Carb overhaul on Vangaurd 23HP, Norwood LM2000 ?

[Thehardway]

I picked up a used LM 2000 Sunday from board member Solomon. He was great at working with me on this mill and helping me break it down and load it for transport. 

Now that I have it home I want to make sure everything is in good shape before I put it to use.  This saw appears to have very little use sawing lumber but a lot of time sitting in the sun and coastal weather.  I did listen to it run although the battery was dead and we had to use the rope pull start.  It fired without a lot of trouble.

No wear on the belts and idler pulleys and all of the original paint still on the log bed is the upside.  Downside is lots of rust on the bolts, screws, and exposed springs, battery box just about rusted out. Some of the paint is bubbled up with rust under it that will need to be wire brushed off primed and repainted.  All this I can deal with.

Here is the real question, when I opened up the breather on the carb and pulled the air filter I noticed quite a bit of sawdust buildup on the intake.  This engine has the 2bbl slingshot carb on it.  Removed the air cleaner base and the pulled the 90 degree velocity stack to expose the butterflies.  More caked sawdust in the velocity stack and on the butterflies.  Removed the three back bolts and the fuel supply line and tried to pick up the carb but it hangs on the anti-backflash sensor under the intake manifold.  No way to get under there to remove it.  To tight.  I believe I have to break the carb down further on top of the engine to access and remove the sensor and then it all comes free.  Is this correct? It is not coming apart easy.  I'm going to see if I can tap a razor knife blade in a little bit this evening too see if I can get it to separate and break open without causing any damage to anything.  Is there any gothchas awaiting me here?

Do any of you LM 2000 users have an issue with sawdust buildup on the air filter?  Seems to be placed in an area prone to picking it up.  I might toy with the idea of a diverting shield to try and extend filter life.  Also going to install the foam pre-filter.

I also noticed that there is nothing connected to the oil pressure sensor.  I assume this should be wired to the ignition as a low pressure kill switch but I can't find a decent schematic anywhere yet from B&S. Only a parts breakdown.  Can anyone provide a picture of where and how this is supposed to be connected?  I'm in the process of getting the saw registered with Norwood but having a username issue on the website so I figured I'd ask here while waiting. Thanks.

[sealark37]

You are going backwards when you tear down a carb that starts easily with a rope and saws satisfactorily.  Put it back together and look for the air leak that allowed the dust to enter.  It did not come through the filter, it traveled around the filter and entered through an air leak.  The foam prefilter may seal the leak.  The low oil sensor simply grounds the magneto, so you need to find a place to connect into the ignition circuit.  Good Luck, and  Regards, Clark

[DeepWoods]

I haven't had any problems with sawdust getting past the air cleaner, just the normal stuff on the pre filter.  When I assembled my Norwood I wired the oil sensor along with a 12 volt lamp to let me know if there was a low oil pressure situation.  To be honest, I don't remember if it will shut the engine down when the light comes on.   I will go out to the mill and see if I can figure out how I wired it and let you know.

Edit:

I wired it so the indicator lamp comes on if there is low oil pressure.  Maybe someone with more knowledge will chime in, but it seems to me that since the switch is closed with no oil pressure, the engine would not start until there was enough oil pressure to open the sensor switch.  If just cranking the engine over would create enough pressure then the switch would open, and let the engine start.  If that makes any sense?

[Thehardway]

OK, I managed to pull the carb off last night. After pulling velocity stack I tapped a razor knife blade in and separated the carb from the riser. This gave me enough space to get an open end wrench in and remove the anti-backflash sensor.  Had to snip the nylon tie to allow the wire to twist enough for removal. once that was out, I was able to remove the carb body and get it to the bench for cleanup.  Sawdust was all the way through it.  Separated the carb body pieces and cleaned out the float bowl which also had sawdust down in it.   Either someone didn't get the filter in right or the lid snapped down all the way or it was run for a few minutes without filter.

Even though the engine was starting and running I suspect this would have caused some issues at high idle and under load somewhere down the road.  I was able to salvage the rubber seal gasket.  The carb is back together and I should get it back on tonight and be able to fire it up.

One thing I did find after removing the carb was that wasps had about three nests built on the back side of the #2 cylinder head.  I have no doubt this is one of the reasons the saw shows very little use time. It would be pretty tough to kill them where they were or start the saw without getting stung. Fortunately they were all evicted.

I sanded the rust off the muffler and hit it with some high temp paint, repainted the air cleaner cover and ignition key panel which were showing some rust from exposure. Things look and should run better.  Going to change the oil and take a look at that pressure sensor tonight as well. 

[macpower]

Hardway,
You need to solve that sawdust problem for sure. That can/will eat that engine alive! Nothing should be getting by that air cleaner. One of the biggest problems we see is with crappy fit air cleaners, non OEM and just poor quality. Briggs does sell an air cleaner that works great,  much better than some aftermarket stuff. I sell 4-5 short blocks a year due to this. If you had sawdust in the bowl, it was getting in through the vent or even with the gas,(hope there is a fuel filter). Are you sure it was sawdust in the bowl? E10 will leave a granular deposit that could look like saw dust or even like rust particles.
The oil switch is usually just hooked to the mag wire to short it to ground,low oil kill switch. It could be used to activate a light also.
If you run into problems, or need help with parts shoot me an email. I'm a B@S dealer,(also a master tech), so I may be able to help you. I would want the model, type  and code of you engine.
mac

[Thehardway]

Mac,

It was definitely sawdust on the choke butterfly and in the velocity stack.  It might have been E10 deposits in the bowl but could not say for sure, all I know is it looked like it shouldn't be there.

I reassembled everything last night and in the process it appears as thought the gasket under the Air cleaner assy. may have not been sealed completely and be the access point for the sawdust.  I could not find any gaskets locally, checked with 5 B&S dealers and all said they would have to order it.  I reassembled using some RTV rubber gasket sealant until I can get the proper gasket.  I will email you with the model number etc.  I believe the correct part number for the gasket is 692087.  I know B&S uses a cyclonic filtration unit on the larger Vangaurd models, will it bolt on my 24HP?  Might be worth the investment.  The way the air intakes are situated they are right over the saw blade and likely to get a lot of fine dust, especially when milling hardwoods. It is sealed up good for now.  It fired right up and seems to run nice and smooth at all speeds.  Hope to put a load on it soon and see how she pulls.

After finding the wasp nests I thought it might be good to pull the engine shroud and make sure I had it all out.  It was good I did, both cylinders had large mud dauber nests packed in the cooling fins, larger than a golf ball.  I cleaned it all out and flushed it with a garden hose 'til it was nice and clean, then reassembled.

Tonight I plan to unload off the trailer and assemble the bed as well as do a oil and filter change.  Starter has some salt air related rust so I will probably pull it and give it a thorough going over as well.

Will post some pics when I have it set up.