Double Zero Cylinders

Matt_E

Matt_E

steals hub caps from cars
Site Supporter
Location
at peace
So....I keep hearing that Yamaha marks their cylinders with two digits to mark how well the sleeve lines up with the casting.
Supposedly, "00" cylinders are the best match.

Out of curiousity: Has this "double zero" rumor ever been confirmed with facts? I keep hearing this, but I've never seen them actually be of any qualitative difference between numbers.

Also, why would Yamaha care enough to qualify their cylinders?

(I am not saying it's BS, but so far I've never seen proof)

In my experience, ever single 61x cylinder I have seen and/or worked on had horrible port matchup.
The best have been 650 cylinders.
 
Q

QJS

X-
Location
GONE
The numbers on the cylinder have nothing to do with port timing or how good the cylinder is, its to do with a process called selective manufacturing.
Chris.
 
W

waxhead

wannabe backflipper
Location
gold coast
its the bore clearance so they can get the right pistons in it from factory
if you pull a new one down you can sometimes see the numbers on the pistons
 
Matt_E

Matt_E

steals hub caps from cars
Site Supporter
Location
at peace
That's what I thought....I have noticed the double digits on the pistons before.
 
willycrumb

willycrumb

mmmm......beer.....
Location
califony
having rebuilt 100's of 650's and 701's I can say there is some truth to it. The 00 definetly line up better than the 14's and i never saw a crooked 00 or a straight 14 unless it had been resleeved.

I brought the same thing up before and I thought you shot it donw Kahuna?
 
'Crockett

'Crockett

Freelance Smartass
I'd have to agree with BK on this one. . . . . I ported a 6/12 once that had about 70% mismatch on the rear boost port and quite a bit of blockage on the transfers as well on the "12" side. The "6" side was pretty bad too. Overall, It was the worse one I've ever seen.

Just recently got a 61x cylinder that was a 1/2 and it was really nice, and a lucky find because it was going on a friends ski wo didn't want it ported at all. I think it's gonna run great.

I personally have never seen a actual "0/0" but I have known about these markings on the top of the cylinder above the exhaust port for years and from what I have seen there is something to it.

I don't think it really relates to problems with the sleeve themselves at all though . . . the mis-match is in the cylinder itself due to core shift during the casting process.

JMO . . . . .:biggrin:
 
M

madoyster

01/10/08
Location
The Durty South
Big Kahuna said:
hmmmmm, I have seen 00 cylinders where the windows matched up really good, and 7/14's where they were all out of wack..........
Click to expand...

I concur, I have a 00 cylinder in the garage and it matched up very good. Years ago when everyone was racing superjets, a 00 cylinder would be an easy item to sell for a good price.
 
Matt_E

Matt_E

steals hub caps from cars
Site Supporter
Location
at peace
do the numbers/meanings matter once the cylinder is ported???
Click to expand...

Not at all. Other than the thickness of the wall to the water jacket.

I am trying to look at this from Yamaha's perspective. Why would they care about the port matchup?
On the piston numbers: this could make a bit more sense, but not much more. By the time someone needs replacement pistons, the cylinder most likely needs to be bored.....negating any usefulness of marking the piston clearance on the cylinder.

However.....I will research a bit further and see if there's any truth to the piston theory.
 
Last edited:
the only couch rider

the only couch rider

Location
Jersey
they did a similar thing on the 66E/66V cylinders..... they had an a/b/c/d cylinder code... you had to get pistons for that exact cylinder type for some reason


maybe it's another conspiracy theory
 
Matt_E

Matt_E

steals hub caps from cars
Site Supporter
Location
at peace
I know...I was just pointing out the fact for others.
 
You must log in or register to reply here.
Top Bottom