I was out on my gg250 monday and noticed a strange ticking ratlling noise when opening the throttle under load,I thought it might be  rings or a bearing but it got worse in higher gears , sounds like I've got a lolly stick in the spokes , I need to tighten chain but sounded like it was from engine to me .so any ideas would be greatly received. 

Engine feels a bit vibey but havn't heard another to compare it with but will check the mains for play. Also what would be the recommended piston to bore clearance at the exhaut port?

And does anyone know where I can download a workshop manual online , I could only find owners manual on gasgas site which is fairly useless.

cheers

 If it`s a constant knock like almost a rod, but not as severe it could be kick start bits floating around. The kick start pawl chips and travels to the primary gear and becomes inbedded in the teeth. Sometimes it takes a magnify glass to see it.  Good luck on finding the noise.  

thought I'd the easy things today so I checked the mains and seemed to be no play also had  look through the exhaust port and piston and rings look in good condition.

tightened the chain as that was a bit slack ,pulled the plug and that was a bit off white for my liking ,the fuel screw was about 2.5 turns out, so will look into that when I next run it up.

I did notice the rear brake reservoir was touching the exhaust so that may have been vibrating on that, . If I ain't already cured it ,then next step will be checking the primary drive and then check the big end , hope its ok as I've only just bought it.

would be nice to get some hours out of it before I split the cases

Another easy thing to check is that the rear wheel is aligned straight. One side of my snail cam knocked out of alignment, made the chain and sprocket make a clicking noise and caused the rear disc bolts to come loose.

I had an intermittent clunking/clicking noise.  It didn't matter what gear I was in.  Sounded like it was in the transmission.  Pulled the chain tensioner block down to give the chain some slack and the noise seemed to go away.

So split the cases and discovered the shifting forks were bent, replaced with new and replaced all the thrust washers. Also replaced the large diameter bearing for the clutch shaft.

Slap it all back together and it still did the same damn noise.

 

come to find out the rear wheel bearings were bad......................very bad

Had some new ones on the shelf and 15 mins later......noise was gone. 

 

Not sure if this would be your problem, but just remember it's not always something catastrophic.

I was thinking reading the post he maybe meant the engine was pinking ?

Are you sure you have the correct petrol oil mix ? Forgot to put oil in a bike years ago it pinked terribly

I adjusted fuel screw and plug is a nicer tan colour, still getting a noise but it seems  more so when I'm in the top two gears

is there an easy/quick way to check the "mains"? I assume you need to pull the barrel off and check crank for up/down play. I thought I read you could also pull the flywheel coverage and check the magneto?

 

Trying to find cause of a knock I have. Already replaced idler gear, clutch basket, checked piston/rings via exhaust port, etc.

Every GG I've ever ridden makes a noise that's sort of like chain slap, mostly noticeable in 5th.