I am just finishing assembling an MC21 and want to make sure I use the right battery. The battery specified is "YT4 L-BS by YUASA". Is this a wet cell battery? I appeard to be and I am affraid to use a wet cell battery due to the angle the battery sits at once installed. Is there a "gel-cell" I should be using instead?
Thank you for your help.
Mark
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That's the correct type of battery, it's been used for the last 20 odd years so don't worry about the lean angle, unless you've got some strange bike that leans it more than what it should

They are a sealed lead acid battery, so in theory you "never" have to top up the electrolyte.

I suppose the battery as it sits on theOEM "rear mud guard" or inner fender, is at 30 to 45 degrees.
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You could always use a TurnTech or similar style battery. You'd save weight, they're supposed to last longer and they aren't a lead acid type. The trail bike guys uaually run them and you'd get away with running the cheapest, smallest 2.5 amp I'd imagine, in the absense of electric start.
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MC21 Honda NSR250. TYGA 300 conversion.

Shorai? Or a roll your own LiFePO4? Phil has a teeny tiny 4 cell in his MC21. Weights under half a kilo IIRC. Wet cell, gel cell, that's some old heavy tech!

Thank you all. I hadn't thought about the fact the battery runs very little on this bike. Is 2.5 amp enough?
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The amp hour rating is how long the battery can sustain a certain level of current drain before running flat, so a 2.5AH battery is rated to give 2.5 amps for an hour, or 1.25 amps for two hours.

If you have a charging system, then it's basically moot, as that will charge the battery in any case. Unless you spend a lot of time at lights idling (where the charging system is least efficient) as this is when the battery takes up the slack. The other time it matters is when you have a start motor to drive, so not applicable to us.

The Shorai battery is about the cheapest way to lop 2.5kg from your NSR AFAIK?

Or you could save 3.0kg and eliminate the battery all together! You shouldn't miss having headlights for the ten or so seconds from when you turn the key till it's running.

Works on other bikes, but perhaps the PGM would not like this. Have to see what others have to say....

SSR440B wrote:I suppose the battery as it sits on theOEM "rear mud guard" or inner fender, is at 30 to 45 degrees.

eh?
It's virtually upright.
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fontyyy wrote:eh?
It's virtually upright.

That's what I was thinking.
There is very little wrong with the NSR the way it came out of the factory.

I put on a Motobat gel battery. This was from Wemoto and went on nearly a year after buying as I didn't realise the terminal posts were missing until I put the same make on my VFR. They sent them out as soon as I ask, which is great customer service

The both bikes start a treat. I'm not sure if the extra current makes any difference on the NSR

The only issue is the plastic guard doesn't fit over the top of the battery and sits at an angle
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Last edited by RobH on Sun Jun 19, 2011 4:51 pm; edited 1 time in total

After having a closer look, You're right, the battery is on a bit of a lean.
Nothing to worry about being a sealed battery.

Thank's for the info.
I didn't put an "angle finder" on the battery box (but I will), I just guessed at the angle. The problem is I am putting together a "basket-case NSR" for a friend of mine, I am down to the last details and having troubble getting it perfect. The bike is turning out beautiful with Repsol livery and I don't want battery acid getting on the frame or swing arm and messing it up.
I guess I am too picky.
Mark
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Is it possible to eliminate the battery on an NSR? Just curious really.

No, you cannot totally eliminate the battery.
Neither the PGM nor the tacho, servo mechanism etc will work. In fact, most probably you will ruin some of the electrics letting the AC voltage from the stator pass through... this is a great possibility before the fuses eventually blow out.

I'm using a "battery eliminator" for more than two years on a mc28 bike equipped with mc21 electrics, without problems except not very good lights at idle. For 40 grams and maintenance free it's the best alternative to a battery.

I occasionally make a few and sell them on ebay but If you want to roll your own, it's a 30.000mF capacitor at 25V rating.
Just keep in mind to use a low esr computer grade capacitor and you''ll be fine. Cheaper alternatives might work but I do not know how good. Let me know if you need more details.
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