Engine RPM Help

[r_chez_08]

By the looks of things you bolt the engine to the jackshaft plate and motor mount plate with the same bolt. (4x bolts needed)

You only need one sprocket on the j/s.

You have the driver on engine transferring power to the driven on the jackshaft by a belt. You then mount a sprocket on your jackshaft which transferrs power to the axle sprocket by a chain.

 

[tramont]

Woah hang on there...
I run a 6:1 ratio with a 6.5hp clone and 19" wheels. Not an ideal ratio, but I managed donuts. Am I crazy? Actually that is highly debatable BTW I am still on belt no.1, no wear visible yet. These 40 series tc's can take abuse...

He has a 16hp powerhouse-I would suggest you still gear 5:1 to 6:1 like southkart suggested, afterall you are removing the governor, you want to allow your engine to rev up to make use of those higher rpm. with a 4:1 ratio you could theoretically get almost 70mph. With a 6:1 you are looking at 45mph @5k- Plenty in a kart IMO.

As for setting up the jackshaft- install the 40 series driven on there, and slide into the bearings using lock collars either side of the torqe converter and bearings.

im still not understanding unfortunately does my setup have to be like it is on this kart its the same as mine.http://www.youtube.com/watch?v=nVVFd-lIfGU
or like this torque converter setup http://www.youtube.com/watch?v=oro_yAgalD4

 

[tramont]

By the looks of things you bolt the engine to the jackshaft plate and motor mount plate with the same bolt. (4x bolts needed)

You only need one sprocket on the j/s.

You have the driver on engine transferring power to the driven on the jackshaft by a belt. You then mount a sprocket on your jackshaft which transferrs power to the axle sprocket by a chain.

will i have to drill a hole in the jack shaft plate because once you put the jackshaft plate over it you cant see any holes to connect the 2 together

 

[r_chez_08]

Have you got the engine and comet 40 yet? You may have tor drill your mounting plate and jackshaft for the larger engine mounting points.

Your jackshaft should be setup like the first vid.

 

[tramont]

no i plan on getting the engine and stuff next month

 

[r_chez_08]

Ok. You will probably understand better once you have it.
I reccomend you get a 10t #40 sprocket 3/4" I/d and a 54t #40 axle sprocket.

 

[Doc Sprocket]

4:1 are you crazy? No way even with a tc, if you want any bottom end or Non flat ground riding. Get a 5:1 AT LEAST, I THINK YOU NEED A 6:1 RATIO. With a 4:1 ratio you will be burning 40.00 belts in minutes. I know a 40 series is tough but thats asking way to much of it. (A 40 series is what you need for a tc)

While I would not suggest a ratio as high as 4:1 for this application, I wouldn't go so far as to suggest that he'd be burning up belts "in minutes". For the first year I ran my kart at 4:1. While it was lacking power, I find it important to note that in a total of four years running with my Comet 40, I only replaced the belt ONCE. And believe you me, I drove the everloving snot out of it. The ONLY reason the original belt cooked is that my niece ran the kart into a tree, panicked, and pinned the throttle. With the tires unable to move, and the throttle jammed at WOT, the belt burnt hard in one spot. A month or so later, the belt snapped at that spot.

That said, 4:1 is too high for the purpose. I regeared to 4.8:1 and picked up quite a bit of oomph, with room for more. 4.8:1 was as low as I could go without having to install a second jackshaft, or purchasing a very expensive, very large axle sprocket for my #50 chain components, so I settled on it.

For best performance, I do suggest something in the 5.5:1 to 6:1 range.

 

[tramont]

While I would not suggest a ratio as high as 4:1 for this application, I wouldn't go so far as to suggest that he'd be burning up belts "in minutes". For the first year I ran my kart at 4:1. While it was lacking power, I find it important to note that in a total of four years running with my Comet 40, I only replaced the belt ONCE. And believe you me, I drove the everloving snot out of it. The ONLY reason the original belt cooked is that my niece ran the kart into a tree, panicked, and pinned the throttle. With the tires unable to move, and the throttle jammed at WOT, the belt burnt hard in one spot. A month or so later, the belt snapped at that spot.

That said, 4:1 is too high for the purpose. I regeared to 4.8:1 and picked up quite a bit of oomph, with room for more. 4.8:1 was as low as I could go without having to install a second jackshaft, or purchasing a very expensive, very large axle sprocket for my #50 chain components, so I settled on it.

For best performance, I do suggest something in the 5.5:1 to 6:1 range.

how would i set up a 5:5:1 Ratio

 

[r_chez_08]

10t on the jackshaft, 55t on the axle. I would go with #40 chain.

I don't think 55t sprockets are very common, so just go with a 54t. They are $10 or something from bmikarts.com

 

[tramont]

10t on the jackshaft, 55t on the axle. I would go with #40 chain.

I don't think 55t sprockets are very common, so just go with a 54t. They are $10 or something from bmikarts.com

wouldnt that be like a 5:4:1 ratio i thought that wouldnt be good for my application

 

[tramont]

where can i just get a kit for everything i will need on the jackshaft very confused

 

[souperman000]

maybe something on this page you can use for reference?

http://www.bmikarts.com/shop/?shop=1&cat=272

 

[r_chez_08]

What diameter is your jackshaft, and does it have a slot running down it? I think comet 40's only work with a 3/4" diameter jackshaft
Here is a link for a #40 sprocket with 10t and 3/4" bore for the jackshaft.

You also require a comet 40 driven for the jackshaft- here. This one gives more torque/bottom ed than the standard driven.

For the axle you require a sprocket, here is a link to a 54t one. If you wanted more bottom end here is a 60t.
You also need a carrier. What diameter is your axle? You can get a carrier and 54t sprocket and save money, if you have a 1" or 1 1/4" axle here.

You then need a chain to connect the jackshaft and axle.
Hope that helps.

 

[r_chez_08]

wouldnt that be like a 5:4:1 ratio i thought that wouldnt be good for my application

Yeah that is 5.4:1 but thats only the slightest bit different. I run 6:1 with taller tyres and half the HP, you will be fine. 5.5:1 is like 1mph slower on top end!

If you want just go 6:1, you will probably still get 40mph, and tonnes of torque with a comet 40.

 

[tramont]

Im sorry to be a bother but im new to the kart world. And im trying my best to understand this one topic. Do I need to get thishttp://www.bmikarts.com/item/34-Keyed-Shaft-400134--1357 if i do what size to get because my original jackshaft is 16in. Also once i get it how would i like set it up like the one on the first video because me and him have the exact kart. when i say set it up i mean like lock collars and stuff because i cant find a video explaining how to do it all i see is kits with two sprockets

 

[r_chez_08]

Is your jackshaft still good? It so you don't need a new one. What diameter is it?

You need a method of stopping all of the components from moving. One way would be by just putting a lock collar either side of each component, but that could get quite expensive and OTT. you could just put one at either end of the jackshaft and push all of the components together so they do not move.

You need some 3/16" keystock too.

 

[tramont]

My jackshaft it looked like someone welded a nut on it i guess so it wont come out when you slide it in the hole other then that its good

 

[tramont]

well im officially getting a engine next month so ill post updates