The 100,000 mile XS

[JRP01]

I got this 74 TX650A from Littlebill in Feb. this year. Again, many thanks LittleBill. I forget all of the history but allegedly has 100k miles on it.

Checked the oil, quick cleaned the float bowls then tried to start it using alt fuel supply. No go. It has a full PAMCO ignition and I found a loose ground wire. After fixing that it fired up but ran very rough, but it ran, yay.
I planned to clean the fuel petcocks and test ride it.
During a quick once over,I discovered that the rear wheel had almost a half inch of play side to side. Not gonna ride that haha.

Thanks to all of the great people who shared their info on this forum ( and some online hand holding by gggGary). I was able to replace the bushings and pin to achieve a nice tight fit.
The rear wheel bearings were pretty rough so I replaced those, straightened and tightened a few spokes and got it all back together.

 

[YamadudeXS650C]

You've got yourself a sweet bike.

 

[Paul Sutton]

Nice bike!

 

[mrtwowheel]

I have side covers and other parts.

Scott

 

[JRP01]

The chain was shot bad. The sprockets were serviceable but the rear was a 520 and the front a 530. Decided to replace both sprockets and chain with a 530 oring style from JT Sprockets.
While waiting on these parts I drained the oil and found the dreaded cam chain guide pieces. Oh Boy.

 

[59Tebo]

After 100K miles, you're lucky that's all you found!...

 

[xjwmx]

I'm sure it does have 100k. Bill has what they call a greasy thumb.

 

[JRP01]

Here is the engine out and on my homemade stand.Of course once I got the engine apart everything had to be checked and measured. I knew it had been burning oil but not how much or from where. Most parts were within the service limits. It had been apart previously, maybe more than once. I was able to lightly hone the cylinders (this was previously replaced) and installed new rings. I cut the valve seats (exhaust was really bad) using a Neway cutter borrowed from local small engine shop. Unfortunately no 60 degree cutter to the narrow seat, but came out ok.. Then cleaned up the valve faces (don't ask how but it involved a drill press). Reassembled the head using new stem seals of course. Replaced both cam chain guides and the chain. The tensioner side guide looked marginal so I erred on the side of caution.

 

[JRP01]

I used the great info published by JimD54 to keep on track during reassembly. Very helpful and highly recommended. Thanks JimD54.
the cam bearings were shot, rusty and rough I tried cleaning them but ended up replacing. everything else was pretty straight forward.
The new cam chain was too tight to get the master link through. After snugging up the head bolts I was able to fit it and peen over.

 

[xjwmx]

How did you get the rear guide off? I tried mine just for fun and it was pretty doggone tight.

 

[MaxPete]

How did you get the rear guide off? I tried mine just for fun and it was pretty doggone tight.

Impact driver....gently....

FWIW - back in the 70s’ I owned a 1975 XS650B which I bought in about March of 1978 with about 20,000 miles on it. I absolutely rode the wheels off that thing till the early summer of 1981 when it had around 85-90,000 miles on it (not sure exactly because the speedo cable wadded up at some point and I couldn’t afford a new one at the time, so I’m guessing). I rebuilt the top end at about 40,000 miles and it was still running OK when I traded it in on a new leftover 1979 Suzuki GS850G.

The XS650 was likely designed around 1967-68 and was based on an earlier German engine called the Hosk 500 as I understand it. The XS650 went into production in 1970 (it can take quite a while to tool-up) - so it is a 50+ year-old design at this point.

The engine makes around 50 HP on 0.65 litres (about 77 HP/litre) while in the auto industry, any engine that makes from 70-100 HP/litre is considered fairly “hot” - so even though the XS650 isn’t high-tech, they’re not dogs either. Also, our engines turn at around 4000 RPM @ 60 MPH, versus around 2-3000 RPM for most cars, so given the decent specific output and the higher RPM, plus air cooling, which means that the odd time, they going to get darned hot, these old gals do alright.

Pete

 

[JRP01]

I used an impact driver on the screws with a JIS bit. The screws on one side go into shoulder holes . Then I tapped on the edge of the metal base with a brass drift.

 

[xjwmx]

1/4" drive hand impact?

 

[Jim]

Very helpful and highly recommended. Thanks JimD54.

I'm just happy you guys are makin' good use of it.

 

[robinc]

I'm just happy you guys are makin' good use of it.

Makin' good use of it? It's THE go to buddy! THANKS AGAIN!

 

[Mailman]

JRP01,
100,000 miles! Unbelievable! How great is it , that it wound up in the hands of a new caretaker that’s going to give the old girl a new lease on life? Good for you man! Keep the updates coming ( with more photos please ).

I'm just happy you guys are makin' good use of it.

Seriously? That is such a well written piece. Better than my Hans Paul book for sure!

 

[59Tebo]

...reminds me of the DC-3 that sets new records for longevity every time it takes off... Somebody get Guinness on the line...

 

[jetmechmarty]

This thing will make the rally, right?

 

[JRP01]

1/4" drive hand impact?

Mine is a Snap On 3/8. Been using it for 40 years. PIT 120 3/8 drive, hand impact.

 

[JRP01]

This thing will make the rally, right?

Making the rally is the plan. Ive been ignoring / postponing everything else to get this baby going for the rally.