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itguy05
join:2005-06-17
Carlisle, PA

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Re: Honda Northstar 13,000 generator upgra for Generac 7000 EXL?

said by disconnected :

someone here might observe something and speak up about something that might not be right.

Where to begin.....

1. These small engines can be quite sensitive to backpressue and such. You're running it through an exhaust system which it was never designed to be run through (car muffler with lots of piping). That alone can interfere with the engine in weird ways.

2. You're running it in an enclosed building, which it was not designed for. You need lots of intake and exhaust air for it to work. Looks like you have lots of exhaust but little intake. How is that intake fan getting held open?

3. Fuel economy has nothing to do with ignition. Electronic ignition has been on these engines for 20-30 years and it's still a simple system. You doubled your engine power and will burn more fuel.

4. Running lean is a great way to nuke a piston. Lean = heat and that's not good for an air cooled engine in a confined space. So don't lean it out to get better economy.

Run it outside at max load and see what happens. If it works then you know you have an issue with your building and hack muffler setup. I'd try ditching the car muffler (doesn't help much anyway as most noise is from the engine and alternator) and try running straight pipe from the generator's muffler to the outside.

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Anon

Lots of people run car mufflers on generators with no problems. I even straightened my exhaust setup yesterday (no bends in the pipes, just straight into the muffler and out) with little to no improvement. Unless the Honda V-twin is unusually sensitive to this back pressure, I find it hard to believe that the muffler is causing this.

I have 1843CFM of air flow via the exhaust fan and two intake vents.
The intake vent with the shutter is powered. When the generator starts, the vent is opened by a motor. When the gen stops, the motor lets go and the vent closes by spring load.
I have a secondary air intake (the aluminum drier hose) from the floor, which sucks air from a PVC pipe on the south side of the building behind the evergreen.

Fuel economy can be affected by fuel/air ratio though, and if there is not enough air...

I was concerned about running too lean for that reason. I know that's a good way to burn valves on automobile engines.

The muffler is knocking about 30dB off the noise level. The building, with the door close, about 40dB off the engine, intake, valve, generator noise. See video, where you can hear the relative noise levels with the door open or closed. It goes from 105dB with the door open, to 72 dB with it closed. It's 64dB a distance away, at the end of the video, where the sound of my footsteps are louder than the generator.
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I did a test without the fan running. Mind you, it's in the 90s today, so the hottest day so far this summer.

I ran the generator til it was good and hot (hotter than it was with the fan) at no load. Then I connected the house. Came out and watched the generator. Okay with the static load of appliances and computers. Went back inside and turned on the electric oven on Broil. Came out and watched the generator for five minutes. The only smoke I saw was the plastic labels on the iron pipe outlet of my exhaust setup starting to burn off. I went back inside and switched the oven to Preheat and came outside and observed. It's not ten minutes of operation and no sign of any problem. 5000 watt + load levels. Generator is hotter than ever without the fan running, but it's running smoothly. Oven reaches set 450F setting in about 5 more minutes and I can hear the generator speed up and the governor kick in and bring it back down to normal RPM.

Even with the door shut (don't want to leave it shut for long without any ventilation), it runs happily, just keeps getting hotter and hotter. I let it run 3 minutes more at static house load of about a kilowatt for a cooldown, then switched the transfer back to utility and let the genny run another minute before shutting it down. By now, the frame and metal gas tank were too hot to comfortably touch, but the engine had no trouble handling the loads.

When I had the exhaust fan running, I couldn't get two minutes out of the engine with a single air conditioner running. Now I can double the load and the engine runs beautifully. I think that confirms my hypothesis that the low pressure inside the building may have been sucking oil in from the PCV breather tube into the carb. It's really THAT sensitive.

As for the pressure, even the 100lb concrete-filled door, 30x36" gets sucked closed as the door meets the frame when that fan is running. There's a LOT of suction there!

What this means is I must get an equivalent fan to put on the intake vent (1843 CFM) to equalize the pressure. Apparently a 12" fan can still bring the pressure down despite a 12" intake shutter and a 4" intake hose. This is a small space (about 100 cu ft) and that fan is the most powerful fan I could find.

garys_2k
Premium Member
join:2004-05-07
Farmington, MI

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garys_2k

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Glad to hear the gennie's not defective! Could you cobble up a forced air intake from another of the forced exhaust units, reversing the louvers and turning the motor/fan around?

