**Pulleys for Jackshaft>??

[skiz]

*Clutch working but bike won't move.*

In another thread I mentioned putting a 5hp Briggs in a dirt bike frame. I added a jackshaft. It's all pulleys...no sprockets. Engine strains...won't rev all the way up....and the Hilliard Heavy Duty centrifugal clutch tries to work but the bike won't move forward....even without me on the seat.
Hilliard clutch is 4"....then goes to a 5" pulley on jackshaft....then next to that is a 3" pulley....then the belt goes back to a 12" pulley attached to the rear 18" wheel. Works great if the rear wheel is off the ground. I think the gear ratio is 8-1 now.
Things that I did that didn't work>>>adjusted carb for best rpm's...unhooked governor....loosened the belts.
Clutch has orange springs that engage at 1800 rpm's. Maybe I should get springs that engage clutch at higher rpm's to give the engine a chance to have more power???
I'm lost with this one.
Your info is certainly appreciated!!!

 

[mckutzy]

Your ratio is 5:1...
That might be a start...

Also I'd say the front belt looks a bit loose though

---------- Post added at 04:12 PM ---------- Previous post was at 04:03 PM ----------

After looking more into this, flipping that lower 3" around and using a 6" jackshaft-in pulley will bring it to a 6:1. Again, changing the 6" to an 8 will bring it to a 8:1.

 

[Poboy kartman]

In another thread I mentioned !!!

So WHY are you starting a new thread?????.Please read the forum rules.....

EDIT: #1: Answered in your other thread and you were told ahead of time about ratios.
#2: Please fill out a profile location....(takes about 1/2 as long as starting a worthless new thread).....

 

[ML-TOYS]

Your ratio is 5:1...
That might be a start...

Also I'd say the front belt looks a bit loose though

---------- Post added at 04:12 PM ---------- Previous post was at 04:03 PM ----------

After looking more into this, flipping that lower 3" around and using a 6" jackshaft-in pulley will bring it to a 6:1. Again, changing the 6" to an 8 will bring it to a 8:1.

Sure looks like its loose

 

[OzFab]

The simple answer is the power:weight ratio is off the charts; you've replaced an engine that makes ~50hp with an engine that makes 5hp & wonder why it doesn't work?

 

[skiz]

So WHY are you starting a new thread?????.Please read the forum rules.....

EDIT: #1: Answered in your other thread and you were told ahead of time about ratios.
#2: Please fill out a profile location....(takes about 1/2 as long as starting a worthless new thread).....

So this is a worthless post huh! Why the **** do you think people post questions??? It's because they don't know the answers and don't have the experience as you know it alls. I started a new thread because I changed pulley sizes and added a jackshaft. I don't know how to do the math for gear ratios. So why don't you explain the math. Pulley sizes are...4" 5" 3" 12".
Thank you.

---------- Post added at 10:49 AM ---------- Previous post was at 10:40 AM ----------

Sure looks like its loose

Front belt is loose...that's after the fact. I might not be able to squeeze in a 6" pulley where the 5" pulley sits. But are you saying to reverse the two pulleys on the jackshaft>>>put the 3" pulley on the outside-belted to the clutch?
Thank you!

 

[Poboy kartman]

My...my...my....Obviously, we are dealing with a failure to communicate here and maybe just a wee bit of arrogance?

It's not the post or question that's the problem, but the fact that you should have posted that in your other THREAD!!!!!

Also, you obviously did not read the forum rules or you wouldn't be using foul language.....I suggest you peruse 'Posting and You', and please check your attitude and foul language at the door.....

 

[itsid]

You called for Math?

here we go:

first set of pulleys:

JS in / Clutch

5 / 4 = 1.25

(btw exactly like with sprocket teeth)

second set:
Axle (wheel in your case) / JS out

12 / 3 = 4

Overall ratio: first * second .... * last
1.25 * 4 = 5

your ratio: 5:1 (means per five rotations of the engine, you'll get one wheel rotation)

It's unimportant if it's diameters or sprocket tooth counts you enter, the relation will always be identical!

Now the bad part:
I take a bet that you do NOT have a 18" rear wheel..
you have a 18" rear RIM.. big difference! (likely in the realms of 6")

So a 24" rear wheel, with ~ 750 rpms... that's roughly 51mph..
and that's a NOPE I'm afraid.

'sid

 

[skiz]

I really appreciate your reply. You were doing good until the "overall ratio." This is where I can't get a grip on. How did you go from 1.25....4....and get 5:1??? Or should it be 5.25:1....so you always add the first and second ratios to get the final gear ratio??
Yeah....you're right about the rear wheel. So then I have to divide 3 into 24" tire diameter instead of dividing 3" into 12" pulley diameter?
I feel like a monkey tryin to screw a football with this ratio stuff.
Ok....if I put a 9" pulley in place of the 5" pulley...will the problem be solved. I'd have to refabricate the brackets because the 9" pulley will have to sit outside the frame over the foot peg.

 

[mckutzy]

With the 9"- 9:1
I'd change it to a 6" instead, and go from there. Try that...

 

[skiz]

I'm not trying to challenge your experience but now there is a 5" pulley and I can't imagine going to just a 6" pulley would make barely any difference. The bike won't even move with me not on it. I don't need speed on this bike....it needs torque to run on the inclines on my property.
Thanks.

 

[Poboy kartman]

You don't add the ratios, you multiply them....see how that makes 5:1?

