School of ROK

[elmt1]

Fellow classmates, my plans to race in Strathmore this season took a quick detour a few months back with the Covid 19 pandemic and even though I was able to travel back to the US from Spain last week, it looks like the US/Canadian border may stay closed for a while so no racing for me at least until July 21st. My fingers are crossed.

I put my go-kart together as soon as I got back so I have a better idea where everything is at and I have some new questions. For the most part, I followed the OTK guidelines except the seat, which I left where it was because it fit me reasonably well and I didn't want to drill new holes unless it was wrong. According to the OTK guidelines, it is about 2cm too far forward. The seat was in pretty rough shape but I put a couple of layers of fiberglass inside and outside and it seems fine now.

1. Ground clearance seems pretty limited compared to similar karts I have rented. Seated in the kart, it is about 15mm to the frame rails and about 9mm to the new frame protectors that I installed. If I bounce in the seat, I go can get to 2-3mm of clearance. Is that enough? I did check the frame on a surface table and it seems to be true but that seems awfully tight to me.

2. In addition, I may be in a bad place as far as total weight. The weight with me in the kart 12#'s in the tires, a helmet, chest protector and one gallon of gas is 341 lbs. My racing suit may add 2-3 #'s. With LF 83, RF 79, LR 79 and RR 100. The scale says I have 53% right and 53% rear weight. Should I maybe move the seat back to where OTK recommends or is that OK? Also, not sure what to do about adding LR weight. I set a 2kg lead weight near the brake mount and it didn't help very much.

3. When I got done putting my go-kart together, I had a few extra parts I am not sure what they are or if they are important, but there were two wire clips in the bag I labelled engine and exhaust that might lock something in place that seem important. I also had a few new parts from Rok that are probably related to the battery but they look like floor tray bolds -- not sure what to do with those. I have attached a picture, please let me know if you recognize them.

Thanks for the help, I am looking forward to seeing you at the track soon.

--David

[dvelpel]

Hey David!

Good to hear that you made it back safe!

Looks like your on the correct path with setting up the kart, in regards to the extra parts the silver clips/red bushings looks like its apart of the battery setup, if you have the manual it's shown on the bottom picture of page 11. not to sure about the black clips, next time im at the track i'll take a look.

The club has updated most of our regulations/registration process to compile with current COVID-19 measures so I would recommend reviewing them, As you might be traveling in from the US there could be a 14-day self-quarantine in place.

I'll update this post once I check out my kart, or maybe someone else may know those parts.

[elmt1]

Thank you for the feedback. I really wish I could make it up to Canada, but my best guess at this point, is that won't happen this year until at least September, if at all . The quarantine requirment makes it very difficult because it means two weeks in a hotel doing nothing even though I live outside the city and am effectively quarantined here, but the quarantine time can't start until you actually get into Canada. In the meantime, I have my kart assembled and have plenty of free time. I really hope I can at least test it this year even if I have to drive a really long way.

I went ahead and moved the seat back about 12mm to the recommended location and moved it left about 12mm. I am about 6' and 180#'s (183cm & 83kg) with helmet, etc. I also completely leveled the scales I was using and now my weights seem closer to what I have read is a good starting point. Right now it is something like 47.5% front and 52.5% rear. However, I still have quite a bit of weight on the front, which seems odd based on what I have read. The corners are LF 80, RF 83, LR 84 and RR 98 for a total of about 345. If I put 20#'s on the frame behind and next to the seat it seems to add about 16#s to the LR, 2 to the RR and 1 to the LF. With that 20#'s of lead added, I get to about 54% rear and left and right get very close to 50/50. However, I think I need to add about 30#'s to hit 375 so it seems like I will be pretty close, I just don't have that much lead on hand.

Thanks again!

[elmt1]

Good evening Canadian Rokers.

