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Discussion Starter #1 (Edited)
Hey guys long time lurking trying to make sense of a grom (my first bike)

So I bought a 2015 msx almost a year ago with the intentions of riding but my circumstances changed and has now allowed me to use finally but I have some issues.

I bought the bike 2nd hand with 3000 miles on the clock 1 owner from new who did some mods.

Hid headlight (I think it's called)
New tail tidy
All led indicators
New louder horn
New exhaust (tyga)
New rear suspension (bbs)
Handle bars and usual stuff without listing

Probably a few more which I might be forgetting but anyway, I tried the bike when bought it and he said the battery is dead his son left his led lights on, (a mod just below the main light, used with an external button)

But my mate bumped it and rode nice so I bought it, my mate also had a charger which got the battery to life which is a motobatt mbtx4u

So all was well I bought in may, which is nice in the UK, not hot or cold, was riding it evenings and weekends for maybe 5 miles per ride, now I've let it slip as I use a car for my real journeys I've rode it less and less and started noticing the battery drop voltage overnight to the point the bike won't start.

I bought the same battery as thought it could be that and the new one is the same dying overnight to around 7v, but it's only starting around 11.34 View attachment 86530
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to start, are they bad batteries or what?
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Also the bike is idling when eventually started via a bump and chocking then dying. I looked at her spark plug and we'll...I'm lost for words, plug is broken, bent, burnt...what else..

So I've ordered a plug which explains alot but any ideas on the battery? When I rev the voltage goes up on my meter so the charging system seems ok.

I'm thinking this guy I bought it from has wired his mods wrong and there's a draw somewhere, how would I go about checking? I'm a complete noob in terms of bikes I just know the absolute basics.

Any help welcome. A poorly grom.

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Hello and welcome aboard.
Your multimeter should go into high 13s to low 14s when when holding around 3k revs per minute (rpm), and about 12.3 to 12.7 when ignition is off.
Is there any extra wiring on the bike for a usb charger,which would have a reducer to 5v and if not switchable or intelligent could gradually deplete and battery?
I one wired up a 35w hid kit to see what the load was on the battery and noticed it pulled the charging rate down to very low 12s and high 11s at tick over,which made me not finish the install due to charging concerns, although at around 3k rpm it was touching 13v,but plenty of people seam to have no issues with them fitted.

Colin J
 

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Discussion Starter #3
Hey colin thanks for the reply, theres no usb at all, my 2 batteries I have hover just over the 11 volt mark standard, and increase to 13 at 3k rpm. I installed a battery yesterday at 3pm 11v, checked it throughout the day, 11v still before bed, and overnight depleted to 7v in the morning when I looked.

Is it worrying my batteries are not even 12v?
 

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When you get the new battery is it a gel type and already precharged to 12v .
Surely it's not a dry charged battery that you add the sulphuric acid too,the one with 6 caps.

Have you any non original additional wires attached to the battery,or spliced into the loom, possibly behind the headlamp,near the rear of the ignition switch,that could be attached to something draining the battery over night,and be temporarily disconnected to eliminate them from the equation?
 

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Discussion Starter #5
Yeah it's a sealed battery, but both of them are 11v, 1 volt under the norm?

There was 2 wires which I've removed the 2 led lights in the front fender, which were button operated anyway always in the off position.

This is from memory,I'll go check the bike soon try and get a picture, the wiring doesn't make much sense to a new biker maybe you guys can inform me.
 

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:cool: Try with engine off, key off, hook up your meter between the neg battery terminal and the neg battery cable to check for draw, If you show a draw, try removing fuses one at a time and then put back till draw is gone,once gone that is the circut that needs to be checked out, works on cars but they have lots more fuses, hope that helps ya.. also check all arround the steering neck for chafted wires...
 

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1. Get a 2 amp charger ( Ideally one amp) & fully charge up your batteries. If they do not charge up to 13v+ (disconnected) they are bad. Replace and charge battery before install.

2. Test for parasidic loss. Upon install of battery, hook up the positive first. Attach your multi-meter between the - post and the - main lead wire. See this video if you do not know how to do so.

3. If no amp draw with the key off, you are good to go . If there are multiple + wires, disconnect one at a time until amp draw disappears. If your down to the stock main 12V+ and still have draw, remove fuse one at a time until you find the problem circuit.

4. Let us know the outcome.
 

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Discussion Starter #8
Thank you for the insight guys when it stops raining I'll have a look, if not will have to wait till the weekend sadly I work sway from home.

I managed to get a snap of my underseat before the rain, anyone know what this is box is? So there is the negative cable 1 single wire, but for the positive there is what looks like 2 made into 1, maybe he's spliced the headlight into it? Dunno how it works like I said I didn't do the mods
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Mmmmm. Looks like an battery backed alarm/ immobilizer box,with a battery inside, that's the Li-ion reference.
 

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What’s wrong with the cheap acid batteries? Been using the $20 one from Walmart that comes with acid on the side for 2 years haha. Works great.

You’re going to have to go through each component to find the problem child. Testing each fuse is a good idea. Unplug the fuse and cut a current mode multimeter on the female plugs with the bike off. See what’s still drawing something significant. It’s likely something the previous owner wired around fuses. I’d test headlight and any other mod disconnected in current mode to see draw while off. Worst case, temporarily, you could wire a switch to the battery and just turn the whole thing off when you turn off the bike. Electrical gremlins suck, but it’s ultimately fixable. Keep probing.
 

