...on my big green tractor (91 KX500 Build)

[jgturbo]

Flywheel puller finally came in. Here's the breakdown:

Ready to come apart:


There's third gear! Popped the clip out of the groove:


Here's why the clip popped out (probably combined with a slightly bent shift fork):


Found the main bearing play. The cases are ok!


Explosion on the workbench:


Notice the DeWalt impact driver. I highly recommend it for working on bikes. Plenty of energy to knock fasteners loose in a really small package. MUCH better than spinning wrenches in my book.  Ziiip ziiip ziiiip done!

[jgturbo]

I'm in the market for a service manual (pdf would be cool)... PMs welcome.

[Brute]

Just was reading this again and noticed you are in Washington! Have decided to SM and plate mine, but will probably Rim-n-spoke an extra set of wheels so I can throw the stock ones back on if I want to dirt the bike again quicky. Told a guy at work about the 'plan' and he went ape about it. He is a road racer that rode for Cagiva over seas. He would be a good choice to have wring it out at a track me thinks! Got to get it built first. Good to see you found the slop problem in the crank. Are you going to get it metal sprayed, welded, or just replace it?

[jgturbo]

I'm actually in Portland, so it's registered in Oregon. I don't know yet what I'll do with the crank. Can someone recommend a crank repair shop that could fix this? Otherwise I might try to grab one off eBay and have it rebuilt.

[jgturbo]

Picked up a crank assembly from an '04 on ebay. It's got to be in better shape than mine.

Also made a bit of progress on the cylinder:

Cutting .050 off the top (super low quality video):


A couple minutes with a stone yielded this:


I should now have close to zero deck clearance. I'll be fine tuning the squish with base gaskets.


Now I need to research head designs so I can 3D mill my squish band and combustion chamber 

[Motorrad]

Finetunesquish with the head... not the base gaskets..

get it all assembled with the port time you want...


Measure measure measure..


THEN

cut the head.

[jgturbo]

Good call. I'll wait to modify the head until I have the engine together. I'm waiting on an angle attachment for my dremel so I can get in there and modify my intake ports. Then it will be time to send it off for plating.

Motorrad, did you have the plating company weld up the roof of your kips ports or did you do it yourself?

[Motorrad]

Good call. I'll wait to modify the head until I have the engine together. I'm waiting on an angle attachment for my dremel so I can get in there and modify my intake ports. Then it will be time to send it off for plating.

Motorrad, did you have the plating company weld up the roof of your kips ports or did you do it yourself?

company..

[jgturbo]

Well, it's been a while since I've posted in this thread. I spent the summer and fall dumping all my money into my wife's 69 VW Bug. That project is finished, so now back to the KX!

I've got the bottom end back together. Transmission from a '98 ish bike. New bearings throughout. Crank from an '04 rebuilt and balanced.

I just finished the porting today. I'll try to get some pics up soon.

New numbers are:
195 deg Ex and 130 deg In with .040" base gasket.
197 deg Ex and 133 deg In with a .055" base gasket.

Deck is zero with a .050" base gasket.

Planning on cutting the combustion chamber this week. Does anyone have a head cc recommendation? I was thinking 36cc, but haven't crunched the numbers yet.

Anyway, it's good to be back!

[jgturbo]

I apologize that it's not as pretty as some people's builds (coughmotorradcough) but I think it will get the job done. It had a new piston in a worn cylinder when I bought it. I'm thinking of riding it for a day to test my porting before I get the cylinder re plated and toss a fresh piston in.

Bottom end together. There's a component here that's positioned differently than stock. Let's see who can catch what it is.


Intake goodness


Exhaust

[Motorrad]

Did you lower the main exh port?

I count 3 non oem things in picture :0)

[jgturbo]

No, I didn't lower the exhaust port very much. I'll double check but I don't think I have much piston skirt to spare at TDC.

I shortened the clutch push rod a little. This swings the arm around a bit and places the cam in a position with more initial leverage. We'll see how it works. I can actuate the arm by hand at the moment.

[Motorrad]

No, I didn't lower the exhaust port very much. I'll double check but I don't think I have much piston skirt to spare at TDC.

I shortened the clutch push rod a little. This swings the arm around a bit and places the cam in a position with more initial leverage. We'll see how it works. I can actuate the arm by hand at the moment.

I'm running more base gasket than you..  And mine is lowered about 2-2.5mm.     Check.  There is good power found there..

Oscars motor.  Had .060 with of base gasket, and I lowered his about .125"

Every motor is differant..  Have to measure each one before you cut
The billet clutch arm mod accomplishes that,  with more leverage...

[jgturbo]

Quick question:

How much can I safely cut off the head's gasket surface?

Anyone ever take off too much?

[jgturbo]

And another question:

Does anyone have a recommendation for squish band angle?

My gut feeling is 7deg x .375"ish wide into 20-30deg x .250"ish wide then .125" radius into the hemisphere (width measurements are parallel to the deck).

I'm just shooting from the hip here. Never done this before. If someone would like to save me some trial and error, that would be great.

Thanks again guys!