path). However it seems to me that the bogging is only occurring at a certain point of acceleration. Might be the point at which the fuel feed switches from the pilot to the main jet due to higher engine vacuum, hence a partially clogged main.

The only thing that leads me to believe that it's not electrical is that a weak or mistimed spark would tend to make you run rich (i.e., fuel's not being fully combusted).

One other possibility is a damaged carb diaphragm.

BootScootin'FireFighter · Fri Aug 03, 2012 2:22 pm

I never thought it was possible to have the worst ride and one of the best rides in the same day, but it is. I painfully puttered my way to Scoot Richmond, 110 miles away in the morning. The weather was nearly perfect, and I worried that my crippled scoot wouldn't make the journey. The way home was much better. After a brief thunderstorm delay, I was back northbound, with a light rain the first 30 minutes. Man what a difference a new stator makes! I felt like a pent up animal that just had the cage opened. Soon as I cleared the city limits, I had that thing pegged all the way to Fredericksburg, it was incredible. I guess I just missed that feeling for the past few weeks.

Final verdict, cooked stator. I have a way with stators, as the same thing happened in Mississippi. Scooter shops nationwide, take note.... stock your shelves with stock stator assemblies, labeled "hold for BSFF". I eat stators for breakfast.

Big thanks to Chelsea and the staff of Scoot RVA. You guys rock!

charlie55 · Post by **charlie55** » Fri Aug 03, 2012 2:34 pm

Boy, was I wrong!

Glad to hear that you're back on the road.

Tocsik · Post by **Tocsik** » Fri Aug 03, 2012 2:44 pm

I see the NCY Stator assembly is $42 at SW.
For future reference, how difficult is it to replace?

tortoise · Post by **tortoise** » Fri Aug 03, 2012 3:21 pm

BootScootin'FireFighter wrote:Final verdict, cooked stator.

Was the specific issue a deficient ignition (wrapped) winding on the stator not producing enough volts to charge the capacitor in the CDI module, or a deficient pickup coil not triggering the capacitor discharge to the ignition coil and spark plug?

GY6 trigger pickup coils are available seperately.

Video

BuddyRaton · Post by **BuddyRaton** » Fri Aug 03, 2012 4:25 pm

Nice resolution BSFF!

My next question....how do you check that the pickup is bad?

Post by **jrsjr** » Fri Aug 03, 2012 5:06 pm

BuddyRaton wrote:My next question....how do you check that the pickup is bad?

That's a good question that I'd love to hear an answer to. Back when there was an electronics guy on MB, I thought we might could come up with a simple circuit that would integrate the pulses coming off the pickup and use the output from that to drive a circuit that would hold an idiot light off. That way, if the pickup coil was doing its job, the light would be off. If the pickup coil was not doing its job (e.g. when the motor was not running), the light would be on. The only utility of this circuit would be as follows: If the motor refused to run, you could turn it over with the kick-starter and see if the light goes out while the motor is spinning. Then you would know the pickup coil was not working.

You guys will quickly see the problem with my idea, which is that the 170i doesn't have a kick starter, so it's a no-go except on the 125/150s. Another "brilliant" idea goes in the round file.

Anyway, that was a good question. I'd like to hear what the mechanics have to say.

BuddyRaton · Post by **BuddyRaton** » Fri Aug 03, 2012 6:46 pm

Another thing is that stator related problems often don't occur until the motor gets hot.The typical....will run for 5 mins then die. I have used a hair drier to check to see if I could get early failure...but I never knew which component failed.

For classic Vespas the Haynes red outlines how to check the coils with a VOM...also handy when someone has rewired with wrong colored wires! (What the heck is this purple with red stripe coming off my stator doing????)

I just haven't seen a way to check the pick up but I think I would heat it up first.

viney266 · Post by **viney266** » Fri Aug 03, 2012 7:02 pm

Glad to see you got it fixxed BSFF!, more happy riding!

just check the wires after the pick-up for a "trigger", you should see it change as the flywheel comes around. No trigger pulse? Its bad.

charlie55 · Post by **charlie55** » Fri Aug 03, 2012 7:19 pm

jrsjr wrote:
BuddyRaton wrote:My next question....how do you check that the pickup is bad?
That's a good question that I'd love to hear an answer to. Back when there was an electronics guy on MB, I thought we might could come up with a simple circuit that would integrate the pulses coming off the pickup and use the output from that to drive a circuit that would hold an idiot light off. That way, if the pickup coil was doing its job, the light would be off. If the pickup coil was not doing its job (e.g. when the motor was not running), the light would be on. The only utility of this circuit would be as follows: If the motor refused to run, you could turn it over with the kick-starter and see if the light goes out while the motor is spinning. Then you would know the pickup coil was not working.

