Finished the top end

[scrubs]

rode ten miles starting to break her in - never taking her passed quarter revs, then all of a sudden it went boggy and cut dead
no compression. The top end went - again!
Obviously something else is wrong to cause it to go the first time that iv'e missed no idea what. I know one thing though - I have had it with this peice of shiit bike. Hate it - and hate the fact that if I sold it I wouldent see a penny of what I have invested in it and probably get a pittance for it as is and can't afford to fix it. if i burn it - I will lose my no claims. Rant over, sorry.

[fallenmikethebike]

Oh crap . That's an out and out pi55 pot .
Is it physically getting hot, ? Just can't think of an answer that hasn't been discussed before .
Barrel to bore clearance ? unlikely .
Hhhmm needs some pondering .

Sorry mate .

[petrolhead]

Sorry to here that,nothing worse than hard work and money down the drain , gone to bed with my thinking cap on!

[fallenmikethebike]

Was the mains and big end replaced after the first top end meltdown ? I'm wondering if the bike has an inherent fault with the crank casings thats allowing air into combustion track, post the carb,thereby weakening the mixture , and leading to excessive heat generation.
It was popping rad caps at one point i recall.
some thoughts.
regards Mike

[petrolhead]

Have you fitted a new thermostat along the way? as that may be a cause, also check the oil pump feeds etc, IE. drain the tank check all pipes for blockages leaks etc, check pump out and bleed loads of oil through,
sometimes it's good to revisit the basics,
Was the first rebore for more power torque etc, or had it blown up that time also? did you have any problems in std trim?

[scrubs]

Mains were replaced but not the big end bearing. there is no up and down play in that bearing - but a little side to side play yet the crankshaft seems true. The engine was getting physically very hot. so I pulled into the petrol station and I pulled the coolant pipe from the head to make sure it was going through and it began to shoot out of the head so I assumed that was ok made sme viual inspeactions - no leaks etc..
Oil is definitly getting to the pump but am sure if it's making it's way out - it still has the original thrmo installed

The first rebore was because of another seizure - it's had three now in about 250 miles. but I got the most amount of mileage while it was in standard trim (i.e before the first rebore) the second two seizures wdident make it 15 miles before going again.

[fallenmikethebike]

So excessive heat is what's leading to the seizures.The question remains as to the root cause of that heat build up , and the reasons could be numerous,among which may be ,
AIR LOCK IN COOLING SYSTEM.
RADS BADLY BLOCKED.
OIL NOT REACHING VITAL PARTS .
POSSIBLY SIDE TO SIDE PLAY ON BIG END .
UNMETERED AIR ENTERING SYSTEM GIVING CATASTROPHIC WEAK MIXTURE.
RESTRICTED COOLANT FLOW .
INCORRECT TIMING , HAS WOODRUFF KEY SHEARED ON MAGNETO ALLOWING TIMING TO ADVANCE [ RARE BUT I HAVE KNOWN IT TO HAPPEN ].
POOR QUALITY PETROL [ ANOTHER STRAW THAT ONE ].
CARB NOT JETTED CORRECTLY FOR EXHAUST SYSTEM FITTED .
ITS PICKED UP SOME DETRITUS LEFT IN CRANK CASES FROM ITS LAST GRENADING .
As i said the list is quite long , and that's not an exhaustive list at that .

[scrubs]

Cheers mate, much apperciated - I doubt I am going to do anything with it
anywear in the near future - I need a long break away from it and I'll decide whether
I can bear going through it again or to just sell it on or something then if not

[Gwyn]

Cheers mate, much apperciated - I doubt I am going to do anything with it
anywear in the near future - I need a long break away from it and I'll decide whether
I can bear going through it again or to just sell it on or something then if not

Scrubs. You do know that you have to file/cut back the power valve after a rebore as it will pick up on the piston?

[scrubs]

yeah cheers Gwynn I checked that when I installed this time as I thought that may have been the reason it went the time before, all seemed fine. When I got it rebored it was then relined/nikasilled
so it was back to the standard 66mm bore