Rok VLR Durability/Rebuilds


(Davin Roberts Sturdivant) #21

It’s the same thing in the Northwest.
There is hype around people driving 100cc, but I’ve lost count on how many engines I’ve seen hyped up over the years, so we’ll see when the race season comes along, who shows up.

I do like see these discount/contingency programs though. Hopefully we’ll see more here in our area.

(Nicholas Bruno) #22

There is something fishy here. A top end on an air cooled kart engine should not be $1k. The only thing I can think of is that the parts are super hard to come by and therefore expensive because it’s a new motor. If that’s the case though, I’d expect the bottom end to be about $3k or something. I’d ask for an itemized list of what parts go into the rebuild and how much he’s charging for labor.

If you don’t mind, can you PM me the name of the builder you’re using…I’m from the area and now I’m curious.

(James McMahon) #23

I would be shocked if RoK USA in Orlando didn’t have inventory of the parts. They are pretty organized.

(Dom Callan) #24

He inverted prices. I think he was told top end mid.season is about 500 and bottom
End seasonally is about 1000.

(Ryan Odi) #25

As Dom said, the numbers MAY have been inverted, but either way, he doesn’t actually build stuff from what I’ve heard (he outsources it). I’ll PM you.

(Dom Callan) #26

Yes. Most engines are sent to an engine builder like P1 for their rebuilds.

(Dom Callan) #27

While it’s true that rotaxes are known for really long time between rebuilds, I doubt that the VLR and KA are more expensive to run over time.
TJ has run the KA last season and apparently he had a low maintenance experience. Similar engine.

(Ryan Odi) #28

Yes, I am under this impression from talking with another source.

(Garett Potter) #29

Ryan, find another engine guy ASAP. If you need someone call me 504-377-8221. This engine was designed and built with existing Vortex inventory so any special parts needed or shortage is complete BS. The engine is so over built, bottom end is using ROK GP parts designed for 45+ HP, with the VLR producing less than half of that you will easily see two full seasons or more out of the bottom. 35HP GP’s are getting 50 hours

Based on the average 15 race season I would suggest a top end mid season, not because of the piston or the bearing (again another GP part) but because of the ring and to make sure the cylinder is straight, with a steel sleeve they will lose their shape causing performance loss.

Top-end Kit complete $98.00
Base gaskets $2.70 each
Head Gasket $1.35
Professional hone $100 (this is the most important part)
Total $202.00

Pin $18.50
Bearing $41.00
Thrust washers $6.80
Professional crank pin install $200
Total $266.30

Operating cost if you disassemble and reassemble
Year one-$202
Year Two-$468

Operating cost if you send to engine guy
Year one-$350
Year Two-$860

Anyone charging more than four hours of labor on a full rebuild is ripping you off $400ish is the price nothing more.

I would like to know the name of this engine guy, if they are a Vortex dealer they won’t be anymore

(Charles Kaneb) #30

Rebuild interval: Piston when you stick it, bottom end every winter.

The only reason to do the bottom end is corrosion from not running it all winter.

With the low stresses on that engine (<16k rpm on a basic design good for 19k5 as an ICA) I wouldn’t hesitate to run it three years / 100 hours so long as you race it a few times per winter.

(Aaron Hachmeister) #31

In terms of just running the engine? Absolutely. Run it till it sticks and throw a new piston in.

If you’re looking to be competitive, in my experience with 100cc AC engines, usually a piston goes in every 8ish hours or so. After that the top end starts to drop off and performance is impacted.

Bottom ends with these can go forever, like you said. I actually have no idea what the time intervals are, but I’d confidently go a full season on a bottom end if not two depending on how much/how serious the driver is.

(James McMahon) #32

I’m have to disagree with the idea of running until it sticks. Reason being, the piston can possibly shatter first. You can guess what happens to the engine. It may never even stick unless you keep leaning it down because you are trying to keep pace with a fresh motor. By all means you can go for quite some time when you aren’t looking for absolute top performance.

If you’re going for extended periods I would still recommend at least periodic inspection of the following:

  • Reeds for chips or cracks
  • Carbon build up on piston crown.
  • Carbon\gum buildup on ring groove
  • Ring gap
  • Underside of piston crown for burnt-in carbon
  • Small end bearing for signs of overheating/blueing
  • Crank for (excessive) radial and axial play
  • Bottom end for signs of bluing/overheating
  • (Optional) compression check.
  • (Optional) vacuum test

(Dom Callan) #33

James, while you have it all disassembled… Just rebuild it. :grinning:

(James McMahon) #34

If you have a honing machine, crank press, vblocks and dial gauges. Yes you could

(Davin Roberts Sturdivant) #35

Sounds like having an honest engine builder also will help. Someone who will keep tabs on the life of your engine, and recommend rebuild intervals.

(Ryan Odi) #36

Whoa, thank you for all of that information. Once again, he outsources his engine rebuilds so I do not know who it is.