Troy-Bilt 4 cycle backpack leaf blower has no high rpm

[Tiger Small Engine]

Being this blower is a splash system are there ways to prevent the problem from happening?
This is a back pack blower and I would think not much tilting goes on compared to a trimmer.

The term, “polishing a turd” comes to mind with this unit. You paid $40-$50 bucks initially, and are talking about possibly a short block for another $110. The unit is worth probably about $75-$100 all in used running 100% correct. If you want to satisfy your curiosity and experiment, have at it. If you want a good solid blower that will perform great, and run virtually trouble free for years to come, buy a Stihl, Echo, or Husqvarna.

 

[Richie F]

The term, “polishing a turd” comes to mind with this unit. You paid $40-$50 bucks initially, and are talking about possibly a short block for another $110. The unit is worth probably about $75-$100 all in used running 100% correct. If you want to satisfy your curiosity and experiment, have at it. If you want a good solid blower that will perform great, and run virtually trouble free for years to come, buy a Stihl, Echo, or Husqvarna.

I have a Husqvarna 150BT I've been piecing together also. It does run but spark plug hole needs a heli coil (which I have).
If you know anyone I need the air filter cover gasket and outside cover for it.

 

[Richie F]

OK here's what I did to make this Troy -Bilt run.
Changed out the oil to 10W40 that I had on hand and did the math of adding STP to it.
That's 3oz of oil to .6oz (one tbsp) of STP. Really wanted to use Lucas but at $17 a quart, nope.
The original main jet (Walbro #76) is .013 I had an extra carb so I drill that jet to .014.
Put in a new Champion plug #RDZ4H/979, had an original plug (Chinese?) #794-00082.
Let it warm up and it runs low and high like it should. No oil smoke and doesn't fowl the plug.
I hope this helps someone.

 

[Tiger Small Engine]

OK here's what I did to make this Troy -Bilt run.
Changed out the oil to 10W40 that I had on hand and did the math of adding STP to it.
That's 3oz of oil to .6oz (one tbsp) of STP. Really wanted to use Lucas but at $17 a quart, nope.
The original main jet (Walbro #76) is .013 I had an extra carb so I drill that jet to .014.
Put in a new Champion plug #RDZ4H/979, had an original plug (Chinese?) #794-00082.
Let it warm up and it runs low and high like it should. No oil smoke and doesn't fowl the plug.
I hope this helps someone.

So you drilled out a carburetor jet .001” (one thousandth of an inch), through in some thicker oil, and changed out the cheap Chinese spark plug to a Champion, and now everything is great. Hard to believe, but glad you got it running.

 

[Richie F]

So you drilled out a carburetor jet .001” (one thousandth of an inch), through in some thicker oil, and changed out the cheap Chinese spark plug to a Champion, and now everything is great. Hard to believe, but glad you got it running.

Me too.

 

[StarTech]

Now I am confused.

First you drilled out the jet in post #1
"On the OEM carb drilled out the main jet from .013 to .017 and I can get high rpm but not to spec."

And then you said you drilled out a second carb jet.
"The original main jet (Walbro #76) is .013 I had an extra carb so I drill that jet to .014."

Why would only now going from .013 to .014 works when going to .017 didn't work?

 

[Richie F]

Now I am confused.

First you drilled out the jet in post #1
"On the OEM carb drilled out the main jet from .013 to .017 and I can get high rpm but not to spec."

And then you said you drilled out a second carb jet.
"The original main jet (Walbro #76) is .013 I had an extra carb so I drill that jet to .014."

Why would only now going from .013 to .014 works when going to .017 didn't work?

.017 over jetted the carb, plug was black and couldn't get full RPM.
.013 I had idle but no high idle.
.014 Was the jet size to run without fowling the plug and get full high idle RPM.
Adding a fresh plug helped also.
Putting in thicker oil with a little STP, more than likely helped with compression, though I didn't confirm that.

 

[StarTech]

This is why you don't get to aggressive resizing jets. You have sneak up on the right mixture.

Normally jet are in hundredth of a millimeter. But it sound Walbro might using a different system as #76 would had been .0299" if they were using a standardized system.

I would like to know the Walbro carb model number so I can contact Walbro about the jet sizing.

But would have thought MTD would be using a Ruixing carb clone of a Walbro.

 

[Richie F]

This is why you don't get to aggressive resizing jets. You have sneak up on the right mixture.

Normally jet are in hundredth of a millimeter. But it sound Walbro might using a different system as #76 would had been .0299" if they were using a standardized system.

I would like to know the Walbro carb model number so I can contact Walbro about the jet sizing.

I've contacted Walbro and they were no help.
The letters on the carb are WYLB. There is a number 413 and letters THAI or THA1 on it.
Larger Walbro carbs on say mopeds might relate to a #76 jet that is .0299
I'm a retired auto mechanic of 52 years and am familiar with jet sizing on different carbs, but I could not find a chart for jets for this carb.
I did find the Walbro original carb was a 75205676A and was updated to 753080025, these are MTD carb numbers.

 

[StarTech]

Hmm it looks Walbro has change their website for the worst. It only list six WYLB carbs going from -1-1 to -6-1 and no ipls. Companies just keep trying to shove stuff down the good techs throats.

I was once to look up about everything for these carbs. Now it a major guessing game.