Hey everyone.
I’m finding that I’m getting chattering under acceleration with my R1 shifter engine.
It can be very difficult to deal with as it shakes your whole body, so very hard to stay in control.
Not sure if I’m in too low of a gear with the rpm’s to high when I start to get in the gas but I’d very much like to get rid of it.
Any suggestions would be greatly appreciated
Gonna be hard to diagnose behind a keyboard and not the wheel. It can be anything from bent axle, wheel, driveline, something out of balance, etc. Can you provide video?
Is it a chattering or a “bucking”
Chattering makes me think chain is slipping (tension too low) or bent axle.
I guess I’d call it bucking. Imagine someone putting their hands on your shoulders and shaking you back and forth fast. Kinda like a sip lash affect .
Only when I come out of a corner under acceleration . WOT in a straight, no problem
That’s a common thing believe it or not. Sometimes it’s carburation, but most likely it’s a lack of support for your feet and/or the throw on the pedal is too short.
Basically the initial throttle is too abrupt and unsettles the kart, with the bucking your foot moves off the throttle temporarily and it cycles.
Have a look at how the ergonomics are for your feet to have good control and you’ll find it gets better. Make sure you’re not cramped in there and that your knees are slightly bent at full throttle. Heel stops can help a lot too.
Hope this helps. Keep us posted.
+1 on this, feet/throttle control is crucial. Otherwise you are going to shake your brains out 
I agree with the above. Adding one or two springs to the pedal may help with this as it will offer some mechanical resistance, especially if it happens when cornering (coming out or in the middle). If it happens on the straight while you are banging through gears, there is definitely an issue, jetting does not make the whole kart shake in those conditions, so I’d look at fuel, electrical, axle, chain, etc. too much to list.
If you can, post a video
This discussion is actually interesting to me from a sim perspective. We had a build in KK where the shifter started acting odd, similar to what is described here.
Example:
Art imitates life, I guess.
Is it on full throttle acceleration or part throttle? I’ve had bucking or yipping at part throttle when the carburetor isn’t tuned properly and the only way to get it to stop was punch it.
It’s on corner exit, so part throttle. Once I get the steering wheel straight and punch it, it goes away
Not going to lie, I looked down at my right foot and it was bouncing back and forth in the throttle pedal. But I’m not sure if that’s because of the bucking or it’s causing the bucking
I have my gas pedal return springs extremely stiff to help stabilize it.
In a car, clutches can chatter. Could turning the steering be pulling on the clutch cable?
I’d guess you need to get your jetting a little better, especially on the needle and pilot. Once it starts going then your foot starts bouncing and exacerbates the issue. Putting stronger springs on the pedal can help with that aspect like others suggested.
The stiffer spring on the gas pedal will help but in my experience, this is mostly due to a rich carburetor setting. Most of it is main jet but leaner needle setting will correct this.
What is the best way to know which way to adjust the carb?
EGT sensor in Mychron?
Sound, spark plug colour ?
those methods are good to nail the top end side of the spectrum. If your issues are acceleration out of corner, you need to probably play with the idle screw and idle jet/atomizer and get there by feel. What are you running now?
EGT, spark plug, and sound are all used together to get the best idea of how it’s running. You can read the pipe also. If you are on the stand revving the kart, go full throttle for a couple seconds to clean it out. Then bring throttle back to idle-ish and raise to 1/4 or so and listen, then move to 1/2 and listen again, then full. I don’t worry too awful much if it’s a little jumpy sounding at 1/4 but I don’t want too much either. At 1/2 throttle I want it to clean up and not be jumpy, if it’s jumpy i’ll drop the needle or change a pilot. At full throttle it should run out fairly clean, if it falters or flattens out real bad then it’s too rich. Hopefully I’m explaining it well enough.
Explaining the art of carb tuning is quite difficult lol but ricky seems to have done a good job.
I’m no expert, but I get by decently. There’s so many ways to skin a cat with the dellorto.
Thanks for the carb tutorial. I have my first race tomorrow so I’ll see what happens.