EC 300 Rattling & power loss ???

[Porkyblader]

Hello all, I own a 06 300 ec which up untill today was running great,took the bike out today & after around 30 mins an engine rattle developed which was bad enough but when the throttle was cracked open ( bad idea I know ) the engine revs stayed low & flat no matter if the throttle was fully open.

I have removed the power valve cover but nothing loose,damaged or slack & when you move the arm by hand the valve does open & return to closed the position when released..does this operation need to be checked with the engine running ??? lastly the compression is still good.

Any help or advice is appreciated.

[wasp4banger]

Just a thought, I had the central pipe to the silencer / muffler break on mine and the pipe displaced so that the exhaust gases couldn't really get away.
Not saying this is your problem, but it may be worth checking?

[Porkyblader]

I have checked the exhaust system which is clear.I have also taken up the slack in the powervalve mechanism which was a bit sloppy at around 5mm movement before any load kicks in,it is now resting on the stop with a little preload.

The powervalve itself does have movement approx a millimeter or very slightly more,I understand a little clearance is required to maintain free movement but how much movement should there be.With the bike running & cover off the rod/linkage snaps open & closed on reving so I guess the valve is working which makes the refusal to rev out above half throttle a little strange unless I unknowingly freed it when fiddling.

The rattle itself does seem to be worse when the bike is reved and then returns to idle with a steady rattle/knocking sound at tickover & low revs.The compression feels good but I guess my big fear is the crank so will take the head off & check it,but got to say im confused by this like many things I suppose

[noobi]

If you smacked the pipe at all, it could be tweaked and now one of the exhaust springs is vibrating off the pipe, I know they can make a rather alarming rattling noise.

Its not difficult to pull the cylinder off and inspect crank play, just really need the base gasket(s) and an hour or two of your time.

[Jakobi]

Anyone wanna post up a pic of their straight pipe? I'm sure one of my springs has touched the pipe since say 1. Runs down the RHS. Vibrations I get are from the header touching the spigot bolts though.

[Porkyblader]

Took the head off today,the piston looks ok but does have a little play maybe 5 - 10 thou,popped the head back on & started it,what I did notice upon starting & warming up the engine sounded good but as the temperature built in the engine the rattle started would this be in line with piston slap ??.The barrel will come off asap for a more in depth look,I am pretty sure the rattle is within the engine & not exhaust,springs or any external factors,its just finding the bloody cause of it.

[Porkyblader]

Well I have taken the barrel off & had a good look at the piston,not too bad although signs of scorching below the rings so as its a little sloppy aswell will change it.There is 'A' stamped on the barrel & piston so having read other related posts I will replace with a 'B' spec piston.

Unfortunately having had a closer look at the crank the main bearings seem to be shot ,when you turn the flywheel there is a slight clicking noise as you turn & will go stiff then free as you turn the crank & on top of that if you drop a magnet in & around the crank you pull out fine metal particles so guess there is no choice but to split the engine as cant take the risk...oh bugger

[glassman581]

hi i had a problem with power loss on full revs so i checked the power reeds and they where badly damaged so i replaced them and it runs sweet now hope this helps