series 30 vs series 40

[redflash]

I'm running a pred 212 with a series 30 tc. kart weighs 500 plus with rider. It boogies great on level ground, I tried to drive up my trailer ramp (about 45 degrees) about 5 foot long. tc smoked and ground the belt up pretty good from a dead stop. I have not yet tried this thing out on any hills , I currently testing performance limitations now. I have gone up slopes 0f 30 t0 45 degrees with a running start and done well.
Some articles suggest a 40 series tc based on the kart weight.....is this a solution ? One problem is that series 40 all have a 1 inch driver ...and a 212 has a 3/4 inch shaft.......I'm just kinda throwing stuff against the wall to see what you know for sure. Whatcha know fer sure

 

[Denny]

Yes that is a problem. What is your gear ratio and rear tire size? Yes a 40 series could help in this situation if it is set up correctly, due to the slightly lower ratio of a 7” driven. But if I’m not mistaken there is a 7” driven available for the 30 series also. But it is not going to work with a back plate. You would need to go to a jackshaft with either setup. Are you using a Genuine Comet Belt? Cheap Chineseum belts have poor grip.

 

[redflash]

Is there a spring change that will help with the tc, to enable more grunt...less speed ?

rear tires=20 inch
drive sprocket 10 teeth
axle sprocket 60 teeth

Really want to avoid changing axle sprocket as I'm running that mazda miata diff, and changing the sprocket is a ***** !

 

[Denny]

Don’t really know. There should be 3 holes in one of the sheeves of the secondary. You can tighten it up. Or you could drill a hole to move the end of the spring about a 1/4” to tighten it up. Go to Go Kart Supply website and look up 30 series parts. What you want to do is get the primary to engage sooner and secondary later. But I still don’t think that will fix the problem.

 

[redflash]

thanks, I'll call comet tomorrow. Let you know what they say, may help others

Da Flash

 

[Kartorbust]

You have room for a jackshaft? You kind of want deeper gearing for those tall tires. 16" is roughly the max for a 6:1 ratio. The 7" driven will give you about a 1:1 final drive ratio, where as the current 6" gives you a ~10% over drive ratio. You want to be about 7:1 of 8:1 with those tires.

 

[panchothedog]

you can run the 7" driven pulley with the plate without converting to a jack shaft system. I have that on one of my karts. What doesn't work is the stock belt guard. It is not big enough to go over the 7" . Obviously you have to go to a longer bet also. That helps a bit by lowering the ratio without sacrificing anything on the top end. If you want even more hole shot swap out the
10 tooth sprocket for a 9 tooth. That change will probably reduce top end speed unless your setup is struggling to achieve max target RPM because it doesn't produce enough power, in which case it will lighten the load on the engine and it could have the same speed, reaching a higher RPM.

 

[Denny]

All spot on advice. The gear ratio and tire size are all spot on. The thing that is killing you is the weight. The 9 tooth sprocket or even an 8 tooth would help getting torque to the wheels. But at the cost of top end which I’m assuming you don’t want to but may have to give up. Let us know what they say.

 

[ONE-EYE]

I scraped my entire jackshaft and went with a TC with a 6" driven instead of the 7". Also switched to the 9 tooth top and tighter belt. I don't even use the belt guard anymore because of the heat. This isn't necessarily right but I scoot uphill now. Sling so hard sideways I snapped my engine carriage lol. Get to fix all that next week. Good luck!

 

[madprofessor]

I'm also running a 212 with a 30 series on a kart that weighs over 500#, and that's without any rider onboard. Big mistake. Motor's hotrodded up, would make 15+hp., but can't do it because that's way up high in the rpm range. Not enough torque to increase top end to increase rpm to increase power to increase top end, etc., etc. logarithmic ad infinitum to reach that rpm. Not even with my current 9:1 gear ratio.
Top end's not much fun without the power to get there in the first place, and gear ratio is the cure if there even is a cure. I agree completely with Pancho that if increasing gear ratio would cost you top end on paper, but you're already struggling to get up to top end due to low power, then the higher gear ratio may still get you to your same current top end thanks to the power increase of the higher gear ratio.
Increasing gear ratio (currently 9:1 on 16" tires) on my kart didn't cost me any top end at all for that very reason. Even helped the top end a little. And made getting there a lot quicker and more fun.
Don't know about your situation, but the smartest move for me if finances permitted it would be to put my 212 on another kart that's much lighter, and to put a 420 with a 40 series TC on the current kart. That would actually be the best and final solution for anyone with that setup.

