# 2-stroke engine running backwards?



## sunfisher (Feb 19, 2009)

Hi.
I'm working on a bike-to-dirtbike conversion, and unfortunatley, my Craftsman 26cc runs in the opposite direction. The engine was of a weed whacker and has a CDI (electronic) ignition. If i mod the starter so it cranks the engine backwards, will the engine start and run like it normally does?
oh by the way..
I can't seem to find any information on the engine itself. I don't know who manufactures (or manufacture_d_, in the case of Tecumseh) it and I can't find any parts sources or shop manuals.


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## chuck_thehammer (Oct 24, 2007)

A 2 stroke can not be made to run backwards, unless you design a new cylinder with the ports changed. also you will need to rework the CDI for timing changes.
NOT worth the cost..

For a 4 stroke a new designed cam shaft and ignition. again not worth it

thanks for asking :wave:


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## paulr44 (Oct 14, 2008)

FYI

Some do, but some CDI units don't work with the flywheel rotated reverse. As Chuck said, timing is the issue. A piston-ported 2-stroke doesn't care which direction it runs in, but you're hard pressed to get one to run much above idle or have any power with the timing uncorrected. If the original timing was near TDC, you'd stand a chance.


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## sunfisher (Feb 19, 2009)

That's ok, does anyone have a shop manual or IPL for this thing?


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## paulr44 (Oct 14, 2008)

Go to sears.com and enter the trimmer model number to get an IPL.


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## 30yearTech (Sep 14, 2006)

Most likely your trimmer was made by Poulan/Weedeater, the numbers off it will tell for sure.

Can't you just flip the way the engine mounts around to match the orientation that the engine turns?


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