what size rear sprocket/gear

oldfartfarmer

New Member
Jul 30, 2019
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Hi
Im on the 12 step program,
building in 12 steps, 2 forwards one backwards, so its a learning process

im building a cranbrook ive got a springer front, with a Husky front rim with a drum brake,
gonna get a new rear husky rim,

engine is a 2-stroke 80PK

I live in maine, and have slight hills where ill be traveling, not Mountains, not flatland
mostly to go to the store 2 miles away and cruse to my favorite fishing spots,
I weigh in at 220 pds

im NOT looking for speed, im 59 and im over my pocket rocket days,
i want to go slow and steady and safe,

so what sprocket (tooth-count) will give me the right oomph to get up some hills and maybe 25mph tops
or 20mph, im good with 20, or 15 fifteens good too

thanks
John
 
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indian22

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Dec 31, 2014
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John welcome to the forum. Quite a few mature members here.

Greg's advice fits your parameters. Have fun & stay safe.

Rick C.
 

Apache Bronco

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Jul 19, 2019
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In dirt bikes, if I remember right, one tooth down on the countershaft equals 4 teeth up on the rear sprocket. My kit came with a 44, if it is geared too high I will get a 41. Same as you, have hills but not concerned about speed.
 

indian22

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Dec 31, 2014
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Though I normally go with 44t (I'm 50 lbs. lighter) I've used a 48t on one 66cc 2 stroke for years & it really eliminates pedaling except for motor starts. 54 tooth is commonly used on the small 4 strokes. I tried one on a 66cc & it was really too low and the stock motor had to really scream to make 20 mph, but it really pulled from a dead stop...no pedaling on hills for either the 48t or 54t.

I would recommend eliminating the kit rag joint to mount the sprocket to the spokes and buy the appropriate size three bolt sprocket and hub adaptor for your bike. The rag joints tend to destroy spokes.

Rick C.
 

Greg58

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May 1, 2011
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John you can try the kit sprocket to see which way you need to go then do ask Rick suggested and get a adapter/sprocket combo the size you need. Sprocket size made a big difference in vibration on every one of my bikes, as little as 3 teeth down in size made it a lot better on the 66cc , not much on the 48's.
 
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indian22

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Dec 31, 2014
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Greg you're right on the vibes; some setups are really excessive on stock motors (unbalanced) and big sprockets can amplify the harmonics!

I have to watch myself on posts as it's so easy for me to spend another guys money on parts...almost painless, but I've bent spokes on good 12 gauge spoke Workman wheels using the rag joints and I really despise these joints! LOL (kinda')

Rick C.
 

javy mcdees

Active Member
Jul 30, 2018
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hills, 220lbs pk80 store, fishing, use a billet adapter on the rear hub for the sprocket so you can change replace sprockets and a 39/41 sprocket will keep the rpms up enough to battle hills but what makes more sense in making power for hills is a larger carb like a Mikuni 18mm or a Dellorto 19mm that air flow is what makes the power to fight head wind and hills, the gearing not as much. I live on flat land and head wind used to slow me down to pedaling speed using the smaller RT carbs the larger carbs keep me going 40mph with a 30 mph head wind.