Valve Job??

Discussion in 'Mechanic and Repair' started by turfinator, May 5, 2002.

  1. turfinator

    turfinator LawnSite Member
    Messages: 78

    I've got a 5hp engine on my Power Rake that has become almost impossible to start. I change the filter, plug and oil often. I even took the head off and removed the carbon and checked to make sure the valves were operational. I have tried starting fluid with mixed results. It seems to take alot of attempts to start it. I've had better results trying to start it with choke on then off, back and forth about 20-30 times with the filter off. The starting fluid doesnt seem to make too much of a difference. When I pulled the plug it seems to be getting a decent spark. When pulling the starter rope the valves seemed to operate properly. I also cleaned them up as good as I can. Unfortunately all of my mechanical experience has been with 2 stroke dirt bikes so I'm not at all familiar with valves. I have gone over everything I can think of with this engine, so I'm left guessing its needs a valve job. Is there anywhere on-line that explains this procedure. Can it be done without taking it to a shop? Sorry this is so long winded but I just replaced one engine and hope I dont have to do the same with this one

  2. sdwally

    sdwally LawnSite Senior Member
    Messages: 386

    Usually behind the carb is a plate the allows access to the valve springs. Check the clearance, about 0.007" intake and .011" for exhaust. You will need a small valve spring compressor, coarse and fine lapping compound, and lapping tool(stick with suction cups at each end.)
    Adjust clearance by using a grinding wheel. While spinning the valve, lightly touch it to the side of a grinding wheel on a bench grinder. Only remove small amounts at a time.
    Use the coarse lapping compound on valve seat area to start. While spinning the tool between your hands(back and forth), apply light pressure to lapp. Occassionly rotate valve about 1/3rd turn and continue lapping. After a rotating valve completely, clean seat area with dry rag, seat area should be completely polished, if not continue with course compound.
    Once full contact is aquired use the the fine lapping compound in the same manner.
    Recheck clearance. Replace valve springs(keep valve spring separated(intake and exhaust springs are normally different.)
    Best of luck.
  3. Russo

    Russo LawnSite Senior Member
    Messages: 287

    Holy moly. I believe I would check for water in the gas, or worn seat ( or diaphram ) in the carb, or fuel filter, or some simpler things to narrow it down before I voted for a valve job. Have you checked this stuff? I concede that it appears that you know about engines than me, but I didn't know if " I checked everything else" included these items.
  4. floydboy

    floydboy LawnSite Member
    Messages: 24

    Have you checked the flywheel key. If it is bent, worn down or damaged in any way it can cause the unit not fire at the right time. There are only 3 things that run an engine. Fuel, Fire, Compression. Check each one.
  5. khouse

    khouse LawnSite Bronze Member
    Messages: 1,465

    remember to remove the carb from the tank as the tank has a built in bowl in it. This may be where the water and trash have landed. There is really 2 diaphrams to this carb. You should buy a carb kit and install it to help narrow down a fuel problem. This is assuming that it a Briggs?
  6. turfinator

    turfinator LawnSite Member
    Messages: 78

    Ive removed the carb bowel as well as the bowel retaining nut and cleaned both. I havent removed it from the tank though. What type of diaphram is located in the tank? Are there any schematics available for this and the carb. I know I need to buy a manual. This is the type of engine:
  7. khouse

    khouse LawnSite Bronze Member
    Messages: 1,465

    There is no fuel bowl on that carb. Where the carb mounts to the tank - that's where the diaphram is. You must remove the carb from the tank.
  8. turfinator

    turfinator LawnSite Member
    Messages: 78

    Your right I got this motor mixed up with my IC motor that was giving me the same problems. Everything else is accurate minus the carb info. Once I remove it from the tank what is the proper method of cleaning?
  9. khouse

    khouse LawnSite Bronze Member
    Messages: 1,465

    Get the carb kit first. You may need to scrape the resivour out with a dull screw driver or small wire brush. Then spray it out with brake cleaner. You may need to do the same with the tank.
  10. turfinator

    turfinator LawnSite Member
    Messages: 78

    Where is the resivour you are refering to?

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