Brand new predator won't run

[intelon67]

Hey all,

I've got a brand new predator 212cc engine that I put into a bike frame that won't run. The modifications I've made include upgraded jets, a pod filter, and exhaust header. I made these mods before I first started the engine.

If I spray starting fluid right down the intake the engine will start, rev high and then immediately stall out. Even if I open the throttle it stays the same. It starts...revs high..dies. The throttle seems to have no effect on how the engine runs.

I've taken the carb apart and no passages looked blocked (Brand new jets), and no substance anywhere. Gas going from the tank to the carb is good and clean, (Brand new tank, and fresh gas) and if I take the carb off after trying to get it started there's fuel in the carb bowl so I'm guessing that means the gas is at least getting to the carb.

I also checked the spark plug and it looked fine, though it did appear to have a film of liquid over the electrode (Possibly starting fluid, or gas). Also I already disconnected the low oil sensor.

No idea what it could be at this point Any ideas?

 

[Budget GoKart]

Did you install the carb with the all the gaskets and everything right if you dont then it wont run. Also your idle screw might need adjustment or the jet might now be installed correctly

 

[Flyinhillbilly]

I’m betting on a cracked or chipped carb insulator. I fixed one in the pits last year for a fellow racer that was doing exactly the same thing.

 

[Brianator]

Id start by reconnecting the oil level sensor until you've sorted out the issue just in case. When I'm in doubt if fuel is reaching the cylinder I remove the spark plug, kill the ignition, hold a paper towel above the spark plug hole and pull the engine over a few times to see if gas soaks the towel. Sure you can look at and smell the plug but you wont get a good idea of how MUCH gas is making it there that way.

 

[mckutzy]

Let's see a pic of the carb setup you have..
What size jet did you use?

 

[Karts of Kaos]

you said it band new, does it run with the stock carb?

 

[jmaack]

did you put emulsion tube in correctly?

 

[Solomonster212]

How easily does it start?

Sounds like a large vacuum leak or it's flooding.

 

[pearl111]

You put oil in correct? Carb. gaskets on correctly? Could a bare wire be touching the motor block? Also like Flyinhillbilly said over tightnig the carb. could crack insulator.

 

[Flyinhillbilly]

You put oil in correct? Carb. gaskets on correctly? Could a bare wire be touching the motor block? Also like Flyinhillbilly said over tightnig the carb. could crack insulator.

Revving high with the butterfly closed screams vacuum leak to me. I had to get air to rev.

 

[intelon67]

Turns out all of you who suggested the carb gaskets were right! I took the carb back off and found the thick metal/rubber gasket oriented the wrong way blocking one of the ports. Thanks for all the help, really appreciate it!

 

[Budget GoKart]

Ah ha! I actually was right! I said the gasket was installed incorrectly!

 

[intelon67]

New problem however.... I got the bike together, chain connected etc etc. The bike runs and idles now no problem, but it dies almost immediately upon opening the throttle/under load. The bike will move very very slightly before it dies. Could it be the jet is too small/not enough gas?

 

[Texan]

Ah ha! I actually was right! I said the gasket was installed incorrectly!

Nope, it was the insulator

New problem however.... I got the bike together, chain connected etc etc. The bike runs and idles now no problem, but it dies almost immediately upon opening the throttle/under load. The bike will move very very slightly before it dies. Could it be the jet is too small/not enough gas?

What kind of clutch you using? Gearing?

 

[intelon67]

Nope, it was the insulator



What kind of clutch you using? Gearing?

CVT clutch, 10T front sprocket, 60T rear on a 17" wheel with dirt bike tires. Believe that's a 6:1 ratio, and I'm running 420 chain if that matters. Honestly I didn't even think of the gearing but that may very well be the case given the ratios

Edit: It also doesn't start without at least a small spray of starting fluid, once started it'll run but if it dies then I can't pull start it without more starting fluid.

 

[Bansil]

I would throw stock carb back personally. To get rid of 1 possible issue...heck new carb could be machined incomplete

---------- Post added at 06:56 PM ---------- Previous post was at 06:55 PM ----------

I would put stock carb on to eliminate 1 possible problem, he k new carb could be machined incomplete

 

[Solomonster212]

Sounds like it's not getting enough fuel... Won't start without starting fluid, and dies when trying to drive? Must be a lack of fuel.

 

[Brianator]

I had the same problem with my gx200 clone and a new carb (knock off carb from Amazon), I found 3 deficiencies with the carb that I corrected and it solved the issue:

First problem was that the fuel shutoff couldn't open all the way to due a poor casting, I filed it until it could fully open.

Second was also with the fuel shutoff, the slot that lets the fuel through didn't seem long enough but my dremel with a skinny bit made easy work of that and...

Third but not least was the "pry up and out" plastic pilot jet dooflicky under the idle screw.... it was installed cockeyed so the passage that goes through it was partially blocked off!

Before fixing those issues I couldn't run it with the choke open or it would die and even with the choke closed it didn't want to run under any sort of load. Since I've reinstalled and set it up I haven't had one single issue, this may or not help you but it could be something to look into, hope it helps! Brian

 

[intelon67]

Sounds like it's not getting enough fuel... Won't start without starting fluid, and dies when trying to drive? Must be a lack of fuel.

Yep exactly, that's what I was thinking as well but wasn't sure if it was carb related or the gearing was too wonky.

I would throw stock carb back personally. To get rid of 1 possible issue...heck new carb could be machined incomplete

---------- Post added at 06:56 PM ---------- Previous post was at 06:55 PM ----------

I would put stock carb on to eliminate 1 possible problem, he k new carb could be machined incomplete

Well it's the oem carb that the engine came with, just with aftermarket jets. Should I put the original jets back in and try and run it that way? The bike has a different exhaust now so not sure if that would make matters worse.

I had the same problem with my gx200 clone and a new carb (knock off carb from Amazon), I found 3 deficiencies with the carb that I corrected and it solved the issue:

First problem was that the fuel shutoff couldn't open all the way to due a poor casting, I filed it until it could fully open.

Second was also with the fuel shutoff, the slot that lets the fuel through didn't seem long enough but my dremel with a skinny bit made easy work of that and...

Third but not least was the "pry up and out" plastic pilot jet dooflicky under the idle screw.... it was installed cockeyed so the passage that goes through it was partially blocked off!

Before fixing those issues I couldn't run it with the choke open or it would die and even with the choke closed it didn't want to run under any sort of load. Since I've reinstalled and set it up I haven't had one single issue, this may or not help you but it could be something to look into, hope it helps! Brian

I'll definitely look into all of those things! I'll take the carb back off next week to dive back into it. I did notice that there's bubbles within my fuel hose (I'm running clear fuel line at the moment), would that also be a culprit for starving the carb?

As of now thankfully the bike can and does run with or without the choke open at idle, just not under any load

 

[Texan]

Can you post some pictures of this bike? You mentioned in your first post about a brand new gas tank, I assume you meant you are not using the stock tank but rather a remote mounted tank. Does this new gas tank have a breather?