Posted: Fri Oct 30, 2009 8:23 am Post subject: yeah
FPV wrote:
We have taken the head off and was surprised how little effort it took, was not bonded in any shape or form.
The gasket is like a thin piece of black sheet metal and no cracks can be observed so at this stage we are not sure what is going on.
Knowing this.
Check it out for being warped ? any error and it will leak.
Being water cooled then it could use a sealing compound on the gasket.
Check with the owners or a good motorbike shop.
I too in the past have seen these problems.
Warping is the usual problem and getting it skimed the solution.
Even seen motor bike heads lapped in with grinding paste
Knowing this.
Check it out for being warped ? Embarassed any error and it will leak.
Being water cooled then it could use a sealing compound on the gasket.
Check with the owners or a good motorbike shop.
I too in the past have seen these problems.
Warping is the usual problem and getting it skimed the solution.
Even seen motor bike heads lapped in with grinding paste
E X P E R T eh
Top bloke only telling me the other day how to check for warp-age
Does the sealing compound allow for any intolerance's in the head and block, or will it still have to be perfect ? (Is it to aid in tight bond between gasket and head and block only)
Motor have to come out of bike to be skimmed ?
Lapped in with grinding paste Could you please expand on this obe one kenobie _________________ The greatest worth is self-mastery
Posted: Sat Oct 31, 2009 11:18 am Post subject: yeah
If it is not badly warped then a sealing compound will filled the gaps as well as glue it in place.
Try this idea . But if say it is 10 thou warped on the head not on the block then only the head needs a skim.
I doubt if the block will warp.
Now lapping in motor bike heads with grinding paste. The grease type it best for this work.
Put the pistons at the middle or bottom of the stoke depending on the type. Stuff rag in each bore.
Then put on the grinding paste on the surfaces to be levelled if the are not too bad. Never attempt this if it is badly warped as it is only making matters worse.
Slide the head back and forth and remove the high spots.
On a single cyclinder you rotate the head. This is a single head method really.
It is likely the head only is warped. But use a sealing compound like gasket schelack.
Excellento Yep I copy all that RosscoPecoltrain, brill points like the head warpage !
Do you think the overheating caused it or the dealer did not set it exact ? Matie remembers dealer mechanic making reference that gasket may need to be thicker. _________________ The greatest worth is self-mastery
Posted: Sat Oct 31, 2009 8:54 pm Post subject: yeah
Now from this distance I wonder????????
Now let us deal with it this way.
Get the head checked to see if it is level.
Then the gasket. Get the right one.
If the dealer is talking fibre gasket and thicker.I would say they have problems here.
But once the head is OKAY then use a sealant on the gasket.
Over heating may well be the cause so see the RADIATOR is reverse flushed.
The hoses must be perfect if not new ones.
As this is a twin cylinder do the pistons come up one at a time. or both together ?
Joined: 30 Mar 2007 Posts: 197 Location: Sydney Australia
Posted: Sun Nov 01, 2009 10:16 am Post subject:
Dont forget the most important thing.....F'ee
Replace all head bolts with new ones, as the old ones would have stretched.
Replace all barrell bolts and nuts if the motor has a sleeve barrell arrangement, as these strech as well.
Its a single cylinder 500cc 2 stroke roberta - designed to Haul !
Yeah has a sleeve edge so we will give that the once twice thrice over Cheerz, matie does not want anymore short coming - poor bugger works his guts out for little kiwi dollars - will try sort it , could not do any worse than Kawi dealer has.
Kawai forum telling him there is a special gasket that can be imported from the states that "Takes up" the imperfections sent from the kawai factory. Bonds bonds bonds with sealant. Like mentioned previously there was no bonding what so ever, no need to lift the head off by cranking the kick start like it said maybe needed in manual.
Here's the set up (compute wiz roberta - you have to close the wee blurb page that comes up first to see the diagrams - rub your mouse over each diagram and an expanded form should pop up)
Dare say not mny bikes can "Shoot a decent Roost" while on the back wheel, awesome rider, say take some skill with 65 HP bolted to 99 KGs
_________________ The greatest worth is self-mastery
Posted: Sun Nov 01, 2009 11:50 am Post subject: yeah
Okay put it straight back together using an sealant.
If you see no problems with the gasket then use the old gasket.
Yes it may have come appart easily but as long as it was torgued down right that is fine.
Right from the start I could not see any big deal only oil and so far we do not know how it got there.
It is good to find the problem but this time it is ellusive.
Yep no cracks etc to be seen in gasket, sounds like a good starting point your last post Lion Boy. I may have to have it for at least a month to do "test work". _________________ The greatest worth is self-mastery
Posted: Sun Nov 01, 2009 12:20 pm Post subject: yeah
Fpv
Now we are getting places. A single 500. That is much easier.
OKAY it seems they use sealant if it is hard to get the dead off at times.
It is most important to know before dismantling anything to have tested out all angels.
We needed to know exactly where the oil came from and it seems they use a sealant
which would overcome this problem for sure.
Have a laugh as I am 2,000 miles away even if my heart is still at Spreydon school and 12 years old.
Joined: 30 Mar 2007 Posts: 197 Location: Sydney Australia
Posted: Sun Nov 01, 2009 3:26 pm Post subject:
FPV wrote:
Its a single cylinder 500cc 2 stroke roberta - designed to Haul !
Yeah has a sleeve edge so we will give that the once twice thrice over Cheerz, matie does not want anymore short coming - poor bugger works his guts out for little kiwi dollars - will try sort it , could not do any worse than Kawi dealer has.
