02 rmk 800 stalling

[the3880]

Have a new to me 02 800 rmk with 400 miles. On my first longer ride which was done at less than 10 mph nearly the whole way due to terrain on the way back it started cutting out or losing piwer. It seemed to only stay alive if I kept it revved up. Not sure where to srart on this so I'm looking for advice. My uninformed opinion was that its related to the variable exhaust valve? Thanks in advance!

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[Over budget]

Have a new to me 02 800 rmk with 400 miles. On my first longer ride which was done at less than 10 mph nearly the whole way due to terrain on the way back it started cutting out or losing piwer. It seemed to only stay alive if I kept it revved up. Not sure where to srart on this so I'm looking for advice. My uninformed opinion was that its related to the variable exhaust valve? Thanks in advance!

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Sounds like maybe a carburetor issue pilot jet plugged. Especially if its been sitting for a while. Just a thought it could be a few things can you tell if it’s running on both cylinders that’s usually a sign of carb problems or even something as simple as a fouled spark plug

 

[o2bncamo]

Are you sure it wasn't overheating? Going that slow doesn't throw much snow around to cool it.
The sled may just have been going into protection mode from high water temp.
I would also vote on carbs not valves, without hearing it run. It's not that hard to take them apart and clean them.
Just take your time and blow some carb cleaner through every orifice.

 

[whoisthatguy]

1. Check the front left engine mount as they tend to get torn in the 800, which then causes all kinds of engine problems.
2. If the air suction hose from the bottom back of the crankcase, has been replaced with a red plastic hose, due to the 02 crankcase hose connector not having a bend in it, the red hose can get warm from the engine and kink over causing loss of suction to the fuel pump and fuel starvation.
3. The high beam light connector can cause low rpm engine problems when it burns out. Disconnect it to check.
4. A bad reed in the reed valves causes low rpm engine problems. They need to seal when in the rested position. Old ones don't seal and cause loss of compression. Broken ones are even worse.
5. A leaky VES valve gasket will cause engine problem. Look for tears in both the flat gasket and the rubber diaphragms. While you are at it, check the metal guilotines for impact dents with the cylinder head. If they are not getting stopped at the correct location, they could take out the rings and pistons.
6. Check for choke lever having 1/4" to 3/8" free play before it starts to engage on the carburetor.
7. Look for the suction hoses from the carburetor to the air box to be in place and plugged in at both ends.
8. Look for corrosion inside of the spark plug, plug connector. Replace if corrosion is present.
9. Check for idle rpm set too low on top of carburetor.

 

[the3880]

Ah ok so had one ride with no problems and then another with progressively worse problems till it failed. This was at normal speed. Put new plugs in and it fired up. The plugs were fouled. Ive been running 50 to 1 mixed gas and sort of forgot to disable the oil injection tank. (Machine is new to me.) What is the easiest way to disable this? I see that there is a valve on top of the oil tank. Which position should that be in? Or is there some other thing I can disconnect that is a better way to do things? Thanks again!

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[the3880]

Also curious what might be causing fouling of plugs other than my hypothesis of mixed gas running in a machine with oil injection still hooked up?

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[whoisthatguy]

The oil injection pump fed half of the oil into the air stream through the carburetor and the other half went to the end crank bearings. So previously, the engine was getting an 80:1 mix. Now you are at 50:1 and the outer bearings are getting zero additional oil, because the air flow through the carbs never reaches them. If you disconnect the oil pump, expect to be replacing the outer crank bearings sooner rather than later. Before disconnecting the oil pump, you would be feeding oil to the cylinders at a 30:1 ratio, which is responsible for fouling the plugs. There is no valve on top of the oil tank that I am aware. The only way to disconnect the oil pump is to remove it from the pull rope assembly casing by taking out the two bolts that hold it in place.

 

[the3880]

Ok good information thanks. So to confirm I should just leave the injection pump alone and keep it full of oil. If I started mixing my fuel at a higher ratio like 80 or 100 to 1 is it concievable it would run ok?

Also curious if there would be a way to leave the crank lubrication in place and run mixed gas to lubricate the cylinders r is this a stupid idea? Is the oil pump a common failure item like I'm imagining or is my information out of date?
I just grew up mistrusting oil injection systems after hearing of them failing and people losing an engine etc.

So my other machine a 1991 Indy lite gt 340 ive always ran mixed gas in with no problem has a disconnected oil injection but apparently thats a different system?

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[whoisthatguy]

You just don't add oil occasionally and forget it. You put a mark on the oil tank and fill it up to that mark each time before you go out. When you get back, you measure how much oil you have to add to get it back up to that mark. And then you calculate your consumption based on the gallons of gas per amount of oil added. Oil pumps will last 2500 miles. You should use 2.5 gallons of gas for every cup of oil you add for a 40:1 ratio.

 

[BeartoothBaron]

A good way to keep an eye on the oil system is to put some marks on the oil reservoir, I'd say at pint (16 oz.) increments. Then, at 40:1 ratio, you should see it go down a pint every five gallons of gas. You could empty the tank and then add a pint at a time until it's full, but then you'll have to bleed the oil line. What I did was just to run it as low as I was comfortable with (even running it low gives you a chance of getting an air bubble), then add a pint at a time and draw a line to mark the level. Would be nice if they'd done that from the factory... Then, line up the mark on the pump with the arm; you can find plenty of instructions and pictures with a search. If it's way off (especially to the lean side), you may have a problem to fix. They tend to be a little rich from the factory, so if you're at, say, 30:1, adjust the pump down little by little.

Once you've got it dialed in, make sure you're refilling the oil at a 40:1 ratio (some guys go slightly more lean) every time you add gas. If you see a sudden drop in oil use, investigate and replace the oil pump if there's any question. A sudden, complete pump failure could still catch you, but at least by monitoring it you have a fighting chance of catching it. That said, I'm around 4500 miles on the original pump. Usually the oiling burn-downs on these are from losing the pump drive (800s like yours can break the oil/water pump belt; ones like mine are driven off the crank and can strip the gear, though that's less common), so I wouldn't lose sleep over it once you've replaced the belt.

As for pre-mixing, some guys still do that. If it does any good, I'd say it's from adding some lubrication you don't get from the injection more than preventing a burn-down as a result of a pump failure. My thinking there is that if you add enough to go 10-20 miles without damaging the motor, you're going to be stuck running a lot more oil through the motor than necessary. Even at 100:1 pre-mix (a pint to every 12.5 gallons), you'd take a 40:1 mix from the pump to 29:1 total, and even 100:1 probably isn't enough to get far if the pump dies.

 

[CATSLEDMAN1]

If you continue to have engine going into a poor running mode / limp home mode, that year and vintage 800 the head temp sensors were bad/go bad/ some bad out of the box. Try a new one.