Need advice on driveline options

[gguuyy]

Hey guys, it's been awhile since I've been on here. My kart has been down due to a cracked frame at the motor mount. Frame bars were broke on front and back where it supports the motor plate. It broke once before on the opposite side but I took it and had it welded back. Instead of paying someone for a mediocre weld I just went and bought me a new welder!

I welded the cracked bars back up, ground the welds smooth and then took a larger diameter steel bar, split it down the middle, welded into place. I think that should fix those weak points. I'll probably put more support bracing on eventually.

Anyways, now that I can ride it without worrying that the motor is about to fall off at any second, i want to start upgrading my GX200. Im gonna put a high flow header, high flow air filter, remove the internal governor, and do some re-jetting.

So I need some advice on gear ratio, what sprocket sizes should I run? What about using a torque converter? Current setup: Driver- 10T and Driven- 55T and 11 inch tires.

The karts top speed can't be anymore than 15mph. The acceleration is good, it'll spin around on pavement. I want more top end. All advice is welcome. Sorry for the long post. Thanks

 

[justinlogue5_0]

So did I read that right? You have a 12T clutch and a 55T sprocket with the 11'' tires, and you only go about 15mph? With that set up you should be verily taking off but running 45mph on top end (once it gets going).

 

[gguuyy]

No sorry it's a 10 tooth clutch (fixed the typo), the ratio is 5.5:1 I believe. The top speed is like 16 mph if you use the speed calculator. Would a 12t clutch really make that much difference? I can't go with a larger driven unless I get more ground clearance. I read about a torque converter that has 2 speeds, is anyone running something like that? What is a common setup on race carts?

 

[justinlogue5_0]

I am running a 12T clutch and a 53T rear sprocket. Now keep in mind I have hopped up my Predator so take off is still fast and strong. I kept running out of parking lot but according to gps I was hitting 50mph but again my motor isn't stock. Now before I built my motor I was still running a 12T and a 60T sprocket and I weigh 188 lbs. It grunted a little getting going but not enough to smoke the clutch and once you got going it never stopped. Slid through the curves etc... According to gps at that time I was hitting between 32 and 35 mph (up hill V's down hill). Hope this helps.

Oh and those speed calculators get you close but are not exact.

 

[landuse]

A 12T with a 55T axle sprocket gives you a 4.5:1 ratio. that seems a bit steep to me.

 

[justinlogue5_0]

on a stock motor , I agree.

 

[gguuyy]

Thanks for the info. If I could get 35+ mph that would be awesome. I just ordered a high flow air filter,removed the governor,and made a custom header so hopefully that'll free up some power. I'm Still waiting on the filter so I haven't run it yet. I'll prob change the jet but I wanna see how it runs first and then I'll order new sprockets or a torque converter. I'll post some pics up soon and keep u guys updated.

 

[gguuyy]

Here's a pic of its guts! Got the governor out, now if my air filter would just arrive already!

 

[firemanjim]

Post a pic of the kart..... Something ain't right if you only get to 15-16mph..... With that ratio.......

 

[gguuyy]

It was stock at those speeds, i don't know how much faster it'll be with the mods. I'll put some pics up when I get outta work. There are some pics in my other threads, I'm still running the same gearing and clutch on 11 inch tires.

 

[BirdFanatic]

Cracking at the mount could be fixed with this
http://www.ebay.com/itm/Motor-Mount...pt=Race_Car_Parts&hash=item2c7c260f58&vxp=mtr

 

[gguuyy]

It's cracking at the bars right beside where the plate is welded on, not the mounting plate itself. I believe i have that issue solved tho with the extra bracing I welded on.

 

[gguuyy]

Here's a pic of the sprocket setup. 10t driver, 55t driven. And the pic is upside down again! Sorry but I can't figure out why it does that.

 

[gguuyy]

New homemade header installed. I'm gonna paint it with some high temp. paint soon as I get a chance to stop by the auto parts store and pick up a can.

 

[gguuyy]

I got it started today, something's not right with it. It doesn't want to start and then when it does it won't idle without dying. It wasn't revving smooth and some sparks came out the pipe. I changed the exhaust and removed the governor. Guess I'll tear it back down and see what I can figure out.

 

[firemanjim]

Are you SURE you lined up the timing dots?

 

[chancer]

Are you SURE you lined up the timing dots?

That is a good question. When I removed the govnr on my Briggs last month I accidently messed up mine. But I noticed before I put it together. and then got it right with help from the forum.

http://www.diygokarts.com/vb/showthread.php?t=28500

not sure if this will help cause it for a briggs but there you go.

 

[gguuyy]

Yea I made sure they were lined up, I pulled the valve cover off and it looks like one of the lash caps has came out so Im gonna pull the case cover off and see if it has made its way inside there

 

[gguuyy]

Ok guys I think I got it figured out, just had to adjust the idle. It was to low and was just flooding itself out. Now she's running good. Now I'll put the new high flow air filter on soon as it arrives and then I'll be back to figuring out the gearing. It seems to be running mid 20's now with the extra rpm and also the engine keeps stalling in turns which it never did before. Guess the oil sensor has to go too.

 

[OzFab]

When I punch those numbers into the speed calc, I get 21mph but, it's likely you're not getting that because the kart is over geared...

Having high gearing to increase top speed doesn't always work; if the engine can't work to its full potential (as in, if it doesn't hit the governor) it won't reach top speed; sometimes, lower gearing works for more than one reason...