You guys will quickly see the problem with my idea, which is that the 170i doesn't have a kick starter, so it's a no-go except on the 125/150s. Another "brilliant" idea goes in the round file.

Anyway, that was a good question. I'd like to hear what the mechanics have to say.

Well, if the pulses are of a sufficient voltage, you could kill two birds with one stone by splicing one of those "cheapie" battery-powered LCD tachs into the coil circuit. Since there's only one pulse per rev, you wouldn't have to deal with the "wasted spark - erroneous tach readout" issue. If the engine refuses to run, then just crank the starter or kick it. If the tach readout flutters, then chances are that it's not your pickup coil.

Post by **jrsjr** » Fri Aug 03, 2012 7:33 pm

charlie55 wrote:
jrsjr wrote:
BuddyRaton wrote:My next question....how do you check that the pickup is bad?
That's a good question that I'd love to hear an answer to. Back when there was an electronics guy on MB, I thought we might could come up with a simple circuit that would integrate the pulses coming off the pickup and use the output from that to drive a circuit that would hold an idiot light off. That way, if the pickup coil was doing its job, the light would be off. If the pickup coil was not doing its job (e.g. when the motor was not running), the light would be on. The only utility of this circuit would be as follows: If the motor refused to run, you could turn it over with the kick-starter and see if the light goes out while the motor is spinning. Then you would know the pickup coil was not working.

You guys will quickly see the problem with my idea, which is that the 170i doesn't have a kick starter, so it's a no-go except on the 125/150s. Another "brilliant" idea goes in the round file.

Anyway, that was a good question. I'd like to hear what the mechanics have to say.
Well, if the pulses are of a sufficient voltage, you could kill two birds with one stone by splicing one of those "cheapie" battery-powered LCD tachs into the coil circuit. Since there's only one pulse per rev, you wouldn't have to deal with the "wasted spark - erroneous tach readout" issue. If the engine refuses to run, then just crank the starter or kick it. If the tach readout flutters, then chances are that it's not your pickup coil.

That's not a bad idea. The only possible downside is that, if the tach didn't flutter, it still wouldn't rule out a bad electronic ignition module. Hmm...

EDIT: Woops! After rereading your post, I see that you meant to tap the pulses on the ignition pickup side of the ignition module. That won't work because the voltage is not high enough to trigger the tach sensor. You could still slap the tach on the ignition module output and check to see if you have output from there, but that still leaves you with an ambiguous result, pickup or ignition module.

BuddyRaton · Post by **BuddyRaton** » Sun Aug 05, 2012 5:40 am

The main problem I see is that often the pickup/stator appear to work fine when cold and fail when hot. I wonder if the proper approach would be to go by the process of elimination. Test each coil and if they are all good assume that it is the pickup.

I have a Buddy 125 with a stator issue right now (I think), I might just order a pickup to see if it does the trick.

BuddyRaton · Post by **BuddyRaton** » Mon Aug 06, 2012 3:08 pm

OK found a few GY6 stator testing stuff
http://autos.groups.yahoo.com/group/tan ... sage/11870

http://scooterdoc.proboards.com/index.c ... 417&page=4

Post by **jrsjr** » Mon Aug 06, 2012 4:51 pm

BuddyRaton wrote:OK found a few GY6 stator testing stuff
http://autos.groups.yahoo.com/group/tan ... sage/11870

http://scooterdoc.proboards.com/index.c ... 417&page=4

Well, that's pretty clear. We should do a FAQ page with a video that shows exactly how to do that.

The only downside, as you have pointed out, BuddyRaton, is that the Buddy ignition pickup (which is built into the stator assembly), has a nasty habit of failing intermittently when it gets hot from the heat of the running motor. That's why I was looking for a way to monitor that component while it's in the motor. You know, I ruled out my "pulse integrator" idea because the future Buddys don't have a kickstart, but I was just being a dunderhead (again

). There's no reason why the same logic wouldn't apply using the electric start, is there? I mean, if you spin the motor with the starter, you should be getting pulses from the ignition pickup, right? Maybe that wasn't such a bad idea after all. Or maybe we could throw out the whole integrator and just have a light on the dash that flashes when there's an ignition pulse. If the motor's spinning, kickstart or electric, and that light is not flashing, then the ignition pickup isn't working. What about that?

