briggs & Stratton 3hp 80300 MODEL HELP.

What I made actually had two jack shafts as I really wanted a low gear ratio. I still would be going with 20:1, but I got an engine that has a stubby crankshaft and no clutch will fit on it. I sacrificed one of the jack shafts to put the clutch on, but am happy wit 12:1 ratio.

I started out with 8:1 ratio and it was burning up the clutch, so I went to fix the ratio. Only thing I can say for just going with no clutch and a belt drive, the is no clutch to burn. I did this though on a 24 inch frame as a teenager light weight and pushed to start. When stopping the motor had to stop too. There would be more carbon I hear on the head due to chugging from a slow start, but it worked.
 
MEASURE TWICE said:
What I made actually had two jack shafts as I really wanted a low gear ratio. I still would be going with 20:1, but I got an engine that has a stubby crankshaft and no clutch will fit on it. I sacrificed one of the jack shafts to put the clutch on, but am happy wit 12:1 ratio.

I started out with 8:1 ratio and it was burning up the clutch, so I went to fix the ratio. Only thing I can say for just going with no clutch and a belt drive, the is no clutch to burn. I did this though on a 24 inch frame as a teenager light weight and pushed to start. When stopping the motor had to stop too. There would be more carbon I hear on the head due to chugging from a slow start, but it worked.
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My crank shaft is a long odd ball it's nose pokes out so I had to add a rubber washer between my clutch and bolt plate..

Thinking of moving my clutch as well so I can do a angle and ratio jump with the clutch being in the same spot .


I'll draw a layout today got the house to my self.

Pretty sure it should curve left of a solid state pulley from the engine... then go up to the to the clutch, then right to drop down to rear wheel sheave.
 
curtisfox said:
Your clutch pulley is about 3" , so a 1.75 on motor and about 4 or 5" on jack shaft, then clutch to wheel.


Right now, your gear ratio is 4.69:1.

The member named Measure Twice used a minimum of 12:1 to 20:1.

What Curt offered on his jackshaft is:
(5"/1.75") X (15"/3.2") = 13.39:1,
or (4"/1.75") X (15"/3.2) = 10.71:1

I'd recommend a 2" engine pulley(with clutch) belted to a 5" jackshaft pulley.
Then a 2" pulley belted to the 15" sheave.

(5"/2") X (15"/2") = 18.75:1.

QUOTE = Curtisfox: Now before you go any further, go to the DIY section and READ some of the older post and learn! What you are doing is trial and ear, and could get costly before you are done. Learn for others, you have post all over in the forum trying to do short cuts. Hard to read them all at once, and help. ...............Curt
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Several readers have suggested to this OP to READ old posts and learn. What he's trying to do has been done many times.
This guy is trying to reinvent the wheel, at much cost of parts, labor and the readers' time.
If you read the beginning of this project, you'll read that the OP wanted to complete this build as cheaply as possible. Following other people's builds is a sureproof and cheaper way of building.
This guy is not wired to think like that. He wants it built cheap, but he wants to build it his way, which is TRIAL.....BY.....ERROR.

His way.

Instead of lowering his gear ratio as recommended by others, the OP is thinking of buying an expensive clutch or adjusting clutches.

Building this bike won't ever be "cheap".

As he mentioned previously, he likes his car to break down on the side of the road, so he can fix it. He has a sense of satisfaction of FIXING stuff that go wrong, even though it could've been avoided.

Totally reactive, not pro-active.

I'll stick around and watch this comedy of errors.
 
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5-7HEAVEN said:
Several readers have suggested to this OP to READ old posts and learn. What he's trying to do has been done many times.
This guy is trying to reinvent the wheel, at much cost of parts, labor and the readers' time.
If you read the beginning of this project, you'll read that the OP wanted to complete this build as cheaply as possible. Following other people's builds is a sureproof and cheaper way of building.
This guy is not wired to think like that. He wants it built cheap, but he wants to build it his way, which is TRIAL.....BY.....ERROR.

His way.

Instead of lowering his gear ratio as recommended by others, the OP is thinking of buying an expensive clutch or adjusting clutches.

Building this bike won't ever be "cheap".

As he mentioned previously, he likes his car to break down on the side of the road, so he can fix it. He has a sense of satisfaction of FIXING stuff that go wrong, even though it could've been avoided.

Totally reactive, not pro-active.

I'll stick around and watch this comedy of errors.
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Not freaked funny lol figuring how I can smash in a j shaft quickest option I know it will have to be mounted over the tensioner/idler probably weld a metal box under the gas tank which allows Jack shaft space.
 
curtisfox said:
Jack shaft is nothing but a shaft with a key way cut in it, and either sprockets or pulleys, and mounted with bearings.

Car alternator is a AC generator, takes about 18 hp at dead lock ( or full charge mode ) won't work.

