1987 KX500 Head mods for kyser777

[Sandblaster]

The reason I asked is because I ran the numbers and the calculated port timing would make your cylinder a 88 unless a lot of work has been done to it.
I can tell if I see the side and if you post another of the sub ports looking into the cylinder.
I want to give you the best advice that I can.

[kyser777]

the cylinder is black originally, has been painted.
the KIPS badges has been glued.

thanks

[Sandblaster]

That is a 87 cylinder
I'm having a buddy double check a few things for me...

[Sandblaster]

Ok... I verified a few things on your engine
I have a 86, 88, 89-04 cylinders but not a 87
Based on what you have given me I would use a .25mm head gasket with the Wossner piston you should be perfectly fine.
The big issue will be compression and without a accurate CC of your head I can't calculate the exact compression ratio.
When you get the top end built, put a compression gauge on it and tell me what the lbs are and I can get you real close on the ratio.
Of course you can use any of the thicker gaskets but that will lower your CC volume and lower compression..
As far as modding the head it's hard to say without having accurate info on the head.
I can tell you that with a 2.2mm head you could easily remove .040" off the mating surface and be ok for squish clearance.
The problem with doing that is you greatly reduce the CC and up your compression ratio.
Too much compression and the KX500 won't like it without race gas... Even then there are diminishing gains..

[kyser777]

thanks for your feedback

what about your 86 and 88 cylinders, did you mod your head for higher compression?
I am willing to mod according to your experience on 86-88 cylinders with pump gas.

thanks

[Sandblaster]

Both my 86 and 88 cylinders are sitting on a shelf and are stock.
I have made many modded cylinders for those years but what most people don't realize is that KX500 engines had very loose tolerances.
Some people say they are like a snow flake and each is a little different which is the truth
Then add to that every one that I build is for a specific type and style of riding and vary wildly as to porting and compression.
That is why I asked for so much info to help you get what you need out of the engine.
Something else to consider... the 86, 87, and 88 cylinders all used different compression ratio's and port timing so each is unique.
If I knew your head volume I could get a lot more specific for you but without it I have to use the low averages.

[60something]

Hi Sandblaster!

Hope you and yours had a Merry Christmas! Just an encouraging word; I enjoy all the information you share on this site, and check it fairly frequently for new posts. It sometimes seems kinda quiet here, but I bet many benefit from your knowledge without ever posting.

Thanks for sharing and I hope you have a Happy and Blessed New Year!

[Sandblaster]

Yeah, web forums have declined over the years as social medias have taken over.
I don't care as I like to have a nice tidy spot to stash my accumulated info