Help..... Blown head gasket?

[Dave20046]

Originally Posted by dizzyblonde

I got two remember

That's why I said all. So you've deffo got atleast one working sv?

Originally Posted by Wezza87

Wow, firstly thankyou for replying so quickly, you guys at the org are great!

As far as more information goes parkinmj the smoke was blue and from what i remember the sound was coming from the top of the cylinder. i havnt tried starting it again through fear of making matters worse but i think its time to have a proper look-see at the engine today, i shall keep you posted. I hadnt thought of bottom end bearings, but form fizzwheels "i think its more terminal" it doesnt sound good, how bad exactly is that??????

sorry for the late reply been in bed all day ( i work nights)

blue/white smoke suggests that the there is excessive oil in the combustion chamber also water from the cooling system.

this suggestes a blown head gasket or the gasket between the barrell and crank cases which could have been damaged from the following.

and you think the sound came from the top of the cylinder.

from this its sounds like the new exhaust system has caused the bike to run lean. causing it to run hot and this can lead to detonationion in the cylinder ( bike fires early due to heat igniting the fuel rather than at the correct time by the spark plug) . detonation can damage the piston cause piston slap and burn valves so you may have over heated the piston and burnt and damaged the rings and barrell.

the piston slap would explaine the banging, the bits that have broken off the piston would explain the grinding and the fact the oil ring is damaged would explain the blue/white smoke.


so it sound to me like a new piston and barrell all though from
experience i had a similiar senario with a k5 pointy but under inspection i found that the big end had spun on the crank. so until you dig into it you can t be too sure.


both jobs are quite big jobs to get in and put right and require dropping the engine out of the frame.

to check the piston just whip off the rear head, cams and chain and you should be able to see if there is any scoring on the cylinder walls and any damage to the piston plus usually after a detonating bcylinder leading to piston failure the loose bits of metal will be welded to the crown of the piston.

to check the big end slide off the barrell then remove the piston from the con rod then if you push and pull gentley on the con rod you will be able to feel if its spun the crank there should be no movement up and down but a small amount of left to right play try not to get the two mixed up.


all the best

MJP

p.s. if it is either of the two rather than just replace the parts i would strip the full engine and give it a full clean out as any debries from the damage can block the tiny important oil galleries and cause damage later on.

[Dave20046]

Originally Posted by parkinmj

sorry for the late reply been in bed all day ( i work nights)

blue/white smoke suggests that the there is excessive oil in the combustion chamber also water from the cooling system.

this suggestes a blown head gasket or the gasket between the barrell and crank cases which could have been damaged from the following.

and you think the sound came from the top of the cylinder.

from this its sounds like the new exhaust system has caused the bike to run lean. causing it to run hot and this can lead to detonationion in the cylinder ( bike fires early due to heat igniting the fuel rather than at the correct time by the spark plug) . detonation can damage the piston cause piston slap and burn valves so you may have over heated the piston and burnt and damaged the rings and barrell.

the piston slap would explaine the banging, the bits that have broken off the piston would explain the grinding and the fact the oil ring is damaged would explain the blue/white smoke.


so it sound to me like a new piston and barrell all though from
experience i had a similiar senario with a k5 pointy but under inspection i found that the big end had spun on the crank. so until you dig into it you can t be too sure.


both jobs are quite big jobs to get in and put right and require dropping the engine out of the frame.

to check the piston just whip off the rear head, cams and chain and you should be able to see if there is any scoring on the cylinder walls and any damage to the piston plus usually after a detonating bcylinder leading to piston failure the loose bits of metal will be welded to the crown of the piston.

to check the big end slide off the barrell then remove the piston from the con rod then if you push and pull gentley on the con rod you will be able to feel if its spun the crank there should be no movement up and down but a small amount of left to right play try not to get the two mixed up.


all the best

MJP

p.s. if it is either of the two rather than just replace the parts i would strip the full engine and give it a full clean out as any debries from the damage can block the tiny important oil galleries and cause damage later on.

Brilliant post, thankyou. And welcome (I see you're a relatively new member).

[yorkie_chris]

Compression test first IMO.

A fuel can won't make it go lean enough for detonation.

Does it still run? The bottom end demise would still allow it to work, just with lots of expensive noises. But this would not produce smoke unless it has actually spat a rod through the piston or something else very unpleasant.


Also it is not an overly big job to replace a piston, head and barrel with the engine still in the frame. But +1 about flushing it all out.

[Dave20046]

I've heard the best way to clean an engine (don't blame me for this as some of you know what I'm like) is to replace the engine oil with diesel and run it for 5 mins then drain. Apparently it softens all the crap and drags it out.

[yorkie_chris]

That is one way, you can also get flushing oil.

The BEST way (i.e not a bodge) is to strip it and clean it with solvent, blow out all oil passages with compressed air. If it is a 99 motor that has spun the big ends (they are really prone to it) then there will probably be like 1/8" of blackened bearing shell powder in the bottom of cases.

New crank is £550 ish the last I looked. So it's not worth it at all.

700cc kit isn't worth bothering with unless you already have a decent full system and filter on it. But stock crank can last alright with that... I wouldn't advise it to do loads of miles though... the wiseco 700 pistons are really heavy.

750cc on stock crank and liners is just asking for trouble, if the liners will even take that much of a bore.

shhhh dave, thats what we ag engineers do when we can't be arsed

i'm pretty sure its more than just your head gasket, i'd get the head off the rear cyclinder to inspect further.

[Dave20046]

Originally Posted by dual-power sv

shhhh dave, thats what we ag engineers do when we can't be arsed

i'm pretty sure its more than just your head gasket, i'd get the head off the rear cyclinder to inspect further.

haha it's what my mot tester told me to do.

[Sid Squid]

Originally Posted by yorkie_chris

A fuel can won't make it go lean enough for detonation.

Agreed. A can alone simply won't do that.

Originally Posted by yorkie_chris

Does it still run? The bottom end demise would still allow it to work, just with lots of expensive noises. But this would not produce smoke unless it has actually spat a rod through the piston or something else very unpleasant.

Agree again.

Originally Posted by yorkie_chris

Compression test.

If it runs at all, yes, it'd be worthwhile to get all the info possible.

Drain the oil - does it look like metalflake paint? That would be a bad sign.

And as for flushing it out, frankly if the motor has a greater problem than a head gasket I wouldn't probably even bother - replace the motor, it's rarely economic to fix an SV motor.

Originally Posted by Dave20046

at least you got someone who knows their **** from their elbow to fit it...

Sorry, I must have missed something - I thought Chris bolted Dizzy's new motor in, but I don't recognise him from that description

[yorkie_chris]

I just sat around scratching my elbow and watched her feller do all the work...