Go kart project twin engine 18hp 21ft/lbs Duromax

[bob58o]

If you go 60T 420/40/41 on the axle
You can start at 6:1 with 10T on a 3/4" JS.
I'd really like a 7/8" JS for this? But not sure what sprockets are easy to find?
Not sure 3/4 is enough???

With 6:1, I think you'll have CRAZY torque.
2100 RPM launch is 9mph... Seems Go For Lauch?
3100 RPM cruise is 34mph... Seems reasonable for this beast. Cruise too slow and it may not be good for CCs or TCs, if I'm not mistaken. I like to use 3100RPM but this may be completely incorrect. Seems to work for this purpose (for 30 series in my head at least LOL)
3600 RPM (max gov) is 39mph.
4800 RPM (max? NO Gov) is 52mph.


Then you can go faster, with a 12T or 14T.
But this means you have to go even faster while just cruising around, or you may burn up belts?
Also more mph at Lauch, means might burn up belts?

Might be limited if you need to go for less speed and more torque. Not sure what teeth ct. (Under 10T) available in 3/4" or bigger bore?


Spend some time and think about the following

What JS size do I need?
What 40 series driven bore sizes are available?
What size? How many chains?
What size sprockets are available for my JS size and chain size?
What gear ratio range will I have to work with - with these choices?
What is launch MPH going to be?
What speed will I cruise at?

I'd run two 420 chains from the JS to two sprockets on the axle if I could gear it how I wanted.

I like 6 to start with???

Maybe I'm off with the 3100 RPM TC thing??? I think Sid said something similar??
Bad for driver unit and/or belt IIRC?

 

[Jackseale777]

Thanks for the input bob. As of right now I was planning on the TC's going to the 3/4 jackshaft with a single 12t sprocket going to a single sprocket on the axle. I was thinking 80 tooth for 6:1 and 40 tooth for 3.33:1 . I'll keep thinking tho. Main cruising speed will be between 30-50 I'm guessin, depending on pavement or dirt. Thanks for advice. The 40 series kits I'm looking at are 3/4" driven, with 40 chains

---------- Post added at 02:25 PM ---------- Previous post was at 02:23 PM ----------

I'm not sure how fast Rpms will be when I remove the governor, but I think I saw somewhere it's around 5400rpm, I'm not sure if that's correct

 

[bob58o]

1" Axle???

Did you locate 80T #40 sprocket?
$67
http://gokartsusa.com/heavydutyhubandsprocketsfor1axles.aspx

---------- Post added at 03:06 PM ---------- Previous post was at 02:55 PM ----------

If you go 3.33:1

And the TC engages around 2100 RPM

Then....

At engagement (with 2.45 advantage from TC) your ratio will be 8.16.

16.8 MPH.

Might be too fast. I don't really know. It may be hard on driver and belt trying to go from Zero to 16.8 MPH like that.
Somebody else may be able to shine some light for us here????????


And if not in "OverDrive" (1:1) until 3100....
(Again Just Kinda Guessing

Again shine the light if you got it!)

And "IF" cruising in "Low" gear is Bad...

You'd have to try to keep it around /above 60 MPH to keep it at 3100 RPMs.

I am just guessing here!!!!! Not sure if it really applies or not??????

This is JUST WHAT MY CONCERN WOULD BE IF IT WERE MY PROJECT.
I'm just trying to share my insane thought process which may be based off errors and lies. LOL

---------- Post added at 03:08 PM ---------- Previous post was at 03:06 PM ----------

I didn't really think the whole thing out when I said you might be able to get away with 2:1 or 3:1!

 

[Jackseale777]

Yes it's a 1" axle. Lol I'm confused and not knowledgeable about all this stuff since this is my first kart. So what ratio will I need for just say cruising around 35-50. And then I'd like a ratio to see this thing fly. Should I go with the 6:1, and then say something just a hair higher 4:1?

---------- Post added at 04:39 PM ---------- Previous post was at 04:37 PM ----------

Trial and error will always be the best teacher, and I guess I could just buy an 80t for the 6:1, then buy another one slightly lower say 60t. And if that works fine maybe 50t and so on. If that makes sense.

