XS650 and Leaded Fuel

[Orion61]

Anybody here old enough to remember The oil embargos of the 70's and the smell of that funny smelling
new Unleaded Gas? We know the Lead in the fuel was used as a lubricant. What year did Yamaha start using hardened steel in valves and seats and switch the 650 to use unleaded fuel? I just thought of this today as I was clearing up work space so I can get my 1975 650 back up and running when I ran into a half full bottle of lead substitute. I was thinking I had either bought it when I got the bike to use or for my old MGB?
My memory has faltered a bit since I was hurt at work badly, I ended up having 8 total Surgeries, Massive MERSA Staff infection, and several resulting heart attacks, One of which caused by a Pulmonary Embolism.
and which had me "crash" for close to 5 minutes, When they finally brought me back,(on their last attempt), some pages out of the old file cabinet upstairs got shuffled up a bit and lost.
I haven't seen this subject come up, and if the early XS 650's were designed to use the lead in the fuel,
are they being hurt? I just can't remember if mine needs it, I know a lot of Auto's in 1975 used unleaded
and it seems some 1974's as well. I will try to take some video, or images as I go along.
Thanks much,
Cousin Larry

Enjoy every day for the Blessing it is.

 

[650Skull]

Doesn't seem to be a problem running unleaded regular. I used to put a lead substitute in my 650 when unleaded first come out.

Yea blame it on the surgeries and the clots........................we all know it was the drugs from the day, bloody wounder you remembered you had an MG

 

[Orion61]

I was a Child of the 60's........ what can I say? But one thing I do thank goodness for, unlike many of my childhood friends, I never ever smoked
(Cigarettes)....
BUT back to the thread, has anybody used Lead sub and have a high mileage bike to show for it? I remember as a teen just driving, hearing the thump/thump/thump, of a car with a valve out...hardly ever hear that now..
1st car was a 60 Chevy Impala, 2nd was a 68 Dodge Charger.. (Dukes of Hazard)... Still have the MGB tho!!!

 

[TwoManyXS1Bs]

Larry, the unleaded gas was an issue with old, traditional, cast iron engines of that time. Soft cast iron valve seats, non-hardened valves, would experience premature wear and pocketing.

Most motorcycles of that time (well, Honda and XS650s) had steel seats and stellite hardfacing on the valves, didn't need the lead to save the valve seats.

Search "stellite" for more...

 

[Orion61]

Ok so I take it Yamaha and Honda were ahead of their time in Motor technology back in 1970?
I do know that as far as total experience I love my 650! I own a newer Suzuki C50 V Twin Boulevard, as nice as it is I
still enjoy riding my XS better.

 

[azman857]

I recall at that time (mid 70's or early 80's) aircooled VW's and Shovelhead H-D's were OK because they had the hardened seats and valves installed at the factory with the anticipation of the unleaded gas comming. At least the newly built ones. I could be wrong....

 

[txxs]

The 1973 TX650 had hardened valves and seats.
That was one of the subtle differences between the 1972 XS2 and the 1973 TX650 engine.

 

[Orion61]

So that was the answer I was looking for, It sounds like those riding the 70-72 650's should be using the Lead substitute
to protect their engines. I am OK with my 75..
Thanks much guys

 

[TwoManyXS1Bs]

The 1973 TX650 had hardened valves and seats.
That was one of the subtle differences between the 1972 XS2 and the 1973 TX650 engine.

Well now, THAT'S worth noting.
The combined 70-74 service manual shows the stellite facing, implying that it was there for all early years.



But, the TX650 parts manual shows the 'new' valve base number as '341', perhaps due to stellite introduction.
Then, mid-year production, the valve suffix number is revised, for the collet change.



The collet change bulletin matches the serial numbers written on that parts list.



VERY significant info. Thanks txxs...

 

[txxs]

Actually I believe the TX750 was the very first machine with valve seats made for use with lead-free petrol.
This was then used on the TX650 and later the TX500.
The part number for the valves on the TX650 is the same as that on the TX750 ("341") whereas the valves on an XS2 have a "256" part number.

 

[TwoManyXS1Bs]

...The part number for the valves on the TX650 is the same as that on the TX750 ("341") whereas the valves on an XS2 have a "256" part number.

Gads, I didn't notice that. Updated above post for that "341" part number.

Another notch on the '73 confusion totem pole.

Thanks, again...

 

[Orion61]

I am beginning to believe this simple question could end up having significant impact for riders of the XS650 produced in 1970/1971/and 1972!
Those Motors should definitely run with a lead substitute to lubricate the top side of the valve train! Does this also mean the 1973 TX 650 built up until mid year should use it as well?
The research you did in the manuals is fantastic thank you. This may deserve to be a sticky?

 

[TwoManyXS1Bs]

I am beginning to believe this simple question could end up having significant impact for riders of the XS650 produced in 1970/1971/and 1972!

Agreed.

Those Motors should definitely run with a lead substitute to lubricate the top side of the valve train! Does this also mean the 1973 TX 650 built up until mid year should use it as well?

I'm thinking that members (including myself) should closely examine their valves during overhaul, particularly looking for the unique 'square-edged' collet grooves and matching collets. If found, then seriously consider replacing them with the later 'rounded-edge' valves and collets, as those would certainly be stellite hardened.

As far as I know, my stock XS1B has never been opened up, and would have those early valves. I've never used a lead substitute in it, valves seem to be sealing OK. But, at overhaul time, they'll get a closer look, now that this issue has been raised...

 

[txxs]

Does this also mean the 1973 TX 650 built up until mid year should use it as well?

All 73 TX650 had "341" valves.
(The suffix changed mid year).