Junior 1 and learning gear selection.

So my little man is moving to Junior 1 this weekend. Now I need to learn gearing and when to change gears.

When we had the gear rule in red plate, I just looked at his Max RPM.

But correct me if I’m wrong I need to be more concerned with his RPM range then his max RPM when dealing with gear selection?

I do have some gear recommendations from the other Dad’s. I just need to know how to select the right one. I do understand as the track speeds up I will need to that in gearing.
 
Max RPM is key, along with RPM drops. On a more momentum track with very low drops you also wont get to max RPM lots of times, so dont always shoot for the max. A Mychron 5 is a very good tool for this, you can also see at what RPM your driver is off the corner.
Green plate, very easy to become gear bound, dont be afraid to bounce around ideas with other green plate dads.
 

racing promotor

Moderator
First off to be on proper gearing your little driver must be ready to be on it and you must acknowledge that and adjust accordingly, BUT you can only adjust so much depending on the amount of momentum there lacking, you cannot make that up with gearing no matter what you do, most newer drivers or kids just moving up to Jr 1 are not ready to maximize momentum, as number one there not in the throttle as much as they need to be, second they are bottom feeding to much, driving to straight into the turns to make momentum, while there doing that say 15/60 ( example only ) would be where you should be at about all you can do is add 2 teeth to the rear try 15/62 or 14/58, the smaller front driver is usually a better choice until there maximizing momentum as it will help recover rpm little better. For now figure out your MAX rpm and target that first, take notes as you go paying attention to your drops once you are running up front and winning you'll notice when you were best at certain tracks especially more momentum tracks your low was at a certain close range, at that point target your low rpm of your drops regardless what max rpms are, For a green plate clone to get started you can't go wrong using whichever front driver matches up hitting max rpms with having a 58 to 62 gear on the rear, if using standard gears not mini gears. Yes you need to anticipate if the track is getting faster and your hitting max rpm at that point you'll need to remove some off the rear gear, then there the flip at final practice your 200 rpm low however you know the track is going to pick up so you may just leave rear gearing alone, then there is the bigger front driver Vs smaller front driver, general rule of thumb the more natural momentum and grip the track makes the bigger front driver will be best, and of course the less momentum and grip the smaller front driver will be best, if your going to a different track and have no idea on starting gearing and fellow green plates won't give up any info, IF you can get Sr Clone gearing and just go up 2 front drivers to start out you'll be in the ball park at most tracks.
You have a PM as well, Good Luck !!
 

CarlsonMotorsports

Site Supporter
Most engine builders will designate max rpm for your engine (that would be where the HP curve breaks, or falls off drastically.)
Yes, you are more concerned with the power band and staying in the meat of it, but it's easier to tell max rpm and rpm drop. You can calculate the rest if you have the data, but it's not necessary. Aiming for peak rpm and looking at lap times is a much quicker way to get the gearing correct.
Drops are key for determining peak rpm for a particular track. That is, if you are on a momentum track where you scrub less than 500 rpm in the corners, you want to turn the engine less rpm @ peak. If you are on a track where you scrub a lot of rpm (>500) in the corners, then plan on turning more rpm @ peak. Sometimes your builder will specify a different rpm for each application/track. That's the way I do it with our engines. The difference in peak rpm is generally around 500 rpm (less on momentum ovals, and more on tracks that put the engine in a bind.)
Building a positive relationship with the other dads of successful jr 1 drivers at your track will speed the learning curve up considerably on finding the proper gearing as well.

Another way to work on gearing is to take advantage of track practice days or extra track time.
Start with a recommended gear that's at least close, and make some 8-10 consistent laps. (I prefer to throw out the worst and best lap, then average the others.)
Come in, drop 2 teeth in rear gear, and go right back out on the track (before it changes.)
If your lap times are better, come in a drop two more teeth.
Repeat as necessary until the lap times start going the wrong way.

If you find yourself dropping 6 or more teeth in the rear, then go up 1 tooth on clutch sprocket and repeat this process.

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🏁Thanks and God bless,
Brian Carlson
Carlson Racing Engines
Vector Cutz
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racing promotor

Moderator
Some notes to remember, Tires gotta be close to hit proper rpm, the driver needs to be in the groove and throttle maximizing momentum to hit proper rpm. What Earl points out as far as at bigger more momentum tracks your max rpm will be less, this is good info and true BUT be aware for the average kart racer this is happening because there gear bound somewhat, pull rear teeth and watch rpm increase, prove to yourself your actually hitting max rpm before you gauge where your max rpm should be. On the flip side of this at a track where you have tight turns high rpm drop, but longer straights you'll need to target higher rpm than normal to be best.
 
I have seen some very good replies to this thread.
We too just moved up to JR1 5 races ago, we are lucky to have a track where we get 100-120 practice laps per race day!
Our engine builder gave us the RPM we should be shooting for, A clutch engagement recommendation and gearing recommendation .
So we started there, and then went up and down with the back sprocket by 2 teeth at a time
Then repeated the process for the front driver too..
I use the Alfano 6 data logger. to track lap RPM and other things.
I put little man out on the track for 2 lap sessions with each gear set up that we tried. We actually found running less RPM than recommended we’re our fastest times.
This may be due to the differences in RPM measuring equipment, set up, driving style or many other factors.
Just start with a base line and TEST TEST TEST.
We also GO PRO and Record from the fence, overlay these and compare lap times and talk with him about how the kart feels to him. Even at 8 years old her can tell me when the kart feels “flat or slow” and when it “feels really fast”

So short answer to my long winded answer is get yourself a couple front drivers and a good selection of rear gears and test test test and record your results don’t be afraid to change gears at the same track with different conditions.

You can always PM me if you’d like some more info always happy to help fellow racers
 
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