Noisy Mito

overdog · L Plate Warrior Joined: 13 Mar 2005 Karma :

Just rebuilt a mates Mito after she left it standing for 2 years without even starting the thing-I know, I know!
Anyway-disconnected the coil and turned it over on the starter to get the oil pressure up before i fired it up.
There was a horrible clanking noise from the top end.It runs fine but theres a top end noise at tickover increasing with revs.If you spin the motor with the kill switch off the top end clank is still there.
Surely this isnt normal for a 2 stroke? Shocked

Im thinking rings-please tell me Im wrong!
____________________
Ooooh-thats gonna leave a scar!

cagiva gezzer · World Chat Champion Joined: 17 Mar 2003 Karma :

Ignoring the oil pressure bit..

Umm, cagiva engines are noisy. There's a vast selection of gears driven by the primary drive and clutch basket. So, a rattle from under the clutch cover is normal.

Top end rattle suggests a warm small end or piston slap.

What exactly did you 'rebuild' or change. OE parts, pattern parts?
____________________
"because one stroke isnt enough and four strokes waste two"

overdog · L Plate Warrior Joined: 13 Mar 2005 Karma :

LOL-All I did was strip and clean the carb and put all the b"%^$£d bodywork and tank back on-the mechanicals havent been touched.
Oil pressure light goes out when the bikes in gear.
____________________
Ooooh-thats gonna leave a scar!

cagiva gezzer · World Chat Champion Joined: 17 Mar 2003 Karma :

Stop with the darn oil pressure.
____________________
"because one stroke isnt enough and four strokes waste two"

overdog · L Plate Warrior Joined: 13 Mar 2005 Karma :

Now its getting louder the warmer the engine gets-its killed a ring hasnt it?
____________________
Ooooh-thats gonna leave a scar!

cagiva gezzer · World Chat Champion Joined: 17 Mar 2003 Karma :

Doubt it would run with knackered rings.

How many km's? Had a rebuild? Pistron slap should lessen as the engine warms up.
____________________
"because one stroke isnt enough and four strokes waste two"

simon1221 · World Chat Champion Joined: 28 Jul 2004 Karma :

What about the powervalve?

Is it possible he could have dislodged it and its whacking that.

Or, you have a hole in your air intake, carb/manifold hose and that noise is just the engine.

Check stuff like exhaust or whatever for leaks.

You cant have changed anything unless you didnt put the carb back on properly.

Another possibility is that it has nothing to do with you rebuilding it, but maybe the oil pump isnt owrking or something like that.

Is the noise like a rattle or a BANG!?
____________________
DNA50 (sorry) ->> TZR125l >> GPZ500S

overdog · L Plate Warrior Joined: 13 Mar 2005 Karma :

Powervalve does what its supposed to when you turn the ignition on.Noise is a rattling bang!If its been stood for 2 years whats the likihood fo a ring being seized and breaking when I started it?Or is the powervalve more likely(I hadnt even thought of that!)
It does sound like the piston is smacking something-I dont think its just slap.Bike has done 6000-not regularly serviced from what I can gather.
I dont want to condemn the wretched thing if it can be easily fixed but I was raised on inline fours and 2 strokes work by black magic as far as Im concerned-and it does sound fairly terminal.
Closest noise i can compare it to is a piston clattering a valve at the top of the stroke but obviously thats not the case here.
Rings catching the port edge? Brick Wall

____________________
Ooooh-thats gonna leave a scar!

Frost · World Chat Champion Joined: 26 May 2004 Karma :

Ring catching the port edge is very unlikely. Ring catching the powervavle sticking out of the port...very likely. I've had that one ahppen with 3 valves now Laughing

Check the spark plug. You probably put a new one it before fireing it up. If the plug is too long the cylinder might be hitting it...

2 Stroke singles are so easy to strip down it might be worth having a look inside, all it will cost you is a head gasket.

Check bolts too i was once VERY concerned about a loud engine noise which happend at engine speed. Turned out to be a loose powervalve cover Embarassed

Kickstart · The Oracle Joined: 04 Feb 2002 Karma :

Hi

The Mito is a 2 stroke. It has no high pressure oil system and no oil pressure warning light. The light is just to indicate the level of the 2 stroke oil.

Most likely the piston is worn or the rings are siezed. Also the power valve on the Mito has an adjustable stop position. Get this wrong (or just take it out, clean it and reassemble without replacing the gasket so it is more compressed than it should be) and it can touch the piston when it gets hot. If it is run for a while in this condition the shaft for the power valve blade snaps and then the valve drops down.

All the best

Keith
____________________
Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing