HELP!!! I broke it!!! Won't start. Warning LONG!!!

First off I want to say I really appreciate all the help....and I mean that...ALL the help and suggestions. Some of you really went out of your way to help...I'll not forget that.

Right now.....I feel like crawling away and never coming back. Or maybe changing my screen name and pretending Gordon in NC left town for good.

I found the problem...or at least I know what the problem is but not what caused it.

Keep in mind this bike sat unused for many years. I would never start a BSA unit single that's been down for that long without going inside and looking around.....but I know those like the back of my hand and the XS is new to me. So I thought, what the heck...let me see if it would run and go from there....what did I have to lose? The bike started the first time I tried the starter....and all I did was prime the cylinders. It NEVER smoked a bit and ran pretty well.....sounded great. I put a little over 50 miles on it. I had just strobed timed it again and it was running fine when I turned it off. The next day I decided to pull and lube the advance rod......and did....and the bike hasn't run since.

I had always thought that the compression (yep, the key word here) was weak....but heck it ran and ran what I thought was well so again....what the heck. I haven't used my compression gauge in 15 years or more. If you know BSA unit singles.....one push on the kicker and you know if it has good compression or not. But the past couple of days I have been wondering just what compression this bike has....I was saying it was the same as it was when it was running.....but since I never checked it....I really didn't know. It took a while for me to find my gauge....but I wanted to check the compression tonight before I started working on the bike to find out what it would be before I re-torqued the head. At first I thought my gauge was bad....it really hasn't been used much at all. So I try one of my other bikes.......the gauge is fine.

I have very little compression.....not knowing the XS isn't a good enough excuse. I want to apologize for the misinformation and for wasting your time. It never had "good" compression but it ran.....

I'm going into it and find out what's causing it.....I'll need some more help and I'll try to do better the next go around.

Tail between his legs in NC......and not feeling very proud of himself right now.....Gordon
 
- - - I found the problem...or at least I know what the problem is but not what caused it. - - - Keep in mind this bike sat unused for many years. - - - I have very little compression.....It never had "good" compression but it ran..... - - - I'm going into it and find out what's causing it.....I'll need some more help and I'll try to do better the next go around. - - -

Hi Gord,
all the information you need for a teardown & rebuild can be found with the list search button.
The hardest part is horsing that heavy lump out of the frame without rupturing yourself and getting the bastard back in again once it's back together.
And at least you diagnosed the problem so don't be too hard on yourself, eh?
 
Hang in there, Gordon.

But, your low compression and exhaust backfires sound like another common malady experienced on 'rip-van-winkle' awakenings: Sticking Exhaust Valves.

There's several threads on this, follow thru this one, including the links contained in it:

http://www.xs650.com/forum/showthread.php?t=35725

Now, what you can do that may confirm this is:

- Remove both exhaust valve covers.
- Set the exhaust valve lash rather loose, like about 0.020"-0.030" (0.5-0.8mm)
- Using your 'brain surgeon' skills, shoost some penetrant thru the valve springs, onto the valve stems.
- Leave the fuel and ignition turned off. Leave the valve covers off.
- Do some kickstarting. Note if any different feel to compression occurs.
- If so, recheck valve clearances. See if the clearance closed up, indicating valves seating a little deeper.
- Repeat with the penetrant thing.

Could take a while. There's other, more involved methods, like removing the exhaust pipes and gaining access to the exhaust valve stems, where you can do penetrant and 'shoe-shine' type cleaning of the exposed stems.

Overly summarized here. Hope you get the idea...
 
PERFECT!!!!! I've been pounding the search function looking for just that kind of info. I have the tank off and went ahead and removed the coils and condenser and re-torqued the head.....it needed it and I figured that stuff would have to get out of the way if I had to pull the engine.

