by Skywatcher » Fri Apr 19, 2019 8:09 pm
Hi Dart
Going by the 25A- number and looking at the IPL on Partstree, I see this is a high-wheel trimmer. It looks like this unit drives all the time and runs at governed speed only. There is no sign of a separate engine control, so the operator presence system kills the engine as soon as the handle is released. The pully on the crankshaft indicates it's a supplementary flywheel as this engine is designed for use on a lawn mower. by your description of the problem, I'd be inclined to say the culprit is most likely the spindle bearings for the trimmer head. Dismantle the trimmer head spindle assembly and check for foreign material wrapped up in bearings or dry bearings.
The idler arm likely has the belt brake built into it as this unit was probably originally designed with a throttleable engine and a separate control for the trimmer head engagement. These days, it's all about cutting manufacturing costs and cheaping out wherever possible. Hope this gives you some ideas with which to work,
Sky
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