Edit: Even a pressure difference of 1 in. water (very small) would cause a door force of 0.036*36*30 = 39 lbs. of force. Half of that would be at the opening side (other half on the hinge side), so your significant pressure drop is causing a lot of force, I'm sure.
TheMG
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Canada
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Perhaps it's not the low pressure itself, but rather the pressure differential between the exhaust and intake that is causing the problem.

You have the exhaust sitting outdoors at normal atmospheric pressure, but the air intake to the engine is at lower-than-atmospheric pressure.

I'm no expert on engines, but perhaps that could be what is causing the problem?

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This ought to do the job. A bit pricey and the current is high, which adds up to lowered fuel economy, but the higher air pressure will probably improve fuel economy, given how low air pressure made it run too rich.

»www.industrialfansdirect ··· -1R.html

garys_2k
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join:2004-05-07
Farmington, MI

garys_2k

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said by disconnected :

This ought to do the job. A bit pricey and the current is high, which adds up to lowered fuel economy, but the higher air pressure will probably improve fuel economy, given how low air pressure made it run too rich.

»www.industrialfansdirect ··· -1R.html

Dumb idea: Can you reverse that motor's direction and use it as a pressurizing fan? You could reverse the louvers later after trying it running the other way (prop the louvers open). If it works and stays cool you can avoid buying another fan.

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I cannot simply reverse the fan. It's in the wrong location. And exhaust fan is up near the ceiling. The supply fan is down near the floor. So I can't make this ceiling fan the supply fan because the hot air wants to rise.
There is something still a little bit strange about the way the whole system operates with the door shut. I ran about 8000 want load today and with the door closed after a number of minutes I see an increase in the smoke output from the muffler. If I open the door the smoke output gradually decreases. I think what I may do is put some louver vents in the door.
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I did a test today with a 5200 watt load (the electric dryer). This time with the door wide open. It was looking good for about 10 minutes. The dryer got up to temperature and heating element shut off. Cycled back on three more times for about 3 mins each after the initial 5 minute run. It was a minute into that fourth cycle when the engine started burning oil again. (Smoke out the exhaust, smell of burning oil). Even with the door wide open and the fan running. Granted, it was 95°F Thursday. But the Generac never did that and it ran 16 hours a day at better than half its rated load capacity as the minimum load.

I am starting to suspect an engine defect. Generator wasn't very hot at all when I shut it down. Perhaps this is the wrong way to go. Portable gas generators are said to have a service life of 450-500 hours. That's 21 days of continuous operation. A good 1200rpm diesel is rated for 40,000 hours of operation before a top cylinder rebuild may be needed. A good used one for $4-5K. Only problem is shipping is $1500 for 2200lbs and delivery to the house would be a challenge. I was close to considering the affordable Aurora generator, which is fully enclosed and very quiet. But shipping arrangements would be a nightmare. And it was close to $8K. And it's made of Chinese parts (motor and generator).

This Northstar is far too noisy to run outside a building. 105dB from 4' away. 93dB at 20'. It's so noisy the manual emphatically requires user to have hearing protection! Going to look at my options, including returning it, if possible.

landry98
join:2001-08-31
Red Stick

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Northern Tool does not accept returns on gas engine equipment. They will direct you to authorized service center for repair.
itguy05
join:2005-06-17
Carlisle, PA

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What happens if you run it outside as it shipped from the factory?

I still say running it into the extra exhaust and in the building are causing your issues. No matter how cool it may feel it may be overheating. What's the oil temp after the run?
jp16
join:2010-05-04
united state

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You are removing the combustion air with the fan setup. Is there a way you could rig up the carb to the outside so it takes in fresh air? I also 2nd the idea of turning the fans around. You need to be pushing fresh air into the room not out of it. No fuel burning device, be it an oil burner, NG, LP or diesel gen set for that metter, will work properly under these conditions unless adequate make up air is available. The door being held shut when the fan is running is a clear indicator of little to no make up air.

Also I would ding the auto muffler if you have not already done so. The engine is designed to run with the muffler that it came with, not an additional one. A 100 +/- HP car engine can overcome the back pressure in that muffler more readily than the motor on the gen set. I can understand why you want the additional sound reduction but you are attempting to make the motor work in a manner that it was not designed.

garys_2k
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join:2004-05-07
Farmington, MI

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said by itguy05:

What happens if you run it outside as it shipped from the factory?

+1. Don't assume there's a problem with the engine/generator until you've really tested it in the environment in which it was designed to operate in.

