June 7, 2016 at 7:22 pm #66940
Hey there, as the title states Im new to karts. I picked up a kart from a friend and want to learn as much as I can. I know, its a CTS chassis, CR125 powered, and has brembo brakes. I got to try it out at a local track last week and I’m hooked. any info or help/suggestions would be greatly appreciated. Thanks in advance.
June 7, 2016 at 7:29 pm #66942
some of the things I have questions about.
Is that a good chassis?
Typical gearing and final drive ratio
What plastics can be used on that frame
Something I noticed is I dont feel a drop in RPM’s on the upshifts. Bad clutch?, Shifting too late? gearing issue maybe? Seems to be running out of top end. It currently has a 24 rear, 15 front. 1.6 ratio. Thoughts?
June 8, 2016 at 5:37 am #66950Matt MartinParticipant
what track? gearing depends on track. loss of top end might be gearing, might be carb setup, might be engine maint.
how many hours on the motor?
if you’re just starting out, a straight, not-cracked chassis is all you need.
June 8, 2016 at 12:30 pm #67005
Matt, track is Orlando Kart Center. Not sure how long the straights are but that was my initial impression. Unfortunately I don’t have a documented history on motor so I can only speculate. Seems to have tons of power when it comes on. I noticed that there is no “power valve”. From what I’ve read, it has something to do with not needing so much on the bottom end. Not sure.
June 9, 2016 at 4:51 am #67023Matt MartinParticipant
A slipping clutch will cause rise in RPM without a change in speed.
I would ask around the folks at that track what gearing they are running, and what carb setups they’re running. If things are still going awry after those adjustments, you should look into having the motor gone through.
June 14, 2016 at 2:41 pm #67229Jim DerrigParticipant
Jose, except for starting from a stand-still, you don’t use the clutch at all. All upshifts and downshifts are performed without using the clutch.
My guess is that your clutch cable might be stuck or misadjusted, preventing the clutch from engaging fully. Also, an upshift reduces torque so it is strange that the engine does not lower rpm’s on upshifts but the rpm’s are increasing for downshifts (I assume). If the clutch was going to slip it should do it when the torque increases.
Which leads to my next thought, which is that your upshifts are not upshifts at all. Sometimes the shifter mechanism can become misadjusted or run into interference with a seat strut. You pull back on the lever and it seems to move, but in fact there isn’t enough travel to move the tranny into a higher gear. This used to happen to me on an older shifter (usually mid race, of course) when the engine mount would slip back a bit and the shift rod started hitting a seat strut and couldn’t move far enough anymore. This only happens on upshifts because that moves the lever on the engine back toward the rear of the kart; there was plenty of room to pull if forward and downshift.
June 14, 2016 at 5:31 pm #67233
Jim, first off thanks for the reply. Secondly, would it be possible that I’m only shifting into 3rd and THEN it doesnt upshift? just curious cause the first shifts are clear as day. I apologize for not making that clear in the first post but that is what i notice. BTW, today i took out the clutch to inspect and its as good as the new one i bought just in case. Definitely not the issue there. After I read your reply I realized that before I even drove the kart, I took off the shift lever completely because it was sloppy and had some play where it attaches by the steering. I fixed that but ow thinking about it, there is more than one hole to put the rod back to connect the linkage. That alone could very easily make a difference in how far the rod is actually moving. If the weather holds up, I will test your theory tomorrow. I’m anxious as it makes sense and I can relate it to what I’m experiencing. Thanks for the heads up. I’ll keep you posted.
June 15, 2016 at 1:39 pm #67292Jim DerrigParticipant
It’s been awhile since I ran shifter, but IIRC the amount of travel required to upshift increases somewhat as you move up through the gears. I recall that when I had my problem the first 3-4 gears always were available and the problem was with 5-6.
Not surprising that the clutch itself is okay. Honda clutches last forever in this application since you only use them for a start.
October 12, 2016 at 9:20 am #72858Ben LewisParticipant
I’ve been running the ‘stock honda’ package for 3-4 years now and I’ve been karting for much longer, so I hope I can pass on some knowledge. One of the (only) downsides to this class is that there is a real lack of info say compared to a 206. Hope I can help.
Jim is right it sounds like the shift lever doesn’t have enough throw. Make sure that the J-arm which connects to the shift shaft on the motor is as close to 90 degrees to the ground as possible. If it is leaned forward too much it will bind. Also, one thing I’ve noticed with novice drivers is that they let off the gas waaaay too much when up shifting. It only takes a 2-300 rpm drop to up shift, which basically translates to the blink of an eye. I also notice that new drivers tend to bounce their throttle foot. There is a back-forward motion on the up shift and its very easy to hit the gas premature and miss the shift. This might explain the rev. Double throttle springs are a good and cheap buy. Another trick is to shift by ‘squeezing’ with your fingers while your thumb is still wrapped around the steering wheel. Not only is this quicker but less fatiguing. And yes the #1 cause of missed shifts is fatigue!
Down shifts should use NO gas until you are the master of late braking, and then it’s only a teeny bit and corner specific. Fyi in my opinion learning hard threshold braking is one of the most overlooked skills for new drivers. Any guess to where 8/10 passes happen?
The CTS chassis are good but they weren’t produced in large numbers. I believe they take Unico style body work. But look up the measurements online and compare to your chassis.
Also what carb are you running? If you have the stock PJ your will deff be running out of top end. PWM is the way to go in my opinion and they can be had for a little cheaper by searching for a mid 90’s Yz250 carb instead it was stock on that bike I believe and maybe a few others.
Other top end killers:
Fouled plugs should be new Br9eg or Br10eg
Electrical. Solder everything! Connectors are convenient but they fail.
Exhaust. Leaks and cracks will do weird things to the mixture and make it very hard to read.
Lastly Jetting!!!! This is one of the finer points and needs a lot of trial and error. Go slow and read your plugs.
What is your Fuel:Oil ratio? It should be 24:1
Hope that helps.
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