hi all im new to this place and could really do with some help.i have a joyner 650 in the uk,only had it a month. not really familiar with engines apart from the basics, so i dont seem to be getting close to resolving this issue.i can only get the buggy to start wen i bump it down my hill.if i turn the ignition it turns over fine, just wont start up.once iv bumped it down the hill and got it going and warm i can switch it on and off fine using the key,only for about half hour though until the engine cools down, then i get the same problem...
ive changed the plugs, leads and battery.its got a tank of fuel. the fuel pump works, the plugs spark and the battery is fully charged.there is fuel getting to the plugs as far as i can make out.
i just dont know what to try next??? oh and when i drive around in it, it backfires quite alot from the exhaust...
any help will be really appreciated!! thanks luke

1. Check your air filter for obstructions
2. Check your choke to make sure it is working
3. Remove your carburetor and clean all the passages and jets with extra attention on your pilot jet

idk why but that really sounds like a compression ring....

Valves too tight would be my first choice.

Timing advance with the backfiring ... Is it backfiring thru the exhaust or the carburetor?

yeh the air filter is clean,choke seems to work fine and the jets look good..
kavio how would i check the compression ring?
cartin the valves too tight?how would i check?
and its backfiring thru the exhaust..fuel air mix?
thanks for all your suggestions il try and check em all.
could i have an issue with a ground??

yeh ive checked alot of the cables and found a very coroded fuse at the ignition.i cleaned it up n put it back in...no joy.checked the earth from battery to chassis, it was bolted to heavily painted part!so i removed paint and bolted back down...still no joy.so i thought id adjust the fuel air mix screw while turning it over..adjusted it abit and nearly started!so we screwed it all way in and slowly undid it, bit by bit.like a miracle it started!its out half a turn,seems to be runnin better too..the real test is wen i try to get it started tomorrow from cold!!im hoping so much itl start!

im not ahappy man...tried it today n it wouldnt start again.im gettin really frustrated now!how do i go about setting the valves?any1 know a simple way?lol

another thing, i bought a multi meter earlia.dont know how to use it?anyone explain how pls?wat do i do with the red and black pins?lpl im a newb

You have a cold start issue. This indicates that your compression is low when the engine is cold. Once the engine is warm then everything has tightened up and your have the compression to start it. What happened is your valves have recessed into the head and you do not have the proper clearances. You can try to shim the valves to the proper clearance and eleviate some of the excess valve lash. However be aware that you may need to have to head work done and new valves.

oh ryt..that sounds exspensive huh.thanx for the help dude