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gio 250cc smokes bad

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Ok so I didn't want to travel to the place I buy my China bikes in Toronto and I'm way out in the boons. Tahoe + trailer in Toronto = horrible headache. So I find this gio 250 locally still haven't seen so much as a pic (will post tomorrow when I pick it up) but it smokes, its missing some plastic, and the gears are a little wanky but hey I got a shop n tools and lots of free time since I quit drinking so it should be an easy project. My first thoughts are its smoking cause its really lean and needs a good carb cleaning, new plug, valve timing, check intake n exhaust gasket for leaks and if all this fails a new set of piston rings? He claims it has good compression but doesn't know much about motors.without seeing or having this bike until tomorrow these are all assumptions but is there anything else I should be looking for that may be the cause of the smoke? Bottom end issue I can narrow down much quicker I think but has anyone had these bikes and had to repair the smoking issue? Any tips would be appreciated. Thanks.

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Update. Picked this bike up way cheap. Runs ok but needs valve timing done and a new rear brack n some plastics and rear suspension and and and.... The big problem to me is I believe oil is getting into the cylinder and I'm not 100% sure where to start to remedy this. First since I need an oil change anyway I may try some stop leak from crappy tire tomorrow but I doubt it will be that simple to fix. Any advice? Also does anyone know off hand what to set the valves at? Until this is all sorted she has been labeled project Smokey.

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IMAG0379.jpg

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valve timing doesn't go off unless something significant lets go. do you mean valve clearance? does the oil smell like gas? dilution perhaps? did you check the oil while the bike was on the sidestand instead of upright thus overfilling it? have you thought about ignoring the smoke since it is a Chinese bike? since it is missing stuff and it is Chinese have you considered getting a similar bike and using the better one for the primary bike and the crappier one for a parts bike? this may be a super smart move if your making a habit out of farting with Chinese bikes. don't get your blood pressure up about this one too much because I have seen quality control stuff on the Chinese bikes bad enough to imagine a delicate, mis installed oil ring could cause all of this. no way to tell without a teardown of course. don't spend parts money on this thing too much. i'll bet you could get a parts bike for a song and a dance maybey

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This bike was the price of a parts bike. And yes I meant valve clearance and I found another post on here about it already so ill do that in the morning. I'm not going to put any real $ into this I'm going to mostly do it out of spare stiff lying around. Aside of course from fluids and maybe a set of rings n a homemade head gasket because I suspect your right about the oil ring. Haven't checked if oil smells like gas but I suspect so. I just want to do this bike because thus far I have only rebuilt the horizontal China motors n wanted to familiarize myself with the bigger China motors as they seem to be growing in popularity. Thought this would b fun. I just asked b4 tearing it down to see if there was a simple issue I didn't think of.

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Also does anyone know if another rear shock from the local cycle salvage would work on this bike? If so off what bikes? There is absolutely no rebound so I think its shot since most ppl claim there to springy on this bike. It may just b I'm around 200lbs though

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I checked e-bay they were about 68$ cdn + shipping. I have most of this bike done now - piston n rings (found for 35$ not yet installed) and now I have a nearly finished bike for less than 300$. Would have been 260 but I broke the kick start n replaced it with a brand new one from a much bigger Honda as I didn't want to keep having cheap white metal break. Point being 100$ for a rear shock after tax n shipping is more than I want to spend for a bike I may just flip if I finish cheap enough. If an old Honda/ Kawasaki/Suzuki etc will fit I can usually find one in a bone yard for 20-30$. Even if I keep the bike for myself it seems more reasonable to me to retrofit a different shock if I can save a few $.

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If it smokes and has good compression it is usually valve stem seals. Cheap to replace, but you have to pull the head and the valves. A bit of labor but not too complicated. Bad rings usually means it won't run (no compression) and if it does, it doesn't have enough vacuum to draw oil past the rings to get into the combustion chamber.

 

So, check compression, and if it you get good numbers then it's probably valve stem seals. 

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Good to know thanks. I gotta rip the head off tomorrow anyway so ill check there to. Btw I rode it today to the closest "general store" (10min ride) and every time I start the bike it has less compression. I may be wrong but I have a feeling someone tried replacing the rings and put the oil seal upside down on the piston.I was also told valve clearance was adjusted but there was WAY to much play. Gotta love buying bikes from a teen in there learning curve. God knows we were all there once.

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Ok I decided not to pull the head today. Instead I figured I'd try heavier oil first (btw oil did not smell like gas but smelled very burned). After oil change fired it up (I used 1.5 litres) and still smoking and knocking really bad. Pulled the gas tank off again than the valve cover again and double checked my clearance 0.1mm intake and exhaust. Still smoked and knocked and fouled the plug. Started looking on line for valve seals for the zongshen cb250... Can't find em anywhere. Any suggestions? I don't want to rip the head off and then search for parts I was hoping to source everything before digging in. And would bad valve seals have anything to do with the knock? It has plenty of oil and valve clearance is set to the most commonly stated specs I can find for this motor. The only other things I can think of is either there is a worn wrist pin in the piston with a bunch of slack or the top of the piston is chipped/piece of metal fell in the spark plug whole n is slapping around? When running the bike runs great, has lots of power, idles ok since I rebuilt the carb but seems a little on the rich side to me (kinda hard to read the plug when it's always covered in oil). It just smokes and spits oil out the tailpipe. Also after running it for 20-30 min the engine still knocks but smokes a lot less when hot.

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Hi,

I think you will have to change piston rings, because the reason it smokes less when cold is because the oil is thicker when the engine is cold so it doesn't leak past the rings as much. If you decide to the piston rings or piston and rings make sure that you have a spare pair of top end gaskets incase they break, also after new piston and/or piston rings are installed that you don't exceed 3000 revs to let the new parts break in.

Good luck, Jake

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The engine smokes less AFTER it warms up. And I suspected I needed a piston and rings from the start I'm trying to figure out what other problems might be inside to. The knock seems to loud and consistent for it to be caused by bad piston rings alone.

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Ok I actually spent some time riding this bike today and the longer I ride it the more it seems to need. Not that parts are broken but the bike is heavy and rather uncomfortable when riding hard. Suspension can't properly handle my weight, odd riding position, handlebars tapered back to far towards the rider, heavy steering. Nothing that couldn't be changed but at what expense? I still like being back on 2wheels on a bbigger bike but these are very much a learners bike. Even the gearing screams learner. The bike won't wheelie unless you make it but will hill climb anything. It jumps fine but lands like it amplifies the impact because of lack of suspension no matter how its tuned. All this was kinda to be expected but figured anyone that may buy one may want to know. When my quad sells I may find a used larger jap bike n sell this or keep it to teach the wife to ride a bigger bike. Still smokes. May fix it but not soon since it's not causing a problem and everything else is fixed.

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