Choosing the Right Gearing

Boomer14k

Member
I have an old Birel Chassis and an LO206 engine with only one race on it. Running out of gear on straightaway. How do I know if I have a 35 or 219 chain and what brand of sprockets are good for LO206?

I’m used to other forms of racing and fab where there are specific parts for specific brands but it seems that many of the parts for karting are interchangeable between brands. Is that correct or am I missing something?
 

flattop1

Dawg 89
Some say on the side plate . Or measure .
 

Attachments

  • Screenshot_20201023-105425_Google.jpg
    Screenshot_20201023-105425_Google.jpg
    85.2 KB · Views: 30

GClary

Member
Are you racing dirt or road course ? I assume road , which would require you to gear for specific sections of the circuit . I am not a road guy , so I am just assuming from what I have been reading in other posts on here . Al will probably chime in at some point , and he can give you some good advice for road course racing .
 

alvin l nunley

Premium User
#35 is a 3/8 pitch chain. One link is .375" center to center of the pins. Same thing with 219 just shorter.

Gear ratios are the same, #35 or 219. 15/60 is 4 – 1 with each, just smaller diameter gears.

Finding the right ratio can be a challenge if you have no information whatsoever. Ask around, there must be someone there who will talk to you. Find out what RPM they are turning at the end of the longest straight. Gear accordingly. Don't be surprised if you reach peak RPM before you reach the end of the straight. There is a theoretical limit to how fast you can go with the horsepower you have due to aerodynamics. The faster you go, the more power it takes to go faster, and it's not a straight line.
 

J par

Member
I have an old Birel Chassis and an LO206 engine with only one race on it. Running out of gear on straightaway. How do I know if I have a 35 or 219 chain and what brand of sprockets are good for LO206?

I’m used to other forms of racing and fab where there are specific parts for specific brands but it seems that many of the parts for karting are interchangeable between brands. Is that correct or am I missing something?
I have a different chassis and a lo206 on a Sprint course... I'm new to this forum and sport... I'm in the process of experimenting with gears...
I inherited a 16t drive sprocket and a 59t on the axle... The couple people who I've talked to have said that should be fine... Well, my home track has seven corners and two short straight aways and one long straight away that's not terribly terribly long.. at the end of the longest straight away I was only getting about 5,500 RPMs and I'm told these hit the rev limiter at about 6100k...
I put a 62 on the back and was able to get 5800 RPMs but still no rev limiter. I took it out again the same way and was back down to 5500 on what seemed like a cold slippery track..
I went DEFCON 5 today and but 14 for the front and a 58 for the back.. looks like trial and error for me we'll have to see...
 

Boomer14k

Member
I did forget to add that I am running PittRace. It’s been a minute since I raced there last but the last time I had the kart out there I was hitting the rev limiter half way between the kink on the front straight and turn 1. Just wasn’t sure if there is a specific brand that is better than others and after reading the other posts I have another question. Obviously there is a larger change when adjusting the gearing at the motor compared to on the rear. Other than that, is there any benefit to keeping adjustment to one end over the other?
 

flattop1

Dawg 89
That's a statement I have not heard , in relation to gearing .
Quite true I believe .
Now I gotta get some popcorn , this could be interesting.
 

alvin l nunley

Premium User
Other than that, is there any benefit to keeping adjustment to one end over the other?
I can't help but wonder; is this a serious question.
Changing one tooth on the crankshaft is about the same as changing 4 teeth on the axle. Of course it changes as the ratio gets bigger and/or smaller.
For instance.
14/58 = 4.0
15/60 = 4.0
16/64 = 4.0
 

J par

Member
I can't help but wonder; is this a serious question.
Changing one tooth on the crankshaft is about the same as changing 4 teeth on the axle. Of course it changes as the ratio gets bigger and/or smaller.
For instance.
14/58 = 4.0
15/60 = 4.0
16/64 = 4.0
14/56= 4.0 ?..
The reason I think I caught that was because I have a 14 and a 58 that I just bought to try and I could have swore it was more than 4.0...
 

