TA250 Motor

[Diablo007]

Found a TA250 motor in the shop and am looking for the parts and service manuals.  Planning on putting it in the RD350 café racer project I'm working on (on and off...).  Anyone out there know where I can find one, or a pdf of one.  I've attached pics just in case the motor was misidentified.

[EE]

The TA250 is the missing link between the TD3 and the TZ250. It has the same bottom end as the TZ250 it just still had air cooled cylinders for that one year, use 73 TZ250. Ed
https://www.yamahapartshouse.com/oemparts/l/yam/50041732f8700209bc784ac1/1973-tz250-parts

[bitzz]

You don't want to run that on the street.
No kick start and 1st gear is WAY to long, the porting makes the power band REAL small, the cylinders are chromed and the pistons and rings are in short supply.

From the base gasket down that is an "early" TZ motor.
You should sell it to me.

[motodreams]

lol, or me!

[EE]

The Dry clutch makes it look a little intimidating but because the cases are just an DS7/R5/RD variant disassembly/reassembly really is really similar to disassembly/reassembly of an DS7/R5/RD250/350.
The trannies just like in the RD's with their thin gears riding on splined shafts are more prone to damage than modern trannies so either completely disassemble the trans and inspect or have someone do it that know what their doing (like I do). Ed

[Yamaha 179]

That''s a nice find.  I believe that the serial number, DS7 TJW is probably and may have been stamped by the original owner/racer.  AMA rules back in the 70's required that the frame and engine number match so many racers, both pro's and amateurs, bought spare engines and stamped matching numbers on the spare engines.  Yamaha sold bare GP engines stamped DS7 with no numbers and some racers added their frame numbers so if they blew an engine during practice they could simply switch to their spare and go and race.  I don't know if AMA still does this but I do know they did it back then. 

Ed is correct you need to go through the engine carefully.  Transmission parts are available from sources in Europe.  I bought an entire transmission for one customer and an input shaft and three gears for another.  These are high grade built from billet parts.  I can also source dry clutch baskets and hubs for you if you need them.  I recommend you take the clutch cover off and put it on the shelf.  Those one piece covers are like hen's teeth and if you ever want to restore the engine to original it would be a shame to have had the bike fall over and ruin that cover.  The TZ cover is virtually the same mechanically, just looks different and most people don't know the difference. 

If you are going to vintage race the bike you'll need to carefully consider the classes.  PM me or email me and I can give you some ideas.  vintspclty@aol.com is my address. 
Lyn Garland

[teazer]

I suspect that it's a TD3 rebuilt into a set of replacement crankcases which Yamaha used to sell to racers when their cases wore out.  Clutch should be 4 dog design if it's 72-74.  Top end appears to be TD3 and clutch cover is TD3.  I have only seen one other unmolested cover and that was the NOS one I bought at Mid O back in the early to mid nineties and fitted it to a TD which I sold years ago.

There are various stories about TA250's but I haven't seen any factory documentation to support them.  Being a bit of a skeptic, I believed they were twin shock TZs retrofitted with air cooled TD top ends to get around the No water cooled rules.

Any way that's a valuable motor, either in one lump or as parts. 

Is there an ignition under the left cover and if so is it OEM Hitachi` or aftermarket Femsa or Motoplat?  If there's no ignition, there are more modern options from the basic PVL to fully programmable digital HPI etc.

MeadSpeed might do a resin side over to use.  Vice at Fondseca and others you a bunch of parts, but if the chrome bores are worn, you might be better with Nicasil and matching rings>  Ed and Lyn are experts in Yamaha Race motors.  I have only built a handful over the years.

Lyn sells a great RD one piece base gasket that would probably be better than either OEM TD base gaskets or  a TZ base gasket.

[Diablo007]

Guys, thanks for all of the input.  I'll check with my friend and see what all he remembers about the motor.  He did say it's a TA250 motor, and I believe he bought it as a crate motor from Yamaha.  I should be back at the shop and will pick his brain some more.

This was my plan for the build.

RD350 cylinders with Wiseco pistons (resleeved by LA sleeve for the motor that was going in the bike)
Webco heads (Look to be NOS, or barely run and cleaned really well when pulled)
Bassani pipes
Electronic ignition (don't know what brand, it was run in an RD400 race bike back in the day)

I was going to see if the oil pump could be installed as it seems all of the hole for the cable and hoses are there.
I was also going to see if the kick-starter could be installed.  If so I was hoping to use one of my spare RD350 covers and modify it for the dry clutch.
Oh, and my friend seems to think that I should be able to get the lighting to work by replacing the necessary components.

In reality what caught my eye was the dry clutch and the RD/DS7 style cover.  I like that way better than the RD350/400 side cover.