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Discussion Starter #11
Sorry guys I don't work at home so only get weekends, now I have a bigger problem. The bike once starting is chugging and spluttering then dying, upon a bump because the electric start isn't enough, even after a little ride.

I've changed the spark, it's full, on gas, the oil is good.

Could I be the victim of the fuel pump recall, my bike is a 2015.

When trying to start I hear clicking not sure if it's a bad starter, but that wouldn't explain a cutout.

Or is it the fuel pump? When it's dying it sounds like it's chocking out, being my first bike im unsure if that's what I'm hearing
 

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the electrical problem is the bigger deal. You need a new battery after you find what’s draining this one, the drain killed this new one already likely, acid batteries go inert when they drain this deep, it’s now got a lowered capacity.

The fuel pump doesn’t seem like a problem, when you have the key on and you turn on the engine kill switch the fuel pump should pressurize. It sounds like a small electric motor and runs for about 3 seconds.

the running issue is the battery being dead and the alternator not keeping up. A bump started bike should run, but not if you’ve got a component causing a large drain, that will kill it at idle. You’re going to mess up your alternator if you don’t figure out what’s taking all this current. If it were my bike, I’d measure current with the key off. I’d cut off anything not stock that I could lose, and I’d temporarily disconnect the headlight. Then I would measure total current again with the key off, assuming the battery still provides any.

In a stock system, the headlight is run by the alternator only. It should not come from battery power. It could cause there to not be enough power to run the bike at idle, coil might be under voltage and then might not spark across the gap and the bike will die. It’s also bad for the battery because it will drain when the bike is at idle. The alternator doesn’t make enough to charge the battery and run the headlight at full power when idling. So they connect the headlight to the alternator and make it dim at idle and gets brighter when we rev to get more power and isolate it (likely with a current diode or some circuit) so that it doesn’t run from the battery current. Yours has a different headlight. Who knows how it’s wired and how much power it uses.
 

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Discussion Starter #13
Thank you reply, yeah turning the key i hear a whizz for a few seconds, trying to start I can see the voltage drop to as little as 3v trying to get it started.

The headlight seems wired ok, like you mentioned the stock is dimmed and intensifies with more revs, mine does that.

For now I'm going to buy a new battery and see what it does, like I said I've ridden the bike when I bought it just fine with no issues, I ride it less and less and to a point with no riding for a few months and it's doing this.

Need to find the drain, not being helped by the English weather at the moment.

Do you know any batteries I could buy in the UK that's decent?
 

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I might have misunderstood something. The bike sat for months with the battery connected and no battery tender? You may not have a phantom drain, you may just need a new battery. You said you got a new battery and it’s doing the same thing. I thought you meant immediately doing the same thing (draining overnight) not doing the same thing after sitting for months especially in chilly environments. This is normal battery behavior.

disconnect the battery when leaving the bike for more than a week and keep it charged with a battery tender.

(edit: no battery sources. I bought mine in the lawn mower section of Walmart for barely anything. Didn’t feel like ponying up $100 for $20 in battery. Didn’t need a sealed one. Someone else can explain if they think they need a sealed battery. Mine is my daily driver, literally the only thing I drive, and gets 500+ miles a month and has been working fine on the cheapo battery for years).
 

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Discussion Starter #15
Sorry thought I said, but I bought the bike with a dead battery, he said his son left the lights on and drained it, my friend charged it for me and was fine until one day the bike didn't start, back then I thought he sold me a dudd battery I'll just get another...

So I went for the same brand and model, and it started draining again, but I'm not sure if that's cos I didn't tender in-between weekends or fortnight rides or what.

So have I killed this new batteries capacity do you think?

Gonna feel pretty stupid if this is the case..

Again I'm not a mechanic but would the bad battery,once the bike starts making it idle rough and cut out?
 

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If it was a couple weeks you should be fine. If it was months or several Stents of a couple weeks it’s possible it died because of that. In the future, if you’re not going to ride for a week, disconnect it or leave it on the tender.

If it worked for a while with a new battery, buy another one and keep it disconnected when not in use and see how long it lasts. Once batteries go dead once, thier capacity is severely diminished. Then it gets worse each time they die. Seems likely you need a new one.

If a battery is so bad that it’s a charging black hole, it can kill a bike at idle. If you can keep it running while revving and it just dies at idle, get a new battery. Bike is likely fine it seems like, batteries are maintenance items. They die all the time. No worries on that, we all learn somewhere. It’s not dumb to not realize that the smaller battery needs more care than in the car (although, charge your car battery if you aren’t driving it a long distance for 2 weeks. Short trips are awful). This was a cheap lesson. I hope that’s the only problem. Sounds possible. Get a new battery and enjoy the ride. Check your tire pressure, chain (lube), and oil when the bike sits a week also!
 

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Discussion Starter #17
I'll do some reading on a battery, hopefully someone in the UK can suggest something as well, yeah I did buy the bike as a bit of fun, probably didn't realize it needs love.

I'll get a battery and keep in touch, although I'm not home Monday to Friday, but this Corona might change that.

Thank you for taking your time.
 

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Discussion Starter #18
So I'm home early, damn Corona.

So I've received my order of a battery I went with a shindo lithium one, 40 pounds, put it in and bike fired right up, held for a while and then cut out, over and over sometimes only lasting 10 or 15 seconds.

I noticed when initially firing up the revs are high but after that second it's hovering around 1100 maybe 1200 then bang dead.

So is she starving of fuel or air or something?
 
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