The S.O.'s F2 will start fine from cold with a jump, but not with it's own good battery. Weird..where do I start with this?

The bike cranks over just fine, runs very well. I did the fuel valve at the tank and I've been into the carbs to change the idle air due to a throttle stumble. Everything in the fuel system seems right. The bike will crank for the normal time you'd expect, and about the same speed of rotation as all the other Hondas I've ridden. The choke functions, or at least when running, cold, choking it ups the idle and it behaves normally. It just won't fire from cold start with only it's own battery...But, put a charger on with a 10amp setting and "Vroom" fires right up....

Any suggestions as to how I should go about finding a way to make this bike start better? My SO is now sort of intimidated by the bike always being difficult to start...
TIA, Don Hanson

I have a new battery meant for my f4i, I have tested her battery, after rides and comparing it to both the brand new battery and to my questionable one....Her battery tests almost 100%....

 

sounds like you've either got a weak battery or a weak starter.

I'd pull all the battery cable connections @ the battery, and the solenoid relay, and at the starter - especially the grounds. Scotch-brite or sandpaper them til good and clean looking and reconnect. Maybe a little di-eletric greas over them to prevent corrosion.

That's assuming your battery is as good as you think it is. I'm guessing it is not as good as you think - regrdless of age, it sounds like your battery is down on capacity if a 10 amp charger hooked to it will crank the bike.

 

[QUOTE=adrenalnjunky;1208166]sounds like you've either got a weak battery or a weak starter.

It seems to crank over at the proper speed...I can't tell any difference between when the bike is warm or cold, cranking rpm-wise. I've been busy swapping the motor in my own F4i, so I haven't had a chance to 'test' the battery in real world riding situations on the f2...I have put my multimeter on the battery a few days after the bike has been ridden, and it reads out the same a my fully charged spare MC battery...that is why I think the battery is OK...12.7/12.8 volts...should be good. It just doesn't seem to want to fire like it should, but then with 'extra juice' it fires right up.

I haven't checked the sparkplugs but the bike came to us in almost perfectly maintained shape, and it runs perfect after it fires, so I am assuming the plugs are good.. I've not encountered this behavior on a bike before...

Thanks for the response....I have cleaned the connections from battery to starter and stator to battery and cleaned up the switchgear contacts.

Don Hanson

 

Voltage is not amperage, and amperage is what does the work in this situation. I've had batteries that measured 12v+, but when you put a load on them they sagged to almost nothing.

What you're doing by putting the battery charger on the battery is beefing up the current delivering ability of the battery - you're adding amperage to the situation.

Take the battery out of your bike and install in hers, I bet it cranks just as well as it did in your bike.

 

Thanks,

What I am getting is the battery cranks the bike over quite well. No problem with the speed it rotates or the duration I can crank it. It'll go for probably a full minute, cranking away....."RRR, RRR, rrrrrrr, rrrrrrrrrr----Rrrr RRR, r rrr." but no start! It finally runs the battery down and no longer cranks, so I stick the battery charger on for a couple of minutes and crank it again and away she goes!

I've tested the battery after charging...tests good. Then I turn the light on for a short time (to create a load)....the light is normal bright. I have sometimes cranked it over for a few seconds, too....and than I re check the battery...Still reads good.... That's what has me stumped.

If this were a fuel injected bike, I'd suspect maybe the fuel pump relay or the 'brain' the ECM, or something related to that .....But this behavior when all indications from the battery are good, and yet it doesn't like starting when cold without the extra boost from the charger....that has me asking for ideas here..

I guess I should just put a new battery in there anyhow, even if it makes no sense...see if that might do something...but money is tight.

I'd love to have her bike start easily...Right now it's all...."Hey Don, can YOU go start my bike? I never can get that thing going right"....and then most every ride we do together begins with me taking off her saddle and putting the stinkin' charger on there, while all dressed up in my gear and rarin' to go, and her standing there in leathers, hands on hips.... Takes some of the fun out of it.
Don Hanson

 

Bingo, baby!! What he said (Adrenalnjunky, that is)... the key to starting is the CCA available (cold cranking amps). When you buy car batteries, there is usually a rating for CCA on the battery. For example, when I drag raced high compression small block Chevy engines, both an OEM rated battery for the car, and a high performance battery had the same voltage readings without a load, but the Champion 750 CCA (I think it was 750) could fire up the old girl immediately ('66 Nova - 500 hp 327 - 14 to 1 compression - 10.36@129mph ); the OEM battery could start it, but barely, and of course, it wore down much quicker.

Like junky said, with a load, everything changes... if cleaning all your connections doesn't help, then you might need to replace the battery. Under a starting load, the battery has to crank the motor and provide enough juice for spark as well... you might just be taking all the amperage it's got for rotating the internals.
If you're curious to see the comparison, get your battery load tested, then have the same folks load test the new battery on the same rig, and you'll likely see quite a difference.