I feel rather dumb asking this but I guess I should just let my ignorance shine. I have an HT20D that came with a non-stock fuel tank. It was more like a very heavy bottle mounted where the muffler mount normally is. I'm replacing it with a plastic large frame fuel tank. The cap is the kind with the fuel gauge in it, and it's in pretty bad shape. I'm looking for a replacement cap and I see that there are Vented and Non-vented versions. Mine looks like it has a little hole drilled in the (formerly) clear lens, but it came from an HT23 so it would have been for a gas engine. Do I need a vented cap for my diesel, and if so would just drilling a small hole in the lens of a non-vented cap be sufficient? So far I haven't been able to find a Vented cap with the right dimensions.
Thanks for the help! I'm learning as I go here.