cr80 shifter kart sprocket help

[jdmkid]

So i picked up a cr80 for a doner engine for my birel frame. Im new to this sprocket stuff so just bare with me here. Do i need a new sprocket for my engine? or just for the axle? and im looking to go fairly fast, but still have quick acceleration. im wanting to not lose my torque, but at the same time maximize my top speed. So what would i need? thanks

 

[OzFab]

There's one distinct difference between an industrial engine & a motorbike engine; the bike engine has gears so choosing a gear ratio is not as critical. Even with a really tall ratio (2:1 or 3:1... & I'm in no way suggesting you use those ratios) you're still gonna have buckets of torque.

If you use a sprocket similar to that which was on the bike, your kart is gonna be scary fast so, find out what size sprocket was on the bike & get a bigger one

 

[Nodroz]

Also, be sure you get the correct size sprocket for the axle than your sprocket on the engine!

As far as I know, a sprocket on the axle should be around 40 - 50 teeth.

 

[anderkart]

Kid, what year is your CR-80?
How many teeth does its counter-sprocket have? (and is it a #420 pitch?)
Is your counter-sprocket wore out? (do the tooth edges feel sharp or smooth/rounded off)


What diamiter is your karts axle?
Are your rear tires 11" tall?


_________________

 

[jdmkid]

ill post up the answer to your questions Ander once im back from work

 

[anderkart]

Cool.

 

[Mike85]

HELP.....go kart screeches and runs away on me

Hi... New to the forum and love it... Just recently bought a go kart. It runs good and goes fast but I have one problem... It sometimes runs away on me and drives on its own. It also makes a screeching sound when it does that. Do I need a new clutch? Any suggestions on what to do and how to fix this problem?

Thanks

 

[Mike85]

Also how do I make a post???

Thanks

 

[Nodroz]

Also how do I make a post???

Thanks

Go to the Engines and Clutches board. At the left bottom you'll find a button to post a new thread.

 

[OzFab]

Go to the Engines and Clutches board. At the left bottom you'll find a button to post a new thread.

There's also one at the top of the page...

 

[jdmkid]

So the counter sprocket ( i guessed it was the sprocket on the engine?) had 15 teeth if i counted properly, and it was 420 pitched ( if this is what 420 pitch is: http://www.google.ca/imgres?um=1&hl...w=171&start=0&ndsp=32&ved=1t:429,r:5,s:0,i:86) and the year i think is a 1994 cr80.

 

[jdmkid]

oh and i think its a 30mm diameter axle, ill check tomorrow.

 

[anderkart]

Yes your right, the counter-sprocket is the engine sprocket, and honda CR-80's came with #420 pitch chain & sprockets. I'd just asked you to double check your counter-sprocket to make sure someone hasn't changed yours over to a larger pitch like #520 for instance.

But assuming your counter-sprocket is a 14 or 15 tooth, I'd suggest using an axle sprocket anywhere in the 28-35 tooth range. 28 would give you more top speed, 35 would give more low-end torqe/better acceleration.

If your your rear tires are around 11" tall and your engine is in good running condition, this gearing should result in your kart reaching top speeds somewhere in the 50-60mph range.

Chain pitch and axle diamiter dont effect gearing, I'd just asked those 2 question to try and help you find a shop to purchase the axle sprocket.

 

[jdmkid]

11 inches bottom to top? if so its not. they are shifter kart slicks.

 

[anderkart]

Most rear shifter racekart slicks are around 11" from bottom to top when inflated to 15lbs. How tall are yours?

 

[jdmkid]

So sprockets from this site would be good? and also do i need a #35 chain?

http://www.gokartgalaxy.com/shifter_kart_&_quarter_midget_sprockets_for_2.htm

 

[anderkart]

I'm really trying to help, but your not answering my questions very well and I'm getting a bit frustrated...

I'll try one more time here... :toetap05:

oh and i think its a 30mm diameter axle, ill check tomorrow.

You think? We need to know for sure.

11 inches bottom to top? if so its not. they are shifter kart slicks.

WTF? Yes, you'd simply measured the rear tires from the ground to the very top of the tire, with the tire fully inflated to 15lbs.

So the counter sprocket ( i guessed it was the sprocket on the engine?) had 15 teeth if i counted properly,

Again, your just guessing here...

______________


1 - First, I need you to accurately measure/post how many inches tall your back tires are???

2 - You also need to accurately measure/post the diamiter of your axle?

3 - You also need to compare your counter sprockets dimensions to the #420 pitch chart I posted above, and 100% confirm if its #420 or not?

4 - And also count/post how many teeth your engines sprocket (its called a counter sprocket) has for sure?

Only then... can we can check that gokart galaxy site to see if they stock the correct axle sprocket & hub, plus the chain size that will fit both sprockets. If they dont have it, I'll check some other on-line parts shops I know of and try to find high quality parts at a reasonable price

So If you would also post what part of the world you live in, I might be able to save $$$ on shipping cost's...

 

[jdmkid]

Sorry lol i havnt been getting too much sleep in between work and doing other things - so my heads a bit screwed up. Ill answer then properly and post it in a few minutes.

 

[anderkart]

No rush, take all the time you want. I was just grumpy today

 

[jdmkid]

Alrighty, so i got un-lazy and measured the stuff.

Back Wheels: 11 Inches Tall filled to 15lb
Axle: 40mm
Counter Sprocket: 15 Tooth


And as for the 420 pitch thing - i was having major struggles with the chart lol.

Oh and i live up North in Canadia (Canada lol). Heres a picture of the counter sprocket and the sprocket on the back wheel.