Your clutch pulley is about 3" , so a 1.75 on motor and about 4 or 5" on jack shaft, then clutch to wheel.

Torque converter is in fact a jack shaft with variable pulley ratios, with belt or chain to rear wheels.

Would probably up the front chain ring sprocket so I can assist the motor instead of it assisting me. Get the gear ratio right and you won't need to assist.

The scooter cvt's are for the most junk, for the most part and meant for scooters, and short lived.

Now before you go any further, go to the DIY section and READ some of the older post and learn! What you are doing is trial and ear, and could get costly before you are done. Learn for others, you have post all over in the forum trying to do short cuts. Hard to read them all at once, and help. ...............Curt
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This rough draft hurts my eyes X.¤

If it a Jack shaft it all has to be adjustable.

I don't use tensioners more likely stoppers.
1508271029333352166066.jpg
 
You are one self centered egotistic person, You are driving all the good helpers away. I am 76 years old and have been doing this stuff sense i was 15, built my first motor bike at 16. With a 1 1/2 hp Briggs, it did 35 mph. For the last time, 1.75" on motor, 5" on jack shaft, clutch on jack shaft, belt to wheel.

You will need to cut slots for motor and jack shaft, ( lawn mower and garden equipment have done this for years ). So you can slid them to keep belts tight. Do a search for keyed jack shaft, they come in short lengths. You can get bearings from farm supply, along with pulleys.........Curt
 
curtisfox said:
You are one self centered egotistic person, You are driving all the good helpers away. I am 76 years old and have been doing this stuff sense i was 15, built my first motor bike at 16. With a 1 1/2 hp Briggs, it did 35 mph. For the last time, 1.75" on motor, 5" on jack shaft, clutch on jack shaft, belt to wheel.

You will need to cut slots for motor and jack shaft, ( lawn mower and garden equipment have done this for years ). So you can slid them to keep belts tight. Do a search for keyed jack shaft, they come in short lengths. You can get bearings from farm supply, along with pulleys.........Curt
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You have to remember that you're the one who decided to put the time in to help, even though he won't listen... so don't get mad over it. I gave up a while ago but DID try... see one of the older threads... that's where the 1.75 number came from
 
Not mad just stating the fact, LOL There is a lot that tried to help, and he just don't listen. He is forcing all away, including me.

He has a welder and could do a lot of good building, instead of building junk............Curt
 
curtisfox said:
Help some 24" would be even better.if you get a torque converter it would give you some reduction. Then change the sprocket to pulley, about 2" .....................Curt

https://www.amazon.com/TORQUE-CONVERTER-CLUTCH-COMET-218353A/dp/B00FQQ2CXG
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"Does it have to be a torque converter to work on 24 inch wheels?"

At this point I'd rather go for 24s I'm spending the same cause 24 is a rare size problem with this is I could just keep it as is and build a smaller 2 stroke bike til I'm able to dump some cash on a jack shaft system.

The major difference if beneficial for the bike is that I would not have to add a single pulley or extra belt but only change rim/tire size.

If I end up finding another smaller bike that doesn't have 24s due to lacking on wanting to pay for said specialized size or jackshaft.

I may pull a rabbit out my hat and craft a mini on a high top seat with high bars which would resemble a non foldable dahon.

2t chain drive as I live close by motorcycle shops.

It's a chance to fix a production mistake I appreciate your help, heck everyone's help.

I feel like the first Harley that was built.....

"Explode to ****."

As toward the older ladies and gents here, I know I'm annoying, cheap, and one crafty sob to the point my Co works keep trying to sell me a car....

I've been walking, riding buses, and catching rides for awhile but no doors doesn't bother me at all.

Just makes you more aware, cautious, and alive with what you build.
 
YOUR QUOTES: "It's a chance to fix a production mistake."
and

"I feel like the first Harley that was built....."

You are truly delusional.

There are no production mistakes on this forum.

Briggs or most engines were not produced to motivate bicycles.

As far as the first Harley ever built, don't kid yourself.
Briggs engines on bicycles have been done thousands of times.

Instead of learning from others, you start from scratch.....
just like the first Harley ever built.

I wish you could write and express yourself better.

You are hard to follow.
 
5-7HEAVEN said:
You are truly delusional.

Instead of learning from others, you start from scratch.....
just like the first Harley ever built.

I wish you could write and express yourself better.

You are hard to follow.
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Kinda like when a simple question is asked --- "What is the time?"

Then the 'expert' goes into a 'graduate thesis' on how to build an atomic clock with parts salvaged from an old washing machine, an old coffee grinder, then combined with JB Weld......and chopsticks.

Wait........it should've worked! How do I fix it with an egg crate and a salt shaker?? I'll tell you.......
 
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