72cc bbk battery too small to turn starter enough

[owlkev]

i have just put a bbk on a baotian 49qt12(47mm)and havent really had a problem,apart from the normal to and froing messing with the jets,the only prob i have is that the battery a 12v 6ah isnt strong enough to start her,can someone tell me what ah i can go up to without frying everything.

[prodigit]

You won't fry anything by increasing the amp output on your battery.
The starter draws a certain current at a certain voltage. When the battery is weak, and the current limited to 6A, there could be a voltage drop, resulting in the starter slowing down, or not having sufficient power to start the engine.

But there really is not a 'too big' battery you can destroy your bike with.
All I can say, is my 50cc comes with a 7Ah battery, and my 250cc came with a 9Ah battery.

You can choose whichever you like, starting from 7Ah; but even if you get a 24A battery, as long as the motor can draw the power it needs from the battery, changing that battery to any higher power/amp battery really makes no difference

[skuttadawg]

A larger amp battery would help or install an extra base gasket to reduce compression

[prodigit]

If your scooter has some battery space left, sometimes it helps putting a second battery in parallel with your current battery.
They sell these tiny lead/acid batteries, that could still fit in the battery compartment on some scoots; so you'd basically be running 2 batteries instead of one.

www.amazon.com/UB1250-Battery-Volt-Hours-Electronics/dp/B000YA7SQU/

3.54" X 2.76" X 3.98"

[owlkev]

thanx for the replies guys i gonna try a 10ah battery to start with then as i dont have space for another battery.i dont really want to down the compession because she flies at the moment,what i wanted tokeep up with traffic and switch lanes saftley.

[oo4load]

If you have a 6amp battery and it wont turn the kit even though it's at a 'normal' temperature (not freezing), then you may have a faulty battery or starter motor.

The 139qmb / kymco starter system is simply copied from a 2stroke, it's not really suitable for the higher compression of a 4stroke. So both the battery and the starter motor have to be in very good condition, or it will fail. There is little margin.
When it's cold, adding a second battery may help.

[owlkev]

is here a more powerful starter i could put on it?

[oo4load]

No, but replacing the motor for a new one does help in some cases. It depends on the cause of your problem.

-Cold + small battery
-Bad battery
-Bad starter motor

[prodigit]

To the OP:
The title says your BBK is too smal for the starter to turn,
I'm sure you meant that the starter is too small to turn over the BBK

[owlkev]

yeah thats what i mean ..sorry

[edfr]

Go read this JR EXPLAINS all about batteries.
Lefty
scootdawg.proboards.com/index.cgi?board=discussion&action=display&thread=57914&page=1

[JR]

With the BBK you'll need a bigger CCA battery and 10AH is a good choice as long as you find one in the 150CCA range you'll be fine. When the engine breaks in some and loosens up it'll not be as hard to start except on real cold days on the initial start up.

Got to have the CCA's and even some here have said you'll get them by putting another battery in parallel .


If your scooter has some battery space left, sometimes it helps putting a second battery in parallel with your current battery

Good advice!

JR

[owlkev]

how do you know what the cca of a battery is ?as far as i can see it only tells you the voltage and AH on the battery

[owlkev]

would a 12v 8ah battery with 120 cca be enough?

[prodigit]

Sometimes they say it on the battery, They should always say it on the battery. Otherwise look up the specs online.

[owlkev]

stuff it...fed up messing around with batteries ordered a motobatt mbtz10s 190 cca if that dont crank her i,m stumped...lol
www.wemoto.com/parts/picture/hl-813100/

[wilds]

The original cables to the starter motor, battery and ground has a ridiculously small copper core.
It's only the protective cover which is thicker, but the acctual copper core is too small to deliver enough power.
When you have a problem with the starter motor it might be enough just to replace those cables to a better model with a thicker copper core.

[owlkev]

thanx wilds i,ll bare that in mind

[wilds]

I had problems with my starter after I installing a larger cylinder and a stroker crank.
Compression was a "bit higher" and the starter just managed to start the engine.

I had a look at the cables and quickly decided to swap them, after that I have not had any problems at all.

[owlkev]

what size cable do you suggest wilds?

[Lykos]

very strange... my 5Ah battery is good for over 50 turns on my 63cc, turns it over always unless its completely dead. I guess a few ccs makes all the difference...

[owlkev]

just checked the voltage at the starter moter power point with the starter switch pressed and i,m only getting 6.75v so it looks like it is the wiring wilds

[wilds]

You see, you loose a lot of power before it reaches the starter. And that is only because of the crappy cables...
I'd go for 6-8mm copper core and with fine copper-threads so that they don't break because of vibrations.

[millsc]

I have a small 4ah battery in roketa with a 100cc bbk mine had problems starting with the electric, it was due to a bad ground and a bad starter bendix

[wilds]

Have you tried new battery cables owlkev?