please help...bad cogging

[sleebus.jones]

I agree, the amp draw is likely to be high. I've used GP3300's in a similar setup (12 cells with a 10L, and 18 cells with a 10XL) and found that they drop a LOT of voltage under load...as much (or more than) 7 volts. Yours is geared to about 40 mph, so maybe try dropping a few teeth to see what happens?

I'd also check all your connections to make sure they are clean and tight. I'm assuming you're using deans plugs or similar. Also, how old are the packs? They might not be up to snuff.