crank stuffer

[BDI]

it looks like BDI likes to play with fire. nice pic. is this off topic?

  I bet that 90% of the people on this site have burned something down on purpose at some point in their life, I know I have For me it goes blow stuff up,burn things down and ride my kx500

[bigbellybob]

I bet that 90% of the people on this site have burned something down on purpose at some point in their life, I know I have  For me it goes blow stuff up,burn things down and ride my kx500

for me its burn then ride and blow stuff up. yea i like to burn before i ride

[kaw rider]

stewart, in the mid to late 80's Kawi had three motors designed to short circuit, another words exhaust side cutaways to allow raw fuel to exit cooling the exhaust side of the piston.
The motor lost bottom end, but 80% of that was recovered with electronics and timing curves.
The reason they did the short circuit was to reduce temp in the exhaust side of the piston.
The tecate had the biggest problem passing endurance testing and that was the post production cure.
I have talked to alot of people over the yrs, very few that have noticed the design flaw.

[BDI]

stewart, in the mid to late 80's Kawi had three motors designed to short circuit, another words exhaust side cutaways to allow raw fuel to exit cooling the exhaust side of the piston.
The motor lost bottom end, but 80% of that was recovered with electronics and timing curves.
The reason they did the short circuit was to reduce temp in the exhaust side of the piston.
The tecate had the biggest problem passing endurance testing and that was the post production cure.
I have talked to alot of people over the yrs, very few that have noticed the design flaw.

Thats all great but I still want to know why you cut.020 off the base and why did you take that cool picture off that showed the exhaust mod that I have been talking about doing for some time? And who did the mod it looks like they did a very good job of it?

[stewart]

i thought the reason was to allow more complete filling of crank case by creating a draw at farthest piont from reeds,,,,i have been looking at a number of ways to accomplish this maybe better maybe not ...i feel if i can create a presure drop frathest from reed tip simmiler to venting a gas tank fill tube or filling any area faster i can create a super charge affect on my crank case compression ,,

[kaw rider]

Bdi
i had stewart cut the base. he has the tooling for it. that cylinder was .004 warp. set up for zero deck height. plus tighten up CCR. i did all the exhaust mods and porting, to much time to do for a paying customer. plus there other mods to intake side and alot of exhaust tunnel work. i what to have great buttom end with this set up. 158* closed exhaust to 192*exhaust open kips. stock kips around 165-168* to 182-185*exhaust. i'm up here in sled country and guys have custom cylinder that are 12 port. the kx 500 motor was designed around a bike frame and made for 4,000-6,000 rpm. i'm working on a cylinder now that will have alot of welding done to it.

[kaw rider]

Not trying to get into an arguement over the subject, but as of that time nobody had ever questioned the large side mills on the pistons to the people that we delt with at Wiseco. I was told by "someone who should have known" that the Kawasiki guys didn't realize it at the time either. Once it was brought to their attention I am sure there could have been several reasons for it.....the pipe thing sounds as good as any I have heard, and better than I could have came up with....lol

Like I said, I am sure we didn't discover anything that other builders hadn't already noticed......maybe we just didn't keep our secrets as well as some others did

I have seen the same type of problem with a couple of the Snowmobile engines, (even seen one that opened their hook exhaust ports straight into the crankcase at TDC, with the cutaway under the wristpin), it seems to happen more in the first year or two that they would start using the auxilary exhaust ports.....and then they seem to change the designs.....

[BDI]

The only thing I wonder is why people that want more bottom end dont just make the main exhaust port smaller I'm allways talking about the upside down triangle and there is good reasons that works real good for making good bottom end and you dont really have to make the port a lot smaller Its more or less the shape but thats more then I feal like typing about right now. Happy new year

[doordie]

Playing with mspaint.....

1.Modified portshape and more portarea.

2.Modified portshape to avoid shortcircuing but need refilling with JB-weld and with little less portarea.

3.More portarea with lowered exhaust floor.

1+2+3=maybe more power without shortcircuing!

(Mike Melde have a similair portmap)

I have a barrel with sleeve and can test this mods later.

[doordie]

This is a easy mod to raise ccr...

        Hey doordie those are ceramic main bearings aren't they? very nice 

Yes,but isn?t a KX500 engine.... 
BUT soon will my engines runs with this hybrid ceramic bearings.....and a composit
rod from a Swedish company www.mxcomposites.com
Ceramicbearings from a another Swedish company www.vasatech.se

[doordie]

This is a easy mod to raise ccr...

        Hey doordie those are ceramic main bearings aren't they? very nice 

Yes,but isn?t a KX500 engine.... 
BUT soon will my engines runs with this hybrid ceramic bearings.....and a composit
rod from a Swedish company www.mxcomposites.com
Ceramicbearings from a another Swedish company www.vasatech.se

[BDI]

With the big square exhaust port as the piston travels down and the port opens exhaust gas velocity slows down. With the upside down triangle the exhaust gas velocity stays high as the piston goes down, do to the port narrowing. From what I have read if the port is designed right with the proper taper the upside down triangle port will flow as much as a larger square port and lend to better filling of the cylinder do to the fact that gas velocity stays high longer. This is stuff I have learned from playing with nitro rc cars. The nitro rc car engines that use this technoligy flat kill the ones with the old style square port. If you were to take both engines apart and try to decide which one was going to perform the best based on looking at the ports your knee jerk reaction would be to pick the one with the great big square port. When you take your car out and run it the one with the big square port gets sadly out performed by by the engine with the upside down triangle port.Your rc car goes from fast with the old style exhaust to retarded fast and pulling power wheelies with insane top end with the triangle port.

[Desert Panther]

for me its burn then ride and blow stuff up. yea i like to burn before i ride
[/quote]

me too !   

[maddoggy]

bdi, lets see if i understand your upside down triangle thoughts correctly. the narrow section of the taper will increase the exhaust pipe pressure much like an orfice increases pressure in a hydraulic system. is my understanding correct? i'm not doubting you but if this is how it works i'm still unsure of the benefits. with hydraulic orfices the pressure is increased past the orfice but the volume of oil passing through is reduced. the same would happen with the exhaust flow if i'm thinking right. just doing some out of the box thinking here.   MADDOGGY

[BDI]

I guess a upside down triangle is a bad description It is a trapezoid. The idea is to have the left and right port walls get slightly closer together towards the bottom. when the piston first starts to uncover the port the gasses are under high pressure so it comes out fast but as more and more of the port is uncoverd the pressure drops and the gasses slow down. the idea is if the port narrows towards the bottom the gasses keep moving fast even though the pressure is droping.It's like when the river is wide the water flows slow but when the river narrows the water moves faster. Yes I'm sure the port has to flow less but this should make great bottom end torque and mid range. I want to make up for this with larger secondary exhaust ports but I do not think this would have that great of an impact on top end because we are not talking about making the port a lot smaller and by the time the port opens all the way It has allready done the vast majority of its flowing.