 

[redflash]

Thanks guys....takes a few posts to get to the meat of it.....1st step..... go to 18 x 9.550 x 8 tires......2nd step reduce drive gear to 9 tooth.
I'll let you know the results

Tanks
Da Flash

 

[Kartorbust]

I'd link you to an excellent gear ratio calculator that itsid (Alex) made a while back, but something must've happened because it's now saying Forbidden 403 error. But all you had to do was put the weight of the kart, tire size, engine HP, engine rpm, gear ratio, CVT type and it would tell you if you are good to go or if the belt/clutch will burn up, as well as give the theoretical top speed.

 

[redflash]

That is too cool.... we gotta find that brothers!

Da Flash

 

[redflash]

electric scooter parts....has a similar calculator

Da Flash

 

[panchothedog]

Hey Mad. I am not trying to hijack redflashes thread here but your remark about going to a 420 cc is the best thing you could do. I have followed your post for months and seen many fotos of your kart. While I am in absolute
AWE of your mechanical and building skills, you and I both know that what you have built is less of a go kart and more of a small Mack truck. I have built the
heck out of a couple of the 212 cc engines and it sounds like you have also.
I have also heard you comment somewhat disappointedly about the lack of performance from your VEHICLE. I think you're asking for more than 212 ccs and 30 series torque converter can deliver. It's like putting a built high RPM
small block Chevy making 550 hp in a 10 wheel flat bed truck. A motor with more cubic inches and more torque even if it has less hp is going to offer much better performance. While we're talking about the 420 cc engine did you see the new Red Beards Garage video where he tears down the new Predator
460 cc engine. He liked it so much and spoke so highly of it I thought he was going to start hugging it and give it a kiss right there on the work bench. Hope your finances allow you to do that. Your kart deserves more than 15 mph.

 

[madprofessor]

While we're talking about the 420 cc engine did you see the new Red Beards Garage video where he tears down the new Predator
460 cc engine.

No, but you can bet I will in a few minutes, or after I'm conscious again, losing it right now. Didn't even know about a 460, the money's what counts for me as a retired guy. I really believe what I said about the bigger displacement engine, and you see it too. This is just too much in-my-face truth to handle, I'm going to do it. I'll play with the factors on my steamroller for a while yet, but that overly hopped up monster is coming off and going on "BareBallz", the next kart after the current "SchizoBallz", which is the follow-up to the "DragonBallz" minibike.
Dang, y'all do inspire me.

A motor with more cubic inches and more torque even if it has less hp is going to offer much better performance.

You see that, redflash? At least one other person knows the truth of it, preplanning accounts for that kind of thing. Obviously my preplanning failed me, but I'm willing to adapt with the power tide before it rolls me up. If you have the wherewithal to graduate your build to something with more inherent torque from the outset (like a 420 or 460) then you'll be bunches happier. As I will doubtless be after I roll with the 420 tide too.
Yes, the lingo is real. I boogie-boarded a hurricane off of Jacksonville Beach, was blown North to South a quarter mile before waking up facedown in the sand. Just couldn't ever surf. Thumper dirtbikes need no wetsuits.

 

[Denny]

Mad, I told you all that stuff months ago. Remember, light vehicle=horse power rules the day. Heavy vehicles=torque rules the day.
Now folks back to our regularly scheduled program!

 

[redflash]

Yeah Guys ...I know hp rules ! but a pred 459 is $400 and a 40 series cvt is $150 +......I'm retired and have a hard time slipping $50 past my wife.
No idea how to slide $600 past her on a credit card. If you younger guys would vote to have social security doubled.....then I could fly like an eagle.
Gas here in California is nearing $6.00 a gallon.....and isn't likely to go down for years, as our brothers at chevron pack up their million dollar parachutes. So I'll go down to a 9 tooth driven gear and reduce my tires from 21 inch down to 18 inch, and try to stay married after 54 years at it. !

Da Flash

 

[madprofessor]

Mad, I told you all that stuff months ago.

Yeah, and I still truly appreciate it today. Back when we first discussed my major mistake with the horsepower/weight thing, it was already too late for me to change anything about it. Going to do it now though, find the 420 money some dang where, put that 212 stack of flaming demon jizz on the "BareBallz" kart chassis that'll likely only be 130#.
BTW: Redflash, congrats on 54 years with the same missus. Got 4 ex's myself and only 64 years old. Respect, sir. I wasn't up to the challenge myself, even with the 4 tries at it.

 

[Kartorbust]

Your gearing will be fine with those changes. Sometimes there's clearance sales on parts so keep an eye out of deals so it won't be as painful being on a fixed income. Also, don't go too aggressive with the tread on the tires, more aggressive will make it struggle a bit more plus the overall diameter will be a bit taller.