Ron Black Retired....

[Chuck78]

Arne Cooper and Ken O'Connor Racing are 2 other viable options for head work. O'Connor is a little cheaper. Arne did a head for me and I believe he really know how to adjust chamber volume and squish band.

Arne can be found on ThumperTalk...somewhere.

Ken O'Connor Racing as well as Tom Morgan Racing are two highly recommended sources for 2-stroke head work from what I've browsed while searching the internet for 2-stroke head mod info.

Matt Denecke of Lectron Fuel Systems and also owner of Apex who make billet aftermarket Yamaha YZ heads also offered to help teach me the calculations needed to lathe cut heads to change the squish angle to the most optimal, as well as cc the chamber and figure compression ratios.
What I'm learning is that 1.20mm is the maximum ideal squish band height from edge of piston crown at the pin axis, + head gasket thickness + head chamber squish area relief height. a squish height of 1.40mm or 1.60mm effectively does little or nothing in the way of forcing the air fuel mixture towards the center of the chamber rapidly enough to create the turbulence needed to harbor a much more complete and rapid combustion event. The 220 being a lower rpm torque machine, Kawasaki missed the mark on this department as they gave the head too much squish height to lower the compression for what they considered more favorable woods tendencies, but really what they did was to make the combustion a lot slower and less ideal. Shaving the head at minimum will give better combustion chamber fuel mixing when getting the squish band height down to 1.20mm or even 1.0mm if you like more performance and don't have sloppy crank bearings.

Looking at these heads on my desktop in front of me, and talking to my machinist buddy who was looking at the head installed on my bike, I think Ron must have used the coolant flange surfaces to mount the KDX head to a plate that he'd bolt to a surface plate on a lathe to turn the face down as well as slightly alter the squish angle. I wish I could contact him to ask for advice in machining my own heads now that he's seemingly fully retired, but I get no reply. I wonder if anyone here or elsewhere has any more personal relationship with him as a customer and has a way to reach out to him to get any final word on his status? It seems he's 100% done via no replies for months now in 3 attempts, after being eager to help me back in late March... I hope he's doing alright and in good health in his retirement.


This is a good article I started reading. I have several others pulled up as well to browse.
http://www.powercdi.com/manual/combusti ... sh/en.html

[Chuck78]

Wow. our own Jaguar who makes KDX high performance CDI boxes, REALLY lays it out here:

https://www.everything2stroke.com/threa ... ost-548582

I was going to cut and paste and remotely link his graphs, but that's a lot of info!

https://dragonfly75.com/moto/sqVelocity.html

Jaguar is truly a wealth of knowledge on 2-stroke tuning...

Ron Black as well, and Ron was a master machinist, but Ron never shared all of his knowledge the way Jaguar does, most certainly due in part to the fact that he didn't want to give away the secrets that generated income for him.

From what I'm reading and learning, the squish angle just needs to match the piston. Oversized pistons typically will need to lower their dome volume in order to compensate for the larger bore to keep the compression ratio the same, therefore the angle required for a 70mm 223cc Wiseco piston may be different than that of a 69mm stock 216.8cc "220" piston.
The ratio between overall squish band cubic area vs combustion chamber dome area is a critical relationship to ensure proper squish velocity, and proper squish velocity is dependent largely on port timing. The 200 is a higher RPM engine and thus will have different port timing than the 220 which is a torquey mid range RPM engine. Increasing the compression ratio can be done without fear of detonation to a certain extent IF one does all the advanced calculations involving port timing etc to get the squish area calculated for proper optimization.

Jaguar (Michael Forrest) has some very complex excel programs to calculate everything very precisely, which also requires a lot of various engine inputs and measurements.

I need to do up a 223cc head for a cylinder that I have which was ported significantly on the intake (wider ports and knife edged and slightly wider on the exhaust) and bored 1.0mm oversized. Luckily the port heights were not really altered, which will preserve the low-mid power of the 220 as well as the superior fuel economy that the 220's port timing and duration will give over the 200's. Add to that an optimized head squish band clearance height and squish band width, and a Lectron BIlletron Pro Series or SmartCarb SC2 36 metering rod carbs for even better atomization, and I'll really have the ultimate setup as far as ultimate Kawasaki 2-stroke long distance enduro machines...


A good and very technical video tutorial from Jaguar:

[Chuck78]

From another post here by Kawibunga last year, referencing a post which I have yet to find of Ron Black's on everything2stroke.com :

I just found a post by RB on "everything two stroke"........ he modifies the profile as well to do it correctly. Time to read some Bell and Jennings books......

"Summary:

The above measurements are needed so I can reduce the squish clearance. This is where the power, torque, gas mileage and reliability is to be found. I don't just go with more compression. I also re-do the combustion chamber to maintain the proper trapped combustion volume. You will not give up any reliability or shorten engine life with this mod.

The cost for the modification is $75 (U.S.) not including shipping and handling to Portland, Oregon, U.S.A. For more information, please visit our website at www.rb-designs.com .

About the Author :
Ron Black of RB-Designs has been building race engines of all kinds and his own custom race parts since 1970. He gained experience working side by side with many “old school engineers”. He has built 3 dyno's and has been running them since the early 70's. He has one of these dynos in his shop.

Over the years, he designed a number of motorcycle service departments and managed many of these. He designed his brother’s shop and worked with him for about 12 years prior to starting his own shop 10 years ago.

He has worked with both the Yamaha Road Racing Team and with Kawasaki’s motocross R&D department. He has spent the majority of his life designing reliable high performance parts."

I should also note that Ron found the KDX engines' machining to be so consistent that he never required any squish test measurements, as they were all made with fairly close tolerances enough to make all the heads modified the same.

[Chuck78]

Matt Denecke of Lectron Fuel Systems and owner of aftermarket cylinder head manufacturer Apex Technical Innovations:

https://www.thumpertalk.com/articles/sq ... nce-r1060/

very knowledgeable guy. He offered to help me with the calculations on the KDX220 engine and head, but said he no longer machines stock heads anymore, although this can be done on a manual lathe once you have the correct calculations and resulting specifications.