I have to admit that I am a little jealous when I read that you have been able to put together a race schedule this year. Unfortunately, I still can't cross the border to join in the fun. I did get a chance to try my kart at a few races put on by a Montana club that sets up a track at the Montana Highway Patrol test track. They do a good job working with a fairly limited track. The track itself is not as challenging as a typical kart track and dropping a wheel off the edge can be exciting, but as they say, a bad day of karting beats a good day of working anytime.

I know this is a CKRC/Strathmore track forum but I could use some general advice as I try to work within the restrictions related to Covid 19.

They don't have any other 100cc karts and are all using some form of 125cc tag karts so it provides a good way to see how my kart is working even though I am about a second off the pace of the leaders. What I have found is that my kart handles pretty well compared to the some but is a little loose coming out of corners. I have tried a few different things but in general I think the low 52.5% rear weight, old tires, and green track contribute to this.

Now some specific questions. I found that on their long track with a 10 x 80 gear I was running the entire track over 10,000 RPM and hitting 15,800 on most of laps. I went to a 10 x 78 and the top RPM dropped to about 15,300 and I picked up about 1/2 second, but had to really work to keep momentum on the one tightish corner on the track. My EGT was about 1150 on most laps and the kart seemed to be running well. The area that seemed to matter the most from the MyChron data was a long sweeping turn where it was easy to bind the kart up and lose momentum on the last 1/2 of that turn. It was also easy to push a little hard and have some oversteer coming out of that corner. Not sure what anyone would recommend as potential changes to try when they run this particular configuration.

The other configuration they run there is much shorter. I have only run that for one day and I think the gear I had was too high. I used a 10 x 83 gear (lowest I had at the time) and only got up to about 13,300 RPM on most laps and the EGT never went about 950. Since then, I bought 84 and 85 tooth chainrings so I am thinking of trying a 10 x 85 if they run that configuration again. On that track, the kart felt fairly loose again and I had a hard time getting the tires to heat up so maybe just ran too low of pressure. I was using some old Bridgestone YLR tires starting at 12.5 and ending at about 14 on a day that got up to about 80F or 26C.

My main goal is to figure out what I can and should change to meet the conditions that the track is providing. In the past, I had someone who knew what they were doing to help, but now I am on my own and I really don't know a lot about what to do in a given situation. I have tried a number of changes to see how they affected the kart's handling like going to -2 degrees camber, toe from .5 mm to 1 and 1.5 mm, narrowing and widening the rear, tightening and loosening seat struts and side pods, loose front torsion bar, tight and flat front torsion bar, etc. I feel like I need to get to an understeer condition just to see where that limit is and then back off but the front seems to hook up really well and the back isn't too bad except for a little oversteer out of a corner if I push it.

Thanks for any help!

[kolsen]

Good evening Canadian Rokers.

I have to admit that I am a little jealous when I read that you have been able to put together a race schedule this year. Unfortunately, I still can't cross the border to join in the fun. I did get a chance to try my kart at a few races put on by a Montana club that sets up a track at the Montana Highway Patrol test track. They do a good job working with a fairly limited track. The track itself is not as challenging as a typical kart track and dropping a wheel off the edge can be exciting, but as they say, a bad day of karting beats a good day of working anytime.

I know this is a CKRC/Strathmore track forum but I could use some general advice as I try to work within the restrictions related to Covid 19.

They don't have any other 100cc karts and are all using some form of 125cc tag karts so it provides a good way to see how my kart is working even though I am about a second off the pace of the leaders. What I have found is that my kart handles pretty well compared to the some but is a little loose coming out of corners. I have tried a few different things but in general I think the low 52.5% rear weight, old tires, and green track contribute to this.

Now some specific questions. I found that on their long track with a 10 x 80 gear I was running the entire track over 10,000 RPM and hitting 15,800 on most of laps. I went to a 10 x 78 and the top RPM dropped to about 15,300 and I picked up about 1/2 second, but had to really work to keep momentum on the one tightish corner on the track. My EGT was about 1150 on most laps and the kart seemed to be running well. The area that seemed to matter the most from the MyChron data was a long sweeping turn where it was easy to bind the kart up and lose momentum on the last 1/2 of that turn. It was also easy to push a little hard and have some oversteer coming out of that corner. Not sure what anyone would recommend as potential changes to try when they run this particular configuration.

