Limiting rpm on GX200

[fcr61]

Hey Bob, you may reconize me from over on HCS and ArcticChat...I finally made it over here.

Anyways my question is fairly simple I think I have a GX200 with different cam and 18lb. valve springs along with the govener removed and adjustable main jet(main was drilled out to .040). I am running 10tooth front 30 tooth rear gear and on the stand the motor is revving well above 6k rpm...any ways to reduce the rpms some or is throttle stop my best bet. Thanks

[Bob Vehring]

Does it pull that number out on the snow? If your just reving it on the stand there is not enough load on it. Find what gear will work best for the riding you do. More back teeth or less front will make it acellerate quicker and climb hills, but higher front gear, small rear will give you more top speed. As you change gears the rpm will change out on the snow.
Not sure on the 200 cc engines but the 120 size have a screw on the carb linkage that will limit the carb opening.

[fcr61]

Thanks Bob, I have the same screw on the carb as I modded the stock 120 linkage to work with the 200. Do you happen to know off the top of your head how to do max rpm recall on a Tiny Tach?

[Bob Vehring]

Sorry, no idea on the tiny tach, to be homest max recall isn't a very reliable number for anything even on the really good tachs. It simply is the highest number the tach saw, most often it tells you the split second the track spun alittle and not really the number you sled ran. Often voltage spikes from the ign system will also throw that number off too

[fcr61]

What do you recommend for checking it while my son is out testing, something with playback?? I guess if I set it to a max of 6k rpm on the stand then I should have nothing to worry about, I don't see it gaining rpm's when friction and resistance are in the equation. Thanks for your insight Bob. Hopefully more people find this forum and it grows, we need a site dedicated to the little guys.

[madziarracing]

I use a digatron. You can pick up a used one on ebay fairly cheap. Another place is this forum.
karting.4cycle.com/forumdisplay.php?f=57
This is where I bought mine. I bought a dt52k max and it records RPM, CHT, EGT, MPH, Lap times and hours run. You can download it all to the PC and graph it, save it...
I know Bob is a big fan of the Mychrons as they are light years ahead of Digatron. But they are a bit more expensive. I picked up my set up for $125 used. New is rediculous.
But I will tell you that it is the cats meow for setting up sleds. I can see how fast the sled is going on the track and not on the flats. I can tell when my kid is letting off on the track and can see the diffence gear changes make to speed and rpm. If I would have know about this two years ago I would have had one from the beginning.