BS34 Float Help

[bul_racer]

Excellent!!
The spigot you refer to is a vacuum port. Without a cap it's just a huge vacuum leak. Yes, cap it before running again.
There shouldn't be a "classic" lock washer on the front sprocket. There should be a thin washer that's splined for the shaft and that you bend the tabs over to lock in place. It's very thin and shouldn't make a difference as far as threads "left over" go.
Can you put some pics up?

View attachment 199305

Jim, yeah, that's why I said 'Locking Washer' instead of 'Lock Washer.' There's not enough of the shaft sticking out for the locking washer to engage the splines. I can get it on but I just don't think it has enough of a grip to make a difference. BTW, you know what the torque is supposed to be for this nut? Someone earlier said 95 foot pounds which is enormous...

I'd sure be interested to know why idle is higher with the vacuum port open vs. covered.

 

[Adamc]

Jim, yeah, that's why I said 'Locking Washer' instead of 'Lock Washer.' There's not enough of the shaft sticking out for the locking washer to engage the splines. I can get it on but I just don't think it has enough of a grip to make a difference. BTW, you know what the torque is supposed to be for this nut? Someone earlier said 95 foot pounds which is enormous...

I'd sure be interested to know why idle is higher with the vacuum port open vs. covered.

View attachment 199308

That nut needs to be very FT!
Or the seal behind it has a tendency to leak.
Get the big spanner out.

 

[5twins]

The back of your sprocket nut should be cut out. That will force the sprocket on enough once tightened for the splines to stick past it a hair, enough for the lock washer to grip on. Yes, if you want no oil leaks then go like 94 or 95 ft/lbs on the nut. I originally installed mine at about 72 ft/lbs. It didn't leak really, at least not much, but every time I'd have the cover off, I could see oil streaks emanating from the nut. There were usually some dirty oil drips down onto the starter gear cover too .....

The last time I had the cover off, I torqued the nut up to 95. I haven't had the cover off since but I'm not seeing any dirty oil drips down onto the starter gear cover anymore. When I renovated my '83, I set the nut at 95 and I've never seen any drips from it.

 

[Jim]

There's very little spline for that washer to seat over. In fact, all the spline that sticks through is about the thickness of the washer. It's easy for it to slip when you put the nut on. I usually use lots of masking tape around the edge of the washer to hold it in place while putting the nut on.

95 ft lbs sounds about right. I don't usually use a torque wrench on it. Jus' crank it down 'till it begs for mercy.

Revs are higher because it's a lean mixture. As you lean a carb, revs will climb until you reach "peak lean" then will start to decline.

 

[bul_racer]

There's very little spline for that washer to seat over. In fact, all the spline that sticks through is about the thickness of the washer. It's easy for it to slip when you put the nut on. I usually use lots of masking tape around the edge of the washer to hold it in place while putting the nut on.

95 ft lbs sounds about right. I don't usually use a torque wrench on it. Jus' crank it down 'till it begs for mercy.

Revs are higher because it's a lean mixture. As you lean a carb, revs will climb until you reach "peak lean" then will start to decline.

Jim, so the gas that's squirting out of the vacuum port is leaning out the mixture and raising the idle. Maybe I'll need to adjust the mix screws to get the idle right.

I apologize for not getting terms correct. Remember, this is my first 4-stroke and my first dual carb bike plus using vacuum instead of a cable is a foreign concept to me.

Thanks everyone for your input. For the c/s sprocket I'm not sure if I can get 95 foot pounds. My torque wrench only goes up to 50. Guess I can do what I do when changing tires on my car - put the breaker bar on and then jump up and down on it. Going to have to rebuild the master cylinders first though because both are shot. Maybe I should invest in a new torque wrench...

 

[Jim]

Jim, so the gas that's squirting out of the vacuum port is leaning out the mixture and raising the idle. Maybe I'll need to adjust the mix screws to get the idle right.

