How to make 212/224 more tame for kids?

E

ebrammer252

Member
#1
#1
I have a doodlebug with a 212 on it, 12T clutch, 65T rear. I also have a motovox frame that I'm going to be putting a 224 in, I have a 12T clutch for it, and it currently has a 75T rear, will probably change that to a 65T as well.

I want to make these tame enough for my nieces and nephew to ride when they come to visit. They're ages 8-14 and have never ridden anything with a motor, but have experience on bicycles. Right now the Doodlebug with the 212 and 12T/65T runs great, but it's abrupt on throttle and will pick up the front wheel with my 220lb self on it. Even with the throttle stop screw set ALL the way in, the on/off throttle is still pretty abrupt.

Are there any good ways to make these more tame for kids? I was considering a much smaller rear sprocket, maybe a 12T/50T clutch/rear combo, but I know that's a low ratio and I understand that might toast a clutch quickly?

I've seen some people on FB mention adding a spring to the throttle, essentially adding more force to close it and they say it makes it more docile for kids to ride. Thoughts? Input?
 
ole4

ole4

#2
#2
There is a screw on the throttle mechanism to adjust the governed speed and you can adjust it to limit the RPM of the motor. It will still accelerate the same but will not go very fast and you can actually adjust it so low as to not engage the clutch. Do not lower it so much that the clutch does not completely engage or you will burn it up due to constant slipping.
 
E

ebrammer252

Member
#3
#3
ole4 said:
There is a screw on the throttle mechanism to adjust the governed speed and you can adjust it to limit the RPM of the motor. It will still accelerate the same but will not go very fast and you can actually adjust it so low as to not engage the clutch. Do not lower it so much that the clutch does not completely engage or you will burn it up due to constant slipping.
Click to expand...
Even with the throttle stop screw set ALL the way in, the on/off throttle is still pretty abrupt.
 
ole4

ole4

#4
#4
You are correct the way it works is the throttle just pulls a spring on the linkage that whacks open the throttle until the govenor arm pulls another spring to pull it back. The throttle stop works by limiting how much you can pull on the spring that opens the throttle, but until the govenor starts pulling back against it the gives a lot of throttle.
 
B

BrownStainRacing

Well-Known Member
#5
#5
Are those 14"- 14.5" tall tires???
If so, you can go to the 50t for the kids and not hurt the clutch.

75/12= 6.25
65/12 = 5.41
50/12 = 4.16

When the clutch engages (2200-2500) , you could easily be hitting that SMALL back tire with 35-40 ft/lbs tq. That's with the stock pred 212 and 4.16:1 gear. assuming around 8.5-9.5 ft/lbs from the engine. But you can see the weight to power ratio will be around 2:1 for a 80lb rider. 2.5:1 weight to power, would calm them down. But might still be a bit much for a 80lb rider.

The 224 box says it makes 10.23 ft/lbs tq outta the box, my butt dyno says it's closer to 11 then it is 10.

If you get a new 224, check all the bolts, including the rod bolts, and flywheel nut. Nothing was torqued to spec on the 3 I checked.
 
DaddyJohn

DaddyJohn

Well-Known Member
#6
#6
I don’t think there’s really a good way that’s practical for easily switching back and forth. It might be just as easy to swap a GX160 or GC160/190 on there for when the kids come by.
 
S

SAT

#9
#9
sparkwizard said:
I had to find another frame and put a 79cc Predator on it for the visitors. Rookies and Predator 212s are not a safe combination.
There are great suggestions here, but SAT has the best one, so far. Good luck and be safe.
Click to expand...
Unfortunately, I’ve misplaced the images.
Both are good runners.
 
E

ebrammer252

Member
#11
#11
BrownStainRacing said:
Are those 14"- 14.5" tall tires???
If so, you can go to the 50t for the kids and not hurt the clutch.

75/12= 6.25
65/12 = 5.41
50/12 = 4.16

When the clutch engages (2200-2500) , you could easily be hitting that SMALL back tire with 35-40 ft/lbs tq. That's with the stock pred 212 and 4.16:1 gear. assuming around 8.5-9.5 ft/lbs from the engine. But you can see the weight to power ratio will be around 2:1 for a 80lb rider. 2.5:1 weight to power, would calm them down. But might still be a bit much for a 80lb rider.

The 224 box says it makes 10.23 ft/lbs tq outta the box, my butt dyno says it's closer to 11 then it is 10.

If you get a new 224, check all the bolts, including the rod bolts, and flywheel nut. Nothing was torqued to spec on the 3 I checked.
Click to expand...
I thought they were 16? They're 145/70-6
 
E

ebrammer252

Member
#15
#15
BrownStainRacing said:
Are those 14"- 14.5" tall tires???
If so, you can go to the 50t for the kids and not hurt the clutch.

75/12= 6.25
65/12 = 5.41
50/12 = 4.16

When the clutch engages (2200-2500) , you could easily be hitting that SMALL back tire with 35-40 ft/lbs tq. That's with the stock pred 212 and 4.16:1 gear. assuming around 8.5-9.5 ft/lbs from the engine. But you can see the weight to power ratio will be around 2:1 for a 80lb rider. 2.5:1 weight to power, would calm them down. But might still be a bit much for a 80lb rider.

The 224 box says it makes 10.23 ft/lbs tq outta the box, my butt dyno says it's closer to 11 then it is 10.

If you get a new 224, check all the bolts, including the rod bolts, and flywheel nut. Nothing was torqued to spec on the 3 I checked.
Click to expand...
Any harm in doing a higher tooth count clutch as opposed to replacing rear sprockets?
 
B

BrownStainRacing

Well-Known Member
#16
#16
Yea that's another choice. I was gonna mention it earlier, but you already had sprockets. Some clutches you can buy jus the sprocket, some sprocket and drum combo. The El cheapo clutches you have to buy the whole clutch to get a specific sprocket teeth count.
I think they sell a sprocket adapter for that mini, that uses split sprockets for quicker gear changes and not remove the rear tire. But still gotta change the chain length.
 
B

BrownStainRacing

Well-Known Member
#17
#17
ebrammer252 said:
Even with the throttle stop screw set ALL the way in, the on/off throttle is still pretty abrupt.
Click to expand...
I jus realized something. You CAN control how far the throttle opens before the governor pushes it back Its ez, under the fuel tank you will see a arm and spring, move that spring to the holes going left, until you feel comfortable the kids can handle it. Then you can fine tune it with the throttle stop screw. Far right is more rpm, far left is less rpm.
Sorry bout that. Most people are looking for more rpm. Here's a pic.
20230326_154103_01.jpg
 
E

ebrammer252

Member
#18
#18
BrownStainRacing said:
I jus realized something. You CAN control how far the throttle opens before the governor pushes it back Its ez, under the fuel tank you will see a arm and spring, move that spring to the holes going left, until you feel comfortable the kids can handle it. Then you can fine tune it with the throttle stop screw. Far right is more rpm, far left is less rpm.
Sorry bout that. Most people are looking for more rpm. Here's a pic.
View attachment 300327
Click to expand...
Ah good to know! Thank you!
 
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