Interesting read about squish technology

[RBD]

OK!!!!

This is where I think that I am supposed to chime in...., SO I WILL!

The only thing I want to say is that I have done my mods for 35 years and learning and experience of what works for the racers to the weekend warriors and even the occasional rider.

That being said the .040" (1 mm) squish band thickness still rules (with the proper squish band area)

The pumpkin and other european models like the gasgas like to use lots of compression and thick squish band thickness (.080" to .100") This is good maybe for **** gas and other crap you put in your tank over there.

The O-ring head gasket will work very well and the inner O-ring (next to the combustion chamber) is made of Viton, yes it will hold the pressure and more important the heat!

Just some food for thought.

Ron

[KDXer]

OK heres some more food for thought. The squish band is 55thou high at the outer edge and has an angle of approx 4 degrees. Compression is about 11:1. Sound OK ??

The crank seals and main bearings (along with the top end) were renewed about 3000km ago. He has fiddled *a lot* with the jetting, nothing ever seems entirely perfect but its quite good.
The oil is mobil1 racing 2t at 50:1, the bike gets put through a lot of slow and reasonably technical riding.
The spark plug is a bpr6es, a projected tip version of a 2 range hotter than factory suggested plug.

Oh and the red line on the head pic indicates the exhaust port.

It is not running the dual taper needle he has a JD kit installed but am unsure of exact jet set/needle config. I think its still too rich (main) and running too cold. Thanks a bunch for the offer though Brad your generousity/time is much appreciated (that huge thanks also goes to you IC, I am truely grateful for your expertise and experience).

I will pass the info on and hopefully help him see the light.

Oh BTW CC watch where ya walk next time silly.

[IdahoCharley]

Just some notes - may be useful may not

.055 - .060 inch clearance between the top of the piston near outer edge and head was the clearance I was referring to. So your friend's bike at .055 inch is close to what my 98 was after head modification.

I did not attempt to measure the squish "angle" of the heads after modifications but did attempt to measure total squish area as a percentage of total piston area. My Eric Gorr head had an 45% and my Clay head a 50% squish band. Both bikes had compression readings in the 145-150 psig at 5000 foot elevation. I did not cc either head but did note the following trivia.

98 - pulled harder right off idle and rev'd higher with EG head verses my 00 with Clay head. Both had JD jetting, SLP power pak, same gearing, Twin air filters, DF reed blocks, and I tried both FMF gnarly and OEM stock pipes with same gas/oil ratio.

Apples to apples?? Differences - 00 OEM PWK carb overbored 1mm, 98 had stock PWK carb: 00 had stock engine cases, 98 I had matched the cases to the cylinder: 98 cylinder had been "mo-power" everywhere ported by EG (which really just looked like 'maybe' a slight clean-up on the port passages - very hard to tell if any material was removed) while the 00 had some porting passage work performed by a local shop by previous owner. Both ran well on pump fuel 91 octane.

IMO both bikes ran extremely well after modifications but in both cases the head mods cost some upper rpms. Not really needed by an old guy running a 380 anyway.

Someone mentioned whether or not there was headgaskets on the KTM. Just 0-rings for sealing on the 250-380 models anyway. This is actually similar to alot of other bikes and snow machines.

NOZX needles are TRIPLE tapered where as the JD needles (at least for the KTMs) are custom made DOUBLE tapered needles - FWIW.


Brad - yes I do believe from the first time I looked at the head there was likely some coolant seepage into the cylinder. Even more so now that I see he runs a plug 2 steps hotter than stock. But I did not see any erosion and wondered if it was not intermittent thermal growth sealing problem related to non-uniform sealing of the head to cylinder interface.

[KDXer]

Brad - yes I do believe from the first time I looked at the head there was likely some coolant seepage into the cylinder. Even more so now that I see he runs a plug 2 steps hotter than stock. But I did not see any erosion and wondered if it was not intermittent thermal growth sealing problem related to non-uniform sealing of the head to cylinder interface.

