RPM target, C Clip, and REAR GEAR

kepner

Member
FACTS: Asphalt track, flat no banking, experienced driver, 380 lbs total weight, longer straights and paperclip track, purple restrictor in lo206, mandatory 18 tooth clutch noram driver gear. Straights each are .14 of a mile, turns are 165 feet from very beginning of curve to exit of curve. Really since paperclip there are really only 2 turns, one at each end of track.

Wondering opinions on:
1. Rear gear?
2. Target max rpm, is it LESS then riv limiter?
3. C clip position and why?

Thank you in advance for any thoughts and input!
 
96.7 dia. turn
739 ft straight
This might help someone figure out your gear requirements. That's a long straight. How much stagger do you plan on running?
 

kepner

Member
96.7 dia. turn
739 ft straight
This might help someone figure out your gear requirements. That's a long straight. How much stagger do you plan on running?
96.7 dia. turn
739 ft straight
This might help someone figure out your gear requirements. That's a long straight. How much stagger do you plan on running?
Plan to run 1/2 inch approx unless we decide we must have 3/4. Want to run as little as possible due to long straights.
 

kepner

Member
Have never ran a purple plate lo206? Assuming there is a preferred rpm max and fairly certain it is not 6000/6100 rpm which is the rev limiter.
 
The carb is the big issue. With a restricted engine tune it lean by setting float height around .890 with 1 inch drop. On cooler high moisture days move clip down needle. Elevation could be an issue .
 

kepner

Member
The carb is the big issue. With a restricted engine tune it lean by setting float height around .890 with 1 inch drop. On cooler high moisture days move clip down needle. Elevation could be an issue .
Wish I could. These are supplied and run engines at track. Fairly certain there won’t be any float adjustment done by them. About all I could adjust would be air screw, possibly C clip.

Saw on briggs site that torque and hp meet at 5000 rpm With purple. I know this is not an exact but our we likely best maxing rpm around 5000 to 5200 With purple slide?
 

flattop1

Dawg 89
Is this some sort of rental program or engine draw ?
Flatout racing , i would think just off the limiter .
 

jjchat

Member
I don't have any data with the purple restrictor, but with the blue I can tell you max torque is around 3200-3400 (with black slide it is 3400-3600) and max HP is at 5000-5200 (with black slide it's 5400-5600)

If it were me, I would set up my clutch to engage at 3200 and I would set my gearing to not go below that amount. If that means I don't get anywhere near the rev limiter, great. If it means I hit the revlimiter hard, that's just what the track is going to require. With a restrictor though, too many revs is worse that not enough.
 
Peak torque at 3400 rpms Peak HP and Peak torque at 3800 rpms .I like to use a larger driver at the same ratio . My experience has show.the 206 pulls hard off the bottom end .
 
Wish I could. These are supplied and run engines at track. Fairly certain there won’t be any float adjustment done by them. About all I could adjust would be air screw, possibly C clip.

Saw on briggs site that torque and hp meet at 5000 rpm With purple. I know this is not an exact but our we likely best maxing rpm around 5000 to 5200 With purple slide?
torque x RPM / 5252.1 = HP
10 lb. x 5252.1 / 5252.1 = 10 hp
The 2 numbers 5252.1 cancel each other, so at that RPM, torque and HP are always equal.
 

kepner

Member
The race is not rental but an alumni race where they supply 206 with 18 tooth clutch noram already attached. So really for us it is just about a good kart set up and finding the correct rear gear. Has been 20 years since I messed with a restricted plate engine, now “slide”, at least in 206.

Just kinda figured there was a normal sweet spot max rpm range, like 5000 to 5400 rpm or something similar. I realize that every track and driver is unique but still assumed there was a good starting point for common max rpm in purple restricted 206? Maybe not?
 

kepner

Member
If we have minima rpm drop just wondered if we wanted to “live” in the 4500-5000 rpm range. I figured after 5000 rpm we start to lose too much torgue AND hp and then stop pulling last 3rd of long straights?
 

flattop1

Dawg 89
Carlson or Jimbo will have better info .
 
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