HS 142f sprocket size

runnermike

runnermike

Member
Hey guys

I was wondering what size rear sprocket do I need. 26" tires. I just want an all around good performance sprocket size. This will be my first 4 stroke build.
 
It all depends. Most of the kits have a 56T or more. But like me your in Florida and there's no big hills. I run a 5:1 gear box with a 10T output to a 45T rear sprocket and it does fine. I also get great gas mileage due to the engine only tops out at 30mph+ and I only cruise around 20 to 25 mph.
 
runnermike said:
oh sorry, my bad. 4g belt drive. 12t and 100t
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In that case I would run a 44t rear sprocket giving you an overall ratio of 18.33:1. This is pretty good gearing for this little engine as it does rev high, but don't expect much if you do run into a steep hill climb.

Have fun!
 
Ok guys. Thanks. I will have a little more info when I actually receive the kit. Like I said before, this is my first 4 stroke build, so gearing is a little new to me. I live in central florida and it is flat!

Motorbicycleracing.......is the AGK trans worth the money and is it a good setup? I saw on here where someone posted about it but no one had any real info on it yet......
 
I'm not exactly sure where to buy the engine from. Gasbike is the lowest price, but have heard not so good comments about dealing with them. I see that the AGK jackshaft is for a 5/8 keyed shaft..... Do you guys have any input on where to buy just the engine?
 
chainmaker said:
Do you have a link to that?
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The Jackshaft & Clutch Assembly is a new item.
http://www.affordablegokarts.com/mm5/merchant.mvc?Screen=CTGY&Category_Code=MTRBK49

49ccjackshaft.gif
 
runnermike said:
How does this setup compare to the rest? And what would be a good rear sprocket size running this setup?
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This jackshaft assembly is designed to transfer the power from a 49cc engine to the rear wheel of a motorized bicycle.

Fits Honda GXH50 and the HS 49cc (clone) engine with keyed 5/8" shaft.
Price includes complete jackshaft assembly,
10t clutch for #41 chain,
#35 chain for input side,
#35 master link,
10t engine sprocket,
33t input sprocket and mounting hardware.
You will need a chain guard and the #41 secondary chain.

We use a 56t wheel sprocket for an overall gear ratio of 18.480:1 which gives us a 31mph top speed.
 
I know this is a fairly new item, so....I guess a better question should be....as far as quality and maintenance, is this a superior product compared to the 4G belt drive, Q-matic, etc. Sorry for the ignorant questions. I'm just new to the world of 4 strokes and would like to cover all my basis before I buy is all.

Thanks
 
I got to see and handle the AGK trans at the last race but it was not on a running bike.
Looked like it is well made.

I think 35 chain is better than a V belt.

The trans uses the same made in the USA heavy duty Maxtorque clutch as the Q Matic and is a lot more affordable. :)

The AGK unit is rather long so may not work with a shift kit.
 
Ok...cool. Thanks for the info. I do not plan on running a shift kit so I do not think that will be an issue. I have never dealt with belts (other than on my vehicles) so I would probably feel better with the 35 chain.
 
According to AKG the Max Torque clutch engages at around 1800 rpm, which at 3:1 reduction means the engine would be spinning at 5400 rpm if my math is correct... that seems a little high. My understanding is that the HS engines shouldn't be revved over 6000 or so rpm which really doesn't give you much to work with. Am I missing something?
 
dovedescending said:
According to AKG the Max Torque clutch engages at around 1800 rpm, which at 3:1 reduction means the engine would be spinning at 5400 rpm if my math is correct... that seems a little high. My understanding is that the HS engines shouldn't be revved over 6000 or so rpm which really doesn't give you much to work with. Am I missing something?
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Yes I think you are missing something and I'm not really sure your math is correct. The thing you're missing is that the HS 49cc and the Honda GXH 50 are high revving little 4-strokes and will rev over 8,000rpm with ease and little worry.

The other thing is the gear reduction isn't 3:1.....it's an overall of 18:1 give or take. That's all ;)
 
dovedescending said:
According to AKG the Max Torque clutch engages at around 1800 rpm, which at 3:1 reduction means the engine would be spinning at 5400 rpm if my math is correct... that seems a little high. My understanding is that the HS engines shouldn't be revved over 6000 or so rpm which really doesn't give you much to work with.

Am I missing something?
Click to expand...
Yes.
EDIT. I GOT THE 3 TO 1 REDUCTION BACKWARDS. :(
The engine is engaging at about 2300 RPM when the clutch on the Jack shaft is engaging at about 800 rpm with the 3 to 1 ratio.

It is the same set up as a Q Matic with the heavier clutch shoes.

The motors can be revved to their 7800 redline with no problems and run for extended periods at ~7000 rpm.
 
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