Thanks a bunch IC. Just wondering though, sounds like your suggesting that when it gets quite hot it's letting a little coolant in? Do you know any ways to test for / correct this ??

[canyncarvr]

Don't lose this in the verbiage....IC mentioned the torque being too high at 25ft/lbs. Maybe that's what caused the whole mess in the first place. THAT may well be how you correct it.

Whatever anyone runs or has done..if Ron says .040" with the correct angle is correct, it is.

I'd think measuring that angle/area/depth would be tough anyway. If Joe down the street says he's running a .055" squish with a <whatever> band area, I know I wouldn't believe a word he said.

Everyone knows Joe is an idiot anyway..........

[RBD]

Curious to hear anyones thoughts. Does it look and sound like a logical method ?? I have a mate with a KTM380 who is having problems I will explain more soon and post some pics.

Theory
http://somender-singh.com/
Pics
http://somender-singh.com/content/view/68/49/

What and the HELL does this have to do with where this thread is placed?

[canyncarvr]

heh heh.....


From there:

Read on ! Squish, Squash & finally Squashed ! ! !
US Patent 6237579 is applicable to any 2 or 4 cycle internal combustion engines featuring " Squish or Quench " concepts..


See? Because the word is used!

That's just one of the funnies of the whole thing.

I understand squish to be space between the piston (not crown) and the deck. Here's a webdef that, if it's not right, it at least agrees with what I think!

'The quench area is the flat part of the piston that would contact a similar flat area on the cylinder head if you had .000" assembled quench height.'

From HERE!

I don't think that is related to squish. Right, or no?

Using the terms in the listed thread...AND the way they were used was one of the funny parts.

I didn't get the connection..but..I don't get a lot of things.

[KDXer]

Don't lose this in the verbiage....IC mentioned the torque being too high at 25ft/lbs. Maybe that's what caused the whole mess in the first place. THAT may well be how you correct it.

He is looking at getting it pressure tested somehow to find out.

What and the HELL does this have to do with where this thread is placed?

Hehe simply put, I figured if anyone on here would have heard of this concept it would be yourself. I also figured if anyone would have an expert opinion it would also be yourself. I really didn't mean to offend you Ron, I appologise if I have. Thanks for your input BTW. Oh and Brad

[IdahoCharley]

KDXer - Pressure testing is good for identifying a number of problems with leakage - both intake type and pressure lost leakage. On a head coolant seepage problem it may or may not help identify the root of the problem.

There of course a number of possible factors like head warpage, bad O-Ring, foreign matter, etc which can be the cause of the problem. On KTMs, in particular, the bolt fasteners used on the head can contribute to problems of this nature and are generally over looked, or not understood, by many shops performing maintainance work.

If a head bolt(s) has been tightened beyond its yield strength (even once) then the bolts will permanently loose its ability to hold constant tension between the cylinder head and the cylinder even though the head bolt is "tight". Sound confusing???

Different metals and different alloys expand/contract at different rates depending upon a variety of factors. The purpose of the head bolts is to keep relative constant tension/pressure on the gasket or mating surface between he head and the cylinder. As the cylinder heats-up it grows in length. This is at a slightly different rate than the head which is also growing in all three dimensions as it heats up. As the components cool contraction of the materials also take place.

There will generally be a difference in temperature which is always changing between the mated components due to engine load, stream crossings, natural cooling, coolant flow, etc.

Torquing head bolts is designed to stretch the bolts WITHIN A GIVEN LIMIT ( while remaining in the yield strength range for the bolt). This allows the head to be held to the cylinder within a prescribed range of tension. This allows for sealing of the combustion chamber, coolant flow passages, etc.

Summary - If the head bolt has been stretched beyond the bolt's material yield strength (elastic property) the bolt's molecular structure has been changed and the bolt has lost it elasticity. This elastic property of the head bolts is what works in conjugation with the gaskets/O-Ring to keep the engine sealed.

