It/yz Head

[txsbuckeye490]

Posted this question in the vintage section & didn't get any response . So here it is again! Are the heads on an 1981 IT 465 and the 1981 YZ 465 the same? Can these heads be used on an 1982 YZ 490? If they can would it need the Eric Gore squish band mod done to it?
Thanx!

 

[Tom68]

Don't know if heads are the same. 465 head would probably need clearance mod for bigger diameter 490 piston.Too tight to do squish band mod on last 465 I had so just ran twin head gaskets, ran sweet and started easy.

 

[TRexRacing]

Hey Tom.How tight was too tight?Pump gas or race fuel?

 

[Tom68]

Hey Tom.How tight was too tight?Pump gas or race fuel?

I was too tight to do the mod' let alone pay for race fuel. But from what I'm told the factory squish band needed work for pump gas, I believe that was shape not comp' figures.

 

[TRexRacing]

yeah my YZ465 is .070.Did you happen to measure yours?I wanna do mine and don't want to do it twice.

 

[Tom68]

Sorry didn't measure. Went to twin headgaskets because I broke the RH crankcase and clutch cover kick starting it so decided to decompress for reliable starting, turned out previous owner didn't use a base gasket amongst other assembly faults.Still I'm sure the mod's worthwhile and if you end up a little light on compression there's enough engine capacity for plenty of bottom end.