who knows about minibikes

[lb99]

I have a Honda z50j for the kids, every so often the idle speed heads for the sky.... the carb has been stripped and cleaned, and is set up just as it says in the manual, no jets are blocked, the float level is ok, and the fuel is fresh, and the throttle cable has the correct slack in it. any ideas?

[Qkchk]

Maybe CDI trouble?

[Sensei]

Own a 74 Z50a sounds like an air leak or the spring is not sitting correctly in the slide check this . For air leak start bike let it idle then spray some CRC around the inlet manifold if the revs raise then its sucking in air . Replace the gasket & check again Lets know how ya get on . My Z50 has Ported head Hand made race pipe made by me & runs on Avgas does over 50k with me on it :Punk: .

[lb99]

My Z50 has Ported head Hand made race pipe made by me & runs on Avgas does over 50k with me on it :Punk: .

50k!! I hope yours has better front suspension than mine!!

I tried the crc thing, it didn't show up any leaks, I was getting pretty stressed, so I removed the carb and manifold, made a new gasket, and used silastic on the O rings. It must be sealed now.
still does it :no: you just get the idle sweet then vroooooooooom, its driving me nuts.
the only way to get it settled down again is to wind back the idle screw again, then after a few seconds, it dies and is hard to start.

[Sensei]

Are the valve setting right ? Take the carb of the inlet & check the slide is not sticking in the carb anywhere & check the throttle is free on the handlebar as well as the cable returning freely . Slide in the right way round ?

[lb99]

as in clearances?
I havent checked those yet, the cyl head is quiet-maybe too quiet....

the book I have says .05mm cold
is this right?

where can I get parts from, Honda are way dear, if they even want to help.

rings, fork bushings ect....

[Trakxntrials]

I suggest you contact Malcolm at Econohonda - he is based in Te Aroha. He stocks the largest range of Honda new and secondhand and patterned parts also. He is quite resonably priced and very helpful too. 21 Kenrick Street, Te Aroha. Ph: (07) 884-8810.

[Motu]

Make sure you can hear that slide click down everytime you shut the throttle with the engine off,and make sure there is sufficent pressure on the slide as you push the top down onto the body - the last one that did this to me just needed a little stretch on the spring.

If not I think you should take another look at the float level,often with a motor used in as many models as the 50cc Honda,specs vary wildly....and might not be right for your model.Here's what I do if I don't know the float level - start up,warm up,then turn off the fuel tap and let idle until it stops....if the revs get higher before it stops the float level is too high,if it just stops it may be too low.So go high and bring it back down,until it just gives a slight raise in idle speed before dying.Takes time I know,but you got plenty of that to spare....otherwise you wouldn't of bought an old bike eh?

[skidMark]

on my lifan mini...

z50 replica i had the problem of when i turned the bars to the right give it a rev and it wouldnt rev down is say check if it only revs up when bars are turned a certain way and also check your slide and pull off your cable if you must and make sure it is not binding on something because something is obviously stopping the slide from going down fast

possibly it is going down but really slowly so check that and make sure the cap for the slide is done up tight you don't wan't air leaks there

and also check that where the needle is in the slide that is has the little wobbly piece of metal that keeps the needle in the slide or else it will move around possibly ...

also check your mixture screw bacuase sounds like way to much air...

turn the mixture screw all the way in but not too tightly or you will stuff the needle and turn it out 1.5 turns ... if there is a high and a low jet set the low to 1.5 turns out from full in....and the high...1 turn from full in

remembering that adjusting this will affect your idle as well so it will idle faster/slower by adjust your jets... adjust accordingly

get back to me on how you go with trying those things

before you check all your throttle cable check your mixture if that doesnt help then check your slide and cable best to take the air filter off and look at it while you open and close throttle and also look at it with handle bars in different positions

on the slide when you check the wobbly clip look at the needle and make sure the circlip is in the middle slot on the needle as this is usually the factory setting is this is wrong it could cause problems

hope that helps...

Cheers : Mark

[zadok]

All I know is, is that they are small. :motu:
Sorry :o

[lb99]

the carb has a plastic float, I'm used to the old brass ones that you can bend to suit, but the manual I have describes the same float setup as I have, but not how to adjust it, it just says 12.5mm.
The guy I got it off said he had set the valve clearances, so he may have got it wrong, could that affect the carb?, like if the inlet was not seating properly would that suck the slide open?
I have gone over the lot several times and I am sure it is all set up correctly, but I know I'll get it evenually. Anyway now I have an excuse to hide in the shed with the beer fridge :whistle: .
can anyone offer me an exhaust system?, it does'nt have to be mint, but all I have is a short header with a lawnmower muffler on it, works ok, but it could start a grass fire :nono:

[Sensei]

Hey lb99 Just a couple of pic's of the Z50 The pipe's are very easy to make . I run mine straight so as to get to best power increase .As above check the Neddle clip as this could course some trouble .

[lb99]

I pulled the top end apart, this motor is still nice and tight, but the comression rings are smashed to bits.
I am quite pleased, because now I know what's wrong.
The bore, piston, and oil ring are still sweet, so it must of only just happened.

Can anyone suggest a reliable supplier on the net?

[Motu]

And why are the rings smashed? Detonation springs to my mind.....find the cause before you repeat the same.

[lb99]

the ignition timing is ok, the piston crown is ok as well, it could be leaning out on full throttle, I suppose.
I have given it a good hammeing at times :Punk:

Motu, do yoy want to buy a tool for dismantling the forks on your XT?

[Motu]

Motu, do yoy want to buy a tool for dismantling the forks on your XT?

I've already done the forks....did I miss something?

[lb99]

I made a tool for holding the innards of the XT forks in place while you undo the bolt at the bottom, but I dont need it anymore as I dont own an XT any more