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Due to the fact that the air intake is slotted there's no practical way to put it in air intake scoop to a host of the outside.
Now with the door open things are a little bit better but there's still not quite right. I do get about 10 minutes of run time in the 95° heat. I suppose this hot weather is a good test.
But it's during the summer that the generator would be under the most load running air-conditioning units in the house. So this has to be bulletproof.

Running without a muffler would be a no-no. This thing makes a racket you wouldn't believe it's more than twice as loud as my Generac.

Northern tool states that the noise level is 79 DB well a 20 feet I measure 95 DB so their claim is inaccurate. This generator is unsuitable for residential area. It would have neighbors complaining and no time.
TheMG
Premium Member
join:2007-09-04
Canada
MikroTik RB450G
Cisco DPC3008
Cisco SPA112

TheMG

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said by disconnected :

Northern tool states that the noise level is 79 DB well a 20 feet I measure 95 DB so their claim is inaccurate.

Not necessarily. Depends how the measurement was done. There are different "weightings" for dB noise level measurement.

This allows manufacturers to use sneaky tricks like picking the weighting that yields the lowest dB number.

Also what are you using for the measurement? Do you have a proper calibrated audio meter? What weighting does it use (if any)?

Also, are you taking the measurement with the generator operating in open space away from any structures/objects? Having the generator close to a wall for instance can amplify the noise in a given direction.

garys_2k
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join:2004-05-07
Farmington, MI

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I think you'll eventually be able to get it to work, it will just take some time and more than a few steps.

First, I'd work on getting it to run in the enclosed space with the correct ventilation. You have a very large fan, it's likely loud all by itself. I'd try just about anything to see if this will work as a supply fan, inclluding mounting the whole thing on the OUTSIDE of its "window" in the shed so that it blows from out to in. THEN see if the gennie will work, with its stock muffler, under load for an hour or so. Run the test during the afternoon when people are used to hearing chain saws, leaf blowers and other noisy junk. Key is to get it in that hut and working.

Once you've confirmed that it can run in there (and if it won't then back up and try it for an hour in totally free air, stock everything, and again test it; if it still fails then you do have a broken unit) it's on to step 2, the exhaust.

Maybe you could cobble up a couple of low restriction, high performance automotive mufflers in parallel to reduce backpressure. Engine to a Y-Pipe and each leg of the Y to its own muffler (I'm thinking "glass pack" mufflers for this). Those work well for high frequency sound.

Once that works, you can look into turbo type mufflers, but maybe you'd need more than two.

Anyway, from the way it works for a while and then starts to go bad, my guess is it's heat related more than back pressure. Get that thing running either in free air or in a "forced inlet" situation first. Noise can be dealt with later.
54067323 (banned)
join:2012-09-25
Tuscaloosa, AL

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said by disconnected :

Running without a muffler would be a no-no. This thing makes a racket you wouldn't believe it's more than twice as loud as my Generac.

I doubt your automotive muffler is part of the problem, they are designed to handle way more exhaust gas without contributing to a high back pressure than your engine could ever put out.

None the less, since you are still vertically stacking the exhaust system I would recommend you drill a small weep hole in the lowest part of the exhaust system.

The last thing you need is to do a shut down where the exhaust valve remains open and have any form of moisture back flow into the cylinder, think rust and aluminum oxide an abrasive, an alternative would be to make it horizontal with the exhaust lower then the inlet, then you eliminate any moisture into the engine problems.

alkizmo
join:2007-06-25
Pierrefonds, QC

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Click for full size
You guys make it too complicated.

These pictures are a bit old, things aren't so rough around the edges anymore, but the main stuff remains.

The generator exhaust slides into that huge tube, I stuff some roxul around it (That stuff cannot burn, melt, or whatever).
The fan exhaust the hot air at the top.
There is a hole in the shed floor for intake where it is suspended off the ground (slopes down behind the shed).
I can keep the shed door ajar if I feel it's a bit hot on that day.

I barely hear is at 30 feet and it's only a faint hum inside the home with the windows open.

It's protected from the elements and robbers. It has a direct hook up to the house (underground raceway), and best of all, I don't have to pull it out to use. It's stored where it runs.

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Click for full size
Generator shack floor plan
The most 'forgiving' weighting commonly used would be A-weighting on the ANSI S1.4 or IEC rev 179 standard and is the one which I used. I also took a flat reading, which was 105dB. I've never heard a portable generator this loud. This is close to a CAT 450kW diesel loudness level. I used a calibrated and highly accurate CEL 214 sound level meter, made in England. I use it for measuring orchestra levels at stage performances and determining the proper playback level for a given recording that I make in a venue. Even subjectively, this generator is breathtakingly loud.

