H 721 V Backfire/loss of power/stumble with throttle

[MStanfield]

Hey guys, new to forum

I have a 1500 Ferris with the H721 V with 425 hours. When throttle is opened quickly, I get backfire thru carb and stumble. Also seems low on power...first thought a fuel problem. I have:

Installed new champion plugs
New Fuel Filter
Good fuel flow to fuel pump
Pump seems strong (although I have not tested volume...not sure amount needed)
Adjusted valves
Disassembled carb and cleaned
Checked spark with in-line tester; seemed ok
Partially opened choke...no improvement(floods out like you'd think)
Added Seafoam to tank
Checked compression...forget the numbers but over 100 psi each cyl

What else should I check?

 

[mechanic mark]

Air filter

 

[John R]

Are we supposed to be able to read this, or is it a joke?

 

[BlazNT]

It is a hacker/spammer that can not read or type english.

 

[MStanfield]

You guys want to share the joke with me?

Not a spammer....just have a broken motor

What's the deal?

 

[BlazNT]

You guys want to share the joke with me?

Not a spammer....just have a broken motor

What's the deal?

A spammer posted in your thread. It was taken down so you can not see it now.

 

[MStanfield]

I'll try another forum

Thanks

 

[BlazNT]

I'll try another forum

Thanks

Someone already answered your question. We have been waiting for you to respond with a yea or nay.

 

[mhavanti]

MStanfield,

When you cleaned the carb, did you soak it in a good carburetor soak such as Gunk Carb Cleaner? Leave it in the soak overnight and then pressure wash the fuel circuits. The high speed circuits most likely are not clean and (WOT) wide open throttle at an all in setting doesn't allow enough fuel to create the correct air to fuel ratio, thus it is too lean briefly before the revvs comes up.

If using the choke doesn't allow you to throttle up as well, not unusual because the choke may draw too much fuel from the bowl and cause it to fowl the plug and now you have gone to the extreme the opposite direction. Choke throttling isn't a good way to operate as the amount of fuel isn't metered as closely as the circuitry for staying lean as possible without drying out the cylinder(s) during normal operations.

I'd re-soak the carb, pressure wash the carb., then blow it out with 125 pounds of pressure thru a nice rubberized air nozzle to give the circuits a good cleaning. Try this and let us know how it goes.

Good luck,

Max

 

[John R]

Been a couple of weeks, guess he got it fixed.