SERIOUS 155z Issues.

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Peter1230

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Hey guys.

For about 6 or so months no i have owned a DHZ K1 with a 155z engine in it.

Since new it has had a really really strange gearbox. It had really stiff shifting and would hit false neutrals.. i put up with it and eventually got used to it.

But on the weekend it got crazy.. to the point where i wouldnt wanna get it outta 3rd. neutrals everywhere and almost impossible to shift with your foot and even hand.
I have removed the neutral sensor in the engine as reccommended by pitster pro. no difference.. i have checked that i bolt u replace it with is tight. i have tried more frequent oil changes. But i feel this is some sort of internal problems..
im going to strip it down this weekend and figure out what the hell is going on but i dont really know what im looking for.

So really and help or ideas would be greatly appreciated.
Have any other 155z owners experienced this... its like nothing ive ever felt before on a bike.
 
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yeah a mate of mine just replaced his 155z box cause his sht itself(196cc) but strangely enough the box he replaced it with (genuine 155z from dhz) is giving the symptoms you are describing at the start.
the only thing my mate didnt change was the shift drum and shift forks..tho he should of.

his is really stiff to get into gears and sometimes take 2 goes to go from neutral to 1st..
i said to him that he may have a shim issue or even a bent gear lever shaft..

but other things to look for is worn shift forks and worn dogs on the gears(they become rounded and dont locate the gear properly)...

another thing maybe is the detent spring isnt installed properly, its the lever with a roller on it that locks the star shift into postion. there is an allen key behind the kick start idler gear to remove it. firstly tho just make sure it isnt jammed or stiff to move.. it should spring back pretty easily.

apart from those i cant think of anything apart from a minor case crack in the usual places..
 
so does it sound it like an easy fix to you guys and do you know of any any videos or tutorials to pulling these enginges down or they practically the same to lilfans and that
 
The shift forks should sit evenly in the centre of the dog rings after a shift has been made ...

Each gear needs to be allowed to find its own centre since they float on the shaft and are constantly in mesh with their mating gear ...

If the bike has ever been dropped and the shift lever bent ... then chances are that the shift forks have ALSO been forced and bent ... and that can cause notchy shifting , jumping out of gear and false neutrals ...

When the forks sit in the middle , the dogs also sit deep enough in the slot of the female gear ... If a fork is bent or worn , the dog can hang out in a vulnerable position and wear quickly ... or break off ...

As Sean has stated ... the dogs round off from not using the clutch or not timing the clutch properly between shifts ...

Wide ratio trannies create greater impacts on the dogs than genuine close ratio trannies such as those in 2 stroke MX engines ... As a result you can get away with murder with genuinely close ratios ...

Chinese "close ratios" are not so "close" ...
 
a whole shift arm PBK... they're on ebay for like $60.... u get the whole shift arm with the selector forks attached
 
ok sweet cheers rip and i take it its gonna be complete strip down to fit? and should he replace anything else while its apart like the gearbox
 
no you just need to get the clutch cover off... and the clutch... then you can pull the whole arm out... it's pretty simple... maybe take a couple hours if you've never done it before
 
ok so ive read up on what use have said..

anyone got a link to a shifter arm, i dont think i would of dropped it on the gearlever before..
 
nah i dont think you have but as someone else said they could of come bent from factory they could of dropped the engine it could of got thrown around in the shipping container... but i suppose we will pull it out this weekend seeing as i have a 4 day w/e yesssss
 
i think everyone is mistaking the gear lever shift arm for the actual shift forks that are located on the gear drum..(which is what cactus is referring too)

if it were my engine and it was acting up since new then id buy the following..

PisterPro 155Z Engine Gear Box - DHZ Mini Moto
also this if it is an early engine (ken should be able to add the other gear set from the above link) Dirtmax YX 160cc 150cc Engine Bottom End Upgrade Kit - DHZ Mini Moto
Engine Gasket Kit, GPX YX 150cc 160cc PitserPro 155Z engines - DHZ Mini Moto
ask ken for one of these to suite the 155 (maybe the same as the link)GENUINE YX 140 150 160 CC ENGINE SELECTOR FORK ASSEMBLY - eBay Other Makes, Bike Parts, Motorcycle Parts, Accessories, Cars, Bikes, Boats. (end time 12-Jun-10 17:39:56 AEST)

tho you may vary well be able to get away with just a gear lever shaft tho, so sus it out first.
youll know if its bent cause it will be hard to slide out of the engine..

to do the shift drum the engine has to be split and may be a good time to do the rings too if its got some hours on it.
but if your not then you can cheat and remove the barrel studs in the clutch side engine case so you can leave the barrel and piston untouched and still in the bore...
 
ok, put it this way..

the shaft the gear lever bolts to is the gear lever shaft. if that is bent then it can create similar/same drama's as what you have described..(possibly all your problem is but wont know till you rip it to bits)

if its not bent then the problem is internal..IE..your engine needs to be fully stripped to bits to inspect and repair..
if this is the case then i would replace everything in the gearbox...gear drum/shift forks and both clusters of gears (counter set and main shaft set).
and if it hasnt got the upgraded case then now is the time do do it..

this is a manual of the new 155z and you should be ok to use as the only difference's is in the clutch area.. http://www.dhz.com.au/usermanual/ZS-155CC-engine-diagram.pdf
ill try and find the manual for your version
 
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thanks heaps sean..

Lets hope its the shaft.. it should have the upgraded case.. im pretty sure myn was the 2nd batch of them..
 
I thought all the zongers had the upgraded case?

And nice work on the engine :grinning-smiley-003
 
Hey peter i have the old 155z manual shoot me a pm with your email and ill send it through to ya
 

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