Noob Help Please

[landuse]

OK, let me break this down for you. You have a 2.8:1 ratio at the moment. This is WAAAAAY to high. There are a number of things you can do to remedy this. You can get a larger axle sprocket to get a decent ratio. For tyres that size and a centrifugal clutch, you will need at least a 8:1 ratio, which means you will need a 112T sprocket. That is unrealistic

Another option is getting a 40 series TC (not a 30 or 20 series). You will still need to get a larger axle sprocket though, cos 2.8:1 is still too high with a TC. A 10T sprocket and 40T axle gives you 4:1. With 18" tyres this is still too high. You will have to go down to approx 13" tyres to make it work

Another option is to keep the centrifugal clutch as well as axle sprocket and tyres, but install a jackshaft to get compound gear reduction

I know this is all confusing, but IMO I would get a 40 series TC, and get tyres about 13" - 14" in diameter

 

[crazykart]

Ok, what he said then ^

 

[landuse]

Ok, what he said then ^

I just gave a few options.

 

[crazykart]

You sure he couldn't go to a 6:1 with a tc with those size tires and not be fine? I would think the tc would take most of the brunt of regearing both low and high end. Then again you would know better than I good sir.

Dong.

 

[landuse]

You sure he couldn't go to a 6:1 with a tc with those size tires and not be fine? I would think the tc would take most of the brunt of regearing both low and high end. Then again you would know better than I good sir.

Dong.

You can generally get away with higher gearing if you use a TC, but i still think that it is a little high. He could try it out and see if it works. If not, he will just have to get smaller tyres.

 

[jgreg07]

Yea TC it is. Dang I'm not seeing a 40 series for around $100. So i can't get away with this?

http://www.ebay.com/itm/GO-KART-TOR...087?pt=LH_DefaultDomain_0&hash=item2a4482c857

 

[crazykart]

No. With that hp engine you will burn up that tc very very quickly. I forgot you had a 420cc pred when I said 100. Bite the bullet, pay for a 40 series, even if you have to save up. It is well well worth it.

 

[landuse]

I remember kartfab saying you can get a 40 series for about $150. Maybe PM him asking where that was

 

[noiseguy]

There must have been a jackshaft assembly on that kart at one time... or perhaps it used a GY6 engine, which would have had a lower output RPM. Can you post a pic of the rest of it so we can see?

Are the rear tires oversized, or correct for the kart? If they're not oversized, I'd leave them alone and fix the root cause, which is the ratio issue.

Basically you need to get it down to a reasonable ratio, and if you can't change the axle sprocket (and I'm not sure you can't), you have to drop the input speed before you get there. That's either a jackshaft or a TC.

Since you have a larger engine, everything's going to be heavier, so you can't use the cheaper Comet 30 knockoffs.

 

[jgreg07]

Ok i pmd landuse. Thanks for the info. Ill take a pic tomorrow when i get home. Couldnt i just buy the 30 series kit mainly for the mounting plate and hardware then swap the clutch with a 40 series. Might be cheaper, or no?

 

[landuse]

Ok i pmd landuse. Thanks for the info. Ill take a pic tomorrow when i get home. Couldnt i just buy the 30 series kit mainly for the mounting plate and hardware then swap the clutch with a 40 series. Might be cheaper, or no?

No you cannot. The 40 series requires exaxt center to center distances between the driven and driver. The belt you buy is determined on this distance. The belts are not the same for 30 and 40 series TC's.