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herman pahls
12-18-2014, 12:38 AM
I built a mini sand car for my kids 30 years ago and now my grand kids are driving it ( the roll cage fits kids age 4-8 ).
It performs well with a Honda 50cc 2 stroke scooter engine driving 20x7-8 rear tires.
This engine comes with CVT drive, electric start and a built in brake system.
These engines run great in the original scooter application but if you replace the original air box with a simple K&N air filter (to accommodate installation packaging), it seems almost impossible with my skills to get it jetted correctly.

I am considering re powering with a Predator 212 engine with a Comet CVT drive to simplify the tuning issues.

Doe anyone have an idea how the 6.5 hp Predator will perform in comparison to the Honda 50 cc 2 stroke?
This mini buggy weighs around 120 pounds and the kids weigh 40-60 pounds.
I recently raced a friends 6.5 hp powered dirt kart and was impressed with the engine.

Thanks
Herman

K-fab
12-18-2014, 02:36 AM
The old Honda 50 makes 2.9 hp stock. You can bump that up to around 8 hp by going to the 88cc kits that are available.

I'd think that upping to the four stroke will be a good choice.

Xbird
12-18-2014, 09:55 AM
The predator's a good choice to go with. My daughter's (9 y.o.) is running a tecumseh 195 cc with comet 30 series. It's running small tires and tall gearing and can get over 30mph with me in it and still doesn't strain the belt launching. You can always throttle stop it with a long bolt, couple of nuts and a bracket if it's too much for them.

on the 50 cc tuning issue, if you made or used a tube between the air filter and carb, it might be too long. if you go over 6/8 inches with the 150s, they just can't be tuned in, i'd imagine with the 50 cc if you have a tube longer than 3 inches, you've got the same issue.

dunerocket
12-18-2014, 01:35 PM
I just replaced a tiller engine with the Predator 6.5 hp. I'm very happy with it. One thing to mention that could be hard for buggy implementation is the throttle. It is very stiff linkage and appears as though it is meant to be run at constant RPM.

herman pahls
12-25-2014, 05:28 AM
I appreciate your responses.
I now have a Predator engine but was disappointed to hear that some people have had issues with CVT's and have switched to simple go kart clutches.
Are the Comet clone CVT's inferior to the Comet's"?
I understand Comet is no more.
I got the Honda Aero 50cc running great with jetting changes so not sure what to do with the Predator engine.

darwinpayne2000
12-26-2014, 12:21 AM
Time to build another buggy. :) :)

If you have the 50cc running like you want then it's hard to say what to do with the new engine. Maybe hang on to it for the moment and see how the 50 cc engine performs long-term.

herman pahls
04-09-2015, 05:15 AM
I replaced a good running Honda 50cc Scooter engine with a Predator 212 with a GTC torque covertor in my 4 year old grandsons mini buggy.
The 212 out performs the 50cc 2 stroke night and day.
Only thing he misses is the electric start.
Thanks for the advice
Herman

Xbird
04-09-2015, 11:00 AM
with comet type setups, pulley alignment is critical, especially if you're running the asymmetrical belt. The driven sheave is NOT flat so aligning it to the driver can be tricky. same goes for making sure that you have the correct belt size for the driver/driven c-to-c distance. you also have to watch for wear on the bronze bushing on the driver, if that starts getting chatter wear, replace it.

herman pahls
04-13-2015, 04:22 AM
Hello Xbird
Sounds like you have Torque Convertor experience which I do not have.
I purchased the GTC TC because it takes care of the alignment and the Center to Center distance with a bolt on plate.
The GTC TC works great and it has the asymmetrical belt and the bronze bushing you refered to.
I want to increase the HP of this Predator 212 but was told by Protodie that the small TC's were not tolerating the additional HP when he modified the 212's for his kid's buggies.
So my question for you is how do I know which TC to use for higher HP?
Is there tech department that answers these questions at the current manufacturers of the Comet TC's?
Are there other brands of TC's to consider?
On my next build I want to consider a higher output engine in the 9-15 HP range.
Which engines to you suggest and what TC would you suggest?
Thanks
Herman

Xbird
04-13-2015, 10:40 AM
if you follow the original comet "standards", a 30-series setup is good up to about 8-9hp, and that's pushing it. You'll eat up belts faster and eventually start cracking the driven plates at the rivets near the center if you push to much power through them. For a modded 212, or a briggs animal type setup you want to get into a 40 series or start looking at cvt parts from sleds or polaris quads. Mechheads the real go-to guy here on running the larger industrial engines and modding them. For what you've got right now, all should be good.

herman pahls
04-15-2015, 01:39 AM
Thanks Xbird for the reply and advice .
I assume a TC/CVT uses up some power versus a simple centrifugal clutch.
Any idea if the power loss using a CVT is significant.
Any idea the HP limits for the 40 series Comets and where do you buy them?
Herman

Xbird
04-15-2015, 09:57 AM
Comet Torque Converters | Comet Clutches | Comet Belts (http://gokartsupply.com/comet.htm)

Has an excellent reference page for setup and maintenance as well.

for the performance range you get out of a cvt vs a centrifugal setup any additional power loss falls into the "well worth it" category for me. a centi is just going to slip until full hook and then it's all in. where you need the lower ratio range (hills, initial acceleration etc) that you get with a CVT is just slip, heat and wear losses with a centrifugal.

