Which to rebuild? Honda GVX630 or 670

Discussion in 'Mechanic and Repair' started by kansan, Jul 22, 2014.

  1. kansan

    kansan LawnSite Member
    Messages: 2

    I thought i was getting a great deal. A Hustler mini z with a gvx670 (600hrs) that needed a little work. Bad motor. But the shop owner gave me a "new" gvx630, said that he'd robbed a couple parts but they would interchange.

    Tore down 670 and have 2 broken piston rods and broken camshaft. A couple nicks in the block, but overall looks fairly unscathed. Parts will cost around $750.

    Start to look at 630 and realize there is no intake, exhaust mani., missing coils, missing stator. Cost to secure these parts is about $650.

    630 is almost new, run barely long enough to put soot in exhaust port, but only rated at 20HP. 670 has 24HP and is setup to go on the machine.

    Which motor should be invested in? I am new to this and have never dealt with Honda small engines.

    Thanks in advance.
  2. tundraman

    tundraman LawnSite Senior Member
    Messages: 892

    If the 670 gave out in 600hrs how long do you think the 630 will last if you are able to mount it?
  3. JimQ

    JimQ LawnSite Bronze Member
    Messages: 1,139

    Put the 630 back together. It sounds like the 670 really came apart.

    You'll never notice the difference in HP.

    Nearly new engine for less $$$.

    Good luck with your project.

  4. kansan

    kansan LawnSite Member
    Messages: 2

    I believe if i keep the oil level where it's supposed to be it will last longer than 600 hrs.

    Is there a reputation for either of these engines? Good or otherwise?
  5. ilike2mow

    ilike2mow LawnSite Bronze Member
    Messages: 1,032

    I would say go for the 630. If you only need to get those few parts then go for it! That's interesting to see a Honda blew up in only 600 hours.
  6. BigFish

    BigFish LawnSite Platinum Member
    Messages: 4,191

  7. ilike2mow

    ilike2mow LawnSite Bronze Member
    Messages: 1,032

    Honda engines have a good reputation and burn very cleanly.
  8. tundraman

    tundraman LawnSite Senior Member
    Messages: 892

    I would rather overpower a machine than underpower it. If the 630 was made for that mower it should fit. Honda makes good motors, I would just make sure you are putting the proper motor on the machine.
  9. Downunder Bob

    Downunder Bob LawnSite Member
    Messages: 115

    I would repair the 670.
    My 52 mini uses all the hp it can get.
    I'm coming up to 700hrs now and noticed the engine with a few oil leaks. I started off thinking top and bottom seal but ended up changing pan gasket, governor seal, dipstick and oil filter O-rings.
    In those hours I have replaced a coil, plugs and a bottom seal twice.
    Every seal and o-ring just about fell apart in my fingers. I just feel the design of the mini back then sat the motor low in the frame and surrounded it with a lot of heat.
    That's why I put a couple of coolers on.
    I have never owned a Kawasaki so I can't compare and besides it all depends on the machine the motor goes into and the maintenance it receives, but I still feel my old design Honda 670 has been a very reliable engine.
    After saying all this, my luck, next week it will probably fly apart.


    mini-z side (800x600).jpg

    52 mini-z oil cooler .jpg


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