What on earth just happend?

[lukehanham]

Right so i had just been on a ride on my super(NOT) trust worthy gilera rcr 50

As i were riding along at around 45 ish mph a clunk sort of noise happend and then my bike just shut off, it will no longer kickstart and after leaving it for 5 minutes i pushed it down the hill and had to keep pumping the clutch and keep it at high revs of gears 2-3 in order for the bike to not die.

The pitch of the bike has changed and there is a rattle coming from the engine,

Any ideas?

Also, almost no compression any more

[Nobby the Bastard]

Seized piston.
____________________
trevor saxe-coburg-gotha:"Remember this simple rule - scooters are for men who like to feel the breeze on their huge, flapping cunt lips."
Triumph Sprint ST 1050

[lukehanham]

Ahh, well fuck.

Guess i have some more money to spend on it, god this bike is trouble.

Spent £200 in the last week replacing the exhaust which decided to split while driving :<

Will i need just a new piston and rings for this?

[Just_James]

Top end failure of some sort.

Likely piston rings gone but top end will need to come off for inspection of what has been damaged.

Could just need piston and rings, may need cylinder and / head too.
____________________
Current Bikes / Projects: 1999 Rieju RS1 50
Previous bikes - 1986 DT125R (field bike), 1989 KX250, 1980 KX420 (with 500cc big bore), 1992 YZ250, 1988 KX500, 1989 XR250R, 1988 VFR400R NC24, 1999 Cagiva Mito 125, 2008 Rieju RS2 50 , 1993 Honda NSR 125

[delsol]

Too early for accurate diagnosis, bike will need to go to operating theatre for major invasive disruptive exploratory surgery.

Meanwhile............the power of prayer.

Bummer, hope it ain't too bad.

[lukehanham]

Alright, i will make a start on taking the bike to pieces now, will post pictures later tomorrow

[lukehanham]

Umm, So the fact that i can put it in gear and roll it forward, it is definatley seized?

Don't wanna order the wrong things and waste money

[Just_James]

Not seized, but top end failure of some sort.

You likely have little compression and the bike may be easier to push when in gear than it was before it went bang.

Needs top end taking off and inspecting before you start ordering anything.

You could do a compression test first if you want but it will probably just confirm that you have low compression... and that you need to take the top end off to see what the damage is.

Once you know what the damage is, you can then order any parts that need replacing
____________________
Current Bikes / Projects: 1999 Rieju RS1 50
Previous bikes - 1986 DT125R (field bike), 1989 KX250, 1980 KX420 (with 500cc big bore), 1992 YZ250, 1988 KX500, 1989 XR250R, 1988 VFR400R NC24, 1999 Cagiva Mito 125, 2008 Rieju RS2 50 , 1993 Honda NSR 125

[Rogerborg]

And you may want to seriously consider the merits of throwing good money after bad. If you keep it, this wont be the last time you'll be posting in the Workshop section.
____________________
Biking is 1/20th as dangerous as horse riding.
GONE: HN125-8, LF-250B, GPz 305, GPZ 500S, Burgman 400 // RIDING: F650GS (800 twin), Royal Enfield Bullet Electra 500 AVL, Ninja 250R because racebike

[lukehanham]

The thing is with the bike, i have become to attatched to owning it, i find it a bunch of fun to fix it and i also learn a large amount of new things from it.

I am going to limit myself and say i am not allowed to spend any more than £750 on the bike from now, past that and i sell it straight off.

I will open the bike tomorrow and order whats needed then, any people here have guides on 2 stroke rebuilds?

[Pete.]

[lukehanham]

Well the bike has done at least 10k since the last change of any piston rings / head

[LongJohn22]

[lukehanham]

Just finshed rebuilding my top end, compression is still EXTREMELY low and the bike still wont start.

Could this be because of my new exhaust at all, When fitting it i could already see the exhaust did not fully go into the port, but would this really affect compression THAT much?

The old piston had one seize mark, and the head had no internal damage, only a scratch or two.

Head gasket has also been replaced aswell,

[Just_James]

[lukehanham]

My phone is being a boob at the minute, here is an in depth description of the piston:

The top of the piston had next to 0 carbon build up, still clean silver with a few blackspots.

The piston ring looked like it had been melted into the piston, which would cause the browning of the metal below the rings.

Inside the piston there was a small blackspot at the top of it.

The barrel, the barrel had only one mark where the engine had previously seized up.

However now that there is a new piston, rings and a head gasket all those issues should be eliminated right?

Should i be looking at the crank case seals or something similar next?

I can't do any running engine tests as the engine wont start unless it is bump started and held above high Rpms ( 3k + )

[Nobby the Bastard]

[lukehanham]

The mark has no change on the volume of the barrel, it's only something visual.

[Just_James]

Like a hologram?
____________________
Current Bikes / Projects: 1999 Rieju RS1 50
Previous bikes - 1986 DT125R (field bike), 1989 KX250, 1980 KX420 (with 500cc big bore), 1992 YZ250, 1988 KX500, 1989 XR250R, 1988 VFR400R NC24, 1999 Cagiva Mito 125, 2008 Rieju RS2 50 , 1993 Honda NSR 125

[lukehanham]

Yeah i guess thats a good description, but would this still take the compression down to a level where it won't even run unless the engine is around 3,000 rpms at least?

Is it worth me ordering a whole new top end, including the barrel and head?

[lukehanham]

Allso i forgot to add, the head gasket had coolant on both sides, could and the bike ran very hot ( Coolant pipes were like red hot after 15 minute ride )

[Rogerborg]

[Ooops, replied in wrong thread]
____________________
Biking is 1/20th as dangerous as horse riding.
GONE: HN125-8, LF-250B, GPz 305, GPZ 500S, Burgman 400 // RIDING: F650GS (800 twin), Royal Enfield Bullet Electra 500 AVL, Ninja 250R because racebike

[swampy]

Any pics of the damage to the piston or head ? What have you replaced ? Are you still running the piston that 'has a ring melted' ?

Did it look anything like this:

https://www.jasonmcelroy.com/temp/mahoney/scored_piston.jpg
____________________
"I hate to advocate drugs, alcohol, violence or insanity to anyone, but they've always worked for me." Hunter S Thompson
"Faster, faster, faster, until the thrill of speed overcomes the fear of death..." Hunter S Thompson

[lukehanham]

[Nobby the Bastard]