What shall we find?

Sir,

Check you squish (piston to head clearence). You might have an issue this being too tight. Also, not to sound like a peckerhead, did you check the diameter of the gasket against the dia of the bore? I would assume, if this is the same before the gasket is compressed, that when it does become compressed, it might protrude into the cylinder a bit. BUT, I don't think the pistion should even come up that far past the top of the sleeve.

My thoughts....

-Parsko

That is bizarre. To me, it sounds like a bum gasket. According to Taffy's document, the compressed gasket is "always" 0.059" thick, which is 1.2mm. Are you sure your measurements are correct? If correct, are you torqueing the head on correctly? Overtorqueing would cause the gasket to bulge into the cylinder, I would gander.

When you get the new gasket, measure it. Check it against both your old ones.

Maybe someone else has some thoughts too...?

-Parsko

most definitely sounds like the wrong base gasket is being used.
The "Z" measurement should be checked. The piston should never
come up past the top of the cylinder, mabe two different sized base gaskets should be used.
Earl

when the head gasket is squished to the breaking point this i take it is from the piston making contact the head gasket should not over hang the bore it should not be possibkle for the gasket to be squished even if the rod bearings go when that happens the piston will hit the head or the valves i have seen head gaskets sucked in to the bore and hit, too thin head gaskets used and the head hit bigger diameter gaskets used with no problems except a build up of carbon and lowering of compressin but in the 25 years of being a motorcycle mechanic have never seen a head gasket that was desinged to over hang a bore except those made by di it your selfers and i am fixing there **** up

the gap between the head and the piston should be .040" minimum. yet the gasket is .056" thick when compressed. that means that the piston can be as much as .016" clear and driving in to the gasket area.

regards

Taffy

NSMAN,

I think you are on the right track. One indication I would look for, if I were thinking that the sleeve is not normal to the crank axis, would be larger than usual wear on one side of the sleeve. A condition like that would cause one side of the sleeve to get worn significantly more.

In order for you to have 1mm of movement on one side of the piston, you would need a misalignment of 1.1degrees in the sleeve, that is if the sleeve was centered on the axis. (tan^-1(1/50)=1.1deg. roughly. This seems unrealistic. Machined components normally aren't that bad. Possibly something is stuck underneath the sleeve between it and the case, causing it to not "seat" correctly?

-Parsko

surely the most obvious thing that needs to be done is to check the hollow dowel location on top of the block? it's the gasket that's wrong and nothing more or less i'd have thought?

i'm not sure what the answr is except that you shouldn't make any mod to the gasket by hand but raher with a dremmel type rotary tool.

regards

Taffy

nsman,

What is the bore and stroke on your 03 450?

regards,

Joe

Bore 100mm
Stroke 57.2

-parsko

Thanks Parlso,

I had been hoping it was 97mm x 60.1mm, since it was a prototype. I know thats only 444cc, but I had heard that there were a few made, and reports were that they were really good; better than the 450 KTM of that year and
better than the current Berg (with 57.7mm stroke).

Besides, if it was 97mm then a solution to the gasket problem would be to use a 100mm gasket.

Regards,

Joe

ahead of you there joe and they don't make a 102mm headgasket.

regards

Taffy

Well, then if the bearings are O.K., a solution is to determine how much the piston is rising above the top of the sleeve, and fabricate a shim ring to put under the shelf on the sleeve to jack up the sleeve enough to keep the piston from hitting the gasket.

Regards,

Joe

if the head gasket is not over hanging the bore when you start out
is it located correctly on dowels
if the sleeve was tilting(which could explain the gasget being crushed) why is there no water leak surely the head gasket must be sqished between the sleeve and the rest of the barrell to keep the wter in
is there a dowel that is not allowing the head to be pulled down evenly
if there is enough cyinder surface to seal the water the sleeve must be moving around while the engine is running i think a complete pull down is a must to check the sleeve locating area etc

nzberg

notes on dowel location already made fella-keep up at the back please!

nsman
the 470 lining is a straight swop. all you will ever need to check is the gudgeon pin to top of piston on both and if happy here a final check by checking the squish will suffice.

the way to do this is to lay a peace of 1mm silver solder wire in a loop and then inlay it in some plasticine. smear oil on top so that the plasticine/solder stays with the piston. do two places at once; wide on the piston and above the GP on both sides at once.

drop the piston in the bore 2-3mm and then bolt head down. then rock the engine over TDC and back 10 times.

head off and micrometer/vernier the solder. .040" minimum although if it's .035" i should think your still ok. i've gone to this and will be able to tell you soon incase you beat me to it (mr ammundson!!!!)

i'm amazed at the detonation! but if it's the small head on the 100mm bore then a high comp is easy to achieve. cheap yanky fuel?

my ignition rotor mark is 2/3rds to 3/4 of the way to the left in the sight hole yet i have had no detonation. i beleive this is because of the overlap of the LX2 cam at low revs has stopped the detonation and the extra advance at high revs the engine deals with-no problem!

my engine though had ripples in the lining near the top like waves...

don't worry about the piston numbers at all. get on with it! check the piston for valve pocket depth and width but you will have loads of clearance!

as for the cooling jacket well my bike is the same with the right rear quarter in the head not being machined. i have water cooling down the left at two points but on the right at only one point!

the gasket doesn't help at all!

maybe dale can help with the detonation but i'm flumoxed-bar the fuel. you should consider going up 1 on your plug?

regards

Taffy