OzVMX Forum
Clubroom => Tech Talk => Topic started by: NRD on January 20, 2009, 04:23:29 pm
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I am building a hybrid and need to know if the countershaft sprocket needs to be in line with the swingarm bolt. Mine will end up about 25mm above if I don't alter the frame. Any other advice greatly appreciated.
Cheers.
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My Klub kevlar Maicosport - Honda in maico,his about 19mm higher than level with swingarm nut,i would not go more than that out.Baz
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sorry Typo it is 10mm out.baz
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I just recently finished putting a 125 pitbike engine into a KX60 frame, and run into the exact same thing/problem. Adjusting the chain was abit of a noodle scratcher cause i had to do the process in reverse.
Pretty much at stand still no weight on the bike the chain is tight but soon as you sit on it, it slackins off to round abouts it should be.
I hope that made sense.
The bike rides fine like this, but i dont go too mad.
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NRD,
I have often pondered this myself & reckon it could perhaps be made to work if you put a roller under the swingarm pivot w the return run of the chain going under (not over) that roller. It could then be made somewhat akin to the early 'paralelogram' ATK system, w the advantage of the suspension being somewhat independant of the torque reaction when you apply the power, & would be somewhat self-correcting on chain slack if you got the position of that roller right.
Something sort of along those lines is described in Motorcycle Design & Technology as the "tracklever" system
I have seen an XL engine in a Bultaco frame like what you describe (tho probably more than 25mm). I don't know what it rode like on a track, but I would think you'd have real probs w chain tension if you didn't do something like I suggest above.