kx500 outlaw kart motor

[sandblaster]

Port timing


Compression


Skipping 85---
86 had the highest port timing and compression.
89-04 was next best
87 was next best
89-04 was next best
88 was the worst

86-88 are the easiest to port and can all be made to scream.

89-04 can also be made to scream but it takes a bit more effort.

With my new valve design I'm hoping to make some significant improvements on the 89-04 but time and dyno testing will need to be done.
Mechanically I have it operational... Took me three attempts (welding and hand machining) to get what I wanted.
I'm sending my cylinder away next week to get it bored and machined..
I'm also sending in my crank to get it rebuilt.
So I should have something to test in about a month or so...
I hate sending my cylinder off to the competition because they will see what I am doing  
But they will only get half the story without the valves  

I won't say who it is going to either cause I really like the guy but we don't share everything  

[dave916]

86/ 88 had all almost similiar port timing {120/180duration}
only real differance was main exhaust port on 86 is far smaller

Dont know where clmer got those specs

[sandblaster]

Hmmm... I did not know that.
I'll have to pull the 88 cylinder off the wall and do some measurements...
Do you have the exhaust port height and width for the 86?

[umberto]

I'll have to pull the 88 cylinder off the wall and do some measurements...

Sorry to hijack a thread, but did you ever get an 88 cylinder head in?  I'm still looking for one...

[funkj]

Am I safe to assume the 86 cylinder is a 3 port exhaust with 2 drum valves and no main port flipper?

[dave916]

Hmmm... I did not know that.
I'll have to pull the 88 cylinder off the wall and do some measurements...
Do you have the exhaust port height and width for the 86?

yeah i post a pic if in can find it

[funkj]

86/ 88 had all almost similiar port timing {120/180duration}
only real differance was main exhaust port on 86 is far smaller

Dont know where clmer got those specs

That makes better sense to me.

[sandblaster]

Am I safe to assume the 86 cylinder is a 3 port exhaust with 2 drum valves and no main port flipper?

Yes, that is correct.

[sandblaster]

Here is a pic of the 86 cyl.
Note: no decomp scallops and a smaller exhaust port then the 87-88

[sandblaster]

Here is a 1988 Cylinder..

[funkj]

Great info...

Looks like for me the 86 cylinder would be the best for and application where your wanting to eliminate the power valve. You have the option of lifting the cylinder or raising/the  exhaust or a combination of both and leaves some options for transfers.

[RoostiusMaximus]

I don't have head specs for the older K5's but I can tell you that if a 86 top end is done correctly they can be a rocket..


7X KX500 Drag championship winner Jeff Grawbarger uses a 86 top end on this bike with a 89-04 bottom end.
Yes, I know the specs.
No, I can't tell you 

But I will tell you this... Less has been done to this then you might think..
And that bike is freaky fast...

don't under estimate what all has been done here lol.

[sandblaster]

I don't have head specs for the older K5's but I can tell you that if a 86 top end is done correctly they can be a rocket..


7X KX500 Drag championship winner Jeff Grawbarger uses a 86 top end on this bike with a 89-04 bottom end.
Yes, I know the specs.
No, I can't tell you 

But I will tell you this... Less has been done to this then you might think..
And that bike is freaky fast...

don't under estimate what all has been done here lol.

I would never....