'80 xs11 sg intake valves

[maszkiew]

Hello all, I'm looking for intake valves to my '80 xs11 sg. Buying the right ones in Europe is almost impossible (different versions - different shape). Is there any chance to buy them in US?
PS. Sorry for my english, I haven't spoken IT for a Lang time.

[JeffH]

Check with Andreas:
http://www.xs11.com/forum/showthread.php?t=47806

Send him a PM and see if he has what you need (his latest parts listing showed valves)

Maybe you could find what you want on eBay US and have it shipped over.

Jeff

[MPittma100]

Intake valve

3 of them on EBay used. 3H5-12111-01-00. Can you have yours machined for reuse?

[maszkiew]

Jeff, Mike, thank you for answer. I'll check these options. For now IT turned out that my xs has cylinder head from different model. Thats why I had such problems with fitting valves.
Paul

[mn2346]

The last post reminded me of a question I've been having...or wondering.

As the heads are different, don't recall if cylinders or pistons are identical.

Which combination is best for:

1. Power
2. Low End Torque
3. Fuel consumption
4. Etc.

Apologies of this is somewhere already but I don't recall seeing it anywhere.

[maszkiew]

I've just mounted original sg head and so far can't see any noticeable differences.
The biggest change was when I switched ignition module to european version. My xs, wich I bought in Canad, had power limit.
Paul

[Bonz]

Do a search for Dan Hodges on this forum. He did more work with the XS trying combinations than any other human on the planet.

Ultimately a 78 is the strongest year. Some guys combined the head off of one version with the cams off of a 78 with the ignition unit off of a 78 and the pistons off of another model.

1980 and newer had larger valves than 78 and 79.

[motoman]

Do a search for Dan Hodges on this forum. He did more work with the XS trying combinations than any other human on the planet.

Ultimately a 78 is the strongest year. Some guys combined the head off of one version with the cams off of a 78 with the ignition unit off of a 78 and the pistons off of another model.

1980 and newer had larger valves than 78 and 79.

In reference to last statement, actually not, all 81 models had the larger intake valves. ALL 78-80 models had the smaller intake valves along with the different cam profiles.

[Bonz]

Brant I ran an 80 SG for many years as you know. It had larger intake and exhaust valves starting in 1980. Here's the info from that article.


Several engine specifications have been changed for 1980, but these are limited to the top-end: the cylinder-head combustion chambers have been altered to meet the EPA's emission specifications. Piston crown shape and larger valves give back a little of the performance lost to leaner jetting and a lower 9.0:1 compression ratio (down from 9.2:1). Yamaha designed the original XS Eleven with smaller valves than "necessary" and still got performance they felt was adequate. In anticipation of ever-more-restrictive pollution limits Yamaha elected to increase the valve sizes: intakes from 36mm to 38mm, and exhausts from 31 mm to 32 mm. Exhaust valve lift has been increased 0.5mm to 8.8mm; intake lift remains 8.8mm. A new cylinder head was fashioned to carry the bigger valves and revised combustion chamber. The slightly lower compression ratio allows the four-cylinder to run better on questionable gasoline - something to which high-performance machinery has traditionally responded with acute indigestion.

Apart from the top-end revisions, the XS powerplant remains virtually unchanged.

[3Phase]

Howard's right.

'78 and '79 use smaller valves and combustion chambers with flat top pistons.

'80 and '81 use larger valves and combustion chambers for domed pistons.

'82 XJ11 ('84 in Canada?) use larger valves and combustion chambers for domed pistons with the YICS head.

[motoman]

Thanks guys for correcting my CRS.