Piston and Porting Questions

[BigGreenMachine]

Well I took off the topend. Found a sleeve, some of the ports aren't matched as nice as others. Looking for some pics of a good mid/top end port to copy. Measurements?

Also the piston has "ART" on the side around the wristpin location. Stock or aftermarket?

I have OEM rings here. Wondering can I use them on the sleeved cylinder?


Thanks.

[BigGreenMachine]

Some pics of the bore and side transfer (?) ports along with one of the exhaust ports. Whats with the raised section on the exhaust port? 

Will it hurt to match the cylinder to the sleeve on the transfers?  Whoever did this didn't even chamfer the ports.  Not finding any markings on my cylinder either. The sleeve hasn't moved if any of you are thinking that. Its perfectly level on top. I thought that was my problem at first.

Well please add some input, I can't learn from you guys if I'm just talking to myself. 

cheers.

[hughes]

Matching the sleeve with the ports is not that hard with the right tools and a steady hand. Those sub exhaust ports should not really require any chamfer or very little. The larger exhaust port and intake ports will. The rings can expand into the port and break off or most people call it snagging a ring. The chamfers help to ease the ring back into it's ring groove. Photo's are very dark and hard read. To much chamfer can effect horse power in a negative sense. All my hot roding 2-stroke skills come from years of marine engine work but some and same theroy still apply to all 2-strokes. Hope some other can give some input. Need better photo's.

[KXcam22]

I agree with Hughes.  Get us some better pics and we will be able to steer you right.  I have ported many bikes with steel liners (in the old days). Cam.

[doordie]

At first pic something is wrong,it shouldn?t be any bridge at inlet,you got the oldstyle
barell before -89.

Sleeve seem twisted a few degrees wrong too.
You should chamfer all ports,but this barell need reboring first,just my 2 cent!

This is MUN`s portmap of a 68 rwhp old style barell,if you want "more power" it`s to much to handle for most riders.

//Doordie

[BigGreenMachine]

Do0rdie, its an 88 cylinder.

Guys what would pressurize a coolant system so that coolant spits out whenever the motor revs?

[BigGreenMachine]

Pics.

I know it needs a bore but honestly its going to get honed and reringed for now until I can get a fresh OEM cylinder.

[MadKaw]

how were the head and base gaskets?

[BigGreenMachine]

Base gasket was toast but the head was fine.

[don46]

I wonder if the cylinder is cracked, looks like rust in the cylinder. The bridge on the intake doesn't go all the way to the bottom on the stock 88 cylinder. Maybe you should send it off and have it re-sleeved. or keep an eye out for a 86, 87, or 88. newer style cylinders are more plentiful, have you thought about going that route? either the head gasket was toast or the cylinder has a crack that would cause a pressure buildup in the radiator, check the radiator cap as well, it could be bad.

[BigGreenMachine]

The rust is my fault, cleanup and never got those little ports when I wiped it off with some oil.

How hard is it to convert the old pre 89 motor to 89-04 cylinder/PV setup?

[don46]

Not an issue at all, you need cylinder head and kips. The pre- 89 had a larger pin for the actuation rod, so it needs to probably be replaced but the inner parts are the same, the clutch cover would work all the way to an 04. The only downside is the pre 89 has bigger ports and IMO they flow better.

[BigGreenMachine]

Well say if I had the complete cylinder and head assembly from an 89-04 500, what would have to happen to make it work on my 88?

Just one more hole drilled in the case to accept the extra powervalve??

EDIT*** Yes, from the looks of my manual and cylinder it'll just be a matter of placing the hole for the extra PV.

I would rather buy an older used cylinder to have replated. Hoping to get this 5 buttoned up again soon. Powerwheelies in 5th are great! Never riding a 250 again.