Welcome from Virginia...USA

 

A big welcome to you from sunny Southern California. Glad to have you on board.

 

i would check the cca of the battery as it will take a lot to turn over that engine , on the big dogs which have a 117 s&s engine you need at least 400 cca and they always keep on a tender so you have max power to start them .
and welcome from Australia

 

Welcome aboard from New York.

 

Welcome from Northern Illinois !!!
I would say that the starter is bad !!!

 

Welcome to the forum, if the starter won't spin the motor with the plugs out, I'd go along with others and vote for a bad starter.

 

If you have the time just for the heck of it try running a heavy wire from the battery ground to a clean ground on the starter..

 

Thanks again for those who welcomed me...and those who are trying to help me.

So The CCA of my battery is surely not enough (only 185 CCA) this is the reason why I have to use a battery booster to help a bit...but it is still not enough.
I am about to order a lithium FeO4 battery (not lithium polymer) which should give 900 CCA.

I have done a wires check and everything is well bolted on and there is no loose at all.

The idea of adding a thicker wires and see what happens is a good one...thank you. I should be able to do this during the week.

If nothing really change, I think I'll have to change the starter.

I let you know what happens as soon as I can.

Thank you all.

cool-rider

 

Hello There,

So I am back with good news.

The problems were comming both from the starter and the battery.

The magnets of the rotor of the starter were off of it and stuck on the stator.
So it was very dificult for the starter to rotate and crank the engine.

So I bought a new COMPUFIRE GEN III 2kw starter and remove the old one.

But it was still impossible to start the 120ci JIMS engine. Not enough energy

So I bought a LITHIUM BATTERY (Li Fe O4) with a CCA between 800 and 900... Enough to start quite anything.

And guess what... My 120ci started very easily even without the compression release.

Now, according to me, and for those who have big inches engines, don't hesitate to purchase a lithium battery. It is so powerful with many other advantages.

I'll be in Virginia this summer for the first time and only for 10 days... If someone could give me some advises of what to see and where to go, I would really appreciate.

Thanks for all, drive safe and see you some day

 

Great to hear you got it figured out!