Re: Vortex VLR 100 - FAQ
Posted: Tue Apr 20, 2021 6:59 pm
Good evening Calgarians,
I hope you are all doing well and everyone is getting excited as the racing season gets near. Over the last few weeks there have been a lot of changes here in Florida and I was very happy when Rok stepped up and added a 3 race series here in Florida. I am still a complete beginner but am learning as I go and have received a lot of help on this forum and from some locals here in Florida. One thing that I occurred to me is that there can be situations where things aren't going well and it is hard to figure out why. I am way too new at this to give advice, but i have made some observations.
One of the most common is when your motor won't start or is running poorly. Again, I am still new to give anyone any advice, but I have run into situations where my motor was hard to start or ran poorly and have received help that got things back on track. Specifically, when the motor won't start easily. There are generally 4 things that have gone wrong for me (so far). The first is that fuel isn't flowing so tapping the intake with an open hand to stop the air flow (choking it) may help. Next, it may be getting too much fuel, so open the throttle and pinch the fuel line. No spark could be that the wire to the coil is not connected or the sparkplug boot is not fully engaged. ALso, double check that the red kill button is up . Finally, difficult to start can be caused by a cracked or broken reed. If it won't turn over at all, for me it has always been that the connectors on the battery need to be pulled off and put back on.
The other frustration that I have encountered is the motor running poorly at some RPM. Usually for my kart it is in the midrange when the motor hasn't warmed up. In the cases where that has happened for me, which were usually in the morning, I turned out the high speed jet about 3 minutes and it usually fixed it and if that was the case another couple to make sure it wasn't too lean so 5-6 minutes total. When my motor is running it's best here in Florida, the exhaust temperature is between 1150 and 1180. I'm not sure if that varies based on altitude and ambient temperature since it seems to always be about 80F (27C) in the afternoon but in the morning when it is cooler, it seems like I have to go richer and as the day progresses I can put it back where it was. As the day warms up, the motor seems to run strongest if I keep the temperature at 1150-1180 by leaning it out 1-2 minutes at a time. I have been told to be careful not to go too lean and make sure that temperature is always climbing as RPM increase.
Talking with the motor builder, I think the reason my new motor seized at 2 hours was related to a few factors. I mixed the oil at 5 oz per gallon (4% which is the minimum), it was new motor, it was somewhat lean due to the change in weather. Those factors along with rain and running it at 16,400 at the end of the straight because the track was relatively dry and I geared down 2 teeth for rain. If I had a do-over, I would have gone a little richer and mixed my fuel at 5%.
This weekend another guy with a Rok VLR had the ring gear spin the woodruff key so it mat be rare but it is probably a good idea to know that a spare woodruff key and ring gear are available. Another part that wears out is the drive sprocket, for me they seem to last about 3 chains. I would stay away from the non-Rok part that you can buy, because my experience was that those break.
--David
I hope you are all doing well and everyone is getting excited as the racing season gets near. Over the last few weeks there have been a lot of changes here in Florida and I was very happy when Rok stepped up and added a 3 race series here in Florida. I am still a complete beginner but am learning as I go and have received a lot of help on this forum and from some locals here in Florida. One thing that I occurred to me is that there can be situations where things aren't going well and it is hard to figure out why. I am way too new at this to give advice, but i have made some observations.
One of the most common is when your motor won't start or is running poorly. Again, I am still new to give anyone any advice, but I have run into situations where my motor was hard to start or ran poorly and have received help that got things back on track. Specifically, when the motor won't start easily. There are generally 4 things that have gone wrong for me (so far). The first is that fuel isn't flowing so tapping the intake with an open hand to stop the air flow (choking it) may help. Next, it may be getting too much fuel, so open the throttle and pinch the fuel line. No spark could be that the wire to the coil is not connected or the sparkplug boot is not fully engaged. ALso, double check that the red kill button is up . Finally, difficult to start can be caused by a cracked or broken reed. If it won't turn over at all, for me it has always been that the connectors on the battery need to be pulled off and put back on.
The other frustration that I have encountered is the motor running poorly at some RPM. Usually for my kart it is in the midrange when the motor hasn't warmed up. In the cases where that has happened for me, which were usually in the morning, I turned out the high speed jet about 3 minutes and it usually fixed it and if that was the case another couple to make sure it wasn't too lean so 5-6 minutes total. When my motor is running it's best here in Florida, the exhaust temperature is between 1150 and 1180. I'm not sure if that varies based on altitude and ambient temperature since it seems to always be about 80F (27C) in the afternoon but in the morning when it is cooler, it seems like I have to go richer and as the day progresses I can put it back where it was. As the day warms up, the motor seems to run strongest if I keep the temperature at 1150-1180 by leaning it out 1-2 minutes at a time. I have been told to be careful not to go too lean and make sure that temperature is always climbing as RPM increase.
Talking with the motor builder, I think the reason my new motor seized at 2 hours was related to a few factors. I mixed the oil at 5 oz per gallon (4% which is the minimum), it was new motor, it was somewhat lean due to the change in weather. Those factors along with rain and running it at 16,400 at the end of the straight because the track was relatively dry and I geared down 2 teeth for rain. If I had a do-over, I would have gone a little richer and mixed my fuel at 5%.
This weekend another guy with a Rok VLR had the ring gear spin the woodruff key so it mat be rare but it is probably a good idea to know that a spare woodruff key and ring gear are available. Another part that wears out is the drive sprocket, for me they seem to last about 3 chains. I would stay away from the non-Rok part that you can buy, because my experience was that those break.
--David