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GPX 600R Crankshaft

Trojan441 May 29, 2019

  1. Trojan441

    Trojan441 Well-Known Member

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    Thinking of fitting the lighter n' stronger GPX 600R crankshaft in my ZL 600A engine build, anyone done this before?
     
  2. Trojan441

    Trojan441 Well-Known Member

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    Plus con'rods pistons n' barrels!
     
  3. Trojan441

    Trojan441 Well-Known Member

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    FYI:
    GPX 600 is post 1987 circa 1988 version of the GPZ 600 with engine revisions including a 10 bhp higher power output, a claimed 85 bhp @ 11,000 rpm. Importantly, the Head has lighter Inlet valves with revised porting; the pistons are lighter, the con-rods are chrome molybdenum n' the crankshaft I believe was lightened n' strengthened and the frame is different being double cradle based on the the GPX 750, with also 38 mm forks, a different fairing and balanced upgraded brakes.

    Breakers, salvage dealers often in their adverts put GPZ, GPX ZX on their parts "Banner" e.t.c, but the GPX is a different beast from the GPZ and a more upgraded product in every way, forced onto the "market by the birth of Honda's CBR 600F in 1987 which was faster, handled better n' had a higher top speed circa 140 mph than the earlier model GPZ 600. Kawasaki had seen how the 600 cc market, rapidly altered allegiance to a rival company in this case being Honda!
     
    Wissler likes this.
  4. Trojan441

    Trojan441 Well-Known Member

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    GPX barrels & complete set of pistons arrived, just awaiting complete crankshaft n' connecting rods it means the ZL 600 A stuff can be refurbished n@ worked into another engine!
     
  5. Trojan441

    Trojan441 Well-Known Member

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    Crankshaft now received too!
     
  6. 87kawzl

    87kawzl Supporting Member

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    Are you doing any head work to the ZL, using a different head or just swapping internals? The heads on the big gpz or zx (I forget the specific one) have a different angle on the carb port and the carbs would hit the frame (so I've read). Watch for that if you're looking to swap heads.
     
  7. R. J.

    R. J. Supporting Member

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    :hello: Madman put a ZX 1100 motor in his ZL 9. The carbs do clear the frame but he had to run pods.
     
  8. Trojan441

    Trojan441 Well-Known Member

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    Thank you for the information, but I have no plans to swap the cylinder head , but I think on the 592cc bikes the heads are all the same except for the inlet ports being 30 mm on the ZL and 32 mm on the GPZ/GPX respectively. The smaller inlet ports breathe better in the main through out the rev' range except @ extreme top end scale 9,500 rpm & above. The GPX 600 pistons are even more trimmed down than the GPX 750, (Ninja 750 R), & completely different at the top from the GPZ & ZL variety. Both the 592 cc GPX , GPZ & the ZL heads copy the earlier GPZ 900 R valve trains in operation & adjustment & are unlike the GPX 750 lay out, which incidentally has a later specifically designed 748 cc engine unit for some new Racing class introduced @ that time.
     
  9. Trojan441

    Trojan441 Well-Known Member

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    Compression of the GPX 600 pistons is 11.7:1 As soon as I free up some phone memory or find my Digital camera I will take some photos!
     
  10. Ed

    Ed Active Member

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    Isn't the GPX motor pretty much the same as the ZL600B? The '96 motor might even be an updated version. If the compression ratio is the same, the old GPX motor has no advantage other than better breathing thru carbs/airbox and exhaust for more HP.
     
  11. Ed

    Ed Active Member

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    The heads are different but the cams same. The GPX probably requires higher octane. A late model ZL with the higher compression GPX head and lighter rods would be the easiest route. I don't believe there are any other improvements between the GPX, ZL600A or B that are power related. Parts like the camchain tensioner and such that were prone to failure were updated but not much more.
     
    Last edited: Jun 11, 2019 at 12:28 PM
  12. Trojan441

    Trojan441 Well-Known Member

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    Would have to weigh both crankshafts to find out if there was a difference between ZL/ZX/GPZ unit & GPX crankshaft, however, the GPX Connecting rods are stronger Chrome-Molybdenum, the pistons are trimmed , lighter n' higher compression 11.7:1 , more like a slipper piston n' the valve cut-outs extend all across the piston face & not like Valve cut-out pocket pattern on the other 600 cc pistons. I didn't want to use a GPX Cylinder head as you loose all the increased gas velocities set up by the smaller Carb's n' Inlet ports. This gives more Bhp in the Low range n' Mid range and is an big advantage on the road, that is power, where u need it . So I wanted to keep the ZL 600 A head in place
     
  13. Trojan441

    Trojan441 Well-Known Member

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    Pistons! GPX variety. Screenshot at 2019-06-11 21:59:14.png
     
  14. Ed

    Ed Active Member

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    I was comparing a different model with same pistons as the later ZL. I take it you did all the research to make sure bore/stroke are compatible. They changed throughout the years and seem to be all over the place.
     
