Predator 212 Stage 1 & Comet 30 Series TC "engine brake"

[sbagnato]

I recently had to build a new frame for my kart. While doing so, I added the Stage I Predator 212 performance kit (header, intake, drilled jet, 18lb springs). I also disassembled my Comet 30 series torque converter and adjusted the springs to the higher torque setting (from the default medium setting). Since getting the kart running again, I've noticed that when I let off wide open throttle, the engine rpms dropping almost acts like an engine brake, in that you can hear the engine sputter some and there is a noticeable "braking" of the kart, even though I am not touching the brake. Now, I don't think it is the engine actually causing this, but the torque converter. I am wondering if when letting off the throttle, the belt is staying engaged at higher rpm, thus literally slowing down the live axle as the engine rpm drops. Maybe that means "something" was not reassembled right? Although, don't know what it could be.

Any ideas (or does this even make sense)?

 

[madprofessor]

As far as I know, the anticipated loss from a CVT is about 15-20%, which it makes up for with torque. Also as far as I know, that also applies in the reverse, that the resistance inherent in belt drive self-adjusting sheaves units acts as a brake. I know all mine have.

 

[sbagnato]

Okay, that does make sense. It SEEMS like it's more than 20%, but again, I wasn't experiencing this before, so I may just be overly cautious since I didn't know if it was actually an issue. I know the torque converter is pretty straight forward. As long as I didn't leave anything off (I didn't), kind of hard to mess it up. Also confirmed the belt is installed the right way too.

 

[bob58o]

Clean and lubricate the driven unit as recommended by Comet. I know YouTube has some good videos. Make sure the springs are straight and the weight packs slide.

 

[OPmini]

yup, clean and reassemble, maybe try new springs. But dont worry engine braking on 4 strokes doesnt hurt em one bit!

 

[madprofessor]

Never hurts to clean TC's. But do you have any Dry Graphite Lubricant? Need to lube that TC while you're at it, but you must not get the spray on certain surfaces, and you must only use Dry Lubricant. Dry Graphite Lubricant seems to be the accepted norm for TC's. Here's a link to a video where he also uses some anti-sieze in the right place, and has a neat way to only get dry lube on the targeted surfaces. Lots about 40 series, but it'll be interesting for you anyway. How to Clean a Torque Converter, 40 Series - YouTube It'll translate well enough to a 30 series. He's a well known and respected gokart fella.