---------- Post added at 05:04 PM ---------- Previous post was at 04:39 PM ----------

What about exhaust and jets? I'm assuming a gx390 exhaust will fit? I haven't measured ID on exhaust. And I currently have a 100 jet and was thinking after air pods and open headers, I'd need somewhere between 102-105 jets? & do I need a new emulsion tube or will the stock one work?

 

[bob58o]

Like everyone said before, nobody has experience with this.

I said I liked 6:1 because the launch EDIT MPH won't be too high.
And I think you can get out of low gear and still be around 35 MPH.
This might work for everyday cruising and be OK on the belts / driven units.

I think the torque will be incredible, not sure if that will create problems by itself.


If you want to set it for racing (4:1), this may work too.
Just be warned that belts may not last as long.
Maybe Driver Unit Springs too.

With 22" wheels
And a Heavy Kart
With a Massive Twin Powerhouse
and 40 series TC's

I think a 4:1 - 6:1 is a decent range.
itsid would probably be of more help.
He (itsid) have a better understanding of this stuff.

Maybe he'd forgive me if I suggested PM'ing him.
He has a app he made for this type of stuff..

---------- Post added at 05:12 PM ---------- Previous post was at 05:07 PM ----------

Yes it's a 1" axle. Lol I'm confused and not knowledgeable about all this stuff since this is my first kart. So what ratio will I need for just say cruising around 35-50. And then I'd like a ratio to see this thing fly. Should I go with the 6:1, and then say something just a hair higher 4:1?

---------- Post added at 04:39 PM ---------- Previous post was at 04:37 PM ----------

Trial and error will always be the best teacher, and I guess I could just buy an 80t for the 6:1, then buy another one slightly lower say 60t. And if that works fine maybe 50t and so on. If that makes sense.

---------- Post added at 05:04 PM ---------- Previous post was at 04:39 PM ----------

What about exhaust and jets? I'm assuming a gx390 exhaust will fit? I haven't measured ID on exhaust. And I currently have a 100 jet and was thinking after air pods and open headers, I'd need somewhere between 102-105 jets? & do I need a new emulsion tube or will the stock one work?

Assume 5000 RPM max?
1.25" - 1.38" ID Exhaust tube perhaps?

I have a 390 carb and open header exhaust on my 212cc.
Main jet I am using is like 0.048"
(think that is like a 122 jet (1.22mm)).

 

[Jackseale777]

Okay I've definitely got some more thinking to do. With the sprocket setup, I'm definitely using 12t to 80t for my 6:1 with either #40 or #420 chain. Would it be easier to find another jackshaft sprocket with a higher number of teeth say 22-25t? Or just swap the axle sprocket to a higher ratio? My brain hurts haha

---------- Post added at 05:53 PM ---------- Previous post was at 05:41 PM ----------

Like I said I'm new to all this. How would I get a rough estimate of what jets I will need? I'm planning on I ungoverned, open headers, and air pods.

---------- Post added at 05:54 PM ---------- Previous post was at 05:53 PM ----------

Thanks for everyone's help on this build. I'll post a YouTube video closer to finishing it. and first test drive for sure.

 

[bob58o]

Compare prices for a axle sprocket vs prices for jackshaft spocket.
Changing a live axle sprocket may require disassembly of the entire axle.
Unless it is a split - two piece sprocket.

Swapping the JS sprocket means disassembling the Jackshaft.
I'd rather do the Jackshaft, I think?

 

[MrC.]

You could mix and match
use one long jackshaft use #35 chain from each engine to the long jackshaft and use #420 from the jackshaft to the axle.
Just a thought for extra gear options
Because some sizes or more common in specific chain size.
I like all my stuff to match, as in I cut up my belt driven system and replaced it with 420# chain just cause I think chain is stronger and now both chains and gears on that kart match.
MrC.

 

[Jackseale777]

I talked to itsid and he told me what I'm trying to do won't work. But I'm going for it anyway! I appreciate all the advice guys! Well he said going 100mph with industrial engines aren't possible with the gear ratios, but I guess I'll aim for a little less speed and more torque.

 

[Jackseale777]

What holds the Driven Pulley in place on the jackshaft?

 

[Jackseale777]

Is it a keyway or do I need to buy some key shaft collars?