High compression issue

[scott]

My Gpz1100B1 has high compression pistons fitted. The standard starter motor, with new brushes etc, struggled to turn it over. Battery went flat very quickly. I replaced the starter motor for a 4 brush Z1000J item. A bit better. I replaced the starter clutch rollers and springs. It still struggles. What else can I do to improve this? Would stronger starter clutch springs help?? Would a bigger battery help??

[warren3200gt]

Higher amp hour battery. Motabatt gel batteries are generally about 20% higher amp output than stock lead acid. Make sure all the connections from the battery positive to the the solenoid, then onto the starter are clean and tight so there is no flow resistance. Same for earth's.
Volts do the carrying, amps do the work, Resistance impedes both.

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[scott]

Would anyone know what the biggest capacity battery would fit ??

[Al]

Hi Scott, its not just your HC pistons that are to blame, its just as much to do with your cams and cam timing increasing cranking compression pressure!
Battery internal configuration gives XYZ parameters and one variable is CCA. This can be increased by manipulating the AH capacity and other design parameters etc to give higher or lower CCA.
You need one with a high CCA and figure less on size and AH capacity in total. I have been using Yuasa Powersports batteries in mine. These are a series they produced to give maximum CCA and for me in a tiny size battery too. I dont need AH capacity but you will need the best compromise as a high AH capacity may make things worse not better. A high AH capacity will necessarily have lower CCA. A high AH battery (eleventy zillion AH for example) may never reach full charge and may therefore not discharge full amps when required but that last comment is between you and I only, i am no expert as we know.
The 'powersports' variety are not spectacularly more expensive than standard Motobatt or lead acid generally but i have found them to be more short lived!! Nothing is for nothing.
I was getting mine from Halfords.
Cables; the highest current carrying capacity cable is not based on diameter or cross sectional area alone. The highest or best current carrying ability is with the cables with more but thinner internal strands. This gives greater 'saturation' of conductor per unit of cross sectional area. Vehicle wiring products do these multi thin strand cables in 'made up lengths' with connectors attached or you can do youre own of course.
Also; where the starter return is on the RHS rear of the engine cases with its six mm bolt, i have found it necessary to periodically clean this and mean it. The engine case gets a layer of aluminuim oxide at the point where the cable attaches and i scrape this off with a broad flat blade screwdriver back to clean alloy. If i dont, it wont start.
If there is any doubt about the earth return for starter motor continuity, you can run a temporary 'jumper' cable from that earth location to one of the long 6mm bolts that holds the starter onto the engine just to see if it makes a difference! Temporarily removing the starter chrome cover is a small price to pay to find that your cables are overheated, brown and crusty inside their outer sheathing where you cant see them.
AL

[Robw]

Check your starter motor and put new brushes in, if you haven't already done so. Purchase a motobatt battery, you can get black ones as well as yellow.
Mine was a pain to start until I done the above,no probs now.
Rob

[scott]

Thank you kindly gents. Plenty of food for thought.