Welcome to Netrider ... Connecting Riders!

Interested in talking motorbikes with a terrific community of riders?
Signup (it's quick and free) to join the discussions and access the full suite of tools and information that Netrider has to offer.

GPX engine into GPZ250R lives!

Discussion in 'Technical and Troubleshooting Torque' started by Heinz_Guderian, Mar 3, 2008.

  1. I had to post because yesterday I finished the hard bit of a project that's been dogging me for a few weeks.

    A bike-illiterate friend of mine bought an 86 GPZ250R rat bike at the auctions. He was assured it worked and it even had a 2-week old inspection certificate. Except, it didn't: when a mechanic eventually started the engine for him, it had death rattles indicating top and bottom end damage. The steering head bearings were shot to shit (anyone got any 90-130-01s?), quite a bit of repaired crash damage evident (welding on the footrest hangers, straightened handlebars). The blown fork seals were hardly worth mentioning.

    On the up side, the bike was straight and complete, had excellent tyres, chain/sprockets, and my friend loved the oddball GPZ2-R styling.

    With wifey hacking at him for wasting money on the bike and the couple of hundred in spare funds not extending to paying a mechanic to install a new engine, it was decided that he'd get a motor from the wreckers and I'd install it. Although I knew there'd be dramas and I didn't know what they were (er, 'known unknowns', as Donald Rumsfeld used to say), finding a GPZ engine was clearly a challenge so we went for a GPX motor.

    Putting the engine itself in was very easy, the trial and error of what parts had to be brought across from the GPZ took a bit longer.

    In the unlikely event that anyone is attempting this, you need to put the GPZ flywheel and ignition pick-ups onto the donor engine, which will make it plug into the original CDI (so you don't need the GPX CDI). This could possibly apply to doing a swap between GPX and ZZR.

    This week we'll do the steering head bearings and the fork seals and then there'll be one more of us on the road- for $1600 so far all-up, we should be riding for a bit over $2000 with rego, which probably isn't too bad.
  2. coool nice to see somone doing some reel mods.

    btw for some awsome rat bikes

    awsome tip about the pickup it will save someone some cash
  3. $2,000 on the road, pretty good going I reckon. :cool:
  4. Two things that you should bear in mind with that old GPZ engine.
    1. The GPZ had 32mm carbs - Now almost unobtainable as for the most part they have all been wrecked or replaced over the years.
    2. They had a different cam grind to the GPX.
    These two things allowed the GPZ to put out a claimed 4 horses more than a GPX.

    Have got a few GPZ items banging around the garage. If you are after something in particular let me know if I can help.

  5. That's interesting...every GTR1000 has FOUR CVK 32's under the fuel tank.
    Clearly you weren't looking hard enough...........

    Regards, Andrew.
  6. Interesting. We have the old engine so maybe a cam swap will bring out that awesome power.... but I'm not convinced the old engine is GPZ as the engine number seems too high and it could easily have had a dozen engines in it.

    Bike was ridden into the scenery last week (new rider a bit too ambitious and not realising that having to really concentrate means a whole new thing on a bike... just a momentary lapse after 1 1/2 days' riding).

    Looking for right side fairings front and rear, tank cover, mudguard assembly, mirrors.
  7. u might be able to repair the fairing cheaper than payin for new ones. Depends what wreckers in your area charge.