Hi all. I just got a used EF1000is off a guy because he could not get it to run (not sure if he is the original owner). I initally figured it was a gummed up carb and I tore it down and cleaned it up. The carb was extremely dirty and lots of green goo in it. I'm fairly confident I have that problem solved. So after reassembly I still couldn't get the thing to fire up so I dug deeper and pulled the valve cover off. Thats when I discovered that the intake push rod was bent. Exhaust push rod was fine and appears to open and close fine when the engine is turned over. So my question to everyone is should I just replace the push rod and set the valve lash and give it a try or should I split the case in half and check the cam? I don't think the cam is damaged because the end of the push rod looked good so I would assume the follower is ok and nothing jammed up. I'm just questioning why the push rod bent in the first place and don't want to see it happen again. BTW the engine feels like it has good compression, and I can open and close the intake valve by pushing on it. So people please give me some wisdom on what I should do. I have a push rod ordered and new carb jets, as well as a service manual ( I found a CD version on ebay for $4.00)
A bent pushrod can only happen when the engine runs past redline RPM and the valves float, for who knows how long. That's when the piston hits the still open intake valve hundreds or thousands of times, causing severe trauma to every part in that mechanism. The pushrods appear to be the weakest link . . . and it bent. On these engines the valves are at (or near) parallel, sliding back-n-forth on the same axis as the piston, so the valve is hit straight on. Normally, valve/piston contact always bends the valves. That's amazing it has good compression! You may want to take the engine all apart . . . the camshaft is made of plastic.
You should be ready for a runaway RPM over-speed condition when it does start. First, make sure the throttle is fully open with your finger, engine stopped. That properly sets it where it belongs. Other than noted items, you appear to be on the right tracks.
Thanks CycleRob, that is what I was afraid of so it looks like a complete tear down is in order. I was hoping you were going to say that the valve may have siezed in the valve guide temporarily and that caused the push rod to bend. You senario sounds more likely. I will post my findings once I dig into it
A corroded and seized valve is possible too, but that almost always is on the very hot running, sparsely lubricated exhaust valve. The bending force damage could have happened on the first recoil start after the long idle period -or- the valve seized from lack of lubrication while running. That would have happened to the former owner, who very likely was unaware of what was happening.
Small engine manufacturers typically also use the same valve springs on both valves, even when the intake valve often has a larger head diameter and is heavier. That provides an economical built in RPM limiter, as soon as the intake valve floats . . . even a little, the volumetric efficiency and power drops way off. Maybe because the EF1000is was deemed to need one in beta testing, Yamaha installed an electronic ignition RPM limiter, independent of the throttle control system. You can easily hear the point of valve float on other less expensive generators or power equipment if you manually over-rev the engine with what is affectionately known as an "Italian tune-up". It's a very noisy clattering sound.
Another possible scenario is that an excess of carburetor cleaner was used in the fuel, especially with a hot engine. It will dilute and wash away the engine oil that lubricates the intake valve stem, causing only the intake valve to stick open. The exhaust valve stem is immune because it only sees already burned carb cleaner. The piston keeps hitting the stuck open intake valve right after the intake cam keeps opening it, until the engine coasts to a stop. That's why fuel system cleaner mixing recommendations should never be made "stronger, to speed up the process".
While you have the engine apart, go all the way and remove both valves to check for scored stems/guides. The valve springs are so weak, you can easily do it with your fingers.
On my 1988 EM-3500 Honda generator I always completely drain the carb bowl, fuel tank and lines prior to storage. Then when it is needed to power the house, sometimes 2 years later, I roll tip the unit over on it's cage rails so the engine oil partially fills up inside the valve cover. After trying it with the valve cover removed, I know it's only a couple seconds to provide enough oil lubrication to the longtime ago drained away oil starved valve train area. The same goes for the EF1000is, but with a sealed fuel cap and fuel shut off, only the carb bowl needs to be drained so inversion doesn't flood the intake port with fuel. It's always a good idea to screw drain the carb bowl for transport or storage. Because the EF1000is is 29 lbs, it's almost easy to tip or roll over and flood the engine, which causes fuel-oil dilution on a stopped engine. Only bad part is it takes 8+ recoil pulls for the crankcase air pulse operated fuel pump to fill the carb bowl enough for starting.
