First project- Invader kart

[DannyT]

This is an old Invader that I picked up for $100. It has a 5hp tecumseh and a 5:1 gearing. It had a little frame damage to the bumper up front, but it doesn't seem to affect the steering at all. So far I've replaced the sprocket, sprocket hub, and chain, rebuilt the carb, replaced both back wheels and tires, ported the intake, milled the head 0.025", replaced the straight pipe with the stock muffler (I live in a suburban area), replaced the brake band, and given it a thorough, thorough cleaning. I've clocked it with a bike gps at 34.9 mph.

Any thoughts on what I should do next?

 

[DannyT]

forgot to mention, i got an identical spare engine and clutch included in the 100$, so I've got boatloads of spare parts to work with.

 

[rushking19]

Nice cart man good luck with that carburetor I heheard it's a pain in the ,it's easy to get dirt and have problems, but other than that it's a great go kart Wat's your plans for it?

 

[DannyT]

The carb wasnt too bad. Between the two engines and an old toro lawn mower that had the same model carb, i salvaged enough parts to make a pretty good carb.

Eventually I want to have enough output to gear it to hit 50 mph without it being unbearably slow off the line.

My friend down the street has one that's almost identical, so its a lot of fun to race around parking lots.

 

[landuse]

The carb wasnt too bad. Between the two engines and an old toro lawn mower that had the same model carb, i salvaged enough parts to make a pretty good carb.

Eventually I want to have enough output to gear it to hit 50 mph without it being unbearably slow off the line.

My friend down the street has one that's almost identical, so its a lot of fun to race around parking lots.

I think you are going to struggle to get it to 50mph. Cool kart though

 

[rushking19]

I think you are going to struggle to get it to 50mph. Cool kart though

True it might need a little more hp and gearing to get there

 

[firemanjim]

True it might need a little more hp and gearing to get there

And little more hp and a lot of gear work. You COULD do a 2 speed kart transmission.... BUT those parts will cost you around $350-400..... You'd be able to hit your 50mph goal with no further mods.
Speaking of mods.... To the OP..... With all the "mods" you did, like decking the head..... You took a step backwards by putting the stock exhaust back on..... Put the straight pipe back on it. Put a round muffler from a 8-10hp briggs engine or an RLV muffler..... Almost as quiet, but let's the power come alive.....

 

[CoroTheCat]

Well you could build your own 2 speed gearbox
http://www.thepixelpump.com/widdershins/how-to-2speed-transmission.php
I haven't build one myself, so I have no idea how well it work, but you could do something like that, and it should increase your top speed, without making it slow when accelerating.

EDIT: you could also use a torque converter.

 

[firemanjim]

Well you could build your own 2 speed gearbox
http://www.thepixelpump.com/widdershins/how-to-2speed-transmission.php
I haven't build one myself, so I have no idea how well it work, but you could do something like that, and it should increase your top speed, without making it slow when accelerating.

EDIT: you could also use a torque converter.

There is one that's much simpler, smaller, and more attractive than that monstrosity you linked to.....

 

[DannyT]

I know I don't have the power for it now. I'm hoping to eventually have enough power to put a small sprocket on the axle and not have incredibly terrible acceleration. I know it'll be slow off the line when the gear ratio is that small, i just don't want it to be UNBEARABLY slow.

 

[DannyT]

also, as for the straight pipe, it was homemade by the guy who owned the kart before me, and pretty terribly done. the pipe diameter where it hit the exhaust port is less than a quarter inch diameter. i'm fairly sure the stock muffler is a much better design.

 

[DannyT]

Seats

Any seat recommendations? Its for an old invader, mostly just for drifting around parking lot, so something that'll keep me in pretty well.

 

[landuse]

Any seat recommendations? Its for an old invader, mostly just for drifting around parking lot, so something that'll keep me in pretty well.

Please keep info relating to your build all in the one thread. You will get a lot more help that way

 

[CoroTheCat]

There is one that's much simpler, smaller, and more attractive than that monstrosity you linked to.....

well, didn't think about that. I have only seen a picture of that kind of gearing once, but it would probably work better.

 

[OzFab]

There is one that's much simpler, smaller, and more attractive than that monstrosity you linked to.....

I'd like to know how that works; any details, Jim?

 

[Mammoth]

Any seat recommendations? Its for an old invader, mostly just for drifting around parking lot, so something that'll keep me in pretty well.

It took me forever to find the original type of seat for my Invader, but I found it here http://www.goped.com/shop/sgq30_list.asp
Its the non folding type. You have to call them to place the order for that specific seat. I hope this saves you all the search time it took me.
I'm a big fan of the Invader fun karts. Had one when I was a kid, and I built another one now that I'm older, and there still a blast. Best drifting kart I've ever ridden.

 

[DannyT]

Next, I'm putting on a higher flow air filter and homemade header exhaust with a silencer. Is a carb rejet needed for this, or will it just yield more hp/torque gains? Would adjusting the main mixture on the carb work just as well?

 

[OzFab]

If it has an adjustment, most modern small carbs don't...

 

[DannyT]

So far I have the air filter and header on, but I need a decently quiet muffler that fits a 1" unthreaded header. any ideas?

 

[DannyT]

after a lot of cutting my hands, as well as finding out that JB weld IN NO WAY lives up to its claimed 550 fahrenheit heat resistance, my homemade exhaust is complete.