Pumps do just that, PUMP fuel mechanically to the carb. Regulators use a check valve in the muffler pressure line to hold the pressure created by the muffler in the tank. The pressure forces the fuel up to the carb where the regulator meters out only what the engine demands.

I put off getting my Cline(s) for quite a while and finally gave in, now there is NO looking back. This thing is so simple and it weighs virtually nothing, just put it on and set the needles and fly. As simple as that and you get a VERY smooth, LOW idle and great transition and top end.

Just get the regulator and be done with it.....I know it's not cheap but the headaches it saves you make it worth every penny.

To use a pump with a four stroke you need to go with the VP-20 ocsillating pump that requires you to make a mounting plate so you can affix it to the back of the engine. Pumps can fail, I had a VP-30 that went south on me after about a month and I gave the Cline a try on my OS 1.60 and was so shocked at the difference in performance and ease of tuning that I didn't even bother getting a replacement for the Perry, just bought another Cline.

Yes I like my Clines THAT much...nuff said

The hardest part was, of course, mounting the tank in the fuse but even that wasn't all that bad. With a little sanding the stock tank fits between the formers very easily. Once you fly with your tank on the CG it's a no brainer, and trust me you'll notice it from the moment you take off. CG changes are INSTANTLY noticeable too. If I add a .5 oz. weight to the tail of my UCD it flies completely differently now. With the tank in the nose it took a while to notice the difference as the fuel burned off and the nose got lighter.

All of this sounds like a lot of trouble but it's really worth the effort.