My GPW which was still on a 6v system was sluggish turning over when I first bought it. I figured what was good enough when the bullets were flying was good enough for me so I decided to stick with 6v. I searched the internet and found a site in America that said pretty much the same. Most problems with sluggish starters are an earthing issue, I found that the earth leads on my jeep were 12v ones these are not able to take the load, 6v earth leads are much thicker and once I changed my earth leads for the correct 6v items my jeep spins over much faster than many of my friends 12v and 24v jeeps. Another tip is if the jeep has been stood for a while always prime the carb by manually pumping the fuel up this avoids using alot of your batterys power trying to supply fuel. The 6v system obviously means that should you drain the battery doing this there will be a weaker spark as the battery winds down , you will often find in this case that the jeep fires just as you release the starter and the remaining battery power goes to the points. My jeep NEVER failed to start once I addressed these issues. Hope this helps ? :-)