Hi, struggling to find info on a pair of old Super Rok motors I recently got, circa 2010. One new in wrapper and one used. Lots of calls to known builders, including OTK etc, and very little is known/remembered…
1st question is base timing advance. Both the new (factory set) and used motor came with considerably more advance than the GPs recommended 3mm. OTK said this was due to different coils but couldn’t give any specs.
The pics show advance ring difference between 3mm and new factory setting.
Tied to this is the coils are PVL 500-192 (not subsequent 500-211 or current 500-212.
An Italian site lists this as old 2-wire 17000 rpm model but nothing else.
Second strange thing is it came with Dellorto VHSB-36mm carb (!).
Currently not running right but is was set to 3mm advance, and not sure where to start now I know it’s a much larger carb.
Bottom line is that this ended up being quite different than the current GP specs for carb and ignition.
This motor is “supposed” to have 43hp…
Does anyone have any experience (or remember who does) with this old ‘open’ level TAG motor?
I’ve searched all around including my TAGUSA archive and cannot find anything on this engine, despite remembering it. Edit, I did find the homologation form linked in a different topic on the forums: Vortex Super Rok Homologation pic_13_01.pdf (792.8 KB)
I can only give some generic info unfortunately. Do you know the rod length and stroke, from that you can at least calculate the static timing in degrees to get you started on ignition advance…
36 does sound pretty large, especially for a single gear kart, but the powervalve will help make up for the lack of bottom end. That said, the homolgation does show a VHSH30
If you search the forums for Super Rok you should find some more topics on this.
I’m not actually sure how much in deg the super Rok should have. But if we take the regular rok GP, it calls for about 23deg which is 2.7mm. I guess that would be my starting point to be conservative and you might pickup some overrev. They have the same 54mm stroke and 102mm conrod length
I have the regular Vortex ROK and was looking to up the rev limiter by swapping coils. Informed with “Kartstore.it” and they told me i could swap it with the 500-211 but that the phase needed to be set at 5,5.
In the end i went with a 500-178 which PVL list on their site as an unrestricted coil for the ROK. With the standard 2,2mm setting it only revs up to 12K and hits a hard limiter instead of the 16K the coil is capable. After many unanswered mails i got an answer from PVL that timing needed to be set at 30° about 4,5mm. Have not tested it yet.
Verry hard to find info about these engines, but maybe the above info will get you in the right direction. If anybody more knwoledgable can elaborate on more vs less advance and the effect on the engine.
Seems like the 500-211 is the more well known Super RoK original coil, and Kartstore.it advertises the 500-192 as its direct replacement.
With you being directed to give the 211 5.5 mm of advance, this is consistent with what OTK mentioned in terms of the Super coil needing more advance, and that both motors were originally set with more than 3mm.
I can at least measure the unused motor to better confirm how it was set from the factory. Fingers crossed it’s 5.5mm…
If so, is it reasonable to test 5.5mm? (I’m running 110 leaded Sunoco). I still haven’t gotten fueling figured out yet since I was chasing GP settings and ran out of time.
I’m reverting back to jetting how it arrived. Should I do fueling first, or, at the same time if Timing is going to throw off the carb and EGTs falsely?
My process is to get ignition dialed in first with jetting a little on the rich side. I’d still play it safe and start with 3mm and creep up on it from there. Then again, 6mm could be just fine based on those recommendations
You might see higher EGTs with the later burn. Performance wise, in an ordinary case I would say you’ll see an increase in overrev, but with the timing being that much off… you’ll probably see a drop all around.
Time has been short, so was only able to hit a few laps with an even bigger jet (168) still at 3mm.
Very boggy down low, like too much fuel, requires part throttle feathering to get going, soft in mid range, but pulls pretty well between 10k-13k and kinda peters out. Power valve set in middle of adjustment range.
EGTs were somewhat inconsistent at top end, mostly 1100, but couple cooler and still saw peaks above 1300 a time or two.
I let a Pro driver do a couple laps. He too maxed at 14k and saw a 1350 at end of straight. Said same boggy low, but that the small window of power pulled similar to an X30 power wise.
Finally got a response from OTK Italy who informed that base timing advacnce is 6.5mm (!!).
So I put in 5.5mm as a test and visited a parking lot for a quick test of full throttle on few pulls Unfortunately much of the same for characteristics, though 10k-12k may have pulled a little harder by feel. Ran out of road but believe running out of steam at about 13k
Didn’t like what seems like a new smell from exhaust, but piston doesn’t look obviously bad.
So just reporting back with inconclusive data… but wanted to share update and pics.
I think I will get this on a dyno to stop guessing.
Here is OTKs reply and some piston pics. One is cleaned just to confirm piston surface.
Any detonation obvious?
Are current descriptions likely just carb combo (albeit same as previous owners)?
And should I continue to dial in fueling with the 5.5mm advance?
Thx again
I actually ran out of gear at the track, lifted on the straights due to hi EGTs or RPM peaked before braking zone.
Long story but I do have a new VHSH-30 CS from a TM R2. To use will require about $150 in new vortex mounting plates (36mm to 30mm).
Is there anything special about the CS carb, or a reason it won’t work for this Rok
And separately, how do KZ motors make 47+hp with the same 30mm carb that the 36hp RoK GPs use? Obviously it’s several factors but seems to confirm that this old 36mm carb was overkill even for the supposed 43hp Super.
Porting and pipe. With gears the KZ can work with a narrower powerband, say 2500 RPM. Imagine a KZ doing a full lap in 6th. Gutless, possibly would be passed by a 206…
Single gear karts have to pull well over a wider RPM range, something like 9000<>12,000 RPM, so they don’t make as much peak HP to account for this.
I’m also trying to make open race engine from ROK GP.
1st About the timing.
I currently use 500211 and i went to 4.5mm the engine is much more responsive but i have some unvanted high EGT temperatures. From my opinion it’s the moment when the digital ignition retard the timing too much and i have burning in open exhaust port.
I for sure will try the 5.5mm.
2nd About the Carb
I use the vhsh30 and i found that for the Boggy low you need to go down with the spray nozzle.
If you can tell me what is your carb setup i will tell you what to try.
Also what i find that the squish need to be at least 1.3mm on lower squish i have degradation on piston.
If you can tell us. On which track you are driving the kart. How long the straights are… Maybe some picture from telemetry… Maybe we can figure out somthing new.
I’m from Serbia and our tracks are short, tight and with very short straights.
