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Old 06-08-2019, 12:26 AM
Mrmonk7663 Mrmonk7663 is offline
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Default 8 tooth (8t) jackshaft sprocket ok? Pictures inside

My 3203 has a 10t jackshaft sprocket. I want to replace it with an 8t sprocket. I ordered an 8t and it came in today. It has a built in keyway. The thickness of the material is much different. I am wondering if the lack of thickness is due to the smaller overall diameter or if is just how they made it. Any strength issues to be concerned about?

The width of the new sprocket is smaller too. To space it properly can I simply add a couple 5/8” washers between the sprocket and bearing on the jackshaft? The washers would be smaller than the outer race.

Not sure if I should run the 8t or get a 9t which I imagine would be beefier.

The sprocket is an Azusa. 2182-k

This is on a predator 212.

Pictures below.
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A9B9E9BE-E11A-46F9-B890-B2665E324F42.jpg   5A2643D0-000C-43B2-883C-32B180EB6F47.jpg  


Last edited by Mrmonk7663; 06-08-2019 at 12:42 AM. Reason: Part number added
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Old 06-08-2019, 07:58 AM
mckutzy mckutzy is online now
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That is how its made... it cant be thicker due to the geometry... They are inherently weaker that the typical next size up... like you have there...
You can use washers to space it correctly..
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Old 06-08-2019, 08:03 AM
Mrmonk7663 Mrmonk7663 is offline
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Ok great. That is what I was thinking but wanted some confirmation. I appreciate it.
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Old 06-08-2019, 08:27 AM
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anickode anickode is offline
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You might find that regular 5/8" washers are sloppy around the shaft, as the punched holes in washers are usually about 1/16" larger than the bolt they are meant to be used on. A 9/16" washer may be a better fit, or you can use what's referred to as a "machine spacer" or "machine bushing", which are basically just washers available in different thicknesses, with precisely sized holes. They are available at most hardware stores.

And yes, the 8t sprockets are weaker and prone to cracking between the teeth, though I think the risk would be minimal on a 212.
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Old 06-08-2019, 08:32 AM
Mrmonk7663 Mrmonk7663 is offline
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Yes. I use machine bushings and thrust bearings because of the slip. My local ACE carries them thankfully. Good looking out. I finished drilling/tapping the low oil sensor and govenor arm hole last night. Almost finished!!
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Old 06-08-2019, 11:39 AM
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The difference between an 8 and a 10 is huge when it comes to overall gearing. An 8 on a heavier kart and a 212 might make it slower and less responsive.
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Old 06-08-2019, 11:51 AM
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anickode anickode is offline
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Quote:
Originally Posted by Guapo613 View Post
The difference between an 8 and a 10 is huge when it comes to overall gearing. An 8 on a heavier kart and a 212 might make it slower and less responsive.
An 8t on ANY kart will make it slower.

Less responsive? Not a chance. Putting it into a lower gear will give it better acceleration and QUICKER throttle response.

Going from a 10t to an 8t driver is like going from a 60t to a 72t axle sprocket. 20% increase in gear ratio.
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Old 06-08-2019, 12:18 PM
Mrmonk7663 Mrmonk7663 is offline
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Most guys are running an 18” tire...I’m running a 20” tire. 8 will work fine. But I’m not sure if a 9 is better balance.

Stock on the 3203 was 20” tires
60t/10t

My engine is ungoverned so it should rev to 5k rpms or so before valves start to float.
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Old 06-14-2019, 01:55 AM
Mrmonk7663 Mrmonk7663 is offline
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I decided to err on the safe side and got a 9 tooth sprocket. After comparing the 8,9,10 and calculating potential, Iím going to run the 9. I have a picture for reference in case anyone wants to see the thickness differences.
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