Just finished restoring this Jonsered 490. This is 50 cc features heated handles fed from heat exchanger in the exhaust you can see the spring leading into the handle in the video inside that is a Teflon tube. A second tube runs into the trigger area. These are oddball in that they are actually made by Partner. The Partner P500 has matching internals and the engine is the same as the Husqvarna 55 closed port. This is one of my go-to saws since I have a weakness for such oddballs and the heated handles are great in winter. The power to weight ratio seems quite favorable. It's a combination of a free 490 I got from a friend and a parts 590 I got for eight dollars as part of a package deal of non working saws. The 490 had a bad pull cord and had been thrown out of a tree by a landscaper who got frustrated with it. The handle and av mount became bent but today I completed the rebuild substituting the good 590's after drilling a hole for the tubing. I plan to keep the parts saw around since parts for these are pretty much unobtainium. Other than the pull cord all it needed was carburetor rebuild and lines mechanically.