In setting the predator RPM limit on the stand does it make sense to set it at 4850 to not go over 5000 when the motor is only turning 45-4600 on the track? Why would you flirt with over 5000 setting the rpm at 4850 when you are not turning the motor but 4600? I'm new to predator and not and engine guy so I'm trying to make sense of this.
Predator RPM on and off stand
- Thread starter Cakalac
- Start date
racing promotor
Moderator
Our guys have a 5500 rpm rule max on stand, they set them at 5400 to 5470 on stand and race them at 4800 to 4900 and it works well.
Is there any advantage hp wise to do that though and risk going over my 5000 limit? I'm trying to understand does my engine produce anymore power at setting it at 4850 on the stand and racing it at 4600rpm v/s setting it at 4700 on stand to not flirt with 5000 rpm rule and racing it at 4600?
So with that said Don, would you set the governor on mine at 4700 and leave it? We were trying to get it at around 4850 but i went to 5077 when I did that after the race. I have a 5000 rule. Gov must be hooked up but doesn't have to surge. I've yet to turn more than 4650 on the track.
DynoDon
Moderator
I can’t actually tell you exactly where to set it. However I will share with you one situation that I recall. One racer did not have a tack on his go kart for me to check at the end of the event. So I put the go cart on the stand. His RPMs only registered on the stand at 4850. He won the race so I really don’t know what he turned in regards to being on the racetrack but I do know his RPMs were not above4850
racing promotor
Moderator
Don and the tech guy's here have there own tach with them to check RPM or confirm RPM.
1fasttiller
Member
Do you guys free rev these things on the stand like that often to check? I would think that is absolutely KILLING your valve springs.... I will never free rev an engine above 3500rpm. These chinese springs are soft and weak already!
Yes and I assure you I've asked the same exact question and I am not a motor guy. Lol. I don't know another way to set the RPM though. I think the rule set at 5000 is silly. I think 5300 minimum and the other tracks around my place are 5500.
I'm kinda new to the sport, my grandson races a champ kart, and ours "surges" as well, but a few others we race against don't surge. Our little guys are RPM restricted at 4000, stock predator out of the box. We have no rule that the karts have to surge. I have asked this of several other and haven't been able to get good accurate info re: the governors on these things. What does the surge or no surge matter? Are we at a disadvantage somehow because ours does? How do you stop it or make it? I'd appreciate any accurate feedback. Thanks
1fasttiller
Member
The surge is usually indicative of a very lean main jet in my findings. Swap the jets out and it will likely go away.
I ran 2 features on a new spark plug the other weekend. When I pulled it out if looked as if it came right out the box brand new. There was zero soot on it. I thought it would have at least shown some wear after 35 laps. Would this indicate lean?