Smoken DHZ Zongshen 140

[azar]

Hi Guys, new to the website and forum. Just bought an 08 DHZ 140 with the Zongshen motor. Picked it up cheap with the idea of fixing it up for my kids. It runs at the moment but makes more smoke than a blue light disco smoke machine and leaks oil/smoke thru the exhaust manifold but other than that is in ok nic. Just ordered rebuild kit and was wondering if there is anything else I should be looking for or at doing while I have the engine apart? Not looking at mods for the moment just want a reliable bike. Love the website, heaps of great info. Thanks

 

[DvDRip]

DHZ pitbike 140cc Zongshen - eBay Other Trail Bikes, Trail Bikes, Motorcycles, Cars, Bikes, Boats. (end time 02-Feb-10 13:42:26 AEDST)
you bought that didn't ya?

what exactly did the rebuild kit come with?

you're gonna need to hone the bore and replace piston and rings, new head and base gasket. check the valves are ok and lap them in, valve stem seals would be good too. new exhaust gasket.
change the oil and ideally flush the sump, use castrol activ 4t mineral oil


once done should be good to go give the carby a tune up and put a clean oiled unifilter on and go over the bike to make sure everythings up to scratch

 

[azar]

Yep! Have everything you just listed coming plus a couple of other bits. Pulling the engine apart tonight.

 

[azar]

Strip the engine down last night. Timing chain guide roller had a seized bearing and the chain had chewed out the roller, oil wiper ring shot but other than that not to bad. Anyone know where I can get a new timing chain roller from can't find one ebay or web??

 

[sean01]

you could try this ebay seller eBay Australia Shop - JR Just Ride: pit bike part, pitbike, dirt bike

not listed in his store items but i recon he would have one...you may have to send him a pic of it..

failing tht throw a pic up of yours and we ll see if we can match it.. also add measurements of it.

 

[DvDRip]

i'm pretty sure I got one, not sure what motor from

 

[azar]

Hi Guys, Update, Got all the parts together and bolted the engine back together and it has run beautifully for 2 weeks now. Then today I noticed it wasn't sounding right and running a little ruff, took it into the shed to tinker. With the engine running in the shed the exhuast pipe was glowing red hot! Is this normal or have I got a stuffed valve? Thought I'd ask the question before tearing engine down again. Thanks

 

[DvDRip]

carby is out sounds like you're running way lean, get an oko
check the valve clearance too if you haven't already

 

[hman]

also check that the exhaust is tight in the head and the inlet manifold is not leaking at the head. if there is an air leak it will run lean and the pipe will glow. if the bike was not doing it before the rebuild it should not be the carb.

 

[motoluver]

ive seen a few pittys exhausts glow when been pushed hard. Ill check my rx's exhaust and see if it glows when riding home from work tonight.

 

[azar]

Thanks for the info guys. It supprised the s*** out of me! Is any one wrapping their exhaust? Whould hate to touch it, serious burn potential. Have reset valve clearances, exhaust valve was out a little, will give it a good check over, bike was running really well before it went off song. Then onto the carby!

 

[azar]

Ok went and played no visable leaks. Pulled carby and it all checked out, all ok. Started up and its not sounding great, sounds like a rattle in the engine, backfiring a little and bogs down when you open the throttle. It idles ok for a while then pops and dies??? Have backed out the air meter screw 1 full turn, jets are 20 n 100.

 

[sean01]

check ya tank breather, it may be nearly or totally blocked...
when you pulled the carb apart did you disassemble it completely and blow out with compressed air?
also did ya check the float height?
and what setting is the slide needle set on...
maybe go a little more on the mixture screw too...
also check the plastic carb spacer between the carb and the manifold, they crack and sometimes the oring goes to sht..

other things to try is another plug,cdi,coil.. iv seen cdi's let an engine idle fine but try and rev it and it will stall or splutter like hell.

as for the rattle, check ya valve clearances while slowly pushing down the kick start(remove spark plug so its easier)
iv seen engines where you set the valve clearances then do a couple of rotations on the engine then the clearances are either massive or none. not sure what causes it but reset them where the clearances seem the largest... then recheck in the normal location

also just check ya cam timing, 1 tooth out can let it run but also let the valves come close or even touch the piston...would also give a rattle obviously and will make the valve clearance act up too...

but im gonna bet its probly the cdi...is it running an inner rotor?

 

[azar]

Found the the problem, the rotor keyway on the crank is stuffed little bits of metal everywhere stuck to the rotor! The rattle ended up being the rotor nut hitting the cover. Did a dodgy fix-up reset timing and valves, started second kick and ran well but didn't run to long before the dodgy fix up let go. So it looks like a new crankshaft is needed. Got to love it! Thanks for all the ideas guys its been a great help.

 

[azar]

Qik question, Zongshen 140 and Lifan 140 crankshaft the same??? Can find Lifan parts easy but Zonger parts don't seem to exist.

 

[sean01]

no, but im pretty sure yx140 and zonger 140 are the same.

message just ride on ebay, he has the cranks for like 95 i think but yeah get him to compare sizes or specs if he can..

this seems to be a pretty common problem on the yx/zonger140's, my guess is the magneto nut isnt getting tightened enough..
i always use a rattle gun and have never had one come loose..

 

[DvDRip]

mate stick the flywheel on there with no key and max strength bearing retainer, then rattle gun the nut on with red locktight. it should up fine, with your quickfix did you rattle the nut on? if you didn't that's why it let go....
u'll need to mark the timing on the crank end and flywheel to make sure it stays where you want it after you put the nut on

 

[james_troke]

hahaa that's what happens when you buy second hand you don't know how they been riding it .