Boomer14k

Member
I guess what I’m asking is if you need to make a 4 tooth adjustment is it better to make that adjustment on the engine or axle end? If the ratio stays the same is there a benefit? One way over the other?
 

alvin l nunley

Premium User
Comet Karts gear ratio chart is accurate and complete. The only problem I see is it so big, how are you going to take that to the track?

With my Excel program "nine sheets", you can change the starting engine gear and/or the axle starting gear and the whole spreadsheet changes. The whole thing will print on a 5 x 8 piece of paper. I use photo paper, it's cheap and plentiful. Request your copy at:

alvinnunley62@gmail.com

It's free! 44 pages in one Excel spreadsheet program.Most pages will work in other spreadsheet programs too.
 

J par

Member
Comet Karts gear ratio chart is accurate and complete. The only problem I see is it so big, how are you going to take that to the track?

With my Excel program "nine sheets", you can change the starting engine gear and/or the axle starting gear and the whole spreadsheet changes. The whole thing will print on a 5 x 8 piece of paper. I use photo paper, it's cheap and plentiful. Request your copy at:

alvinnunley62@gmail.com

It's free! 44 pages in one Excel spreadsheet program.Most pages will work in other spreadsheet programs too.
For me it's just here on my phone..
 

GClary

Member
Getting away from topic and question guys . I am a dirt racer , so all I can tell you is from my experience . Dirt guys don't use as much of the engines torque once we get rolling , we use more of the Hp and rpms than road guys , because of being on and off the gas and braking for corners , they are in the lower rpm range more . But going thru the corners ,we do experience drops in engine rpms , which we don't want . If the drops are to much , we drop our driver down 1 and gear the axle to get the same desired ratio as with the bigger driver , which in most cases will bring those drops up . G forces in the turns creates our drops along with tire grip ect . But once we do that on a larger track with long straights , we become what is called gear bound , which the gearing will not let the engine turn any faster rpms , so we kill teeth on the axle to remove the gear binding . On a road course you are having to set your kart up for where you want your kart best at . Coming off the corners or on the straights . With testing , you can find that perfect middle between the 2 , but someplace in there between the 2 , you may give up some to other racers that gear their karts to a specific part of the track . A lower driver will pull better out of the corners than the next one up on the same ratio . So you will need to use your practice sessions as much as possible , to hit that sweet spot on gearing . JMO
 

Philo

New member
New on the forum here , but we run a 2018 Tony Kart with the LO206 and between five tracks that we run , the ratios we use are 20/70 , 21/74, 19/68 which is pretty much all around a 3:50' ish final drive.
For example at one track where my son's on the rev limiter before the end of the front stretch with 19/68 sprockets with a final ratio of 3:57, we will use a 21/74 with a final ratio of 3.52 so we don't run out of rpms before the next corner ... small increments make a difference on a small track !

Anyhow , this is my first post so take it like you wish , but that's a good starting point !

Cheers
Phil
 
Center to center on the side pins on 219 chain is .300 while on #35 chain it is .375 (3/8 which is why it is called 3/8 pitch). as for ease on the clutch the smaller the gear on the clutch the easier it is on the clutch and the quicker it can lock up. as you increase in sprocket size on the clutch you go faster but you slip a little more with each increase in tooth. The advantage of 219 chain is you have more gear ratio choices because of sprocket size.
 

MikeB7372

Member
New on the forum here , but we run a 2018 Tony Kart with the LO206 and between five tracks that we run , the ratios we use are 20/70 , 21/74, 19/68 which is pretty much all around a 3:50' ish final drive.
For example at one track where my son's on the rev limiter before the end of the front stretch with 19/68 sprockets with a final ratio of 3:57, we will use a 21/74 with a final ratio of 3.52 so we don't run out of rpms before the next corner ... small increments make a difference on a small track !

Anyhow , this is my first post so take it like you wish , but that's a good starting point !

Cheers
Phil
Are using 219 sprockets?
 
Top