Microfiche has been known to be incorrect before. I'm only referring to hands on verification.silverstrom wrote:That's interesting, because the part numbers for the 86 heads are the same as the part numbers for the 84 heads. They changed in 85 but for the S model went back to the 84 #s.WVWRZ500N wrote: The ONLY engines with corrected compression from the factory was the 1986. I've built two 1986 engines.
Rear Head Question
Moderator: rztom
Re: Rear Head Question
Regards,
Bill Wilson
Wilson Performance
Lee's Summit, MO
http://www.wilsonperformance.net
Member RZ500 Owners Group #573
816-377-3185
WVWRZ500N@aol.com
Bill Wilson
Wilson Performance
Lee's Summit, MO
http://www.wilsonperformance.net
Member RZ500 Owners Group #573
816-377-3185
WVWRZ500N@aol.com
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Re: Rear Head Question
That's true. I have a hard copy 86 S parts manual from Yamaha and it is the same as the microfiche.WVWRZ500N wrote:Microfiche has been known to be incorrect before. I'm only referring to hands on verification.silverstrom wrote:That's interesting, because the part numbers for the 86 heads are the same as the part numbers for the 84 heads. They changed in 85 but for the S model went back to the 84 #s.WVWRZ500N wrote: The ONLY engines with corrected compression from the factory was the 1986. I've built two 1986 engines.
The more I talk about this the more I'm convinced it really doesn't matter. I haven't seen anyone else bring up the subject and it seems 99% of the owners don't know about it and have been using whatever heads they happen to have. Anyone doing a performance build, like yourself, will cut the heads anyway, so again, it doesn't matter.
I was looking for something conclusive to state why there are differences and what those differences/changes accomplished, if anything. So far we're where we started. We know there are differences, but no definitive explanation from Yamaha's literature. I was hoping it would be as simple as it is with 350 heads. No such luck.
Re: Rear Head Question
i checked some spare heads too , they also have the step on the front ,no steps rear
btw ... are u using stock pistons ? coz they differ in height also ...if i remember well it was 0,4 mm that the lower pistons are shorter ,so to equalise everything u need to mill the front ones extra
btw ... are u using stock pistons ? coz they differ in height also ...if i remember well it was 0,4 mm that the lower pistons are shorter ,so to equalise everything u need to mill the front ones extra
my bikes :RD500 2X ,RD 350 F2 , RD 350 31K,RD350 4LO,RG500,RG250 WW,RGV250,TZR250 3MA,TZR250 3XV,NS400r,NSr250 mc21,KR1250S,