Project Predator Advise

SAS289

Well-Known Member
#46
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I wasn't able to find anything bigger than a 60t for the 420 chain that I have. However, I did find this nice little calculator:

https://www.gokartsupply.com/mobile/sprocket.htm

I have a 12t sprocket and it seems I should be able to get higher speeds per the calculator by leaving the 60t in and replacing the 10t with the 12t. Would you be able to confirm that is correct?
Do not use a 12 tooth. You would be gearing in the opposite direction and would run out of engine sooner than you are now. You need a higher numerical ratio between the two sprockets. Ole was correct that you should go with a 72 tooth if you want higher RPM at top speed. The 12 tooth you have is probably for a 35 chain anyway. You have a 420 chain.

Those speed calculators are a nice reference but take a couple important things for granted like the load and available power at the given RPM.

Another option would be to get an 8 tooth to go with your 60 tooth. You would need to be careful with pulley alignment because the 8 tooth may be a different width than the 10 tooth you have. I just found this out when I got my 9 tooth which was wider than the 10 tooth that came with the TAV. I had to make a washer to make up the difference for pulley alignment. The 8 tooth may also have a built in key that may be smaller (3/16) than the keyway on your driven pulley shaft which could be 5mm. It would work but is not ideal if the shaft has a 5mm key.

Some people do not like the smaller sprockets like the 8 tooth because there is more friction due to the smaller turn around for the chain..
 
#47
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Do not use a 12 tooth. You would be gearing in the opposite direction and would run out of engine sooner than you are now. You need a higher numerical ratio between the two sprockets. Ole was correct that you should go with a 72 tooth if you want higher RPM at top speed. The 12 tooth you have is probably for a 35 chain anyway. You have a 420 chain.

Those speed calculators are a nice reference but take a couple important things for granted like the load and available power at the given RPM.

Another option would be to get an 8 tooth to go with your 60 tooth. You would need to be careful with pulley alignment because the 8 tooth may be a different width than the 10 tooth you have. I just found this out when I got my 9 tooth which was wider than the 10 tooth that came with the TAV. I had to make a washer to make up the difference for pulley alignment. The 8 tooth may also have a built in key that may be smaller (3/16) than the keyway on your driven pulley shaft which could be 5mm. It would work but is not ideal if the shaft has a 5mm key.

Some people do not like the smaller sprockets like the 8 tooth because there is more friction due to the smaller turn around for the chain..
Thank you for the info! I went and checked to see how many teeth the old sprocket had and it was 10 as well, so I guess I don't have a 12 after all. I will look into the 8 tooth, I think I seen one for the 420 chain. If I were to change out the sprockets would I be able to put a different chain on it or do I have to stay with the 420? I feel like there aren't many options in the direction I'm looking to go with the 420 and more on a 35 chain. I just don't know if that's something that is recommended to change.
 

SAS289

Well-Known Member
#48
No doubt there are more options with the 35 chain. The smaller 35 chains are strong enough to handle big power if you get a good one. I do not know any of the details of making that change on your bike. There is probably an adaptor plate that bolts to the wheel, then you bolt the 35 chain sprocket to that. And some of those 35 sprockets are split and you do not have to pull the axle out to change them. Pretty nice.
 
#49
No doubt there are more options with the 35 chain. The smaller 35 chains are strong enough to handle big power if you get a good one. I do not know any of the details of making that change on your bike. There is probably an adaptor plate that bolts to the wheel, then you bolt the 35 chain sprocket to that. And some of those 35 sprockets are split and you do not have to pull the axle out to change them. Pretty nice.
Yea, there's an adapter that you put in place and then attach the sprocket to that, looks like you can do the split sprocket as well. I'm going to look into maybe changing the chain then to something a little easier to find options for. I appreciate your input on this and clarifying that I could in fact change the chain out.
 
#50
I was just able to order the Juggernaut today, I'm super pumped can't wait to get that in the mail, I'm going to assume I will have it by the end of the week to the beginning of next week. I also ordered the yellow spring for the driven and should have that any day now. I'll keep you guys posted to the results!
 
#51
Got the Juggernaut in the mail today, I worked a little late so I just had the opportunity to go outside and put it on and wouldn't you know, I need a 3/16" keyway! AHHHHHHHHH!!!!!!!!!!!

Looks like I will have to go to the hardware store in the morning...

Also, there's no brass ring on this driver... Is that supposed to be like that?
 
#52
I got the Juggernaut on there today, 5600 RPMs! on a quick ride down the street and back. Engine is running so much better, everything sounds better and it's nice and smooth getting into the higher RPMs. I can't tell you what a great improvement that was! $135 well spent in my book!
 

SAS289

Well-Known Member
#53
I got the Juggernaut on there today, 5600 RPMs! on a quick ride down the street and back. Engine is running so much better, everything sounds better and it's nice and smooth getting into the higher RPMs. I can't tell you what a great improvement that was! $135 well spent in my book!
Nice. And you are still running the 10 and 60 tooth?
 
#54
Nice. And you are still running the 10 and 60 tooth?
Yea, still 10/60, I didnt even put the yellow spring in yet, I wanted to see what the Juggernaut was going to do first. But the spring is in the tool box and next on my list is sprockets and a new chain. I can't even tell you how much better it's running, I have no resistance on the engine now and it's so smooth.
 
#57
Looks like one of the driven unit's slider inserts is broken.
Yea, I'm missing a little chunk, I picked up 3 more of them when i purchased the new spring. I'll be replacing them here soon. My chain in this picture is a little too loose as well, I took care of that after the picture was taken too.
 
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65ShelbyClone

Well-Known Member
#58
The chain looks okay to me, but I'm used to motorcycles with rear suspension that need to have a lot of chain slack.

What I also noticed is that the driven unit's ramps aren't touching when it's stopped. The chipped one should be up against the outer ramp that's forward of it. I'm thinking that engagement might have caused them to smack together and break the insert.
 

SAS289

Well-Known Member
#59
Yea, still 10/60, I didnt even put the yellow spring in yet, I wanted to see what the Juggernaut was going to do first. But the spring is in the tool box and next on my list is sprockets and a new chain. I can't even tell you how much better it's running, I have no resistance on the engine now and it's so smooth.
Would be real interesting if you get higher than 5600 RPM with the yellow spring.

Looking at your sprocket...Are you sure that's a 60 tooth? Just by size alone looks like a 50 to me.
 
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#60
The chain looks okay to me, but I'm used to motorcycles with rear suspension that need to have a lot of chain slack.

What I also noticed is that the driven unit's ramps aren't touching when it's stopped. The chipped one should be up against the outer ramp that's forward of it. I'm thinking that engagement might have caused them to smack together and break the insert.
Yea, definitely right about the driven! I'll take care of it when I do the spring though! Good catch, I appreciate it!

As for the chain that was touching the frame at the bottom, it was definitely to loose. She's all good now though.
 
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