  15. Trojan441

    Trojan441 Well-Known Member

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    Screenshot at 2019-06-11 22:06:15.png GPZ/ZX/ ZL Screenshot at 2019-06-11 22:06:15.png Pistons
     
  16. Trojan441

    Trojan441 Well-Known Member

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    Various websites have data sets about the 600 cc bikes but I think some R wrong. To me what happened to the displacement of the 600 cc engines was a compromise of production logistics and Racing class stipulations in which usually the engine must be slightly less than the capacity class.
    Firstly, the crank throw of the old air-cooled 652 cc KZ/Z 650 was 54 mm. The first generation Liquid-cooled 600 was 52.4 mm not much difference & to keep the 600 cc engine under 600 cc you cannot have a cylinder bore greater than 60 mm, using the usual increases of 0.5mm & 1.00 mm piston size graduations. This means in the highly competitive 600 cc class, the ZX/GPZ/GPX engine was 8 cc down from the class limit & 6 cc down on the Honda CBR 600 F, (Hurricane), little bit of a gift the extra cc's if you R racing!

    So unless they were very special, all First generation Liquid-cooled 600's are 592 cc, (60 x 52.4 Bore & stoke).
    Kawasaki didn't make the same mistake on the next generation complete engine redesigned ZZR/ZX-6, the bore & stroke was 64 x 46.6, giving 599 cc!

    Funnily enough earlier on 1986-ish the all new ZX/GPX750R had a crank throw/stroke of 51.5 mm.
    As for the ZL 600 B engine, surely it would be strange if they used GPX components as I have never as yet seen a 600 cc ZL with
    GPX type pistons, plus the power drop to 61 Bhp indicates to me the ZL 600B model was just a "cooking" model, perhaps using up engine components n' bike parts previously stock-piled.
    Has anyone run a ZL 600A against a ZL 600 B model to see how they perform against one another?
    Pollution controls, n' running engines "lean" does lose power n' cause all types of issues including excessive heat, ( think of the Harley Davidson "V" twin emissions saga!
    But the reason I was looking at the Carb' data was to see if there was any clues to what had gone on between the different models because according to data, the ZL 600 B puts just about 6 Bhp more than the ZL 400 A & is 198 cc greater in capacity! Granted it will be a more flexible engine n' have more grunt, perhaps by the mid-90s the EPA were strangling performances down to a point where the old 592 cc engine introduced in 1985 in he ZX/GPZ 600 was castrated to meet emission requirements. If everything that caused the drop in power is down to the Air-box n' exhaust/ silencer system , though I would think carburettor internals would vary too, it was/is certainly some de-tune!
     
    Ed and R. J. like this.
  17. Ed

    Ed Active Member

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    In the years you mention there were a lot of ZX models using similar components and HP figures as the old GPz600. I haven't compared individual part #s but I bet you could use parts from any late 600 engine that has a centered camchain. I assume they would have the same spacing.
     
  18. Trojan441

    Trojan441 Well-Known Member

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    The 592 cc engine is based on the old air-cooled Central Cam-chain, ZX/GPZ 55O cc unit, Kawasaki Liquid- cooled it of course, introduced 16 valves & used a scaled down head & valve mechanism off the GPZ900 R/ Ninja.

    But again inter-changeability of parts is restricted as Kawasaki altered the Bottom-End in that on the 592 cc unit the bore-centre spacing of Cylinders 2 & 3 are 1 mm closer together, so the crankshaft on the older unit does not line up with the later 592 cc unit

    I know that the 98 Bhp ZX-6 /ZZR circa 1990, engine with a central cam-chain is a completely different beast & has very few interchangeable parts.

    Then in 1995 due to pressure from Honda's CBR 600 R they brought out the ZX-6R Ninja again a completely different engine, Off-side camshaft drive , 599 cc 66 x 43.8 mm, 30 mm narrower crankshaft, 5 main journals instead of 6 (ZZR), on the ZX-6R, transmission distances, Crankshaft/Driveshaft/driven shaft were shortened, ; bigger vales, valve angle 25 degrees, pent-roofed combustion chambers, cylinders canted forward.

    In short Kawasaki threw shed-loads of money @ the 600cc class to try n' outpace Mr Honda, who was quoted as saying, " No one steps on the tail of the Tiger"! Until Japan de-restricted the Home Market Licensing rules, (not sure when this happened), the most important class in the Home market was the 400 cc displacement class n' apart from specialist production for racing class machines & rules it is reckoned that both he 400 cc & 600 cc category's had more money thrown @ them than any other! Before then the 250cc Class had been crucial to sales n' Brand loyalty; but in 1981 in the UK they restricted learners to 125cc machines so that Class started to fade away in importance. In the mid-70s the 350 cc displacement, moved up to the 400 cc mark creating a completely new market for smaller middleweight machines. The rest as they say is just history!
     
  19. Ed

    Ed Active Member

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    Ok , I see the different configurations on the parts diagrams. Models A and B were the original ZX motors and also used in ZL600s. From '88 to '97, the C model used different valve guides, intake valves, pistons and rods. Bottom end (including crankshaft) is the same as late ZL and cylinder head might be different but it could've gained the claimed increase in flow with just the change in valves and guides. There's no part # for head without those parts so don't know for sure. Were the intake valves a different size or just a different material or both?

    So, models A, B and C parts are interchangeable ('97 C10 was the last GPX). Models D and E used the central cam drive but completely different engine. Models F- ? cams were driven from the right side.
     
  20. Ed

    Ed Active Member

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    There's also 3 different ignition rotors. The ZL used 21007-1130 (12 degree) and 1135 (8 degree). The GPX used 1159 (10 degree) and the 1135.
     

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