Plate motor vs unrestricted

Colt sr

Member
Is there a major difference in gearing when setting up a plate motor vs a unrestricted. I currently own an unrestricted flathead that is super fast at our track. He is running a 14 driver with a 67 rear gear. My sons jr sportsman with a blue plate flathead is geared with a 13 driver and 65 rear gear. I watched my son race his best race keeping up with the blue plate animals and i am confused on why the gearing is totally different. My sons highest rpm was 6450... Please intrigue me on why this is going on
 
It could be a lot of different factors. Track configuration, line, tires, set-up, amount of braking being used, etc etc.
Typically though, our small plate drivers are a tooth BIGGER on driver than unrestricted.
(ie 14:67 adult would equate to 15:67 for the jr1-2 driver on the same race track.)
6450 is a bit high (in my opinion) for blue plate flathead, but your engine builder (and moreso a stop watch) will tell you better.
Restrictor plate racing is all about momentum -- never lift and keep the corner rpm drops to a minimum.

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Colt sr

Member
Engine builder told me that between 6400 and 6700 was a safe rpm to run. He drove pretty close to my sr drivers line and only burped the engine through 1-2 he was quite faster down the straightaway than the other karts. The track is a 1/6 mile track in northeast indiana. Only time he used brakes was when there was a wreck/spinout in front of him. Jr1/jr2 drivers run purple plates here as i said he is on a blue plate. But it still confuses me that with the same type of engine that gearing would be different. I realize all a plate really does is removes power for a less experienced driver.
 

racing promotor

Moderator
Is there a major difference in gearing when setting up a plate motor vs a unrestricted. I currently own an unrestricted flathead that is super fast at our track. He is running a 14 driver with a 67 rear gear. My sons jr sportsman with a blue plate flathead is geared with a 13 driver and 65 rear gear. I watched my son race his best race keeping up with the blue plate animals and i am confused on why the gearing is totally different. My sons highest rpm was 6450... Please intrigue me on why this is going on
Confirming ON THE SAME TRACK ?
 

racing promotor

Moderator
It beats everyone by a straightaway or more
That's with a flat kart ? or a SR Champ ? only asking because you say your son is a Jr Sportsman which is a champ ?
Also what was the determining factor that you started on a 13 one lower driver with a blue plate ?
 

Colt sr

Member
The unrestricted is a flat kart... Started with a 13 driver because the blue plate animals were pulling him off the corner when he ran a 14 driver...
 

racing promotor

Moderator
Is there a major difference in gearing when setting up a plate motor vs a unrestricted. I currently own an unrestricted flathead that is super fast at our track. He is running a 14 driver with a 67 rear gear. My sons jr sportsman with a blue plate flathead is geared with a 13 driver and 65 rear gear. I watched my son race his best race keeping up with the blue plate animals and i am confused on why the gearing is totally different. My sons highest rpm was 6450... Please intrigue me on why this is going on
Your gear bound( you will get beat out of the hole when set-up and gearing is off to start ) and your kart set-up is way off NOT making much forward drive and your trying to make it all up with gearing.
I agree with Brian 6450 is to much rpm for a blue plate flathead, and NEVER should a plate motor front driver be smaller than a unrestricted on the same track, 80% of the time it's 1 bigger and If it were a flat kart usually 2 bigger, the fact that it's a Jr Sportsman Champ MIGHT keep it the same front driver BUT it would be lower rear gear for sure.
 

Colt sr

Member
What would you recommend as a high rpm for the blue plate... The engine was originally built to be unrestricted that is possibly why builder told me tge higher rpms
 

racing promotor

Moderator
What would you recommend as a high rpm for the blue plate... The engine was originally built to be unrestricted that is possibly why builder told me tge higher rpms
I'd shoot for 6300 Max and a 14/62 or 15/66 should be much closer on a 1/6th mile with lower grip track, Keep in mind once you get everything right you will gain a lot of rpm.
 

racing promotor

Moderator
Biggest thing I see with kids causing the scrub of speed is running to low, then as soon as kart comes off Turn and starts to build some momentum they turn down which reloads the chassis and kills it.
 

Colt sr

Member
I'd shoot for 6300 Max and a 14/62 or 15/66 should be much closer on a 1/6th mile with lower grip track, Keep in mind once you get everything right you will gain a lot of rpm.
Setup was great sat night... He was catching the 3rd place kart by at least a kart length each lap... He just ran out of laps to make the pass... But i will try one of those options and see where he ends up... Only issue we have is that he is the only flathead against animals...
 

Colt sr

Member
Biggest thing I see with kids causing the scrub of speed is running to low, then as soon as kart comes off Turn and starts to build some momentum they turn down which reloads the chassis and kills it.
He was running his kart in middle of the turns and definitely was not pinching off the kart from the sound of engine on the gopro videos. He could flatfoot it through 3-4 and in 1-2 he was burping the throttle... 1-2 was a dust bowl... Only true issue i seen was that he was sleeping on the start
 

racing promotor

Moderator
Setup was great sat night... He was catching the 3rd place kart by at least a kart length each lap... He just ran out of laps to make the pass... But i will try one of those options and see where he ends up... Only issue we have is that he is the only flathead against animals...
Don't fool yourself A Good Blue plate Flathead will run right with A Blue plate animal, now that's the only color plate there close. I would just lower rear gear to a 61 ish with the 13 driver first to prove it's somewhat gear bound, If rpm does not drop a good bit stays 6350 or more it's gear bound.
 
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