I need advice on 79 cc Drift Drike Build.

[TRACKER007]

Im going to motorize a Razor Gravity Drift Trike for my Pastors 8 kids.They run from about 12 years of age and down and the church's parking lot might be 3/4 of an acre,so its gotta be a variable speed for now.Basically I'm going to fabricate a frame that bolts right up to the Razors down tube,the same way the original axle does,beefed up at the 2 mounting points.With 7 nephews Iv'e accumulated new and old Go Kart parts over the years.I will be using a 40 inch live axle with 5 inch wheels and disc brakes.I plan on using Harbor Frieghts 79 cc 4 cycle Predator engine.I dont know wether to use a Clutch or a CVT.Ive read where you can change when the Clutch engages and play with the gear ratio to slow it down.I dont know jack about CVT's and gear ratio's.I would like to buy the engine and drivetrain before I finish the drawing and start cutting steel.Any help you guy's could give me would be greatly appreciated.Thank You.

 

[OPmini]

I would put a 212 with a CVT on it I don't think you can even get a cvt that fits onto a 79cc engine, so if you HAD to use the 79cc engine just put a clutch with a jackshaft and chain tensioner.

 

[Karts of Kaos]

um or you could get one for a 212 and make a sleeve for the shaft, and an adapter plate, but that would take some machining.

 

[TRACKER007]

Thanks Guys,the bolt pattern on the 212's PTO side seems to be the same as the 79's side,and sleeves are cheap and available for all sizes;

XtremeAmazing 5/8" x 3/4" x 3" Inch Engine Pulley Crank Shaft Sleeve Adapter Pulley Bore Reducer Bushing Sheave & Key​

Amazon even offers a package; Sleeve,CVT and an extra belt.I cant use the 212 yet because these kids are different ages and sizes,but THEY ALL are "feeling the need for speed",and the church parking lot is not an open area.So i thought i would start with the 79 cc.The question remains,what would be the easiest set up to raise or lower speed(if possible).The CVT or a clutch with those spring "thingies" ...........laughin.Once again I appreciate any kind of help.

 

[OPmini]

The question remains,what would be the easiest set up to raise or lower speed(if possible).The CVT or a clutch with those spring "thingies"

Do you mean change your gear ratio to get a higher speed? if so; CVTs are Constant Velocity Transmissions so the gear ratio is constantly changing so you can't really control the speed from a gearing perspective that way, unless you want to start changing axel sprockets and driver sprockets. However, if you go with a clutch you will need to build a jackshaft to reduce the gearing ratio to at least 6:1 or you will burn clutches, so you could control the max speed with gearing that way, by changing out jackshaft sprockets. The CVT would be the easier way to go as it is a bolt-on setup and an even better way to control the max speed is to simply install a throttle stop that doesn't let the carburetor open more than you want it to. Although with a 79cc four-stroke I doubt you will be able to go very fast at all, so speed shouldn't be an issue.

 

[TRACKER007]

Do you mean change your gear ratio to get a higher speed? if so; CVTs are Constant Velocity Transmissions so the gear ratio is constantly changing so you can't really control the speed from a gearing perspective that way, unless you want to start changing axel sprockets and driver sprockets. However, if you go with a clutch you will need to build a jackshaft to reduce the gearing ratio to at least 6:1 or you will burn clutches, so you could control the max speed with gearing that way, by changing out jackshaft sprockets. The CVT would be the easier way to go as it is a bolt-on setup and an even better way to control the max speed is to simply install a throttle stop that doesn't let the carburetor open more than you want it to. Although with a 79cc four-stroke I doubt you will be able to go very fast at all, so speed shouldn't be an issue.

Thanks OPmini,I went with your suggestions.Pretty much mocked up a frame design with some scrap and I'm getting ready to cut and weld.I'm wondering if its safe to elevate the CVT's backplate to its highest position and to a lesser degree jacking the motor up an inch or more,like you see in the picture.Eventually the Trike will have a 212.I'm trying to keep the wheelbase and total length as short as possible and allowing for 6 inch wheels and a larger sprocket(80 tooth) for later.The Kids will be using the Trike in a 65' x 100' parking lot with an exit/side alley around 180' long.Space is tight.I will use either 6:1 or 5:1 starting out with the 79cc.I have those sprockets on hand now.Any advice would be welcome.Thank Y

 

[OPmini]

That looks like it should work. I would straight pipe that thing, make it sound fast lol.