The 1843 CFM fan I have installed in the building is not even audible next to the generator noise, when the door is open. When closed, you can hear the fan just a bit over the generator noise leaking out of the fan opening (I still need to put in baffles to absorb some of the intake noise and valve train clatter.)

I suspect there is an irregularity in the air flow around the engine side (air intake side) of the generator, which may be starving it for air. Bear in mind, that EVEN WITH THE DOOR OPEN, it still develops a problem. I suppose Honda engines are different from Generac OHV engines in how they respond to heat. The Generac would just misfire once in a while when it was nearing the end of a 16 hour run on a hot summer night. It didn't smoke like this and start clattering and knocking and belching huge quantities of white smoke.

My earlier 3000W load test out on the platform with stock, open air situation, was probably not conclusive. It should have been a 10kW load for 30 minutes at the least, not 3kW for 5 minutes. I may try to set something up this weekend where I can power the house load while out on the platform (have to make the cable reach).

As for mufflers, I may have to scrap the car muffler. Even so, I can feel (with my hand in front of the exhaust) a large difference in output depending on whether the exhaust fan is on or off. With it off, the velocity of the exhaust is pretty high. With the fan on, it's about 2/3 that velocity. Either the some of the gas is being sucked into the structure by the low pressure when the fan is on, or the flow of gasses through the engine is actually being reduced, which would be a serious problem.

My alternative muffler idea would be just straight pipes, lined with fiberglass pipe insulation (amazingly effective at sound deadening). 2" stepped up to 3" and that larger pipe lined with 3" OD fiberglass rigid insulation for steam pipes. Maybe make that 3" dia section 4' long and then cap it with an elbow.

Drilling a weep hole would be a noise problem. I had to seal every crack and crevice, as any little slit was producing a fairly loud noise as the gasses forced their way through. It sounds like an exhaust manifold leak.

Plan is to add a more powerful supply fan to the now passive intake vent. I have to fabricate a 4" spacer however, and cut a slot at the bottom for the chain and cam for the vent opening motor drive. Then mount the panel fan on that spacer. For extra insurance, I may mount a rain hood, sideways, directing the air flow to the generator, so it passes over the entire unit. Some air would escape through a 12x18" vent louver I plan to install in the door and the rest would exit via the exhaust fan. The curved line at the supply fan is the cowling to direct the air flow toward the generator. This intake supply fan is not yet installed; this is a future plan in the development stage at this time.

I'd like to think that my low restriction muffler is fine, but perhaps it's just not moving the gasses out fast enough. Thought occured to me to install some sort of inline turbine to pull the gasses out faster, but that gets involved. Maybe I can get buy with a tall stack lined with fiberglass. My straight pipe was too noisy in its 3' length incarnation, so I moved to the car muffler idea.

I chose to build this structure out of concrete for several reasons:

Noise abatement
Fire control
Maintenance

Wood burns, rots and lets a lot of sound through. Anything with flammable liquids is a fire and explosion potential, so these absolutely must go in a concrete bunker style structure. That way, if a gas line leaks onto the muffler and the thing ignites a fire, the fire will be mostly contained. This structure was built in 1986, when I got my first generator, a 5500W unit. In 2003, I replaced that with a Generac 7000EXL, purchased used. I put 500 hours on that generator during Oct-Dec 2011 when the state was paralyzed by an early snow storm which brought down tens of thousands of trees in our area. Over the ten years we've had it, I likely put on 2-3K hours on it. It's amazing that it's still working, given that the general rule is that a gas generator is worn out after 450 hours and should be replaced. Diesels can go 40K hours if they're the low rpm Detroit/Perkins engines. 450 hours is 3 weeks of round the clock operation. One natural disaster and you 'theoretically' need a new generator. I should have held out for a diesel. Big mistake going with this Northstar. I believed the customer reviews, and I figured Honda would be better than Generac. I misjudged that one.

John Galt6
Forward, March
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join:2004-09-30
Happy Camp

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What is the recommended oil for this generator?

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Anon

The manual recommends synthetic 5W-30 oil for my climate range. And that's what I'm using.

Raphion
join:2000-10-14
Samsara

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I load my generator with a blow-dryer and heater when I'm "exercising" it, and sometimes I've messed around with the blow-dryer to see how the generator would react to more air being forced into it's intake, or the air being pre-heated.