That being said, taking everything into account it may be better to sell the motor as is, buy the components I want to dress up the current motor being built, and bank the excess $$$.

Any offers?  It would ship from Hawaii.

[Yamaha 179]

The TA is a real designation for the 74 250s sent to the USA and probably Canada.  I've never had any confirmation of the real reason why but it is either that Yamaha didn't have enough water cooled parts for world supply or they had too many air cooled parts left over and were afraid they wouldn't be able to sell them so they thought they would stick them with the Americans who weren't into road racing anyway.  Either story could be true, maybe it is a bit of both, who knows. 

You need to talk to Joe Spooner.  He built a water cooled street bike and can tell you the ins-and-outs of the projects.  I know his is a reed valve engine.
Lyn Garland

[Diablo007]

Interesting piece of history:

Hawaii was considered the 'Pacific' market in the early days through the '70's.  (I'll have to ask my friend when that changed.)  As such we were able to get some motorcycles that were not available on the 'mainland' US.  My '75 RD350 is actually a New Zealand bike.  The demand for them was so great that at the end of the run that Yamaha diverted a shipment of approximately 20 to Hawaii.  The bikes had the kph speedos and headlights for riding on the left side of the road, the mph speedos and correct for US headlights were included in the shipment. The dealers had to change them out.  I have the kph speedo, still looking for the original headlight.  Also, also due to high demand there was a shipment of RD400s with spoked rims sent at the beginning of RD400 manufacture.  Same reason, high demand.  I found a spoked RD400 hub in the shop also.  I also had a DT175 that was not US market, found that in another friend's shop.

Because the motorcycles here were considered 'Pacific' and not 'North America' service members who bought motorcycles here and took them with them back to the 'mainland' often had problems having them serviced under warranty.

In any case, I wonder if being 'Pacific' market has anything to do with the TA motor...

[teazer]

The TA is a real designation for the 74 250s sent to the USA and probably Canada.  I've never had any confirmation of the real reason why but it is either that Yamaha didn't have enough water cooled parts for world supply or they had too many air cooled parts left over and were afraid they wouldn't be able to sell them so they thought they would stick them with the Americans who weren't into road racing anyway.  Either story could be true, maybe it is a bit of both, who knows. 

You need to talk to Joe Spooner.  He built a water cooled street bike and can tell you the ins-and-outs of the projects.  I know his is a reed valve engine.
Lyn Garland

You are probably right Lyn, but why TA like a TA125 and not TD250 to continue the TD naming system.  Just out of idle curiosity, has anyone got a copy of a TA250 parts list?  My TD and TZ250 parts listing doesn't mention them, but mine might be for the Australian market.


And back to the OP.  The gears are not suitable for a street bike. If you change out the dry clutch and transmission and primary drive and ignition as well as barrels and head to make it streetable, that doesn't leave a lot.

[EE]

I've done a couple RD dry clutch conversions. There's a German company that makes a special longer mainshaft to use an RD400 gear set, Fondseca sells one also and a dry clutch cover with the kick starter mount and I believe Nova makes the special mainshaft too. Ed

[Jspooner]

I don't know anything about that motor but to me it doesn't make much sense to do that with that motor.

[motodreams]

The TA is a real designation for the 74 250s sent to the USA and probably Canada.  I've never had any confirmation of the real reason why but it is either that Yamaha didn't have enough water cooled parts for world supply or they had too many air cooled parts left over and were afraid they wouldn't be able to sell them so they thought they would stick them with the Americans who weren't into road racing anyway.  Either story could be true, maybe it is a bit of both, who knows. 

You need to talk to Joe Spooner.  He built a water cooled street bike and can tell you the ins-and-outs of the projects.  I know his is a reed valve engine.
Lyn Garland

You are probably right Lyn, but why TA like a TA125 and not TD250 to continue the TD naming system.  Just out of idle curiosity, has anyone got a copy of a TA250 parts list?  My TD and TZ250 parts listing doesn't mention them, but mine might be for the Australian market.


And back to the OP.  The gears are not suitable for a street bike. If you change out the dry clutch and transmission and primary drive and ignition as well as barrels and head to make it streetable, that doesn't leave a lot.

When you look prior to the RD series it would make more sense.  AS3 = TA, R5 = TZ.

[bitzz]

The TDs and earlier had vertically split cases... and the clutch on the end of the crank
The TA125/250s and the TR3 have the first horizontally split cases, with the clutch on the transmission input shaft, thereby spinning at a third of crankshaft RPM, making almost everything more better. That clutch would weigh a literal tonne at 10,000 RPM.
... then Don Emde won the Daytona.