Leakless XS Assembly

[crazypj22]

look at picture 7 posts above yours

[oldschool]

The point of retorquing is not to increase the torque each time, but rather to reattain the inital torque applied. As the engines run, or as any machine goes about its business, the parts 'settle.' That simply means that the parts move together such that distances decrease. This generates the opportunity for parts to have less torque than specified. The amount of this let-off depends upon many things, such as, the type of material, the heat curve, the length of time, and others. By going back to reapply torque the parts are brought back to the specified range. At times the more sensitive parts are to assembly torque, the more often they should be checked, that is, retorqued. This is a complicated subject for which many engineering articles have been written, and I do not pretend to be an expert. I hope this helps to explain the intent of retorquing: a reapplication to specs., not an additive effort.

Roy

[crazypj22]

if you have a genuine Yamaha service manual, take a look at first service information (I dont, so I cant verify) Most bikes require head re-torque at first service, I know I've done it on Honda's and Suzuki's and probably a few Yams as well. Not all bikes require it but most do. the engineers specify when and how , with exact detailed instructions.
PJ

[grizld1]

Yes indeed, Slide. If ya put one together with the rubber washers again, try rechecking torque before first fire, after the motor sits cold overnight. I've had 'em lose up to 6 foot pounds that way. I set the torque wrench way under spec to find out where things are; tightening up at that big an increment could do some harm.

[slide]

Bottom line. If you do not retorgue, how do you know that you are still within spec?

[71XS1B]

O.K. Mathius - Per your suggestion, I dug up my old Yamaha XS650 service manual published in the early 70's and found some information that hopefully will put an end to this over-torqued subject.

Page 13, "Engine Disassembly Notes" Para. C) 8) states "Occassionally, after several hours operation on a rebuilt engine, oil leaks will develop. This is caused by gasket compression. Re-torque all cylinder holding bolts should this occur." "In addition, other fittings MAY loosen during the "settling in" period after the rebuild. Make a point of checking motor mounts, brackets, etc., after 20 - 30 hours engine operation."

[71XS1B]

BTW - Yamaha also recommends that the threads of the Cylinder Head Studs are lubricated liberally with 30W engine oil before torquing them down to prevent shearing of the studs. (Page 18 under CAUTION)

[grizld1]

John, let me add my thanks for that and my apology for getting riled and contributing to the mess. The right response (if any) would have been "Gee, that's an interesting approach. Let us know how the build goes." Sorry.

[Six-Five-O]

It ain't no problem Griz...I understand these things and have gotten into these types things myself.....

I hope everyone here realizes that it is very tough thing to do, when either myself or Bob have to make a judgement call on some deletions for the overall good of the board and it's content..

It's not personal, but sometimes people take it personal..

Thanks for all you guys input.

Best Regards

John

[slide]

Jack, I sure hope you do not do anything rash as you have too much expertise that you can offer and share with most members of this board. Stay around!!!!!!!!!!!!!!!!!!!!
..........Mel...........

[crazypj22]

Sorry, just had to make a reply.
Still couldn’t find XS650 manual but found this for XS500
500km (300miles) re-torque to service specification.
I’m still trying to find a genuine manual for 650
BTW,Mathius,
I’m not taking sides but I have done this for a long time and it’s quite normal to re-torque cylinder heads.
Honda specified 300 to500 miles for most models
As for Japanese engineers getting things wrong, Honda rarely make a good cam chain tensioners,, transmission problems, etc Suzuki had problems with clutches, second gear and generators for years. Yamaha had problems with connecting rods, second gear on various models and real biggie, when they made brake rotors so thin they distorted and caused people to crash when wheel locked up at 100mph+ (had to change fork lowers, brake calipers and rotors) Kawasaki had problems with people riding in cold weather, carbs would freeze up, plus the usual wiring transmission etc. This stuff is not written in stone, it can be 'adjusted' if needed.
PJ

[acormier7]

Jack,
In my opinion your one your the most valuable members. Stay and help the one that went
help out. I really appresiate your help.
Art in Peterborough

[grizld1]

Ditto that, Jack! Don't go away, man!

Mathius, I'm responding because Six-Five-O has asked me to, not to try for the last word. Please understand that I did not conclude that settling had relieved pressure on engine components on some (not all) builds by 5 to 6 footpounds by guessing. I found that out because I do the recheck with the torque wrench set to 20 pounds on the large fittings and 10 on the small ones and go up in small increments. If I get any rotation I stop, back off the setting to one that applies maybe 1/8 turn, go around the fittings at that setting, and work back to spec in 2-pound increments. I do not under any circumstances reclick repeatedly at spec. torque, and I may have been unclear on this.

One of the biggest sources of trouble is the rubber washers, but the collars that align barrels to cases, head to barrels, and head cover to head also cause interference; they often seat fully only with sustained pressure, which is relieved when they settle. On my most recent engine I removed the collars, polished them and their seats, and lubed them with assembly grease. With copper sealing washers on the outside studs, that engine gave up no pressure in the overnight settling.

By all means build your engine as you see fit, following whatever procedures you think best.

[jeepurze]

acormier7 said:

Jack,
In my opinion your one your the most valuable members. Stay and help the one that went
help out. I really appresiate your help.
Art in Peterborough

ditto for me too jack, we got rubber to burn , sportsters to smoke and bikes to build.

[Mathius]

Ditto that, Jack! Don't go away, man!

Mathius, I'm responding because Six-Five-O has asked me to, not to try for the last word. Please understand that I did not conclude that settling had relieved pressure on engine components on some (not all) builds by 5 to 6 footpounds by guessing. I found that out because I do the recheck with the torque wrench set to 20 pounds on the large fittings and 10 on the small ones and go up in small increments. If I get any rotation I stop, back off the setting to one that applies maybe 1/8 turn, go around the fittings at that setting, and work back to spec in 2-pound increments. I do not under any circumstances reclick repeatedly at spec. torque, and I may have been unclear on this.

Thank you for making that clear. Your original post did not seem clear to me on that issue, and whether or not you were doing it correctly, this post was originally was meant to help other members. That includes myself, or it would not have arroused my interest. Just like everyone else, I opened the thread because I too wanted to learn about the weak links in the xs650 assembly and how to correct them.

With your information being unclear, I felt I had to give the information I did. It's useful to anyone who ever picks up a torque wrench, and it's not in my experience common knowledge. Most people when asked how to use a torque wrench will tell you, when it clicks, you stop. No one ever addresses what happens when it clicks twice. Myself in my early days of wrenching before I learned of my dad's testing, used to click it a few times "just to make sure".

When you argued what I was trying to say, I assumed (incorrectly) you were doing it wrong. Now that you've made that perfectly clear, I think this can all blow over.

One of the biggest sources of trouble is the rubber washers, but the collars that align barrels to cases, head to barrels, and head cover to head also cause interference; they often seat fully only with sustained pressure, which is relieved when they settle. On my most recent engine I removed the collars, polished them and their seats, and lubed them with assembly grease. With copper sealing washers on the outside studs, that engine gave up no pressure in the overnight settling.

By all means build your engine as you see fit, following whatever procedures you think best.

So it sounds like a major fault is in the gaskets/seals/washers. I already said I haven't torn down an xs650, so I want to ask for clarification on a point. The rubber seals are on the inside, and you replaced the outside ones with a copper washers? Or did you replace all the rubber with copper seals?

Mathius