 

[madprofessor]

Just to clarify, CVT is abbrev. for Constant Variable Transmission............. For independent axles etc., CV joints are Constant Velocity joints.
FYI: The CVT's have a standing start ratio approx. 3:1, and top out approx.1:1.1............You'd need that 3:1 for the 79cc to drift.
Looks like you didn't build in any slide adjustment on the motor mounting, needed for tensioning the chain in the beginning and/or after it possibly stretches out with use. That calls for an idler pulley you can slide or pivot or whatever to take up the slack.
Yes it's safe to mount CVT at angle you want. Also safe to mount motor with a little bit of front/back tilt to it, just use the higher of the 2 dipsticks when setting or checking the oil level. As with any new motor, use break-in oil.
Attaching pic of idler on my secondary chain that can't have any movement at either end of chain. Built a little oversize, but you'll get it.

 

[OPmini]

Just to clarify, CVT is abbrev. for Constant Variable Transmission............. For independent axles etc., CV joints are Constant Velocity joints.
FYI: The CVT's have a standing start ratio approx. 3:1, and top out approx.1:1.1............You'd need that 3:1 for the 79cc to drift.
Looks like you didn't build in any slide adjustment on the motor mounting, needed for tensioning the chain in the beginning and/or after it possibly stretches out with use. That calls for an idler pulley you can slide or pivot or whatever to take up the slack.
Yes it's safe to mount CVT at angle you want. Also safe to mount motor with a little bit of front/back tilt to it, just use the higher of the 2 dipsticks when setting or checking the oil level. As with any new motor, use break-in oil.
Attaching pic of idler on my secondary chain that can't have any movement at either end of chain. Built a little oversize, but you'll get it.

l wouldn't tilt your engine at all, as it could lead to frothing / oil starvation

 

[madprofessor]

Have given a lot of thought to that in the past. Decided if there were any frothing at all caused by the dipping of the rotating mechanism, it wouldn't be much if any worse than what happens already with the dipping of the rod's dipper arm into the oil.
Only talking about a few degrees of tilt, and I already run my oil levels at the spillout point from the dipstick hole, not by the markings on the dipstick itself. The extra amount of oil to get to spillout point if tilted would make up some fault also.

 

[TRACKER007]

Just to clarify, CVT is abbrev. for Constant Variable Transmission............. For independent axles etc., CV joints are Constant Velocity joints.
FYI: The CVT's have a standing start ratio approx. 3:1, and top out approx.1:1.1............You'd need that 3:1 for the 79cc to drift.
Looks like you didn't build in any slide adjustment on the motor mounting, needed for tensioning the chain in the beginning and/or after it possibly stretches out with use. That calls for an idler pulley you can slide or pivot or whatever to take up the slack.
Yes it's safe to mount CVT at angle you want. Also safe to mount motor with a little bit of front/back tilt to it, just use the higher of the 2 dipsticks when setting or checking the oil level. As with any new motor, use break-in oil.
Attaching pic of idler on my secondary chain that can't have any movement at either end of chain. Built a little oversize, but you'll get it.

Thank You.Beautiful Work.I'm planning on using a Go Kart Motor Plate,I got from A+A Manufacturing Chassis Components WWW.AA-MFG.COM. Its the smallest one I could find,I'm tight for space.3/16 Steel,5" x 8 11/16" with (4) 3/8" x 1.679" slots.I hope that will cover adjustment and stretch.I plan on teaching these kids Preventive Maintenance.Ive never worked with a CVT,I seem to remember Bonanza Mini-Bike's being first to use them.I moved on to Drag Racing,and ratio-wise i'm still frozen in 3:56 to 4:88 rear's and what ever 4 Speed Transmission we could find.I then went in the Army.So your information is greatly appreciated.I will probably break-in the 79cc with the CVT on for part of the time.I want to see it working,and then I will sit down with the literature and force this 70 year old mind to absorb and utilize it.What break-in oil do you recommend?.Once Again,I really appreciate your knowledgeable response.

 

[madprofessor]

I'm fairly OCD, so my oil choice is $11 per qt. stuff that has to be ordered in to my usual parts house, it's never sitting on the shelves. I swear by "Royal Purple Break-in Oil". Even stay with it for oil changes.
If tight space availability means chain adjustment doesn't get quite right for you with just a master link putting it together, you can get small packs of half-links on ebay cheap. It's just what it sounds like. Every time you "break" (open up) a chain to shorten it or something, 2 rollers have to come out to put a master link in to rejoin it. With a half-link you can remove just a single roller. Uses the tiniest shear pin I've ever seen to retain it, unlike the split clip of a master link. Should have said tiniest I've ever just barely been able to see.

 

[OPmini]

Ooh time to start an oil debate that goes nowhere!

