500 Two-Stroke Tech

What other heads can be used as an individual cylinder head.
YZ125
TZR250 ?
Stud pattern looks the same

Cheers

David de Botton wrote:What other heads can be used as an individual cylinder head.
YZ125
TZR250 ?
Stud pattern looks the same

Cheers

I believe the TZR250 3XV SP ones will work but there is a little work to be done on the waterways. But good luck in finding a full set of 4 as i have been looking for a while!
Thanks Ade

Not being nosey but what's the end game? Looking for head mod?

Hi came across these billet heads on ebay.
https://www.ebay.com/itm/RZ500-RD500-RZ ... Sw42dZDWTc" onclick="window.open(this.href);return false;

Ron57 wrote:Hi came across these billet heads on ebay.
https://www.ebay.com/itm/RZ500-RD500-RZ ... Sw42dZDWTc" onclick="window.open(this.href);return false;

Hi, sorry to hijack. I've also noticed those heads and wondered what advantage they are over the stock ones? Anyone have these fitted and if so why? Just curious.

One of the Costin/Micoproducts bikes if I recall correctly. Awesome looking and the cooling circuit is improved also. Busy plowing out from a snowstorm but I can try and find it later

ns86 wrote:and the cooling circuit is improved also.

I'd like to see proof of that. I just don't see how the upper cylinders would push coolant down into the jugs any better than stock. Especially without the headgaskets that the stock heads use to help control flow. It does appear to be well made and has other advantages over stock.

In the upper/rear cylinders, coolant enters at the center of the heads.
I can't see this in these heads !

I always thought these are 3ma sp heads not 3xv's which are quite different. One year only 1990 sp version, so very rare. Pretty sure this is Mick Costin's Doohan NSR500 engine with the modded 250 sp heads

Other heads I have seen include the individual set of 4 on eBay from aikasot64. Gus [ the crank guy] had a one piece billet unit like the stock ones with removable domes a few years back. Once again If? I recall correctly. I have also seen sets of 4 from a company called Sodertal Racing?



These may be from Gus? His were similar to these.



Not sure about these? Similar to aikasot64


Individual heads on eBay from aikasot64 https://www.ebay.ca/itm/RZ500-RD500-RZ- ... 0005.m1851" onclick="window.open(this.href);return false;

And a complete conversion kit if you have not seen his stuff.

https://www.ebay.ca/itm/RZ500-RD500-RZ- ... 0005.m1851" onclick="window.open(this.href);return false;

3MA SP heads are one source- - that's what the engine in the Costin YZR use. Or George (of the dry clutch kit fame) from Greece - the Bay auction.

I just think they look the part and are of course lighter.

Originally Costin used DT125 heads ; not sure of the head gasket arrangement though .
The genuine / aftermarket headgaskets are somewhat shit ( big time ) and really f*****g expensive . A better alternative is splitting the originals & O ringing the cylinders . The coolant runs between the front of the cylinder banks and exits thru the bottom cylinder inlets & between the uppers .The bike in question needs a GSXR 1000 radiator to cope with the foolishness . Pictures to follow .
Sorry for the tease .. engine is coming out for frame mods & I shall post / explain the logic & execution .
Coolant inserted at exhaust ; thru the heads exiting rear of barrels ...
A .Graham Bells ( & mine ) wet dream .

Yes I did and am again making the 1 piece Billit head again, and I believe they have a lot more cooling capacity over stock, in January I'm gonna machine up 20 sets. Gus

Vinpg wrote:Yes I did and am again making the 1 piece Billit head again, and I believe they have a lot more cooling capacity over stock, in January I'm gonna machine up 20 sets. Gus

Now this is tempting.

Gus, do you have a price for a set yet?