Still smoking left side DAMIT

[TwoManyXS1Bs]

...My point is that a lot of manuals and info in the 70's and early 80's were written for the tech who hadn't ever been trained. Like HonTec, MMI, AMI or whatever they're called. IMO if the 78 manual was written today for exactly the same bike with todays trained techs, OEM tools, etc the procedures would be different.
You'll notice todays OEM manuals are written without the simple procedures "how to check cable free play" etc because it's written for a competent tech.

Honda had training facilities back in the early '70s, following the mantra "Sell the customer what he needs, not what he wants".

Yes, I've seen a disturbing trend in the evolution of manuals and schematics spanning from the '60s to the 2000's. Motorcycle manuals for asian imports back then were often oddly translated renditions similar to the strange Chinese instructions found with import gadgets. Automotive manuals, on the other hand, provided a lot of 'theory of operation' for various components, like a complete description of how the internals of a Delco alternator worked, or the hows and whys of setting the critical advance curves of distributors. Folks back then seemed to have a better grasp of how and why things worked.

I've found the modern manuals omit these 'theory of operations', and have supplanted them with endless repetitions of "disconnect battery negative ground" plus other idiot-proofing disclaimers of safety, to satisfy an ever-increasing litigious business environment.

Schematics can be classed in three systems:

Logical - Where the circuit layout reveals the logic and functional understanding of how things work.
Physical - The wiring layout for specific vehicle regions or zones. Attuned for factory assemblers and techs trying to find connectors and such.
Harness - The actual loom layout, attuned to harness manufacturing.

Older manuals showed 'logical' schematics, which greatly aids understanding in diagnosis. You're on your own to find the connectors.
Newer manuals show the 'physical' schematics, you can quickly find the connectors. But, unless you know what's the problem, or successfully follow the cookbook troubleshooting charts, about all you can do is replace parts until it's fixed. Parts departments love this, sells more parts.

Newer automotive manuals have to include an ever-increasing array of ancillary systems that don't relate to the primary purpose of the vehicle, like emissions, air-bag safety equipment, exotic convenience gadgetry, 12-speaker sound systems, security, ...etc. Today's tech has a much higher taskload on these newer vehicles.

But, the trend I've been seeing here is a move away from 'understanding and repairing' to automatons that simply replace parts. A shrewd business strategy.

A good example is that questionable practice of putting grease on float valves. You don't know why, but do it anyway because that's what you were taught.

Sorry, funky.
Thread hijacks like this are probably best put in their own thread...

 

[funky]

TWOMANYXS1Bs

You have been found guilty of the most heinous online crime and by your own written word have confessed to the crime of HIJACK.

Mr TWOMANYXS1Bs all that is left to do, is to pass sentence on you, Your devotion and endless knowledge to the Yamaha xs650 will be taken into consideration, along with your exemplary service to the forums. This has saved you from banishment to an online gaming forum.
In saying this i cannot condone the crime of hijack and therefore you leave the court no option but to bestow upon you the maximum sentence as follows.

In the hope that the following sentence will vanquish you of the undeniable remorse and guilt you should be feeling right now and that you could be rehabilitated back into this social network .....You will be taken from this place to Suffolk in England there you will find my good friend Funky and you will re-build his engine to the best of your ability you will also mow his lawn and refer to Funky as Sir funky and once Funky is pleased with his Bike you may return to the USA where you will be 5twins man slave for the remainder of you existence and 5twins may take pity on you and let you fix his bike now and then or touch his computer to play pack man .

 

[funky]

Hi all sorry Twomany couldn't resist I did for clemency ...

Right pictures of my pistons[/URL][/IMG]

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Hope the pictures are of the right area whats the verdict the slight scoring on the pistons and like the cylinders are quite light and when i touch them they feel smooth will have this all measured if the whole lot needs changing then i will consider a bigbore kit
All the best Funky

 

[TwoManyXS1Bs]

... saved you from banishment to an online gaming forum.

But, but, that has been my lifelong dream! Guilty! Guilty!

could be rehabilitated back into this social network

Now, we all know that's impossible.

.....You will be taken from this place to Suffolk in England there you will find my good friend Funky and you will re-build his engine to the best of your ability you will also mow his lawn and refer to Funky as Sir funky

What? Extract me from this rattlesnake infested cactus patch, to a lush English setting? Oh, the horror!

Well, alwright. But, Sir Funky, I gotta warn ya, I confuse easily, and your lawn may endup doing wheelies and burnouts, while your bike is trimmed nicely to 2 1/2".

you will be 5twins man slave for the remainder of you existence and 5twins may take pity on you and let you fix his bike now and then or touch his computer to play pack man .

Waitaminit... Now we're punishing 5Twins?

Oh, well. At least his place is a "tools playground"...

 

[TwoManyXS1Bs]

... couldn't resist I did for clemency ...

Haha, I love British dry humor.

To wit: http://www.xs650.com/forum/showpost.php?p=298191&postcount=39

 

[TwoManyXS1Bs]

Okay, now those pistons.

Not good. With those score lines, and matching lines in the cylinders, you can assume that there's been some abrasive grit in the oil. A big-bore kit may certainly be in your future. I'd also recommend a bottom teardown, and bearings inspections...

 

[funky]

Twomany Your response was great I forgive you enjoy your rattlers
as for the total tear down i was frightened you would say that I suppose your right looks like I got my work cut out I really feel this is beyond me but I will try my best.


HELP I think it would be cheaper to buy a fully rebuilt unit re phased from smed speed

 

[TwoManyXS1Bs]

Hey, Sir Funky. Sorry, didn't mean to frighten you. These things CAN be 'grey area' judgement calls. Depends on your dreams and tolerance levels.

