story of 2 year yard kart build, with questions

[PaulK]

A couple years ago my kids flipped their go kart. I'd bought a few upgrade parts and took the opportunity to "slap them on". I'm really not a very mechanically skilled guy so one thing led to another. It took me two years, but we finally got it going.

General Specs:
Non Hemi Predator 212, billet connecting rod and flywheel, slightly upgraded piston, I think 22lb valve springs, removed governor, Black Mamba Jr cam, and a Mikuni carb.

It's been insane how many things I've learned the hard way. I think I've made every mistake.

I have an Inferno Flurry racing clutch I hoped to use but I couldn't quite get the chain on. I REALLY wanted to get it going though, so I put the Comet 30 torque converter on, at least temporarily.

It runs a bit rough. I guess I'll need to adjust the carburetor. It also looked like gas was streaming out from the bottom of the carb. Not sure what's going on there. I may bypass the fuel pump to see if that helps.

It didn't feel to me as though it was really hooking up well. I suspect it just has too much torque/power for the Comet.

It sounds like a Harley, and the kids were loving life for a while. Had a hard time starting it at some point. Dawned on me later it was probably flooded.

Aside from the carburetor / fuel flow issue, my main questions relate to getting the power to the wheels. The chain was either a millimeter too short or too long with an added link. I'm hoping a jackshaft sprocket with fewer teeth may be small enough diameter to get me that extra millimeter. I suppose another option would be a Comet 40 but I suspect any belt drive will just slip too much.

I'd love to hear input/thoughts from others about either the carb or the power transfer.

I almost gave up about 50 times but it's been a great project with kids. Proof that anyone can do it.

-Paul

 

[mckutzy]

What no pics.... ???/

 

[Dingocat]

can you not move your engine? And as Mckutzy says, pics please!

 

[PaulK]

Pics will need to wait until I get out there next. Sorry. I'll do my best to remember though.

The engine mount was custom made by a friend of a friend, and doesn't adjust.

 

[Hellion]

Sounds like a leaky carb. A seal and gasket set might be in order, or just uh, um. Well you said you make a lot of mistakes... Just stop it from leaking.

....The engine mount was custom made by a friend of a friend, and doesn't adjust.

Well it needs to adjust. Something needs to slide, just like on go karts, mini bikes and honest motorcycles to take up the ever growing chain slack.

I agree McKutzy. Needs pics. Pics tell the whole story and creates an instant recognition and understanding of all the detail that's involved and draws it all together, blah blah blah...

 

[PaulK]

Ok. Finally got some pics, and got it running enough to share a couple more stories and ask a couple questions.

It's pretty **** fast, and it's SO loud!
Very cool.
Sounds like a Harley, and you feel a bit like a test pilot when you sit behind the wheel. Taking your life into your hands a bit.

The main problem at this point seems to be the carburetor adjustments - I think.

It runs fine at full throttle.
It doesn't really like to idle, and it's hard to get it moving because you need to give it a little throttle to get it started but if you give it too much it revs really quickly and tends to slam "into gear", which stalls it. If you back off the throttle for a while, it can be a bit squirrelly. Sometimes it bogs down a bit.
When you stop, you see a stream of fuel from the bottom of the bowl. I’ve tried to close the screw but there’s no stopping the fuel. Sometimes it just drips.

The other problem is that one of the springs in the driver pulley broke and ended up stretching into a long metal whip.

 

[txluke]

Your carb was probably leaking due to float adjustment.

 

[txluke]

I think your belt might be too long. Measure from the center of the driver to the center of the driven.

 

[PaulK]

It's a Mikuni carb.
I've played with the pin adjustments, and at this point it's on the second notch. I'm pretty sure it's the second smallest amount of fuel possible, not the second most amount.
Then I played with the mixture screw on the side and got to run a bit happier, but it only runs with the choke on.

Then I swapped out the jets for those that came ("extra") with it from NRRacing. This made the idle speed lower, which was helpful, so I probably need to adjust the mixture screw again and maybe it'll idle.

I really can't figure out the fuel drip problem though. Seems like there's too much fuel going to the carb, but that the carb doesn't just dump it to the engine so it pools in the bowl and flows out that drip spout. I'm making that up, but it's all I can think of that might describe what's going on.

Maybe I need to bypass the fuel pump?

As for the Comet 30, I'm hoping that by getting the lighter weights and new springs that might avoid that happening again.

---------- Post added at 10:13 AM ---------- Previous post was at 10:09 AM ----------

belt length is a good thought. The engine mounting came loose (along with nearly every other bolt and most of the fillings in my teeth) so I probably moved it closer without realizing. I'll check.

 

[JTSpeedDemon]

The leaky carb is a common problem with Mikunis when they're hooked up to a pulse pump. It's just too much for the float valve to stop, so it overflows. I believe there's an upgrade kit out there, I'm sure someone can link it.
I see you have a gas tank mounted above the engine. You don't even need to have a fuel pump! Go ahead and hook the fuel line up directly to the carburetor!

Wait a second...... Is that engine WELDED to a plate???

 

[Flyinhillbilly]

Sounds like trash in the needle and seat to me. Pull the float bowl, remove the float pivot, remove the float and needle and rinse it out real good with carb cleaner. That could fix it, it has many times for me.
I also second the statement that there’s no need for a pump if it’s gravity fed

 

[PaulK]

Here’s the inside of the driver pulley

 

[PaulK]

2nd try

 

[landuse]

2nd try

Well there's your problem

 

[PaulK]

Wait a second...... Is that engine WELDED to a plate???

I'll try take some pics of the engine mount. It's the only piece that someone else did for me, so I can't really tell you much about it. I don't remember why he did what he did. Mostly I think the idea was to elevate it somewhat. I thought it was in a fixed position but this past weekend when everything got loosened up I realized that it is separate from the clutch mount / jackshaft, and I think somewhat adjustable.