Been thinking about tarting one of the old girls up a little. Nuts n Bolts. But which?

Alu?

Stainless Steel?

Titanium?

Phillips Screw type?

Hex socket(Allen key)?

Hex Head?

Race Spec?

Not racing so I dont need them drilled. Weight isn’t really a factor so I can’t justify the expense of Titanium. Aluminium? Stainless steel?

Pro Bolt has an interesting selection. Outlets in the UK, USA, Australia, Germany, Denmark, France, South Africa.

 

aluminium, hex socket – allen key … gold, silver, red, purple, orange, grey, black, blue

 

stainless steel … hex socket – tapered head (allen key)

 

stainless steel … flanged head hex bolt

 

Titanium … race spec – drilled … flanged head hex bolt … silver, purple, gold, blue

 

aluminium … race spec – drilled … hex bolt

 

titanium banjo bolt – single … 10mm – hex socket (allen key)

 

 

Next problem. List of required items. Went through an old engine. Put this list together…Haven’t checked it right through so may not be 100% correct. XS650E.

		5.0 x 0.8mm
Alternator Cover	2	5 X 10	Hex socket
Carb Top	8	5 x 16	Phillips
Washer	8	5mm	Plain

		6.0 x 1.0mm
HEAD:
Breather Box	4 4	6×60(large) 6×25(small)	Hex Socket
Points/ATU Cover	4	6 x 20
Bolt	1	6 x 35	Hex Bolt
Washer	1	6mm	Plain
Tri. Tappet Cover	9	6mm	Crown Nut
Washer	9	6mm	Plain
BARREL:
Cam Chain Adj	4	6 x 18	Hex Bolt
.. with shoulder	2	6 x 19	Hex Bolt
Washer	6	6mm	Plain
Front Guide	2 2	6x20M10-special	Hex Bolt
Washer Washer	2 2	6mm/11mm	Copper-Plain
Carb Boot	4	6 x 20	Hex Socket
CRANKCASE:
Starter Cover	6	6 x 25	Hex Socket
Oil Sump Cover	6	6 x 25	Hex Socket
Gear Lever	1	6 x 20	Hex Bolt
ALTERNATOR  SIDECASE:	4	6 x 25	Hex Socket
Bolt	2	6 x 40	Hex Socket
CLUTCH  SIDECASE:	4	6 x 75	Hex Socket
Bolt	1	6 x 40	Hex Socket
Bolt	7	6 x 25	Hex Socket

		8.0 x 1.25mm
HEAD:
Squ. Tappet Cover	4	8mm	Crown Nut
Bolt	4	8 x 60	Hex Bolt
Bolt	2	8 x 35	Hex Bolt
Washer	10	8mm	Plain
CRANKCASE:
Bolt	2	8 x 75	Hex Bolt
Bolt	1	8 x 55	Hex Bolt
Bolt	1	8 x 90	Hex Bolt
Nut	8	8mm	Short Open
Nut	6	8mm	Long Crown
Washer	12	8mm	Plain
Kickstart	1	8 x 30	Hex Bolt
Starter	2	8 x 35	Hex Bolt
Starter	2	8 x 35	Hex Bolt-flank
Washer	4	8mm	Plain
Washer	4	8mm	Spring

		10 x 1.25mm
HEAD:	8	10mm	Crown Nut
Washer	8	22×10.5x4mm	Copper/Brass Plain
Banjo Bolts ..Oil	2	10mm Single
Washer	4	10mm	Copper Plain

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It’s a better machine. The way it should be. When you know how they’re built. Traditional and tough.

Simply the best!

 

XS1B graphic … motor schematic for the Yamaha 50th

I made this list up some years ago. This version is arranged in Model Code numeric sequence. This code is found on the steering stem ID/VIN plate and Registration Papers. This is not necessarily the same as the first 3 places of the Engine Number.

MODEL       YEAR       MODEL CODE          ENGINE NUMBER

XS-B            75-76                 533                        447-500101

I’m sure it’s not complete. May include errors. If you have a machine with a model code not listed here let me know.

 

… by model code – page 01

 

… model codes – page 02

 

Or here listed by Engine Number.

… by engine number – page 01

 

by engine number – page 02

 

As you can see, there are questions. (???)

… my original tables included these model code/engine number combinations … they are not however confirmed by Yamaha … if you have a machine covered by one of these please let me know and I will reinclude it in the above tables

 

Have a Model Code that’s not listed here? Let me know.

