Hi Guys does anyone have any experience with Hyundai engines sold by Gemini karts?
Is it okay to use this engine? 212cc 7HP, also recommended sprocket size for rear axle.
an help or comments would be appreciated
Cheers Nick
... As for the ratios, well it all depends. I did quite a bit of reading about this and still am not sure if I got it right. I will assume firstly that you are running a TAV30 style torque convertor. I will also assume that your rear wheels are 17" pit bike or Honda style wheels as they should be.
If you search this forum, Rhys put up a post where he looked at the ratios the faster guys were running in the states whilst he was over there. IIRC the consensus was that TAV to rear sprocket was a 7:1 ratio (e.g. 10 teeth at the TAV30, 70 teeth on the axle, 420 chain) Some run 60 teeth, some use a jack shaft and take the ratio even higher.
If your gearing is too tall and you run a heavy cyclekart/driver, you may find yourself "bogging down" when exiting corners where the revs are not high enough to supply a reasonable amount of torque to the rear wheels to accelerate you as you might wish. If your ratio is too far the other way you may run out of revs before you reach an ideal top speed - the chances of the latter happening are perhaps smaller than the former on most of the courses we run.
Adding to the complications of gearing is how the variable drive TAV30 performs. You can change springs, weights and spring positions in them to have engagement not until higher revs and/or drive not maxing out as soon. I would start with stock TAV30 and work that out when you know how your machine performs. Last time I looked, Gemini were out of stock of 70T 420 platewheels.
I hope this helps, but I fear that it is just adding to the confusion. I am sure people with more experience than me will chime in, I might learn something so thanks for bringing this subject up.
Jim
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