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JZ Engine build for the road?

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  • JZ Engine build for the road?

    Hi all,
    I just picked up my second Monkey - a 1980 JZ which will be restored to look stock, but I want a 'nice' engine build to handle some miles and be 'safe' on the road.
    I'm restoring my '77 J1 to be 'out of the factory' so will be stock 50cc, but, my JZ, I want to ride more on the road so will need a bit more power &, I'll be replacing stock suspension with Takegawa shocks and fork inserts.

    Basically, after looking through dyno section here, and reading a few things, I'm a bit unsure of which way to go with the JZ engine. Basically I want a bullet proof engine, not 'TOO STRESSED', that I can ride 'safely' at 80kph, for a ride to my local hinterland cafe which is a 70km round trip. It's a 90kph country road, but I ride my old pommy bike on it at 80kph with no issues holding people up. I'd say, if the monkey can do 85-90flat out, it should be ok to cruise at 80ish.

    So, would a 88cc with stock 3 speed do that? Or 88 + 4 speed? Or, do I need a 108 and 4 speed? or ??? I'd like to be able to do that 70km ride a couple of times a month, so kms would add up, so I don't really want a full blown race engine that wears out in 5 mins. There is a couple of decent hills on that ride though.


  • #2
    Further thinking - and investigation of the Dyno threads.... It would seem that 90 odd kph is achievable with a Takegawa 88 kit and race head. Am I correct in believing that the 88 kits install without needing to bore the crank cases? Also, I'm thinking that if I can keep the 3 speed, that would save me some money initially to speed up the restoration process.

    So, what say you?
    High volume oil pump, Take 88 top end including race head, and Take auto clutch + 20mm carb? or TB equivilent ? Will I be able to run it 80kph flat out?


    • #3
      Agree that an 88cc engine will do the 90 odd km/h you require, but, when you get to a long hill you need more power and more gears.

      save your coin and go for a 124cc with a 5 or 6 speed gearbox and that will do everything you can think of.


      • #4
        Cheers Monkiesuncle. I guess it'll come down to $. I also like the idea of modding my 50, myself, but totally aknowledge the benefit of dropping in a Daytona engine!


        • #5
          Bang for buck tb108 4 speed with manual conversion especially if your keeping it 6v will get (10hp) and good torque for hills, if going to 12v then spend the money and go to the taki range but pockets will need to be deeper. remember its not just hp the torque is what pulls these bikes along, personally I find the 88kits you will end up ringing the neck out of them when doing 90km/h range all the time, best all round taki combo I found would be the 106 and they work well both with 4 & 5 speeds.


          • #6
            Thanks Alfie - I'd like to stick to 6V if I can - just got MonkeyPower to make me a 6V harness! I can't for the life of me understand why I want to stay 6V otherwise.... ahahahaha.

            So, TB108 will be my go to.
            I'd like a better option for a 4speed box than the AHP though. I've read that the ratios are a bit silly, and not particuarly durable? But can't seem to find a 4 speed Taki or similar??



            • #7
              Honda OEM 4 speeds work well if you can get hold of one.


              • #8
                Thereís about a trillion engine gearbox options. To get the good speeds etc, like the others have said, an 88 will get you there. A four speed would be nicer. I have a TB88 with Honda 4 speed and itís nice to ride. Will get to 80kph and has enough zip to get you into trouble. I also have a Takegawa 88 with 5 speed. I donít think Iíve ever got to fifth, so donít waste your money on a 5 speed unless youíre planning on going big bore later on.


                • #9
                  OEM 4 speeds? What are these mythical creatures? Is that a later model z50 bottom end?


                  • #10
                    some ct70's had a 4 speed also sl70 i think it is. old 1970's bikes
                    You have two parts of brain, 'left' and 'right'. In the left side, there's nothing right. In the right side, there's nothing left.


                    • #11
                      Most import monkey bikes has 4 speeds too
                      still learning.....