Xs1 internal change over 73 TX

[Robhoon]

Hello guys. I'm look at buying bare gearbox casings from a 70 XS1 and a 70 XS1 head. My question is can I install all the internals of my 73 TX engine into the lower 70 casings? My thought is to run my gears/crank/rods/cylinders/cam/cam chain & tensioner and run the 70 head on top. Is this at all possible? Thank you.

 

[Jim]

Both the '70 and '73 are 256 engines, so I would be inclined to say yes. '74 was the first year of the 447 engine.
Not 100% sure, but I think it'll all swap.

@650Skull ?? You'd know better that me...

...and welcome aboard!!

 

[Jim]

If you're old engine was a '73, it had electric start. The '70 engine doesn't have provisions for it. It'll be kick start only... in case you weren't aware.

 

[Robhoon]

If you're old engine was a '73, it had electric start. The '70 engine doesn't have provisions for it. It'll be kick start only... in case you weren't aware

Both the '70 and '73 are 256 engines, so I would be inclined to say yes. '74 was the first year of the 447 engine.
Not 100% sure, but I think it'll all swap.

@650Skull ?? You'd know better that me...

...and welcome aboard!!

Thank you, I've been back and forth on here for a while as a non member and the advice on a lot of posts is exceptional helping a lot with my build. I always thought the XS2 and 73 are known as 306 engines and as you say the 447 coming about in 74, could be wrong? I believe it's possible the gears/shafts are different sizes reading probably too much into it to suit different sized bearings but that's where I'm not sure and don't see why they would change much other than the ratio of the first gear over the early 3 bolt engines. Yes I won't be running a starter motor as the bike is set up as an XS1 with wiring and controls. Thanks heaps

 

[Jim]

If you go to partzilla.com you can check what parts work on what years.
For instance, I just looked up one of the tranny bearings for a '70 and it shows it also fits a '73. Not 100% accurate, but for the most part it is.

 

[Robhoon]

If you go to partzilla.com you can check what parts work on what years.
For instance, I just looked up one of the tranny bearings for a '70 and it shows it also fits a '73. Not 100% accurate, but for the most part it is.


View attachment 334249

That's brilliant, thank you I'll check that out. I think the 306 designation only really means a starter added but really the rest is 256, really it's a case of them gears fitting and having the right cam tensioner to the barrels used. I'd rather use mine with the 6 bolt and avoid the XS1 4 bolt and bridge between the cam chain.

 

[gggGary]

I think the length of the right end of the crank, drive gears might have changed with the addition of electric start on the (72-73) 306 motors.
70

Couldn't find any pics of a 72-73 in that area, @GLJ ?

 

[Its been a long time]

I think the length of the right end of the crank, drive gears might have changed with the addition of electric start on the (72-73) 306 motors.
70
View attachment 334268
Couldn't find any pics of a 72-73 in that area, @GLJ ?

Hmmm. Good question. Sounds feasible that it happened.

 

[GLJ]

Here is a pic of a 73 engine. I'm sure the lengths are the same as a 447 engine. I have a 447 crank in XS2 cases. I think someone told me that only 70-71 cranks will fit in 70-71 cases. Something about the crank is wider because of the starter gear teeth. I could be wrong, I do not have a 70-71 crank or cases to check. I would bet Gary Hoos would know.

 

[Robhoon]

Wow thank you guys, that just opened a can of worms. That may explain why I've heard of rod and piston swapping 447 onto the 256 rather than just swap the entire crank. I'm really starting to doubt it being so straight forward.

 

[Robhoon]

Ok guys I'm going to go for the top end as the crank really makes me uneasy. I've secured an early 70 head with matched number rocker box, is there any drama putting it onto a 73 engine from the barrels down? I'll be keeping my cam and other goodies at the sides of it so just the basic head.

 

[Jim]

Double check the timing gears. The 256 engine had 17 teeth on the crank and 34 on the cam. 447's had 18 and 36... so they won't interchange. Both yours should be 256 engines, so no worries. Still wouldn't hurt to check on the off chance someone prior swapped the innards of the '73 engine.

 

[Robhoon]

Awesome stuff, thanks so much

 

[motormike]

I swapped a 73' crank assembly in my Xs1.... the needle bearing con-rod packed up... No issues.

 

[Robhoon]

I swapped a 73' crank assembly in my Xs1.... the needle bearing con-rod packed up... No issues.

Ah thank you, getting very excited.

 

[Robhoon]

The family history is my dad's mate had the first XS1 into New Zealand (Rodgers Yamaha, Invercargill (Yes Burt Munro Invercargill)). At 15 I was lined up to trade in my RD400, RM80 & KZ400 on a 70 XS1 and then Dad stepped in and said no they're too dangerous for a 15 year old. He seemed to think the RD handled better, well I crashed all 3 RD400's I owned.... So it's been a dream to put something together as they're not common bikes here and let dad sit on it before he passes on. So far I'll have 90% original paint and just installed the external spring forks, lots of the bike is NOS too. I've learned it's not the cost but the love of what they are.

 

[650Skull]

Welcome Robhoon, ex Taranaki'ite here. Have a Son in Blenheim who has my old XS.

Sorry can't help with the swapping info. Did hear somewhere they would swap and looks like it has been confirmed by Mike.

Both the '70 and '73 are 256 engines, so I would be inclined to say yes. '74 was the first year of the 447 engine.
Not 100% sure, but I think it'll all swap.

@650Skull ?? You'd know better that me...

...and welcome aboard!!

Sorry Jim, seems I am not getting messages, couldn't positively confirm anyways

 

[Robhoon]

Welcome Robhoon, ex Taranaki'ite here. Have a Son in Blenheim who has my old XS.

Sorry can't help with the swapping info. Did hear somewhere they would swap and looks like it has been confirmed by Mike.



Sorry Jim, seems I am not getting messages, couldn't positively confirm anyways

Small world for sure. As you'd know there doesn't seem to be a great deal of the early bikes here. I see Rodgers Yamaha has a XS1 but they never did reply if it is the same bike from way back, a good excuse to fuel up the dodge for a road trip down south.