Agility running extremely rough

[grazo22]

Back in June 2009 I destroyed my agility 125 engine crankshaft when the clutch exploded and I didn't realise until all the splines had disappeared.

This week I finally found an identical engine from a 2005 model. I have a 2007 model. I'm pretty sure they are the same. I boshed the engine in yesterday, have done an oil change and put a new plug in. Thes carbs I have noticed are slightly different as the newer one has an extra connector on the throttle body. I'm just wonder what Ideas are on the engine running rough. The plug is burning at a light brown, so correct, but it lacks soo much power. I wondered about the carb being all blocked up as it's laid in my garage for 8 months. Before my old engine ran pretty sweetly and this engine supposedly has done 5000km, i'm not too sure about this because I was told over the phone so never checked, but it still has the original tyre so must have done less than my 13000km.

I've taken a video which I'm posting on the net so I'll link that when its finished uploading

Roughly running agility 125, what on earth is wrong with it

[axy]

Hard to judge from audio on that youtube clip.

Did you consider the fact that engine sounds much louder and harsher with Tupperware off scooter, and in closed space (garage)?

What about power? Does it rev freeely?

[grazo22]

Yeah i realised it was vibrating like a errrr bike without plastics but you can hear a little that it has a little knock or something when it's close to the fan. It doesn't rev very freely at all and it extremely sluggish when I take it up the road, like my old 50 version. The exhaust is also very very beating, not a smooth affair like it used to be. I might wack the cylinder head off later to see whats going on. Also might clean the carb. I'll keep you all updated. I'm desperate to get my little scoot on the road again as my land rover is killing my wallet 

[zombie]

That sounds like a valve being beaten to silly land by the cam. Check the drive chain on the cam and adjust the valves is my guess. Also check the cam bearings because if the engine was run w/low or no oil the cam will have some play, and NEVER adjust right. Just a guess but likely...

[grazo22]

That sounds like a valve being beaten to silly land by the cam. Check the drive chain on the cam and adjust the valves is my guess. Also check the cam bearings because if the engine was run w/low or no oil the cam will have some play, and NEVER adjust right. Just a guess but likely...

Actually I took the top of the engine apart and swapped over the cylinder, head, cam and tappets with my old set and it runs soo much better. I'm actually leaking oil so need a new base and cylinder head gasket as compression is a little low but it is a huge improvement on how it used to be.

When i took the old head off I noticed there was a lot of scoring on the bearing casing, a sign the oil has never been changed in its 5000km. It was like water when I drained it out. The bearing on the cam wasn't smooth though and a a little gritty.

Gaskets coming this week so should be able to sort it out once and for all

[zombie]

Utube to the rescue. It was a great idea posting the vid! Keep us informed...

[grazo22]

I've now swapped over the cylinder head for my old one, and my old camshaft. New head and base gaskets, although its still underpowered and I can only get 65mph max out of it when I used to get 10 mph more than that on the same stretch of road (downhill this is ) Goes along at 55 on the flat, and no where near as much on hand power as it used to have, I'm going to look at the roller and belt, because I got smoked by a chav today on a 50cc 2 stroke  The exhaust gas is still very hot and when I turn it off and look into the exhaust it is red hot like the EGT is very high. With 2 people on it, it's very slow. No confidence to over take now knocking noise felt under my feet occasionally when I'm driving, feels like the exhaust is tapping on the frame :S don't know if this ever happens.

[zombie]

I would pull the spark plug. It should be coffee color. Your set up may be too lean. That will reduce power in a 4t big time. As you said the roller set up may be off as well. you can tap/push/pull/twist all the parts on the scoot until you here the sound or knocking you described. Check the plug first tho! you don't want to melt a piston at this point.