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Retarding the engine.


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I've read 😕 to retard the engine all I need to do it off with the flywheel unloosen the back plate bolts move plate, retighten bolts ??


Is this correct and if so, and please excuse my ignorance, do I move the plate clockwise or anticlockwise and how far do I move it ??



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To retard the timming, you need to rotate de plate same direction flywheel rotates.

Flywheel nut is veery tight. You will need a impact wrench. Mark nut and axle with a chisel. So, you will know how much you should tighten on reasembly to keep same tension.

Lack of torque in this nut can cause sheared key

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I think the 290 Sherco engine in my Scorpa was retarded by moving the back plate about 2mm.

Easy enough to experiment with different positions after you've done the first alteration. Be sure to mark the plate and the crankcase at the original position so you know how far you've moved the back plate.

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Just a note as nobodies told you NOT to over-do it, If you go too far engine will run hotter, and also there's a possibility of the engine kicking into reverse if you go beyond TDC. Do yourself a favour and learn/read something on how engines work. I would recommend phil irving-tuning for speed, its available for 2strokes and 4 strokes or really anything that get's you to understand the basic's. Remember the saying is a little knowledge can be dangerous. Whether you're using a motor for trials or racing if you know how they operate you can adopt it to your needs. ie carburation,compression,exhausts,timing,camshaft's or porting, it can all be worked on and when you understand it will make you better at many other things.


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Better still, if you Google "Sherco timing" you'll pull up loads of past threads on this subject. Also shercousa.com has an online ignition timing manual page which shows you exactly what to do.

Or, just move the back plate 2mm like I said.

Edited by cleanorbust
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