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Discussion Starter #1
So last year I decided to "modify" my Honda MB5 from the stock look to more of a bobber/cafe racer type thing because you know, why not ruin a perfectly good motorcycle?

What I really managed to do though was modify it into a pile of motorcycle. But now I've decided to re modify my pile of motorcycle into a fully functioning motorcycle again. I feel like it'll be more fun this way. Who can say, though?

Well anyway it looks like among my several modifications, I modified the battery box into the trash or something. I looked at trying to make a new one or just shoving the battery where it will fit somewhere else. Despite the fact that it is quite small, it doesn't really fit anywhere else. So I've decided to modify that into the trash as well.

The problem with that plan is my minimal understanding of electrons and their modus operandi. The battery is a tiny little 12 volt with a 2.5 amp hour rating. I know a few of you have replaced the battery on the TW with capacitors, so my question to you is: do any of you know what size/rating capacitor would I need to replace a 2.5 AH battery? That bike has no starter or turn signals and the battery's only real job is to keep the headlight bright when the engine is at idle.
 

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Discussion Starter #4
Thanks.

I found that kit on Amazon, and in the reviews some people are saying that it works well on bikes with magnetos like old Harleys, but doesn't work with DC electrical systems. While I don't necessarily think that they're lying, I can't think of any reason why not. It seems the internet is flush with conflicting information on the topic, so I really have no idea what to think. But I've never been one for understanding the theoretical side of things, so I ordered one anyway and I suppose I can figure out how to make it work somehow. How hard can it be, right?
 

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Batteries were required on motorcycles back in 60s or 70s (in California) so that a stalled bike would still have a taillight.
A TW may have a voltage challenge at idle, so that an incandescent headlight may dim.
To compare battery capacity with a capacitor, both need to be converted to joules.

However, voltage drop on a capacitor is so quick, it is not a fair comparison.

I think you'd be better off with a very small battery.
Lithium Ion is small and light, but is expensive, has issues with cold weather starting (not a concern for your bike) and charging voltage is critical.
I'd look for a very small AGM battery...preferably vacuum filled.
They are lighter than lead-acid, no liquid to leak, can be deeper cycled without harm, etc.
 

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Discussion Starter #8
The battery on that bike is already very small. Smaller than most 6 volt batteries. You're not going to be able to find much smaller.

s-l400 (1).jpg

The problem is I got rid of most of this. No more oil tank, oil pump, air filter box, or battery box. The problem now is putting the battery there is "ugly".

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It's similar to this now.

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I realise getting rid of the battery may not be the "best" choice, but for better or worse that's what's going to happen.

This thing only does like 45 on a good day, and I've never ridden it at night or in poor weather, so the lights being dim are not too big of a concern. It's more of a toy than any serious mode of transportation.

I was just wondering really if there was any kind of minimum specification I should look for that you guys knew of before I go off buying things.
 

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I vote for a flux capacitor install. It will then be the fastest and slowest Honda MB5 ever, simultaneously.
 

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Discussion Starter #10
A flux capacitor would be a waste of money unfortunately, so a regular one will have to do. The only way that thing is ever going to get to 88 mph is in the back of a truck. Not my truck though. My truck won't go that fast either.
 

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A capacitor will start your bike but it won’t run anything when the bike is not running.


Sent from my iPhone using Tapatalk
 

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Discussion Starter #12 (Edited)
As long as there's enough juice for the ignition coil to make spark for the spark plugs while the engine is running, then I'm ok with it. I would prefer for the lights to work as well. I don't really care if they don't work when the engine is off.

This thing has a 'Low Power Vehicle' sticker, not a license plate. I'm not even entirely sure a light is legally required...
 

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If you have an AC CDI ignition you do not need a battery at all. The battery eliminator will NOT run lights except when engine is running. It will NOT make headlight brighter at idle. It will NOT start any size bike. It is meant only for bikes with a DC ignition system so you don't need a battery.
 

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Discussion Starter #15 (Edited)

It lives!

The internet was wrong, a capacitor will power a DC system just fine. Also the internet was right, your headlight will immediately explode. I need to test what voltage is at the headlight, and adjust it with some resistors or something, but that's for another day. For the moment the thing does run.





P.S. the "fuck you" was intended for someone else, not you.
 

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Discussion Starter #16
If you have an AC CDI ignition you do not need a battery at all. The battery eliminator will NOT run lights except when engine is running. It will NOT make headlight brighter at idle. It will NOT start any size bike. It is meant only for bikes with a DC ignition system so you don't need a battery.
The light won't cut on except when the engine is running on this bike even with a battery installed. It was probably made before that was legally mandated.

And I realize a capacitor will not maintain headlight brightness, I was just saying that was the only point of the battery's existence as far as I can tell.
 
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