 

[mckutzy]

Let me put it to you this way....
I have a car tire on my bike I built... A car spare tire...
It has a 24" outside diameter(measured with a tape, none the less). I now have a cent clutch and a 7:1 ratio... I had a 6:1... They both work fine with a similar motor....
My bike is probably about the extreme end of examples shown here, except one guy who built a cool looking bike out of a smaller dirt bike(I can't remember the member or the thread name), so I guess Id say it could most likely work somewhat or fine, with my suggested ratios...

The math has been explained and also a suggestion for your own thoughts of ratio formulation...

Take it or leave it......

 

[itsid]

I really appreciate your reply. You were doing good until the "overall ratio." This is where I can't get a grip on. How did you go from 1.25....4....and get 5:1??? Or should it be 5.25:1....so you always add the first and second ratios to get the final gear ratio??....

Overall ratio: first * second .... * last
1.25 * 4 = 5

your ratio: 5:1 (means per five rotations of the engine, you'll get one wheel rotation)

Okay, in words:
first <times> second ... <times> last

1.25 times 4 is 5

You don't add the ratios, you multiply them....see how that makes 5:1?

THAT!

Yeah....you're right about the rear wheel. So then I have to divide 3 into 24" tire diameter instead of dividing 3" into 12" pulley diameter?
I feel like a monkey tryin to screw a football with this ratio stuff.
Ok....if I put a 9" pulley in place of the 5" pulley...will the problem be solved. I'd have to refabricate the brackets because the 9" pulley will have to sit outside the frame over the foot peg.

No no, forget about the wheel when figuring out the ratio!
it's strictly GEAR ratio.. gearing is either cogs, sprockets or pulleys..
The wheelsize and overall vehicle weight is only a hint for what gear ratio you'll need.
It's not part of the calculation.

And this is easy (really.. very basic math!)
simple division...
the pulley (sprocket or cog) closer to the engine is the divisor of your fraction, the next in line the numerator
the larger the numerator (or the smaller the divisor) the bigger is the resulting number...
(uhh big words.. sorry...)
example:
Clutch Pulley 4"; Jackshaft in 5" (like yours)

divisor: 4; numerator: 5

Result: 1.25... up until here we're good I assume?!

Now, if you need a bigger number, you have two options:
1) increase the numerator
example Jackshaft in 6" , keep your clutch pulley at 3"
Result: 6/3 = 2 (was 1.25)

2) decrease the divisor
example clutch pulley 2", Jackshaft in remains to be 5"
Result: 5/2 = 2.5 (was 1.25)

see? "little" changes can have big effects!

And that's exactly what mckutzy tried to explain with suggesting a 6" pulley.

since you cannot change the clutch pulley (very likely you can't)
6/3 means as we know by now.. 2
and with the last part of your transmission (12/3 = 4)

you would end up with 2*4 = 8
an 8:1 overall gear ratio
very different from the 5:1 you currently have...

BIG difference

'sid

 

[OzFab]

So this is a worthless post huh!

Show me where anyone said there was a "worthless post"

Why the **** do you think people post questions??? It's because they don't know the answers and don't have the experience as you know it alls.

"Know it alls"? Really? How much help do you think you'll get with that attitude?

You admit to not knowing the answers but, you've challenged every answer given...

As stated, please read the forum rules

I started a new thread because I changed pulley sizes and added a jackshaft.

Irrelevant, it's still the same subject; again, read the forum rules...

I don't know how to do the math for gear ratios. So why don't you explain the math.

...& yet you still challenge our findings? (see posts #29 & #31)

Now, you've already broken three rules that I can see, can you give me one good reason why I shouldn't ban you or do you intend to take the same attitude with me & give me a reason?

 

[landuse]

Show me where anyone said there was a "worthless post"



"Know it alls"? Really? How much help do you think you'll get with that attitude?

You admit to not knowing the answers but, you've challenged every answer given...

As stated, please read the forum rules



Irrelevant, it's still the same subject; again, read the forum rules...



...& yet you still challenge our findings? (see posts #29 & #31)

Now, you've already broken three rules that I can see, can you give me one good reason why I shouldn't ban you or do you intend to take the same attitude with me & give me a reason?

That /\/\

 

[skiz]

Guess what? Because of you guys...I have finally learned how to figure out gear ratios! Thank you!!! I really appreciate your time explaining it all.
But if I go from the 5" JS in pulley to a 6"....my gear ratio will be 6:1
That will still not get that bike moving. With the ratio I have now at 5:1 the bike wouldn't budge "with me NOT on the bike", so I'm looking for a 9" pulley and that will put me at 9:1 and hopefully that should get er goin on rough terrain and hills.
Hopefully I can get this done in a week. I'll post the results.
Thank you !!!!

 

[itsid]

Guess what? Because of you guys...I have finally learned how to figure out gear ratios! Thank you!!! I really appreciate your time explaining it all.
But if I go from the 5" JS in pulley to a 6"....my gear ratio will be 6:1
That will still not get that bike moving. With the ratio I have now at 5:1 the bike wouldn't budge "with me NOT on the bike", so I'm looking for a 9" pulley and that will put me at 9:1 and hopefully that should get er goin on rough terrain and hills.
Hopefully I can get this done in a week. I'll post the results.
Thank you !!!!

Well it's fair to say: No.. you still haven't figured it out yet!!

I'm a bad educator, I always was... but I think the main issue we're having is that you somehow can't wrap your head around this to be simple division and multiplication.
You still keep adding numbers for some reason.....
I don't know why

(talking jackshaft in)
a 6" pulley will get you to 8:1
a 9" pulley to 12:1

And now, excuse me, but I'm out...

'sid

 

[skiz]

You're using 3" for the clutch size but it's 4".

 

[mckutzy]

I hate to say but I concure.
I guess in the melee, things got confusing... Reading back his clutch is 4".