P.S. Ever been tightening a bolt and feel it "give" and you just know be experience that another little nudge will result in a broken bolt? If you have experienced the aforementioned then you have reached or exceeded the "tensile" strength of the bolt. The bolt is elongating/stretching and being pulled apart or tensile failure. The yield strength is usually somewhere in the range of 60-70% of the tensile strength and you cannot "feel" it when it is exceeded.

BOTTOM LINE -The head bolt can still be tightened down to a prescribed torque value and not function as intended. It will be "tight" when torqued down but will not 'grow and contract' with the temperature changes as originally intended by the engine designer. This can lead to coolant seepage, failure of sealing gaskets, etc.

[KDXer]

Awesome info IC, thanks a million buddy. I will pass it all on. I really appreciate your time it took to respond and for sharing your knowledge with us.

So what would be the best way to test if the head studs are in fact causing the problem ?? Replace them ?? Measure them someow/check thread pitch ?? Cheers, Trev...

[RBD]

OK guys,

I now have a new revolutionary turbo boost cylinder head mod. It will more than double your HP.

It is three very super high velocity clock wound springs and super trick material fan blades (top secret material) that are very strategically placed (again, top secret)

How this works is, when the piston is coming up to TDC the volume of the mixture is creating a velocity that makes the special fan blades spin in one direction. Hence winding the special spring.

Next the ignition fires creating the burn and kicking in the wound up fan blades and releasing there force causing a super turbo flame doubling your HP.

So who wants one, send me your head

[canyncarvr]

....but...if I send you my head, I won't be able to taste my food!!


Gee, Ron. You been holdin' out on us green dweebs!

[IdahoCharley]

KDXer - Replace the bolts. Should cost less than $20.

You can measure the new ones if you want and then compare them next time the head is pulled - trouble is we are just talking about changes of maybe .010-.020 inch in total length on a fastener about three inches long. Trying to compare old to new length likely does not work since these type of bolts are not held to really high quality standards associated with their overall length.

"....but...if I send you my head, I won't be able to taste my food!! " ROFLMAO

[scheckaet]

I now have a new revolutionary turbo boost cylinder head mod. It will more than double your HP

A!wesome! I want 1 I want 1! I want 1!
Does it come with the springs or can I find'em in my local hardware store? (the location is also secret)

[KDXer]

OK guys,

I now have a new revolutionary turbo boost cylinder head mod. It will more than double your HP.

It is three very super high velocity clock wound springs and super trick material fan blades (top secret material) that are very strategically placed (again, top secret)

How this works is, when the piston is coming up to TDC the volume of the mixture is creating a velocity that makes the special fan blades spin in one direction. Hence winding the special spring.

Next the ignition fires creating the burn and kicking in the wound up fan blades and releasing there force causing a super turbo flame doubling your HP.

So who wants one, send me your head

Sounds cool, how much and when can I send my head in ??

Thanks IC I will tell him to replace them.

[bradf]

Now I have to choose betweeent the Tornado for the truck or the turbo fan for the KDX. I must have it all.

[canyncarvr]

Re: 'Finally I'll have something on my bike before everyone else.'


But..... ..how will you KNOW? It being such a secret and all...I don't doubt that you can't even SEE it!

Well, I guess you could know it was there, 'cuz you paid $150 for SOMEthing, right?

[scheckaet]

Now I have to choose betweeent the Tornado for the truck or the turbo fan for the KDX. I must have it all.

Do you already have the magnetronic installed on your fuel lign? (align the molecules)
'cause if you don't you're missing sumthin'

[canyncarvr]

Wow. Are YOU misinformed!!!

It doesn't align the fuel molecules. What a silly idea!!!

It breaks apart the CLUMPED molecules!!!

...Of COURSE!!

(who doesn't know that......??)

[scheckaet]

It breaks apart the CLUMPED molecules!!!

That's where U R wrong. I should know, I have secrets PATTENTS PENDING on the magnetotron dohickey > this revolutionary device will TRAIN your fuel moelcules to fall in line when asked to (think of it as a well trained border collie )