odd Yamaha YZ barrel.

[firko]

Can anyone identify a YZ C or X cylinder that's come into a friends hands? It's casting number is 2Y500 and has a chrome bore. It came with a bunch of old Yamaha race bits supposedly once owned by Gally.

[brent j]

The two listings I can find for 2Y5 are
1979 YZ125F
1980 ZY125G

[firko]

Thanks Brent but this barrel has a chrome bore as opposed to the iron liner on the standard version plus there's those extra two zeros Y2500 on the number. My Yamaha 'knowledge' peters out around 1975 so I'm hoping  someone knows what's the difference.

[TwoTees]

That is a strange one. From my experience with Yamaha's is that the number on the cylinder is the prefix from the model code.
The list I have has no 2y5 or 2y500.
A quick Google brings up a few different models as Brentj states. 79 to 81 yz125 but Zedder has no part numbers starting with that prefix for those bikes. Doesn't even have the part number from the piston below. All of the references I found are from Pommy land??


Maybe a Euro only model thats why there is bugger all info out there.

Here's a 2y5 piston.....
http://cgi.ebay.co.uk/yamaha-2y5-yz-125-yz125-78-79-nos-piston-discontinued-_W0QQitemZ120492417384QQcmdZViewItemQQimsxq20091113?IMSfp=TL091113161002r22951




YZ125A   1974   125   YZ125 Competition   Motocross   453   453-000101
YZ250A   1974   250   YZ250 Competition   Motocross   431   
YZ360A   1974   360   YZ360 Competition   Motocross   432   
YZ80A   1974   80   YZ80   Competition   Motocross   462   
YZ125B   1975   125   YZ125 Competition   Motocross   453   453-100101
YZ250B   1975   250   YZ250 Competition   Motocross   483   
YZ360B   1975   360   YZ360 Competition   Motocross   510   
YZ80B   1975   80   YZ80  Competition   Motocross   492   
YZ100C   1976   100   YZ100 Competition   Motocross   1J4   
YZ125C   1976   125   YZ125 Competition   Motocross   537   537-000101
YZ125X   1976   125   YZ125X Competition   Motocross   1G8   1G8-000101
YZ175C   1976   175   YZ175 Competition   Motocross   1L8   
YZ250C   1976   250   YZ250 Competition   Motocross   509   
YZ400C   1976   400   YZ400 Competition   Motocross   510   
YZ80C   1976   80   YZ80   Competition   Motocross   598   
YZ100D   1977   100   YZ100 Competition   Motocross   1J4   1J4-100101
YZ125D   1977   125   YZ125 Competition   Motocross   1W1   1W1-000101
YZ250D   1977   250   YZ250 Competition   Motocross   1W3   
YZ400D   1977   400   YZ400 Competition   Motocross   1W4   
YZ80D   1977   80   YZ80   Competition   Motocross   1T0   1T0-000101
YZ100E   1978   100   YZ100 Competition   Motocross   2K5   2K5-000101
YZ125E   1978   125   YZ125 Competition   Motocross   2K6   2K6-000101
YZ250E   1978   250   YZ250 Competition   Motocross   2K7   
YZ400E   1978   400   YZ400 Competition   Motocross   2K8   
YZ80E   1978   80   YZ80   Competition   Motocross   2J5   2J5-000101
YZ100F   1979   100   YZ100 Competition   Motocross   2W5   2W5-000101
YZ125F   1979   125   YZ125 Competition   Motocross   2X3   2X3-000101
YZ250F   1979   250   YZ250 Competition   Motocross   2X4   
YZ400F   1979   400   YZ400 Competition   Motocross   2X5   
YZ80F   1979   80   YZ80   Competition   Motocross   2X6   2X6-000101
YZ100G   1980   100   YZ100 Competition   Motocross   3R2   3R2-000101
YZ125G   1980   125   YZ125 Competition   Motocross   3R3   3R3-000101
YZ250G   1980   250   YZ250 Competition   Motocross   3R4   
YZ465G   1980   465   YZ465 Competition   Motocross   3R5   
YZ50G   1980   50   YZ50                         Motocross   3R0   3R0-000101
YZ80G   1980   80   YZ80  Competition   Motocross   3R1   3R1-000101
YZ100H   1981   100   YZ100 Competition   Motocross   3R2   3R2-020101
YZ125H   1981   125   YZ125 Competition   Motocross   4V2   4V2-000101
YZ250H   1981   250   YZ250 Competition   Motocross   4V3   
YZ465H   1981   465   YZ465 Competition   Motocross   4V4   
YZ60H   1981   50   YZ50                           Motocross   4V0   4V0-000101
YZ80H   1981   80   YZ80  Competition   Motocross   4V1   4V1-000101

[firko]

The mate that owns the barrel was told it might be an OW item but I'm not so sure whether that's correct.
I've sent an email off to Terry Good in hope that he may know. It's air cooled.

[holeshot buddy]

the ow 250 had a chrome bore

[Nathan S]

Early or late type barrel?
Early barrel has unthreaded holes that go all the way through the barrel (barrel is clamped between the head and the cases, using long 8mm studs).
Late (YZ125D+) bolts the barrel directly to the cases (short 10mm studs screwed into the cases), and then bolts the head to the barrel with four short 8mm studs.

What about the exhaust pipe mounting at the exhaust port? Is there a bolt-on flange, or a spigot that's cast into the barrel?
Is the intake port a pear shape, or three seperate windows?

FWIW, the 'normal' prefix for a YZ125F is 2X3, and YZ125G is 3R2 (shit - or is it 3R3? I need sleep).

There are factory option (but not 'works' parts) chrome bore YZ125F barrels out there. Without seeing it, I reckon that's what it is.

My understanding is that the OW parts had OWxx cast/stamped into them.

[IT400C]

my prefix listing says:

2X3 YZ125F
2Y5 YZ125F (Europe and Japan)

[Nathan S]

Did we figure this out?

[BJJ]

everyone is on holidays,  or getting to holidays.  I am on heaps of other channels and things are very very quiet

[cz400]

have a listing saying, yz 125 f  europe,japan market,cheers