I was so focused on timing I wasn't paying attention....and the bike was trying to tell me what was wrong. It never smoked...not one speck but the compression always felt weak. Right now if I kick it (and I'm getting used to the kicker)with my finger on the plug hole.. on about the 4th or 5th kick it'll blow my finger off. So it's there.....just not all the time.

I'll start soaking them and watching for them closing up.

Thanks for not giving up on me........IOU big.

Gordon
 
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Started the soaking last night and have all weekend to deal with it......longer if need be.

Gota stop by the gun shop on the way home and pick up a couple of wire brushes.

I think I'll go ahead and remove the exhaust so I can get to the stems. If I can't free them up that's another step that had to be done anyway.

I see what Two Many was talking about with his "brain surgeon's skill" comment. Finding the stem with the PB Blaster's nozzle through all those spring coils is fiddley.

I'm picking up a roller XS 650B tomorrow morning. It'll be nice to have some spares around AND if I need to see how something works I'll have an engine out where I can see it.

Take care.....it's cold and wet here in NC today.....hope your weather's better.

Gordon
 
well....that was an interested read :laugh::thumbsup:

Somewhere around the first page when I read that the valves had gone out of spec and flames coming out of the exhausts I said to myself Mmmmmm sounds to me like it is igniting fuel in the exhausts .

There are only a few reasons I can think of why that should happen ,... timing too retarded , spark plug leads switched or the exhaust valves not closing during ignition ie sticky or burnt exhaust valves or some other reason why the exhaust valves are not shutting completely during ignition thus no compression during firing

The only other thing that hasn't been mentioned is valve adjustment proceedure.
Did you make sure that as you adjusted the valves on each half of the engine that you adjusted them with the piston in that particular cylinder at TDC on its compressiuon stroke ? then cranked the engine 360 degrees to adjust the other side at TDC on compression stroke?
 
Gordon, there's no point in spending time trying to free up sticking valves, or other band aid methods. Also, torquing head studs at this time has no value. You have to face facts; you have a 40 year old engine that has sat for 30 years. It was probably run hard, with no maintenance done for its first 10 years of life.

You have an engine that needs a top end re-build. Once the top end is opened up, the components need to be checked against the Yamaha Service Manual. You will almost certainly find multiple items that need replacement or servicing.

The sooner you bite the bullet, and remove the engine to the work bench, the sooner you will have a smooth running engine.
 
Hi Gordon,
so the new diagnosis is the valves are sticking open?
Well, that's one of the very few problems that have a hope of being fixed without pulling the motor.
Let's hope that squirting and scraping in situ frees things up enough to get the bike running and that RG's pessimism is unfounded.
 
Hi Gordon,
so the new diagnosis is the valves are sticking open?
Well, that's one of the very few problems that have a hope of being fixed without pulling the motor.
Let's hope that squirting and scraping in situ frees things up enough to get the bike running and that RG's pessimism is unfounded.

You're missing the point, Fred. Its a 40 year old engine, that almost certainly needs to come apart to repair worn out parts. If we knew the milage on the odometer, that would be useful information.

Sure he can do a few shade tree mechanic tricks, and maybe get the engine running, but he will still have a carboned up engine with worn out internals.
 
<snip>If we knew the milage on the odometer, that would be useful information.<snip>

I mentioned this on another thread.....but not this one. I am the third owner of the bike. The first one was middle aged when he bought it new. He had it for 10 years and then passed away. From what I've seen I'd say the bike was well maintained. It has a little over 7000 miles on it. There was a short period where some of the younger boys in the family got the bike out and rode it around the farm....but that didn't last long and the bike was put back up. Fluids drained and under roof. The first owners son in law started to get the bike running back in 2004 (we'll call him the second owner) but was a Harley guy and didn't want to mess with all the grey primer that had covered the bike from an auto restro.

If I was worried about a smooth running engine..:)...I'd buy a Honda. :laugh:

From what I've seen and had my hands on.....the bike was not abused....(well, except for that damn primer and where the boys beat up the side stand) I am actually very surprised how good things look. I've seen and had my hands on some really nasty bikes in my time.

