Hey everyone. Our local track Jr. 1 division has the standard .425 restrictor plate rule, but allows you to run a .500 plate if kart/driver weighs 265lbs with a 200lb kart max. Last year we were about 25-30lbs light so we added the weight and ran bigger plate. We have a different kart this year and haven't been on scale yet so we have no idea where we are at weight wise. So, is it better to be as light as possible and run smaller plate or would it be advantageous to add the weight (if within reason of course and how much is that) to run the .500 plate? I heard the .500 plate is worth about 1 horsepower over the .425 plate. I need to find out which route to go so I can order a carb setup for the correct restrictor plate. Thanks for any advice!
Run .425 Restrictor Plate or ad weight to run .500 Plate???
- Thread starter race21
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CarlsonMotorsports
Site Supporter
I can't imagine your new kart being that much lighter than your previous one. I'd stick with the .500 plate if it were me. There's not much difference in the lap times between the two (jr1 .425 plate, and jr2 .500 plate) at most tracks....BUT, seeing that your jr2 class only weighs 265# and I didn't catch what your jr1 class needs to weight, I'm still thinking the bigger plate is going to be the way to go. Unfortunately, it means lifting a 200# kart up and down all night (also not the safest way to weight the classes!)
Now, with all that said, most builders build their small plate carbs the same or very similar with only a slight jet change. No need to rush out and spend money if you don't have to. Talk to your builder and get his opinion and starting point on jetting.
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Brian Carlson
Carlson Racing Engines
Vector Cutz
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We went from a 2001 Buller speed demon last year to a 2010 Badmax this year. My son weighs just under 70lbs without helmet, chest protector, etc so we shouldn't have to make the kart weigh 200lbs to reach the 265lb range to be able to run the .500 plate. I guess until we get the kart on the scales and find out how far we are away from 265lbs in race trim, I won't know if I'll need to add 20, 30, 40lbs to make it to 265lbs. Then at that point, justify if the weight needed is worth running the bigger plate.
alvin l nunley
Site Supporter
Going by percentages, the plate size, (area wise) increases more than the difference in weight increases. Going by that, running the .500 plate would give you an advantage. No way to know how much of a lap time advantage. So many variables change.
Dover Power
Member
The biggest issue for me is the fact that the .500 purple plate has quite a bit more throttle response and will recover its speed much better than the .425 green plate.. I too feel the purple is the best choice..
Thanks for responses. I wonder how much difference there is between these .425 and .500 restrictor plate carbs. There may be an occasion where we run a track where the .425 plate is only allowed. Maybe the main difference would be the jetting, but I'm sure there is more that goes into the "blueprinting" of a restrictor plate carb. I'm leaning towards ordering the carb setup for the .500 plate and hopefully can use it if we have to run the .425 plate on occasion. Thanks again.
Dover Power
Member
With your last statement I agree that you should lean more toward a carb prepared for Purple.. In many cases the jets would be the same and if any change would ever be needed you would add .001 when going to the green plate.. Ofcourse I'm speaking of using our carbs.. Others may be different.. JD