Calibuggy
06-21-2015, 03:31 PM
The power loss through a CVT is not as significant as a centrifugal clutch burning from a stand still. I modified a Predator 6.5 to run sideways (in a home built board track racer frame) in addition to some heavy port work and jetting changes and it would push that bike to well over 55mph with about 8hp after mods. Problem is; it used a centrifugal clutch and if it weren't for the pedals to help start it, the clutch probably wouldn't have lasted very long. I'd go CVT if you're still weighing pros and cons. http://i1083.photobucket.com/albums/j384/49dragster/IMG_0093_zpsv6uqfglo.jpg

herman pahls
08-04-2015, 09:42 PM
I now need better shocks for the rear.

The 6.5 HP Predator powered buggy with the GTC torque convertor is working well and plenty of power for the 5-9 years olds that fit in the mini sand car.
I am glad I did not try the centrifugal clutch to save some money since this buggy accelerates very well in the sand and has 30 mph top speed.
The problem now is that it needs better rear shocks.
I replaced the low cost coil overs with Monroe air shocks that can be individually filled.
This buggy probably only weighs 175 pounds and the Monroes on the rear seem to not rebound fast enough at the low air pressures needed to hold this buggy up.
So I am on the search for better shocks.
This buggy only needs 2.5-3 inch travel shocks.
Fox Air shocks come in a minimum shock travel of 4 inches.
AFCO shocks for 1/4 midget cars come in 2.5" travel and the springs are $25 each.
The Fox's seem over kill in size for this small buggy so I lean towards the AFCO shocks.
The main issue for me is figuring out the valveing and spring rates to order for off road use versus circle track that these shocks are marketed for.
Any ideas for the availability of small quality coil over shocks or experience with the AFCO 1/4 midget shocks?
Thanks
Herman

Xbird
08-05-2015, 10:58 AM
You might want to try a set of Fox snowmobile shocks, specifically those from a polaris 600.

Here's a link to a set for an example, i've found better ones for cheaper
97 1997 Polaris XLT XCR XC Carb 600 Snowmobile Shock Absorbers Shocks Springs | eBay (http://www.ebay.com/itm/97-1997-POLARIS-XLT-XCR-XC-CARB-600-SNOWMOBILE-SHOCK-ABSORBERS-SHOCKS-SPRINGS-/161198801860?hash=item25883283c4&vxp=mtr)

You can re shim them to get the compression and rebound dialed in. For your purposes, you'll just be removing shims to soften both aspects. Grab a $25. fox shock 300 psi air pump, no need to worry about nitrogen vs just air (too much mis-informed hoopla over that when it comes to recreational rides). The pink spring isn't too bad of a rate for a small buggy, a bit stiff, but you will likely need to revise the shock mounts for their length. If you set them in about half way between the axle and swingarm pivot, that will put the spring rate right about on the money.

I ran these early on in the rockhound and also tested them in my daughter's buggy before chopping up to make my damper tie rods with them.

CARLRIDDLE
08-05-2015, 01:05 PM
You should be able to pu some from a sport atv cheap that would work quit well.

herman pahls
08-06-2015, 02:00 PM
Thanks for the idea of sourcing coil overs from snow machines and quads.

herman pahls
09-13-2015, 10:13 PM
Regarding the Predator 212 engine.
My grandkids have been having a great time with the mini buggy that I re-powered with a Predator 212 engine for them a few months ago.
Recently it has been quitting for no reason especially in hard right hand turns and then it re-starts and runs great as if nothing was wrong.
I had then turn only left hand circles and it would not quit.
Do these engines have a low oil pressure kill switch that may favor one direction of oil sloshing in the crankcase?
I checked the oil and it came out of the filler tube but the engine is mounted leaning in that direction.
Thanks
Herman

Xbird
09-14-2015, 05:21 AM
if there's a low oil pressure switch, you'll have a couple extra wires in the kill switch circuit going to a sensor on the bottom of the block somewhere. might be a loose wire or wire rubbing through somewhere.

Wheels
09-14-2015, 06:10 AM
Regarding the Predator 212 engine.
My grandkids have been having a great time with the mini buggy that I re-powered with a Predator 212 engine for them a few months ago.
Recently it has been quitting for no reason especially in hard right hand turns and then it re-starts and runs great as if nothing was wrong.
I had then turn only left hand circles and it would not quit.
Do these engines have a low oil pressure kill switch that may favor one direction of oil sloshing in the crankcase?
I checked the oil and it came out of the filler tube but the engine is mounted leaning in that direction.
Thanks
Herman

I've read that they do have oil sensors... If you google it, you should come across directions on where/how to bypass. :)

poordad
09-14-2015, 07:34 AM
here is a video about taking the switch out of play.

https://youtu.be/KnKZ_Y5CaGE

herman pahls
09-14-2015, 11:55 PM
Thanks for the ideas and replies.
I googled my problem and found that several owners of the 212 predator engine either disconnect or removed the low oil switch to prevent the issues I have had.
One comment also mentioned the engine quitting in right hand turns.