I'm going to keep moving forward. I have the top mount off to get at the condenser and will leave it off for now. I re-torqued the head because I wanted to see how loose it was....that was not a waste of time......this is my hobby, not my job.
I will remove the exhaust tonight and have a go at the exhaust valves. If they happen to reseat (keep in mind I was riding this bike) I'll just button it up and ride it. If they don't, taking the exhaust off wasn't a waste of time either.

At my age.....I'm not in this for the long run. My kids have plenty of bikes to choose from when I'm gone...... and they already have their favorites.....the rest will just get sold off and if those bikes aren't perfectly running machines....I'll let somebody else worry about that.

Gordon
 
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- - - Sure he can do a few shade tree mechanic tricks, and maybe get the engine running, but he will still have a carboned up engine with worn out internals.

Hi RG,
Gordon's latest post sez the bike has 7,000 miles from new.
If the shade tree mechanic tricks get it running the bike may perform just fine.
 
Yeah, these things can be tough calls.

The mechanic in me wants to tell everyone with more than 10,000 miles to get a complete "return to new" spec overhaul.

The shadetree in me is at the other far end of the spectrum.

This "unstick exhaust valves" thing is just an easy confirming experiment, since Gordon would like to know what happened. Part of the fun learning experience.

The result of this is, of course, Gordon's call. There's varying degrees of success in these "wake-up" calls, just a matter of risk management...
 
Checked the valves (twice) (this was a puzzler and might be a clue? Exhaust were tight and inlet were real loose...it's been run a little over 50 miles since I adjusted them the first time)

NC

well my money is on the valves not being correctly set at TDC on compression stroke.
If the exhaust valves are too tight they might not be seating properly at the moment of ignition ,reducing compression and allowing ignition to carry through to the exhausts .
If the inlets are really loose the engine may not be getting a sufficient charge of gas on each cycle

It would be worth checking at the points that you are getting a spark just before TDC when on the compression stroke in each cylinder and also checking that at the point that both valves are fully seated in that cylinder
 
Well, Gordon,

Welcome to the monkey house! You already got another XS!! After you have used it to back-check the troubles of XS#1, then, naturally, you'll have to find another one so you can get the second one running.....and the contagion spreads.....

Did you by any chance try tapping the valves like we talked about? Sorta primitive compared to --well, anything, but it could indicate a hesitation.....(insert huge question mark here).

Now I know why I haven't heard much the past few days---got a new toy! Congratulations! If you really do part it out, let me know.....I need a center stand and silencers, and, and, and........:wink2:
 
(Short hi-jack...) Hi Fred--

True enough about the number of parts, but compare it to that XS11, or (Good Lord!!) a new Triumph....it has a *radiator*!! Now, is that rude, or what??

Anyway, I like the XS twin, so that makes it a neat and easy engine....heehee.

And now back to your regularly scheduled thread....
 
Well.....I soaked the stems from the top for a couple of days and kept turning the engine. It did help a bit....but not enough. So I pulled the exhaust and tried the "gun brush" shadetree (my middle name) fix. I have to admit......the way I was doing it was pretty much useless. If you happened to have a chunk of carbon caught on the edge of the seat.....AND it was where you could see it.....it would probably work. But no matter which way I turned (the only way I didn't try was standing on my head) there was 50% of the valve and seat I couldn't see.

So......I'm in the process of pulling the engine. Not something I'm looking forward to....but it has to be done.

It's going to take a while but as soon as I'm inside the head....I'l report back.

I did pick up the roller today.....I'll throw away more bits than I'll keep...wonder if I'll ever learn. :(

Gordon
 
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Pulling the engine was a LOT easier that I expected......now to get into it's head.

Gordon

1975 XS650B......with compression problems
and a few "feeling neglected" BSA unit singles
 
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