The other configuration they run there is much shorter. I have only run that for one day and I think the gear I had was too high. I used a 10 x 83 gear (lowest I had at the time) and only got up to about 13,300 RPM on most laps and the EGT never went about 950. Since then, I bought 84 and 85 tooth chainrings so I am thinking of trying a 10 x 85 if they run that configuration again. On that track, the kart felt fairly loose again and I had a hard time getting the tires to heat up so maybe just ran too low of pressure. I was using some old Bridgestone YLR tires starting at 12.5 and ending at about 14 on a day that got up to about 80F or 26C.

My main goal is to figure out what I can and should change to meet the conditions that the track is providing. In the past, I had someone who knew what they were doing to help, but now I am on my own and I really don't know a lot about what to do in a given situation. I have tried a number of changes to see how they affected the kart's handling like going to -2 degrees camber, toe from .5 mm to 1 and 1.5 mm, narrowing and widening the rear, tightening and loosening seat struts and side pods, loose front torsion bar, tight and flat front torsion bar, etc. I feel like I need to get to an understeer condition just to see where that limit is and then back off but the front seems to hook up really well and the back isn't too bad except for a little oversteer out of a corner if I push it.

Thanks for any help!

HI David,

Glad to see you're at least getting some track time in...

Based on those numbers, the 80 tooth seem to be a bit short - anything over 15K RPM you're just spinning faster but not getting any power (sure you've felt that), so sounds like the 78 is a better choice. The taller gear definitly will make tight corners more challenging, but it's always going to be a trade-off between the the long straights and tight corners....I've been told you want to keep max RPM around 15K RPM. The temp looks OK - I'm hitting 1120 -1150 range...check the plug and inside the pipe - optimally should be a "caramel" brown - black is too rich...and not optimal..

I'm still learning my way through the chassis setup so can't give any meaningful guidance on that - John Kwong is our guru on this stuff. If you're having trouble gettgin heat into the tires, definitely start with tire pressures. We're running Vegas, so night and day with bridgestones - I ran them in Vegas and Fontana but can't recall the pressures used - I really should start logging this stuff

Keith
#5 VLR Masters

[elmt1]

Good to hear from you Keith,

That is really helpful. Last weekend they had another race on the same track with reverse (CCW) direction, which works better for my kart since I am about 20#'s heavy on the right side. I added two teeth and was getting to mid-to-high 14,000's and it was a lot better. The new gearing, new tires (my old Bridgestone tires were completely shot), and CCW direction on short track were like an alignment of the stars for my kart in the 125 tag class they run here. Hopefully they let me keep running 30# under the weight limit There is the slimmest of chances that the border could open on 9/21, and there is no quarantine requirement. It that does happen, I really hope to be able to race in the enduro and now I know at least one other person in Montana that would like to race.

I have been trying new things each weekend that they have racing to see what works and have learned a lot through trial and error and I am feeling more confident in changing things up now. This last week I noticed that my chain was going tight, loose... so checked the axle and found it was about .020" out at the end. I read up on straightening and was able to get it back to about .003". Other things I have learned is that the cables that come with the ROK VLR have some pretty poor quality knockoff connectors. If one breaks you can buy a real Anderson replacement end for about $5 rather than buy a new OTK cable for either $20 short end or $180 (USD) long end. Another learning was if you take the starter apart, be sure to contain the wire circlip when you take it off or it could shoot across the room and get lost (don't ask me how I know that). I don't know if this is common, but I also found out that when I put in a new sprocket it is always out of round by at least .010-.020" and I was centering the chain based on the average. I now know it is pretty easy to get it within a couple of thousandths with a deadblow hammer and grease pencil. Not sure if that is worth it but I feel like it is going to help sprocket wear.

Thanks!