I'm fairly OCD, so my oil choice is $11 per qt. stuff that has to be ordered in to my usual parts house, it's never sitting on the shelves. I swear by "Royal Purple Break-in Oil". Even stay with it for oil changes.
If tight space availability means chain adjustment doesn't get quite right for you with just a master link putting it together, you can get small packs of half-links on ebay cheap. It's just what it sounds like. Every time you "break" (open up) a chain to shorten it or something, 2 rollers have to come out to put a master link in to rejoin it. With a half-link you can remove just a single roller. Uses the tiniest shear pin I've ever seen to retain it, unlike the split clip of a master link. Should have said tiniest I've ever just barely been able to see.

oh no a royal purple fanatic For break-in just run conventional oil for the first two oil changes, then switch over to a full synthetic like Pennzoil platinum synthetic.

P.s Pennzoil is better LOL

 

[madprofessor]

OP, you do realize we're talking about breaking in new parts on a motor that has no kind of oil filtration at all, right?
Predator manual says to just throw a 1/2 qt. of 30w. in it and idle it a long time, then 1/2 throttle or something............. That's because they design those engines to have the tight new mating surfaces just clawed away at when new and tight so they'll break in all loose and free. Without the extra-high zinc content of a break-in oil or a break-in additive to oil, that's exactly what happens. I want exactly the opposite.
Hypothetical question: If a break-in oil is designed to prevent excessive wear of tight (brand new) metal-on-metal parts, what advantage would there be in letting even a high quality oil without any break-in formulation have a go at those tight parts?
NOTE: If anybody can tell me where to buy a magnetic oil drain plug for a Predator, I'll pay whatever the seller's asking for it.

 

[Denny]

I believe in break in oil for flat tappet cams. For roller cams it is not needed or recommended. Infact high zinc oil is not recommended for roller cams. We have had this debate before, it went nowhere.

 

[OPmini]

OP, you do realize we're talking about breaking in new parts on a motor that has no kind of oil filtration at all, right?
Predator manual says to just throw a 1/2 qt. of 30w. in it and idle it a long time, then 1/2 throttle or something............. That's because they design those engines to have the tight new mating surfaces just clawed away at when new and tight so they'll break in all loose and free. Without the extra-high zinc content of a break-in oil or a break-in additive to oil, that's exactly what happens. I want exactly the opposite.
Hypothetical question: If a break-in oil is designed to prevent excessive wear of tight (brand new) metal-on-metal parts, what advantage would there be in letting even a high quality oil without any break-in formulation have a go at those tight parts?
NOTE: If anybody can tell me where to buy a magnetic oil drain plug for a Predator, I'll pay whatever the seller's asking for it.

PREDATOR GENERATOR 2000 MAGNETIC DIPSTICK OIL DRAIN PLUG FITS #62523 | eBay

more lubrication on break-in and the rings won't mate to the hone, if you idle on break-in you will glaze the cylinder.

 

[chuckularone]

OP, you do realize we're talking about breaking in new parts on a motor that has no kind of oil filtration at all, right?
Predator manual says to just throw a 1/2 qt. of 30w. in it and idle it a long time, then 1/2 throttle or something............. That's because they design those engines to have the tight new mating surfaces just clawed away at when new and tight so they'll break in all loose and free. Without the extra-high zinc content of a break-in oil or a break-in additive to oil, that's exactly what happens. I want exactly the opposite.
Hypothetical question: If a break-in oil is designed to prevent excessive wear of tight (brand new) metal-on-metal parts, what advantage would there be in letting even a high quality oil without any break-in formulation have a go at those tight parts?
NOTE: If anybody can tell me where to buy a magnetic oil drain plug for a Predator, I'll pay whatever the seller's asking for it.

Amazon.com: Motoparty For Predator 3500 Inverter Generator Magnetic Oil Dip Stick Silver : Automotive

Buy Motoparty For Predator 3500 Inverter Generator Magnetic Oil Dip Stick Silver: Automotive - Amazon.com ✓ FREE DELIVERY possible on eligible purchases

smile.amazon.com

 

[madprofessor]

Thanks for the links..........ebay for a 79.7cc, amazon for a 212cc, but they look identical.
Still want a magnetic drain plug as opposed to dipstick, but either is better than none. Wouldn't hurt to have both.
See those, Tracker? Cool way to get an idea how much material you're tearing off at break-in.

 

[TRACKER007]

That looks like it should work. I would straight pipe that thing, make it sound fast lol.

OH I WILL,OP.The straight pipe will be on a "reward's basis",when the kids listen to instructions,the sound comes out.The Church's parking lot is in a densely residential neighborhood.I also wanted to Thank You for the thumbs up.