What I found out was that even the slightest bit of additional pressure would cause the engine to choke. I also found out that even just a bit of extra heat in the intake air would also choke it. I could hold the 1875 watt drier 2 feet away from the air intake, and direct the hot air at it, and the engine would start having severe issues with misfiring, nearly to the point of stalling out.

I think both of these things may play a roll in your issue, as you are pressurizing the room AND it will be getting warm in there.

If the balancing fan doesn't fix it, you may want to consider piping the air intake to the outside, that'll get the engine nice fresh, cool air, with no pressure difference between it and the exhaust outlet.

Also, honestly, I doubt that 1900 cfm of airflow through the room is enough for such a large generator, at least not when it's implemented in a way that doesn't force the air to change over 100%, that is, make it so the air only flows through the generator one time. As you have it, cool air goes in, but mixes with the warm air, and then a mixture of the warm and cool air goes through the exhaust. In the end, the result is probably the same as though the generator only had a 800cfm cooling fan, and given how much noise you say it makes, I'm sure it's supposed to be much more than that, probably even more than the 1900 that your ventilation fan moves.

StillLearn
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Streamwood, IL

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said by disconnected :

It's amazing that it's still working, given that the general rule is that a gas generator is worn out after 450 hours and should be replaced.

That 450 number is pretty shocking. Where did you get that number?
54067323 (banned)
join:2012-09-25
Tuscaloosa, AL

54067323 (banned)

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said by StillLearn:

That 450 number is pretty shocking. Where did you get that number?

It's very low, a Briggs or Generac engine is good for about 2K hours before needing a rebuild.

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In the other thread (the one about the iron pipe for the muffler) I posted some videos of the generator exhibiting this behavior OUTSIDE the building, in free, open air. So now it looks like another problem.

Some possibilities:

Northern Tool overfilled the oil when they tested the generator before draining and shipping it, causing breather to be saturated with oil.

The Honda engine may have had some oil left in it as shipped from Honda to Northern Tool. Engine could have been upside down or on its side during shipment.

Air filter may be too saturated with oil.

I inspected the air filter today. Frankly, I'm surprised that ANY air can get through it at all. There's a pleated paper filter, and surrounding that is a foam pre filter that is soaked in oil and then wrung out. The foam is so dense that when I try to blow through it, my hand on the other side doesn't feel any air flow. The pleated paper filter is even denser. The filters may be the reason why it's burning .8 GPH of fuel at no load. My Generac runs the whole house on just .45 GPH.
But the filter is new, and unless it's got an invisible soak of oil in it, if Honda designed it that way, it should work.

I read that the Briggs & Stratton flatheads are good for about 400 to 500 hours. Apparently the Generac Home Depot specials last 200 hours, according to this thread: »www.smokstak.com/forum/s ··· ?t=67434

With particular attention to Wayne 440's post "48 to 96 hours" if the engine takes ounces of oil to raise it from low to full level on the dipstick. I can put 400+ hours in just one storm outage! Thank Mobil for synthetic oil, else I'd be on my tenth generator instead of third in 26 years.
iknow_t
join:2012-05-03

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there is a possibility that northern tool damaged the engine when they mated the Honda engine to the Chinese alternator, and ran it to test it. the engine was made in china too, since Honda has the engines made to their specs, most of the time that's not a problem, but considering the working conditions in china, a few bad one's probably make it out the door every now and then. true Honda generators, everything made and assembled by Honda, have a very good reputation, and are very quiet too.
aroberti
Sarcastic? Me? Never
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join:2000-12-21
Norwalk, CT

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To be fair, the head is manufactured by Mecc Alte -- don't know if it's assembled in China or not, but they certainly could have gone cheaper on the head.

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I could have sworn seeing a "made in China" sticker on the engine somewhere, but I can't find it now. Northern Tool tells me the engines are made in Taiwan.
The alternator performs VERY well. And, minus the oil burning episodes, the engine handles the loads with ease.
Only issues are the higher than advertised noise levels and the fact that the engine burns as much fuel at no load as they specify at half load.
54067323 (banned)
join:2012-09-25
Tuscaloosa, AL

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said by disconnected :

Only issues are the higher than advertised noise levels and the fact that the engine burns as much fuel at no load as they specify at half load.

Thats normal for a lot of the 3600 rpm ones.

Raphion
join:2000-10-14
Samsara

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I thought only metal prescreen filters were to be oiled, I didn't think you were supposed to oil the foam ones. The OEM foam prefilters for my B&S have "DO NOT OIL" printed on them.