Dimensionally smaller battery - need advice on cold cranking amp requirements

[philosopheriam]

Folks,

As part of my 1978 GS1000E custom build/restoration, I am thinking of downsizing the battery to make a bit more room for other stuff. If I dimensionally downsize the battery, it will have fewer CCA's than the original, which is rated around 220.

Does anyone know the amp draw of the starter? Also, I will be running a LED headlight and LED tail light.

What is the lowest CCA battery that is sufficient for these bikes? Just looking for ideas. I understand that it's a smarter idea to have a battery that has a bit more amperage than required as a safety factor.

Thanks!

[jsandidge]

With a 78 can you turn the headlight off for starting? If not, you can do the headlight relay mod which will shut off power to the headlight while the starter is spinning.

[posplayr]

Obviously the easiest way to solve this is to go with a Lithium battery

http://www.thegsresources.com/_forum/showthread.php?235795-Lithium-Batteries&p=2233998#post2233998

[Fjbj40]

Does your engine have higher than factory compression ratio?

If so then you will need the cca battery due to starter kickback leading to starter clutch damage. I run a 8 cell Ballstic lithium in my 1000. Not enough cca's even at an advertised 210 cca, however I have an ignition retard lever installed and now my kickback has been eliminated. The battery is still inadequate but it still manages to get the bike started.

Even with the headlight off it is inadequate/weak for starting unless the bike is well tuned and an easy starter.

[philosopheriam]

Problem solved:

I went to Batteries & Bulbs today and walked around the store measuring batteries - I found this one, that has 225CCA @ 11.2 Ah. I used several of the Xtreme AGM batteries in other motorcycles and had good luck with them.

Because it is an AGM and can be mounted on it's side, I will do just that - mount it on it's side and shorten the battery box. I know the battery box is from a G model - I'm going to modify it to fit my 78 GS1000E.



My motor has a Wiseco 1100 kit in it with a compression ratio around 10.25:1

[Fjbj40]

The Yosh 1085 has 10.5:1, so be careful of kickback.

There is a thread about how to reduce or minimize it.

[philosopheriam]

The Yosh 1085 has 10.5:1, so be careful of kickback.

There is a thread about how to reduce or minimize it.

I'm thinking about either a manual timing retard or a way to delay the ignition until the motor is spinning fast enough...

[posplayr]

I'm thinking about either a manual timing retard or a way to delay the ignition until the motor is spinning fast enough...

I assume you have seen this?

http://www.thegsresources.com/_forum/showthread.php?123877-How-to-avoid-Starter-Clutch-Disaster-Modification&highlight=avoid+clutch

[Fjbj40]

That's the thread I meant to link.

[philosopheriam]

Forgive me if I didn't read far enough into the aforementioned thread, but did anyone try a relay tied into the oil pressure switch?

[posplayr]

Forgive me if I didn't read far enough into the aforementioned thread, but did anyone try a relay tied into the oil pressure switch?

Not that I recall, but that may be an option depending upon your oil pump gears.

modern Headlamp cutouts use a stator wire and you might use that more reliably. The voltage is very proportional to RPM and you can set the threshold easier to what you like.

[philosopheriam]

Not that I recall, but that may be an option depending upon your oil pump gears.

modern Headlamp cutouts use a stator wire and you might use that more reliably. The voltage is very proportional to RPM and you can set the threshold easier to what you like.

posplayr,

I'm not trying to rehash the aforementioned thread, but for a motor that has stock oil pump gears, what about a delay-on-make relay that has a delay of 1 sec that in turn energizes a relay for the coils? I haven't put together the schematic yet, but having a delay on make timer that is triggered when the oil pressure switch OPENS (because there is oil pressure) then waits an additional 1sec before it energizes the coils. This should be more than enough of a delay to get the motor spinning.

[posplayr]

You can give it a try but you might consider my comments here.

http://www.thegsresources.com/_forum/showthread.php?123877-How-to-avoid-Starter-Clutch-Disaster-Modification&p=813686#post813686

[philosopheriam]

You can give it a try but you might consider my comments here.

http://www.thegsresources.com/_forum...686#post813686

Posplayr - please look at the following schematic and let me know what you think

[posplayr]

You do not have a timing diagram about what you are trying to accomplish; I don't want to guess.

It is also not clear what the operation of the relay is when you have two active inputs. According to the description it will not operate with a +12V input on 87 and a ground on 87a simultaneously.

Note there is implicity 3 states available for each signal +12V, Open and Ground.