honda 1211h wont start?

i have just bought a honda 1211h but it wont start unless i put a large battery on it ,when the original battery is used it just clicks continuous when i turn the key, but when the extra boost from the larger battery is used then it starts great , i was wondering if it could be the solenoid or if it is just to replace the battery and if so then maybe to fix a larger battery than the original where there is a place for weights to be fixed at the front to make it more stable,any help would be great, thanks Andy