Need Help Choosing New Sprocket

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Mister King

New Member
#1
#1
Just put a new clutch on my Honda CL100 with a HF 212cc Predator and by the time I got back home the clutch was smoking and bright red. I am assuming it is because the back sprocket is much too small. (I have been planning on buying a new back sprocket anyways because the one I have now has a hard time taking off but does very well at high speeds. Can reach over 50 MPH.) Would much prefer something that gets around very well and has a top speed of 35ish and much less strain on the clutch.

Here is a photo to see how the size of the wheel / clutch / sprocket compare.

Currently running a #40 with 43 teeth and don't know what I should buy.

Any input is MUCH appreciated.

Bike : http://i.imgur.com/e4riFtl.jpg
 
Stangrcr1

Stangrcr1

New Member
#3
#3
I would put a jackshaft on it. Either under engine plate or bolt on like the PMR kit. 15 in, 10 out.


On edit: After looking at the bike again, I would put a TAV on it. Way better bottom end and even more top end.
 
M

Mister King

New Member
#4
#4
I have just come to the conclusion I am just going to buy a new back sprocket that is larger than a 43 tooth. I was thinking something like 60 tooth? Any recommendations to sprocket size?
 
D

davidlamb78

Member
#6
#6
60 tooth may work, but I'm not sure how such a large back tire will affect it. I was told the same thing when I was planning on putting a 212 on a small Chinese four wheeler. I guess the large rear tire changes the gear ratio and makes it really hard on the clutch. As I was reading the original post I immediately thought about a jackshaft as Stranger mentioned. They're fairly cheap, and you can change the gear ratio easily. There are many gear ratio calculators on the web. I think most people like a ratio of 5 or 6 to 1, but don't hold me to that. I'm sure someone will chime in with advise on a good ration. With such a big tire, you may want to go more like a 72 tooth on the rear?
 
C

Camjamsdad

Active Member
#8
#8
I agree with his advice above. There are many ratio calculators available. Play with one that factors in tire size. You want to be in the 5 to 1 to 6 to 1 range for a happy clutch. They'll also give you a theoretical top speed.
 
M

Mister King

New Member
#10
#10
As for the jackshaft setup, I am a little more just looking to get a new back sprocket. Top speed I am not worried about. With this 43 tooth the top speed is slightly over 50 MPH but taking off is ridiculously slow with just me on it. This bike is going to be holding 2 people at most times pretty much so would much rather have it get around easy and be much easier on the clutch. I am thinking something like a 66 tooth. Clutch is a 10 tooth. I would go with the jackshaft setup but the only one I could find was about $100 and I could get a new back sprocket for about $40.
 
Motra

Motra

Active Member
#12
#12
With you current gearing (assuming your drive sprocket is 10 tooth) you're only getting 36.5 lbs. of drive wheel thrust. That's barely more than a stock Doodle Bug with the 2.8 HP engine that nobody seems to like.

6:1 gearing is only a little better at 51 lbs.

Because of the size of your rear wheel, you would need to be at about 8.5:1 reduction to get close to the same performance as 6:1 gives a minibike with a smaller wheel. That would be a 85 tooth sprocket.
 
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