I wish to get an idea of production runs. The engine numbers in the above tables are arranged so … 447-300101 to (400000). I have the start number for each model. Yamaha have given the absolute end number-these are in brackets. Not necessarily the real end number. Where I know this I have entered it without brackets … 2F0-000101 to 006141. The information is from Yamaha Publication #12100-100E1.

I’m looking for approximate end numbers. If you want you could leave me your model and engine number. No Name. No address. When left in the comment box below no one will see it.

Was discussing XS650 heads earlier. The major limitation to developing horsepower in our beloved engines (developing hp is a different topic to actually reliably and effectively getting it to the rear wheel).

Design limitations are found in exhaust port shape and cross sectional area-too large. Inlet ports could be smaller and would be better inclined downwards. The ‘Yamaha Racing Tips’ manual produced in 73 also recommends pocket porting-careful removal of material around the valve seats.

 

XS750(650) Racing Special

 

XS750(650) Racing Special .. valve springs

 

The legendary dirt track battles between Yamaha and HD highlighted these limitations to the extent that for the ’76 season USYamaha brought in Tim Witham. The OW72 (I have seen these called OU72 and OW72-this would indicate 2 separate programmes-as far as I know this was a 1 off so I will, for continuity, use OW72) was developed. Didn’t stop the Harleys. Kenny Roberts lost the AMA Grand National Championship to Gary Scott. Time was short. Frames not properly set up. Shell Thuets eye for detail and reliability was missing too.

Still, from Roberts: ‘Best thing I ever rode’

Surprizingly Yamaha Japan had accepted Withams challenge to produce a new head. Probably as an R&D exercise for future 4 stroke engines. Kept King Kenny happy too. The head was cast totally different to the production ones. To accomodate the steeper valve angles ( racing: 56° production: 76° … inlet: OW72 – 43mm, prod’n – 41mm; exhaust: OW72 – 37mm, prod’n – 35mm) the heads were higher and the rockers shorter, enabling a lower rocker cover. Overall engine height was the same. Interchangeable with production motors.

The heads arrived from Japan in dribs and drabs. No ports, guides, valves, springs, cams. The engines had larger crankpins, improved pistons, rods,  gearboxes, clutches and deeper sumps. I can imagine the stress. Modern business practice could learn a thing or two from this about networked local sourcing for local consumption.

 

OW72 Head vs OEM .. OEM left … OW72 head, right … note, OW72: larger cooling fins, inlet ports 5mm wider apart

 

XS1 rockerbox sitting on an OW72 head

 

OW72 vs OEM rocker .. shorter due to the altered valve angle and head configuration

 

Racing combustion chambers were hemispherical, aluminiun, with steel valve seat inserts. Production heads had a steel cap cast into the alu and valve seats were cut directly into this.

 

OW72 – no steel cap – alu combustion chamber with steel valve seat inserts

 

OW72 inserts direct in alu head

 

XS1 heads showing the steel cap containing the combustion chamber … valve seats are cut directly into this

inlet port

 

inlet port

 

exhaust port

 

Cycle World wrote an article about the development of these motors in their Aug 76 issue.

Original consensus is that 25 of these were produced. AMA homolugation rules required 1 complete bike and 24 engines and transmissions.

‘In order to be approved, a motorcycle must be a standard catalogued production model, one complete motorcycle produced, race ready, and at least 24 identical engines and transmissions must be available for inspection and purchase within the United States.’

There seems to be more (?). There is some confusion about this. It seems that Don Vesco produced some tuned heads back in the 70’s based on production heads and TRD valves. 650 Central sells your production heads CNC machined to tuner Lillies’ racing specs (these are your remanufactured production heads NOT ‘Yamaha’ racing heads).

70 hp motors appear to be relatively reliable. 75 hp motors not so.

I have seen several other attempts to address this problem, including homemade cast heads and machined billet heads. Of course, head modifications increasing available hp will expose shortcomings in other parts of the drive train, namely crankcases, crankshafts, clutches……………..How deep are your pockets?

Shell Marketing getting in on the action. 11/75.

 

shell service guide

 

 

XS500 … XS650

 

 

XS650 shell service guide

This was interesting. The grounds for warranty claims. And what was not covered. Also the accepted Labour Allocations.

For times follow column K.

 

… will turn this into a pdf and reload …

This may be interesting to restorers and others with an attention to detail…

Nuts

Bolts

Old – New X reference … Nuts

Old – New X reference … BoltsNew – Old X reference … Nuts

New – Old X reference … Bolts

 

… will turn this into a pdf and reload …