Non-Hemi predator not reaching target rpms

EthanP3

Member
We race a "modified stock" predator here and I can't seem to reach the target rpms. Everyone I talked to said I should be running 6000 to 6200 rpms and all I have been able to manage is 5700. We aren't sure what could be holding us back.

Governor removed
10.8 springs (tested to make sure they are true 10.8)
Holy Moses carb with .18 idle jet .31 main
CL2 cam
STOCK AIR BOX
 

flattop1

Dawg 89
Is yor engine setup the same or similar to Everyone ?
Air box and exhaust specifically .
Is the chassis tight or way over on weight ?
 

EthanP3

Member
Is yor engine setup the same or similar to Everyone ?
Air box and exhaust specifically .
Is the chassis tight or way over on weight ?
Stock air box and after market exhaust. Everyone is running about the same setup and weight.
Even my race shop guy is stumped as to what is happening.
My only thought is maybe drop down to a CL1.
 

Komet99

Member
Can I hijack the thread?? New to 4 strokes. I dont have any advice to offer you for more rpm...but speaking of rpm, I have been running the stock pred and recently have been tuning with rpm. Last week i cranked it up a little and got a max of 5400 with every lap in the 5100-5200 range. It seems with every gear change Im gain speed and reducing lap times. At what point do I tune this thing? Will the stock cam make it past 5500? It does have the 10.8 springs in it...(I guess). where do I stop with it? When is it going to scatter?

OP, if I over rev a couple hundred, ill jar them up and send them to you!!
 

Komet99

Member
By the way, its a 2 stroke tuning option....rev the out of it if the track will take it and its making power.
 
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racing promotor

Moderator
We race a "modified stock" predator here and I can't seem to reach the target rpms. Everyone I talked to said I should be running 6000 to 6200 rpms and all I have been able to manage is 5700. We aren't sure what could be holding us back.

Governor removed
10.8 springs (tested to make sure they are true 10.8)
Holy Moses carb with .18 idle jet .31 main
CL2 cam
STOCK AIR BOX
Sounds like your gearbound and if there giving you accurate info it may work for them but not you, pull 2 teeth off the rear for a race and see what it does to rpm, you can't test it in practice because of course it's gonna turn less then, if you pull teeth and it maintains keep pulling and it may even go up
 

EthanP3

Member
Sounds like your gearbound and if there giving you accurate info it may work for them but not you, pull 2 teeth off the rear for a race and see what it does to rpm, you can't test it in practice because of course it's gonna turn less then, if you pull teeth and it maintains keep pulling and it may even go up
We tried that same strategy last night. Dropped 2 teeth on the rear and it ran the same rpm but the motor lugged more and the kart was noticeably slower. Borrowing a reletives tach to see if my tach is off
 

racing promotor

Moderator
We tried that same strategy last night. Dropped 2 teeth on the rear and it ran the same rpm but the motor lugged more and the kart was noticeably slower. Borrowing a reletives tach to see if my tach is off
Then it's still gearbound keep pulling till rpm lower
 
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