Predator Carb Help needed!

[jackel440]

Ok guys this is one heck of a problem for me.My 420 HF predator clone was acting up earlier this summer.Would idle somewhat but then would spit and sputter but not rev up.Kids parked it and I never got to it.Now its mad dash to fix so we can go camping over the weekend.
So we pull the carb off and clean it blowing all the passages out with carb cleaner.reinstall the carb and she will idle ,but will not rev up.when you open the throttle wide open it wil keep running but get rough like it fires hard every fsecond.I would try to close the choke hoping to richen it up to gain rpm but no luck.She will idle great.I have pulled the carb 3x and the main jet is clear no corrosion in the carb.I tried spraying carb cleaner in the little bleed holes behind the butterfly.Seems to be getting through there also.
I'm at my wits end tonight.I am at the point of trying to buy a carb tomorrow if I knew what would fit.That way I could modify it at the campground so I would have my cart back.
I know if I try to find a carb Does anyone know what Honda carb would work?A GX390 carb?
Or does anyone have any other ideas I can try?

[geoffw]

Are you sure its a carb issue and not a fuel pump or other fuel delivery issue?

Did you check for air leaks around the carb? Carb Gaskets OK?

[jackel440]

I did pull the carb again and cleaned and blew out all the passages with compressed air.Reinstalled and I got it to rev for a few seconds.then it returned to and idle and would just chug and not rev with any throttle.
I decided to drain all the fuel lines and the tank.I thought perhaps I have gotten some water in the fuel due to it sitting outside and maybe the vented cap letting water into the tank.
I put in about half to maybe a gallon of fresh fuel in the tank.The pump primed right up and I have good fuel delivery.I then got her to reve and engage the clutch for a little bit and then she would lose power.Sometimes I could get it to come back upto speed for a little bit.
I now seem to be able to get her to rev but its inconsistant,and it wont stay revved up.
I am not sure if it is leaking at the gasket surfaces or not.Gaskets looked ok on the filter side of the carb.The gasket between the carb and spacer is not ripped or delaminated but could be replaced.I don't think its not sealing,but then again I thought i caught a flash of a backfire one time by the carb.But i am not sure if it was there or from my exhaust pipe.
I was tring to see if i was getting any blow by back through the carb.I thought i felt a little back pressure through the intake but not positive.
pulled the valve cover and the rockers are somewhat loose.So I dont think I have a rocker holding the intake open.
I believe i have plenty of fuel flow.
I can get it to idle nicely.
I now could get to rev for short periods.But this is not conclusive to driving around the campground tomorrow night.

[jackel440]

Originally Posted by geoffw

Are you sure its a carb issue and not a fuel pump or other fuel delivery issue?

Did you check for air leaks around the carb? Carb Gaskets OK?

geoffw,
I would like to pick up a set of gaskets for the carb,but My local parts house will probably tell me they don't have anything for it since its not a Honda,Briggs etc etc...I haven't tried to buy parts for it yet but I know they work.Would you know what model Honda I could tell them to look at for gaskets and maybe a carb?I probably wont have time to work on it before they close.So if I could get some parts I can work on it at the campground.Since they will probably be closed the rest of the holiday weekend.
Do you have any other ideas that I cn use to attack this problem?
Thanks again for taking the time to help.

[bronsonj]

If you have a gasket or vacuum leak, you can find it with the carb cleaner while the cart is running.

Keep it away from the air intake as much as possible, but spray a little carb cleaner close to the gasket. If the gasket is sucking in air there, it will suck in the carb cleaner and the engine will rev a little.

Make sure you have the rear tires off of the ground, in neutral (if equipped) or the parking brake on because it could take off when the engine revs.

I use the carb cleaner method on vacuum lines under the hood of cars on occasion. Works like a charm. The issue you will have is you likely have your air filter and intake very near to where you want to test. So just use it sparingly and with the nozzle extender/straw looking thing.

Good luck.

[geoffw]

Whats your cold valve lash set to?

[jackel440]

I will check when I get home here in about 30 minutes.I know it seems to feel super sloppy.

[cboger]

3-4 thou is probably where you want to be.

[sho305]

The old honda gx390 parts should work on it if you can get those.

[Seafarer12]

When you pulled the main jet did you pull the emulsion tube and clean the ports out. I use a welding tip cleaner for that. They will get plugged. Did you pull your plug and see if your running rich or lean.