434 - Engine Vin ?

[mtna_buzz]

Hey all, I have two '74 TY 250's one with frame/engine VIN that match (the full 434-000245) and one with the full frame vin (434-015952) and no number stamped on the motor case pad. It has the factory raised fins in that area (hasn't been modified)- just no stamping. Both of these bikes are original - no indication that they were ever used for more than recreational riding.

Also, the barrel on the one with no numbers also has fins all the way around (above the exhaust port) while the other has a gap in the fins in that area. both of these are the full wide case early models.

I'm just curious about the lack of a vin stamp/barrel changes in the one - is it common for these to not have a case vin? From the frame # it's about 15,000 behind #245. Does anybody know how many of these were produced in each year?

My first bike was a TY 80 in '75 and I couldn't pass on picking these up last summer - it's been a lot of fun riding/wrencing on them since!

Thanks for any info -

Jim

[shocker]

my ty50p has just 3 numbers on the frame and engine, it was put on the road in 1983 but is a early 76-77. if this is a prefix number then it has never had a frame and engine number. never say never!

[woody]

I think Japanese home market TY250 Yams didn't have engine numbers stamped on the cases, so if it has been brought in from Japan at some stage that may be the reason for no engine numbers.

[feetupfun]

This may help you with your TY250 cylinder ID. The first TY250 twinshocks (sold here in 1973 and 1974) were called TY250 and had engine and frame numbers that start with 434. These tend to be called TY250A nowadays. The stand is on the frame, the tank is steel, there is a TK carby, the bashplate was fibreglass and they had the bulging engine covers.

I suspect the next model was not sold everywhere in the world but here in OZ there is a model that was released in 1975 we call the TY250B that also has an engine number prefix of 434, but the frame number prefix is 493. The B model has an aluminium fuel tank, the stand is on the swingarm and they had a black Mikuni carby.

The relevant bit here for you is that while the A and B models both had an engine prefix of 434, the B model cylinder finning goes all the way around the front above the exhaust, while the A model cylinder has a wide gap in the finning there.

Later model cylinders (1976, 1977) have full width finning all the way down the cylinder.

I've heard annual sales of TY250, 175 and 80 were around 30,000 throughout the mid 1970s.