BuddyRaton · Post by **BuddyRaton** » Mon Aug 06, 2012 5:56 pm

Well I've got a kick start so it's not a problem. I don't see why using the starter wont work (oh yeah...mine is broken) I used to use a remote starter switch to set the dwell on my 66 Mustang points.Heck...even turning the flywheel by hand should fire the trigger.

I'll be home in a couple of weeks and will start messing with it. I'm also going to try the hairdryer to heat it up and see if there is any difference.

I got this 08 Buddy cheaper than dirt cheap. My goal now is to see how little I can spend to get it running right. Yeah...I can afford a full stator assembly...but where is the fun in that!

I thought the best one was check that the pick up isn't loose....duh...I should have thought of that!

BootScootin'FireFighter · Fri Aug 10, 2012 6:55 pm

tortoise wrote:Was the specific issue a deficient ignition (wrapped) winding on the stator not producing enough volts to charge the capacitor in the CDI module, or a deficient pickup coil not triggering the capacitor discharge to the ignition coil and spark plug?

I couldn't tell, I was given a used stator off a floor model, as they didn't stock any new ones. I should've asked, but it was past me as I was anxious to get home. I'll have to keep an eye on it and see if there is a reason why I've gone through stators frequently.

BuddyRaton wrote:Nice resolution BSFF!

My next question....how do you check that the pickup is bad?

Not sure of the numbers they look for, but when we were in Troy, Rich (the salty mechanic with the limp) was probing around with a voltage meter checking all different contact points to see where it was deficient.

BuddyRaton wrote:Another thing is that stator related problems often don't occur until the motor gets hot.The typical....will run for 5 mins then die.

I've noticed that as well, if it wasn't already hot from sitting outside in the sun and humidity, it would run normally for the first few minutes.

viney266 wrote:Glad to see you got it fixxed BSFF!, more happy riding!

Thanks Viney. We'll see you at 3 Mile Island. If all goes well with the trip there and back, I can go forward with my 6 days of Blue Ridge Parkway, tentatively set for October 8-13.

On another note...

during CBR, the stator was starting to bog down at idle and very low RPM a week before I got to Savannah. I did all the troubleshooting I could at home, including changing the airbox and cleaning the carb/jets, and making sure the valves were set right. I figured I'd try replacing the fuel filter since it only seemed to happen like I said at low idle or stopped, it would stall. So I ordered the fuel filter and swapped it out, that's where I first met BuddyRaton. It ran good on my rainy trip out to the Atlantic lighthouse and back, but started acting up again when I got back around 8pm. I really was out of ideas and time at that point, so I showed up the next morning ready to ride and crossing my fingers. Sure enough once the clouds lifted halfway through the day, it started to stall at the few stoplights left in SW Georgia. Once I got to Troy, we went to work because it would not start at all once I got there. That put me on the trailer for the day to Jackson, MS. The stator was replaced, again with one from the shop, and I was on my way. No other issues.

But this latest stator issue only seemed to occur at half or more throttle, and most frequently when it was hot and humid. Which was why I didn't initially go for it being a stator problem. Wierd. Looks like I'll be packing another stator for 2014.

DeeDee · Post by **DeeDee** » Tue Mar 21, 2017 12:21 am

I'm reviving this old stator thread in hopes of getting some help. I have a similar issue with a Honda Metro. Runs fine until I stop at a stop sign. Then it won't budge past idle. If I get off the scooter and put it on the center stand, I can feather the throttle and get it to open up. Then I get on the scooter give it gas, push forward off the centerstand and it will run fairly well again.

I thought it was a bad clutch causing the back wheel to seize, replaced the clutch. Problem still here.

I tested DC output at the battery. 12.3 with scooter off, into the upper 13's when given gas.

Here is my question. Any chance the stator is bad if the voltmeter says it is charging the battery? Thank you in advance.

babblefish · Post by **babblefish** » Tue Mar 21, 2017 7:57 am

I'm wondering if it's actually the stator going bad or the ignition timing sensor, which is part of the stator assembly (that black thing at the 12:00 position). That sensor is suppose to sense each rotation of the magnetic flywheel (that small metal tab on the outside of the flywheel) and trigger the ignition coil. If that sensor is not working right, you'll have all kinds of problems with engine performance. There is also one winding on the stator (I believe it's the one with the tape on it) that is electrically separate from the charging circuit that is responsible for providing the power to energize the ignition coil, which is triggered by the timing sensor. Not that any of this makes any difference, I suppose, since the stator is only sold as an assembly.

