Honda generator repair

Discussion in 'Mechanic and Repair' started by Rick1, May 20, 2002.

  1. Rick1

    Rick1 LawnSite Member
    Messages: 5

    I have a Honda EMS 4000 Generator. It started to run rough lately. I cleaned and rebuilt the carb with a new needle, seat and float. The spark plug fouls after about 8 hours of run time. Now it is starting to consume oil. I am adding oil every 2 hours of run time. The spark plug is still fouling - very black. A compression test show 50 psi. Does the engine need rebuilding or are there other options? How hard are these engines to rebuild?

  2. sdwally

    sdwally LawnSite Senior Member
    Messages: 386

    With 50psi, it surprising that it even starts. With what you have described it time for a rebuild more than likely. It sounds like the rings are shot since you are using so much oil. Typically this would mean new pistons and rings, bearings, seals, boring the cylinder, and having a valve job done. Its not rocket science, but is for the very mechanically inclined. Apart from the teardown and re-assembly, you'll need to measure the bore to determine the proper oversize piston to order and measure the crank journal to determine if it needs to be ground and an undersized connecting rod/bearing ordered.
    On a 4kW generator, a rebuild will normally be cheaper than an engine replacement, if you do it yourself.
  3. khouse

    khouse LawnSite Bronze Member
    Messages: 1,465

    Your engine may have compression release so a compression test may not give you the correct reading. But from what you said about plug fouling you may need to rebuild the engine. By the time and money to rebuild the engine as stated above you'll have a lot of money in it. Since it's a Honda you will most likely get by in buying a gasket kit, pto crank seal and a set of standard rings. Since your doing it yourself leave the valves alone. These can be done at a later date if needed. Even if the cylinder is worn (not scored) just install the new rings and it will give you several years of service. Get a manual and follow the instructions on ring replacement.
  4. Rick1

    Rick1 LawnSite Member
    Messages: 5

    We were running the generator last night. It was using a lot of oil. It finally quit and would not start. At first I thought it was the plug fouled again. After pulling the starter a few times, it seems to not have any compression at all. I also noticed gas fumes coming out of the carb when starting the engine. Would this indicate the intake valve is bad?
    Should I do a leak down test or at this point is this test usless? If I rebuild the engine, should I have it bored or use a stone to remove the glaze from the cylinder walls? If the valves need replacing, does this need to go into the shop or can they be done lapping by hand? What are the pro's and con's?

    Thanks again.
  5. khouse

    khouse LawnSite Bronze Member
    Messages: 1,465

    I didn't want to get into all the things you need to do to install new rings. That's why I said to get a manual, but yes you need to break the cylinder glaze with a hone. Lapping a bad valve won't fix a burnt valve. First remove the head and inspact the cylinder for heavy scoring. Then rotate the crank and visually inspect the valves and seats. If you need to do any valve work then you can take the tore down engine to a shop for seat cutting and valve grinding. If you have major problems like heavy scoring in the cylinder that doesn't clean up good by honing then I would suggest a short block.

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