engine is DEAD please Help!

Ok I got a chinise midbike have no idea what it would be called but its a 4 stroke, no gears, has 48cc written on the block and looks just like this bike
>http://porkygnome.customer.netspace..../blue_left.jpg
>http://porkygnome.customer.netspace.net.au/detail1.jpg

It seems to be a r1 of some kind and had sp2 written on the back fairing this is all i know about it.
Since brand new its had a few accidents and lost most of the fairing lol but kept working fine, well It did backfire when coming off the throttle and would bog down off the mark but from reading that seems normal. after a bit or running it would get hot and bog down more and more and if I diddnt let it kool down it would stall easily This was ok but it got harder and harder to start, then fuel started ****ing out of the tube from the carb so i figured the float is blocked making it flood, Cleaned the whole carb out and fixed it from leaking then tried again. It sounded like it wanted to
start but would backfire and not start. left it for 2 days and tried it again now it wont even backfire or make any attempt to start. I have tested the spark plug whick seems to be working well then I tried putting peterol down the whole, this did absolutely nothing so It seems to me to be dead.
can anyone relate to this huge problem or help in any way please.
Also U had tried loosening the chain a couple of times but kept going back to tight no matter how tight i make all the bolts could this dogy fram be destroying the engine?.

Try a new plug.....could be partially fouled

Nope didn't help

youre saying it ws running hot n u needed to stop to cool it down.....

sure u didnt fry the engine???

I mean like after riding it for a while it would be really hot and start to backfire , bog down more also it wouldnt idle. And it would be harder to start again while still hot.

I dont know what u mean by fry?
I have a fair amount of knowlege of small engines and I just can't figure it out
The compression is fine it has plenty of spark and fuel could it be that the timing has slowly shifted thats why it worked then all it did was backfire and now it doesnt work at all?
by the way does anyone know what this bike is called like x1, x7 etc?

To Porky; Check your magnet it could be offset (the shim brakes sometimes and the magnet is then out of position). If you hear a loud sound out of your engine when you try to start it or the engine kicks back ( souds like your E starter bogs suddenly ), then this could be your problem. Well you can only check it to see what it is though.
If you allready checked your spark and now you wonder *** am i talking about then check the magnet shim like i said cause these tipe of ignition will fire a spark anyway (if your magnet shim broke it just fires at a wrong time).

U might be spot on r1 I will check that out but um do you mean the magnet on the flywheel? would you be able to give us a short guide on how to do what you talk bout please?

Check your valves, they are usually tight on those motors and get even tighter when they get hot, you will want to loosen them a little and I bet you it will fire right up, in case you did not notice they are exceptionally easy to get to for adjustments under those caps in the head.

Hay I think your right about the tight valves because even with the plug out its almost just as hard to turn over.

I also compared the spark to my other 2 stroke engine, when I held the plug near the head the spark was very strong and would arc at about 13mm away but on the engine this thread is about it only arcs at about 4mm and is much weaker. It also doesnt seem to be consistent.
I think this might be the main problem but i dont know what to do to fix it is there any kind of manual, guide for these engines for how to set the timing etc ?

Hi
Bartw may be rihgt but i didnt wana consider this option cause you have a bike that has been runing only a few hours. You could try to set your valves to have 0.15mm play (use gap mesurement tool for cheking valve gaps (metal sheets)). Since we dont have no manual that would tell us how to do and what gap to set you will have to go for try and run system. Go from 0.15mm gap and increase it or decrease it if necesery, howewer the valves should not rattle after your engine is warmed up. Good luck.

Oops i forgot: with the magnet i meant a flywheel (magnet sits right in there, but we call it the magnet ower here in slowenia).

I am finding that the factory has set the valves at almost zero lash on most of these China motors, I am fixing at least 3, pocket bikes or China dirt bikes with all the variations of this motor, per week with a tight intake valve. The problem is always a backfire which sends most mechanics searching for an ignition problem as they should but what is actually causing the backfire is the fact that the intake valve is so tight it is not closing all the way and some of the combustion pressure that leaks through will actually shoot back through the carb. The intake valve is the top one, just remove the cap there, loosen the nut on the rocker arm and use a pair of needle nose pliers to turn the tip of the valve out a tad. The setting we are using is .003-.004 inches on a cold engine, it seems to work well, I did see a China manual that suggested a little more but they were too clickety clacky which is why I never listen to China manuals. Your diagnosis of a lack of compression, I assume that from you saying the engine turns over with the same amount of effort with or without the plug, is leading towards this valve problem as well, it is difficult to get compression with valves not sealing. All in all you can just take 5 minutes and back out that valve just slightly and see if the bike starts, I am betting that it will.

Yes I did what you said, backed out the intake valve a bit over a quarter of a turn and she fired right up. Is that too loose or what?.
actually im not sure weather thats what did it but it bloody works now thankyou to whoever helped and thanks to this great forum.
wait i have 1 ?, what peterol should I use in it regular unleaded or premium?.
and if the answer is premium can u use unleaded?

"porkygnome" where abouts in Melbourne u from? Where do u ride??

I use premium unleaded.......

Inner eastern suburbs mate and well where can you ride these things?
I have a beach house around the mornington area and before it busted we used it there for a while, we would just go flat out around the golf course it was great fun I thought my 50cc was quick then i discover there are 110 ones with 4 gears lol how fast do those ones go I recon mine can get up to 65 70 not positive but?.

Glad it worked for you. You need to stop at your local auto parts store or tool store and pick up some feeler gauges so you can set the clearance correctly like I described earlier, they are inexpensive but very valuable.

we used to ride at Jells Park at night but got busted so we chop and change... got a new spot at lilydale park but its a fair hike from where we are......

our 110cc stock went 80-85km/h flat out, now with the new pipe were hitting bout 90kmH