Post by **jrsjr** » Tue Mar 21, 2017 9:47 pm

babblefish wrote:Not that any of this makes any difference, I suppose, since the stator is only sold as an assembly.

DeeDee · Post by **DeeDee** » Tue Mar 21, 2017 9:53 pm

It's on a Honda Metro. I can buy a new ignition timing sensor by itself off eBay for $12.00. I can get a used stator with 2,700 miles for $55. I have to remove the radiator and refill either route.

If I spend the $12 and the problem is still here, I'll be kicking myself.

Any educated guesses on which route I should take? Thanks for the input.

Post by **jrsjr** » Tue Mar 21, 2017 10:05 pm

DeeDee wrote:It's on a Honda Metro. I can buy a new ignition timing sensor by itself off eBay for $12.00. I can get a used stator with 2,700 miles for $55. I have to remove the radiator and refill either route.

If I spend the $12 and the problem is still here, I'll be kicking myself.

Any educated guesses on which route I should take? Thanks for the input.

Oh

I forgot this was on a Metro. If you can swap out the ignition timing sensor separately for only $12, that would 100% be my choice. That's a cheap way to eliminate a potential problem source that is otherwise the devil to troubleshoot.

P.S. In my haste to respond to your query, I have skipped over what is always the most important step in electrical troubleshooting. You need to verify the battery with 100% confidence. That means a load test (battery stores can do this), not just a simple voltage test. Every time I skip this step, I get burned. I should have mentioned it first.

DeeDee · Post by **DeeDee** » Tue Apr 04, 2017 11:43 pm

I wanted to thank everyone for their input and let you know how this ended up. I've had this scooter in pieces in my shop for a month now. Was supposed to be a basic tune up and fluid change. Got it all back together and took it for a ride. Would not pull away from the stop sign. Thought the clutch was binding. Picked up a low mileage used clutch. Didn't fix it. Based on this thread I'm thinking stator. Honda Metro OEM stator is about $150. An Ebay seller had a "direct fit" igniter for $12.00. Come to find out it was a generic gy6 igniter. I had to oblong the mounting holes. I soldered it into the harness, put the stator, flywheel and radiator back. Fired it up. Wouldn't run past idle. Almost had me fooled into pulling the carb and checking the main jet. I bought a used stator of Ebay. Came from Florida. When I opened the box, I wanted to cry. The Florida salty air was murder on the stator. A lot of corrossion. Seller had listed it as known working from a running bike. I cleaned it up and installed it. Again replacing the flywheel, radiator and coolant. I fired it up, not expecting much. But lo and behold it ran like it was supposed to. The kicker is the stator I removed looked great from this dry Colorado air. The Metro has 12,500 miles on it. I'm breathing a big sigh of relief now.
Boy can a bad stator mess with your reasoning skills.

Post by **jrsjr** » Wed Apr 05, 2017 12:00 am

DeeDee wrote:Boy can a bad stator mess with your reasoning skills.

Can we get an AMEN in the House?

Holy cow. That little Metropolitan really put you through some changes. Thanks for letting us know how this worked out.

skully93 · Post by **skully93** » Fri Apr 07, 2017 4:35 pm

DeeDee wrote:
Boy can a bad stator mess with your reasoning skills.

That metal bat in the lower right might be a solution!

babblefish · Post by **babblefish** » Fri Apr 07, 2017 8:33 pm

skully93 wrote:
DeeDee wrote:
Boy can a bad stator mess with your reasoning skills.
That metal bat in the lower right might be a solution!

Sigh...everyone knows thats only used for adjusting the carburator.

BuddyRaton · Post by **BuddyRaton** » Fri Apr 07, 2017 9:08 pm

Electrical can just drive you nits! I was having a problem with my SS180 and was sure it was carb related. I took that carb apart 3 times.

The whole sheban 3 times. Take it all apart, soak in dip overnight, heated ultrasonic for 20 minutes, distilled water rinse...blah blah blah.

The problem? I had installed a condenser that was bad from the vendor.

This is how I learned the hair dryer trick. I heated up the flywheel the checked for spark after hot and didn't get any.

Good times!

k1dude · Post by **k1dude** » Sat Apr 08, 2017 4:42 pm

People think I'm nuts when I tell them to check the stator. IIRC, even you DeeDee questioned my sanity in one thread where I said it sounded like a bad stator instead of a fuel delivery problem.

Bad stators manifest themselves in strange ways indeed.