Hey Everyone,
I was wondering how often should I get my Vortex Rok GP engine rebuilt?
I get mixed answers every time I ask around - some say 15 - 20 hours, some say 35+ hours. For more context, I have around 18 hours on it as we speak.
Thanks everyone!
I´m new to the hobby, but I have a Vortex SuperRok… almost same motor like yours. It has 15 hours on the top end. My motor is in for a rebuild right now, at a respected motor tuner. When I get it back, I will let you know how much he did on the motor.
Also @Garett_Potter Knows a lot about these engines…
My understanding is that the ROK GP is built with the same design goal as the TM KZ-ES series engines, which is to run longer between rebuild intervals vs standard KZ engines. TM rebuild schedules are based on liters of fuel used, which is a more accurate metric than approx run time, since burned fuel volume accounts for both run time & workload. For reference, the TM recommended rebuild schedules for their KZ-ES engines are: top end @ 100-140 L (26-37 gal); bottom end @ 400-440 L (105-116 gal).
The Rok GP, like the X30, has a soft iron cylinder bore. Too much time between top ends and your cylinder will go out of round. For iron bore TaG cylinders, I recommend a top end every 10 hours and a top/bottom (new main bearings and big end rod bearing) every 20 hours.
For sure you’ll get different numbers which is frustrating. It’s somewhat down to the amount of performance that you’re looking for too. 35+ sounds on the high side for sure. At the very, very top of the sport many (but not all) racers will spend the money to ensure the engine is as fresh as possible but that doesn’t necessarily mean that it’s required.
One thing I will say is that it doesn’t hurt to periodically inspect the internals if you’re going longer between rebuilds.
Tawfig,
Factory says 30 top 60 bottom, for me this is to much. I suggest half 15/30, there are many variables to account for, race conditions, fuel and oil used, mixtures, carb setup, temps etc. I do know many club guys have seen the numbers the factory states, but I have always cautioned on the side of maintenance is cheaper than repair, no matter what brand it is. Someone also stated above about the cylinder liners, these are to help with reliability and repair costs, but as stated they do become out of round, so its important to make sure these are honed properly with regular maintenance. If you want to do the assembly work yourself, make sure you have a known shop do the honing and piston fit for you, its worth every penny and honestly they charge $60-$75 for this work so not a huge cost.
Curious, for X30 national level engines do you still go 10 hours or does the interval come down?
When I was running X30 nationally, we ran less than 10 on the top end, but that was admittedly being proactive. It could go longer for sure.
For national events, X30’s come off our dyno with 40 mins to an hour on them. You have to assume every engine is fresh at a big race.
I ran my Leopard 6-8 hours before sending it out. I was figuring more for the X30. I don’t like to chance stuff as I only have 1 engine.
Better than ICAs, those were 2 hours…but they were only 200 DM to put a piston in which would be about $100.