If your intention is to have a top-class reliable bike, then that complete teardown/inspection/rebuild (or SmedSpeed option) is the path. On the other hand, a good case flush with a honing and re-ring can get you by with a fun, but underperforming bar-hopper. But you'll be constantly monitoring it for failure modes.

A lot of folks over here are riding on worse...

 

[funky]

Thanks for reasurance the fact remains that im am getting 145 and 140 psi with these bores pistons now my options skimm head and cyliner block and reasemble bike which run and goes well.
Second option total strip down but this will cost lots of money and that is not what i need at the moment ...works looking iffy at the moment also. plan was to rebuild the engine in October. I will see what the price tag is for a hone skim and rings will have valves check and valve guides to, rebuild the engine get to october and then full rebuild the truth be known if the engine did not smoke i would be riding it as is. the funny thing is I was assured that the engine was good and bought it for that reason have to be careful now days as they say.
I think for a 35 year old bike its a credit to it manufacture and if more humans had some mechanical sympathy these bike would go for longer... a well made machine

 

[scabber]

Ditto with TwoManny. Pictures are deceiving. Your machinist can advise you. It don't have to be perfect to run good.

 

[5twins]

Exactly. Every motor running around the planet has some wear in it. Problems begin to arise when that wear reaches a certain point. Your clean piston tops are not a good sign. They should be covered in carbon. Excess amounts of oil leaking into the combustion chamber is washing them clean, and keeping them that way, not allowing any carbon to stick.

Your pistons look pretty badly worn. Minor scrape marks on the front and back sides is pretty normal. Yours look to have scrape marks all the way around, even on the sides. There is a three digit number stamped on top of the piston. That was the fractional part of its size when new as in 74.xxx mm. Measure it now to see how much it's worn.

 

[funky]

Hi 5twins the numbers on the Pistons is 954 i measured the pistons across the skirt 74.95mm right and 74.60mm left in inches it is 2.950 and 2.937

My calipers are not the best but thats the readings i got .004 and .017 thou difference

The manual states 50 to 55 thou so right is 51 thou and left is .038 left is 12 thou out of tolerance this will increase when honed so new rings and pistons are on the horizon

The clean piston tops are due to the head trip down a few weeks ago they were carboned up i cleaned them and did about 70 miles before this strip down again the other day

all the best Funky

 

[TwoManyXS1Bs]

Yep. That's a lotta wear on that left piston.

So, your choices are:

1- New pistons and rings, hone job, hope cylinders aren't too far out of spec.
2- New oversize pistons and rings, bore/hone cylinders.
3- New Cylinder/Piston kit.

Item 1 is the easiest and cheapest, but bore measurements (after honing) will tell the risk factor.
Item 2 isn't much more, you're buying pistons/rings anyways, bore job is good cost/risk ratio.
Item 3 is the easiest, no fussing with machine shops.

 

[5twins]

Many are reporting good luck with the pistons and rings from this guy, and you can't beat his prices, about half of what others charge .....

http://www.ebay.com/itm/131196731185?_trksid=p2060778.m1438.l2649&ssPageName=STRK:MEBIDX:IT

I just installed some of his stock rings in a used bore. They had lots of "spring" to them and were easy to fit on the pistons. They were tougher to insert into the bore than others I've used in the past but I'm thinking that's a good thing. It should make for a tighter fit and better ring seal.

 

[funky]

Hi all thanks for all the feedback That is cheap for them pistons 5twins and will consider that thanks.
I am going to make sure with regards to measurements and tolerances I want to be spot on no mistakes. big bore not an option want the engine i got and i feel going big bore is not keeping with the ethos of my rebuild i am a bit of a traditionalist if I have to wait and save my penny's then so be it

Im thinking and hoping hone cylinders skim surfaces new gasket and over sized piston ,Rings and new gudgeon pins or as you lot call them wrist pins.

All the best funky

 

[timbeck]

Hey Funky---I've been following your thread for the mechanical answers for your dilemma but the comical banter with TwoMany is the best. I know you will get your ride straightened out , this site is great for individual help. Good luck. tim

 

[funky]

timebeck thanks for you reply and input I was hoping to do stuff myself but unfortunately the engine is in a tired state so it will soon be off to a technician who specializes in the Xs 650 and will do a full mechanical breakdown measure each component upgrade to new more efficient materials and and parts and rebuild.... it will take him three months but i will have a better improved engine fully functional and reliable ...
all the best Funky

 

[chizler62]

But, unless you know what's the problem, or successfully follow the cookbook troubleshooting charts, about all you can do is replace parts until it's fixed. Parts departments love this, sells more parts

But, the trend I've been seeing here is a move away from 'understanding and repairing' to automatons that simply replace parts. A shrewd business strategy.

That's exactly my point.....There are mechanic's of the 70s,80s and even 90s that just replace parts. Now there are technicians who understand systems and just need references.

A good example is that questionable practice of putting grease on float valves. You don't know why, but do it anyway because that's what you were taught.
Doubt its questionable is Suzuki, Honda and Yamaha have it in there high level tec programs.
Was taught that at Suzuki FAST program from Mark Kauffman, Honda in Cherry Hill from don't remember his name lol he also taught the Yamaha program too. Big guy.
Why isn't it in the manual? Because competent technicians already know how to apply it. Manuals are for reference and not for learning.

As for this guys pistons.....it's exactly a solid point. Those "scratches" are from a dry air filter. Wait, but Yamaha's 1943 manual for the XS says not to?
Oil your air filter.