Xs1 internal change over 73 TX

[Jim]

Hey guys a quick question. I understand the head and rocker cover to be line bored so match numbers a given, is this the case with the gearboxes? Thanks very much.

Yes. the bottom end cases are also line bored as a set. Iirc the numbers (that should match) are behind the clutch basket.

 

[Robhoon]

Yes. the bottom end cases are also line bored as a set. Iirc the numbers (that should match) are behind the clutch basket.

Thanks very much, could ruin one's day a mismatched pair.

 

[Robhoon]

Hi guys. Well things have changed, I am now putting together a very early XS1 engine with the screw clutch cap and wide metal clutch actuator right down to the correct cylinders with the 4 bolt cam tensioner. I plan to get the correct gear set and my question is, is the shift drum, select arms and star unit the same on all the bikes? Also the rev counter drive as my case is early with the 11/5 bolt pattern oil cap? I'd presume the oil pump upgrade off my existing engine wouldn't matter nor the clutch basket unit? Thanks very much, learning as I go.

 

[txxs]

The main axle and first gear is different as the XS1 has a different first gear ratio. Also there are subtle differences between the shift drum and neutral spring on the XS1 compared with the XS2. However the selectors are the same for 70 to 73. There is also is a slight difference in the change gear shaft on the 73 TX compared to the earlier XS1 and XS2. Hope the info is of some help.
I would probably try to keep it all XS1 and not mix and match, but that's just a personal opinion.

 

[Robhoon]

The main axle and first gear is different as the XS1 has a different first gear ratio. Also there are subtle differences between the shift drum and neutral spring on the XS1 compared with the XS2. However the selectors are the same for 70 to 73. There is also is a slight difference in the change gear shaft on the 73 TX compared to the earlier XS1 and XS2. Hope the info is of some help.
I would probably try to keep it all XS1 and not mix and match, but that's just a personal opinion.

Thank you very much. I'll try my hardest not to mix it if I can, really makes a massive difference to me that it's very early engine. Very lucky to still have the shift shaft in place on the case. It's actually working out cheaper to pull this XS1 engine together in parts than the price of shipping a near complete XS1b engine here, I wouldn't have been happy with 1b serial numbers so it works well.

 

[Robhoon]

Hi guys. Ok certainly an obvious difference on these, the right is XS1 and the other come out of my engine that's junk. I see no difference in the shift pattern itself and presume the star is the same. Apart from hole shapes and one having a bearing do you guys keep the original or upgrade to the bearing? I run the XS1 gears in the junk cases by hand and shifted fine with the bearing shaft and forks so I know it works but just reluctant over the shift leaver shaft working at the star, I have both types of shift shaft with the longer and shorter spring. What would you guys recommend? Thank you.

 

[txxs]

Hi guys. Ok certainly an obvious difference on these, the right is XS1 and the other come out of my engine that's junk. I see no difference in the shift pattern itself and presume the star is the same. Apart from hole shapes and one having a bearing do you guys keep the original or upgrade to the bearing? I run the XS1 gears in the junk cases by hand and shifted fine with the bearing shaft and forks so I know it works but just reluctant over the shift leaver shaft working at the star, I have both types of shift shaft with the longer and shorter spring. What would you guys recommend? Thank you.

Yes they are different as mentioned previously above.
I would tend to use the XS1 shift cam drum as it is correct for the bike. Just my 20cents worth of opinion.
You need to be careful to use the correct neutral spring depending on which shift cam drum you adopt as the spring is different.

 

[Robhoon]

Yes they are different as mentioned previously above.
I would tend to use the XS1 shift cam drum as it is correct for the bike. Just my 20cents worth of opinion.
You need to be careful to use the correct neutral spring depending on which shift cam drum you adopt as the spring is different.

Thanks very much. It surprises me how many parts are sold as the real deal but the differences side by side. I have opted to go for the XS1 drum to keep it as close as original, now installed and flicks through gears nice. I had a bit of trouble getting the dowels out so cut a 3mm hex key enough to fit in the hole, a slight lean to hook in with a vice grip attached and a few good pulls had them out no worries.

 

[Robhoon]

Thanks for the help guys, it's nearing completion with original internals. Just waiting on a few parts to round it up. All the paint is 100% factory original with it's shocks now on. I'm waiting on an early lower 27mm triple tree to change to a ball bearing set up and also the slightly different air cleaner cages. Must say the one part cam chain and centre bridge caught me off guard, what a pain flaring the cam link, I ended up crushing it with vice grips after some bad words.

 

[Robhoon]

Here's a shot of the engine stand I knocked up at work. Engines are not that heavy that it's easy to flip by hand. 10mm on the flats to the mounts so with just bolts it a can support till it's lifted away from frame. Made it easy to fill with oil too.