Well I got the parts in and reassembled the genny and what do you know she fired right up. While I was at it and since the carb was so dirty I ordered up a new pilot jet and a new pilot screw. Since I wasn't the orginal owner I did not feel as though any of the carb settings were correct so I had no real base settings to work off. At first I believe I had the pilot screw turned in way to far because the engine would hunt and rev up and down, and pulling the choke out made things smooth out. So I turned the pilot screw out CCW (don't remember how far) and now the engine runs very smooth on both ECO-OFF and ECO-On. I pugged in a toaster and a light separately and the engine jumps up to high idle (ECO-OFF) and seems to run well and the RPMs are smooth and stable. However when I pugged in my girl friends blowdryer (not sure on wattage) the blowdryer and engine began to cycle up and down again, and the dryer never seemed to fully power. So my question is, are my carb settings off? How do I know if I am to rich, as I think I'm not too lean? Lastly what is the proper setting on the throttle stop screw or what ever its called (the one right above the pilot jet)? I don't want to potentially over rev the engine, although the screw only seems to limit how low the engine can idle. Any additional suggestions would be appreciated because I really want to get this thing dialed in just right so it will last a long time and run trouble free.
There's nothing wrong with your carb settings! You overloaded the generator with your girl friends blow dryer, likely 1,200 Watts or higher. The overload light would have been flashing while the engine revs very high, cycling violently on the rev limiter! I got the same response when overloading my EF1000is trying to restart a freezer compressor too soon after unplugging it from the house power. It needed 4+ minutes time to bleed down the refrigerant's pumped up system pressure.
The toaster was a good load test, but even that could touch closely to the 1,000W max rating. The UL power rating on the bottom of the unit will tell you. So will her blow dryer.
The idle speed on mine is around 2,400 RPM on the TinyTach. Your pilot screw setting is right when the cycling just stops and the speed is constant at idle and at the no electrical load full RPM. If in doubt, with a warm engine turn the pilot screw in very slightly, to find the too lean threshold.
A word of warning. . . . do not apply heavy or sustained electrical loads with ANY of the outer panels removed!! They are needed to properly direct the much needed incoming cooling air drawn in by the engine's cooling fan. It gets directed and concentrated around the inverter's Aluminum cooling fins to keep the rectifier/inverter electronics cool. Realize that the same drawn in cooling air, powered by the flywheel's cooling fan first cools the inverter, then the alternator windings, then the engine cylinderhead and finally the thin chamber surrounding the muffler and the hot muffler itself. A very efficient, clever design with a shared series airflow, engineered to keep 5 things cool and dump excess heat.
Thanks again Rob, I thought about the hairdryer being high wattage after the fact and said to my self you idiot you know those things are like 1600 watts. Oh well I only tested it for a second or two. Thanks for reassuring me that I went about jetting the carb correctly. After running the generator for an hour or so I pulled the plug and it looked perfect (not all carboned up and not over heated looking). Also thanks for the advice on the casing providing proper air flow for cooling. I knew that part already but I can see how many people probablly think its better to leave the plastics off and do more harm than good. I left the rear plastic half off long enough to get the carb setup right and make sure it ran well...no electrical loads were run on the generator while it was in this state.
Well off to the race track with the bike. I will give the generator a good work out running a fan to keep me nice and cool between sessions! Thanks again for your help you are the offical Yamaha generator guru.
Hi, my yamaha 1000 generator build up lots of hard carbon, especially on the exhaust valve. When it is carbonized, I can see lots of smoke on start up. After I clean the valve, it runs good and no more fumes. I took it appart and cleaned it up twice in 2 years. I guess it is the carburator adjustement that is too rich. Which screw do I have to adjust?
I read that you adjust it until it runs good at iddle and at full power with no load but which way do you turn the screw?
--It's not the whole manual, but it has enough info in it that you can test the main electricals and measure disassembled engine parts.
-- It also will NOT spoon feed a novice reader on how to do things.
--The complete wiring diagrams are priceless.
-- There isn't a USA section, but the Canadian one is nearly identical.
I have no connection to that website . . . I just found it on screen #3 search results.