Kawai forum telling him there is a special gasket that can be imported from the states that "Takes up" the imperfections sent from the kawai factory. Bonds bonds bonds with sealant. Like mentioned previously there was no bonding what so ever, no need to lift the head off by cranking the kick start like it said maybe needed in manual.
Here's the set up (compute wiz roberta - you have to close the wee blurb page that comes up first to see the diagrams - rub your mouse over each diagram and an expanded form should pop up)
Sounds a bit like my ol Yama TT500. Does this thing have a decomp lever or is it built into the kickstart.
Heres a couple of little secrets, F'ee, dont tell anyone. On those single bangers, mine especially, the oil reseviour was built into the frame, when they idled, they vibrated like all the mothers under the sun. The fitting comes loose and drips oil onto the tappet cover and down onto the engine.
On another one I had, also a single XR 650 Honda, if the sump was too full by even a poofteenth of a litre, that caused to much pressure and normally forced oil back out through the filler cap, or up through the breather and onto the motor.
I havent gone back to the start of the thread to see what your problem was, but if you have an external oil system check all the fittings as well.
Ive just gone back and read the entire thread, got a couple of questions that have been rattling the ol grey matter.
1/ what gave you the impression or thought that you had a blown gasket.???
2/ did the bike suddenly make any strange noises and what did they sound like.???
As has been previously mentioned head gaskets dont blow, they never have never will, they might fail due to old age etc. Something causes them to blow. Being a 2 stroke, its going to be hard to pinpoint noises unlike a 4 stroke, cause it's bangin every 2 cycles instead of 4. So it's makin a hell of a noise anyway.
3/ HERES THE THINKING CAP TIME F'ee.
Does this thing run on straight petrol or does it have a petrol / oil mix. Also what colour was the oil in the sump.
Joined: 30 Mar 2007 Posts: 197 Location: Sydney Australia
Posted: Sun Nov 01, 2009 4:20 pm Post subject:
Ok, Ive been going over this bike prob in my head, and may have a few clues as to why it's doing what it's doing.
So pull up a seat, grab a couple of beers and have a read......
From what I can gather, from your post, the head and barrell have been transplanted onto another crankcase from another model. If there compatible within there own brand, for example kwaka to kwaka, honda to honda, there shouldnt be a problem, however the problem may reside within the engine, not in the actual compatability. Obviously you cant put a 500 head and barrell onto a 250 crankcase, it wont handle it, even if you could get it too start.
I asked the question above about the colour of the oil, did you guys fill it with oil, or did it come from the shop with oil already in the sump, and if so, what colour was it. 4 stroke and 2 stroke oil is completely different in viscosity, if you put 4 stroke oil in by mistake, then theres a chance that cavitation could have occured around the pickup, cause the filter screen is to minute to allow the thicker oil to pass through. Then you have whats called oil starvation, which means no upper cylinder lube, and the fail safe mechanism kicks in, ie; the head gasket blows to avoid total engine failure. thats what head gaskets are designed to do besides seal.
The other problem could be the radiator as you described, which would allow the top end to get hot, thereby cooking the oil, and causing it to turn to varnish, which then hardens and blocks the passages. Same thing again, starvation occurs and the gasket blows. Which begs the question, what colour was the oil in the sump.??
What Ive scribbled may not be the answer, but could be a step in the right direction.
Its a mans bike (mates a Ford Man too) no decomp just find top dead center and let it rip, some say hard to kick but they usually holden owners.
She is premix at 40 to 1 and was running a 1 1/2 turn out on air screw (Recommended setting) Castrol fully synthetic 2 stroke oil - think TTS or similar.
The gearbox oil is Motul - made in France if I recall and what most dirt bikes shop sell.
Yeah another set of crankcases were used cause the housing for the crank seal were buggered. The replacement cases are a matching pair and came of a similar year bike. The bike does not change from 1990 to last year of manufacture being 2004.
Good to have as many ideas as possible - colour of the oil in the sump ? This weeks job - drain and
Never thought of the gasket being there for protection The top of the piston is charred black - sootie.
The plug looks like is could run richer, the kawasaki racing team recommend 2 full tunrs out on the air screw.
Quote:
The other problem could be the radiator as you described, which would allow the top end to get hot, thereby cooking the oil, and causing it to turn to varnish, which then hardens and blocks the passages. Same thing again, starvation occurs and the gasket blows. Which begs the question, what colour was the oil in the sump.??
I was under the understanding that the gearbox oil and the "top end oil" never meet one another, are you asking edge with respect to water changing the colour of the sump oil ?
32 to 1 is the factory mix but all guys with these bikes run at least 40:1 - Duckracer on here runs his at 100:1 on Amsoil. _________________ The greatest worth is self-mastery
Joined: 30 Mar 2007 Posts: 197 Location: Sydney Australia
Posted: Sun Nov 01, 2009 7:10 pm Post subject:
That's cool Dude, would just love to know the colour of the sump oil, curious mind thats all. If the piston crown has soot as you say, or the technical term is carboned, DO NOT SCRAPE IT OFF...........DO NOT, NOT, NOT, NOT.
If you do, it will smoke like a bastard possessed. "Leave the Soot" where it is. Period.....
I was thinking that some water from the rad may have found it's way into the sump, was an idea thats all. Not sure of the cooling systems on those things, but all ideas help. Is the top end of this fed from the sump via an internal pump, or does it have an external feed pipe. Or is it fed via a different setup.
Sorry for the questions, but being an ex spanner turner and prob solver, the more info the better.
any error and it will leak.
Cheerz, matie does not want anymore short coming - poor bugger works his guts out for little kiwi dollars - will try sort it , could not do any worse than Kawi dealer has. 