The gas is squirting out because the port is open to the atmosphere. When the intake valve shuts, the flow through the intake still wants to keep going. Inertia affects airflow as well as solid objects. That causes a temporary surge that squirts gas out along with the air.

 

[gggGary]

That nut needs to be very FT!
Or the seal behind it has a tendency to leak.
Get the big spanner out.

And all parts, both sides of sprocket etc. VERY clean.

 

[5twins]

In many cases, it's actually not the seal that's doing the leaking. The seal doesn't work against the countershaft itself, there's a short metal sleeve slid over it and that's what it seals against. The back end of the sleeve gets pressed against the inner race of a bearing inside the motor and the back of the sprocket is pressed against the front end of the sleeve. This is why the nut needs to be so tight. You're trying to seal metal to metal here, in not just one spot but two. If it's not tight enough, oil gets in between the inner end of the sleeve and the bearing race, and flows out between the sleeve and the countershaft along the shaft. Heiden Tuning makes an upgraded sleeve that has an o-ring on the back end to help seal it. I think this is a great upgrade and I wish some of the U.S. 650 parts places would start selling it .....

 

[bul_racer]

In many cases, it's actually not the seal that's doing the leaking. The seal doesn't work against the countershaft itself, there's a short metal sleeve slid over it and that's what it seals against. The back end of the sleeve gets pressed against the inner race of a bearing inside the motor and the back of the sprocket is pressed against the front end of the sleeve. This is why the nut needs to be so tight. You're trying to seal metal to metal here, in not just one spot but two. If it's not tight enough, oil gets in between the inner end of the sleeve and the bearing race, and flows out between the sleeve and the countershaft along the shaft. Heiden Tuning makes an upgraded sleeve that has an o-ring on the back end to help seal it. I think this is a great upgrade and I wish some of the U.S. 650 parts places would start selling it .....

Looks like a great idea! But Netherlands is a long way from here...

 

[bul_racer]

Been busy with other things so haven't visited here in a while but thought I'd update.

Golly, I wish I'd done the compression test before going through all of these gyrations! 70 lbs on left cylinder, 90 on right.

After I checked compression I reviewed some threads to make sure I was adjusting valves properly, I think so. Set exhaust to .005, intake .0025. One thread I found showed using a block of wood and hammer to tap the top of the tappet in hope of loosing built up carbon, thereby improving compression so I did that. Another said soak it in Marvel Mystery Oil & since I had some on hand I did that and let it set for a couple of days. When I retested I got the same readings. Bummer!

It would seem that there's a serious problem with compression, probably due to burnt valves. So now I have to decide whether it's worth it to delve into what looks like at least a valve job. I take responsibility since I never checked or adjusted them when I was riding the bike. In my defense, I'm not a 4 stroke guy so I didn't know I should be doing that. The bike has 18K miles on it. I thought it wouldn't need adjustment till about 30K. I did have a manual then. Guess I should have read it. Ah well, water under the bridge.

I'm hoping for a little guidance from the experts here. First I need to determine just how big a project this would be. In addition to the valve issue I see from other threads that there's a very good chance that I'll have a problem with the cam chain guide. I haven't drained the oil yet to see if there will be particles from the guide but will do that soon. Saw a thread where Jim, DFA had done a mod to increase longevity & maybe I'll try that or Gary at HoosRacing.com had a mod he was selling for a very reasonable $30. I might try that if he still has them available.

First, I have to determine if this is something I can do. I'm pretty sure I don't want to be splitting the cases on this bike so If the guide can't be replaced without doing that I may have to bag it all. This may be blasphemy to some of you XS650 engineers but I'm just a guy wanting to have a bike I can ride & not looking for perfection like some of you. I already have 3 other motorcycles in various stages of disassembly with parts all over my garage floor and absolutely not an uncluttered flat surface to be found.

I have never done a valve job on a motorcycle before since all of my other bikes are 2 strokes. Many, many years ago I did pull the head off of my 1955 Chevy and took it to a machine shop to have the valves machined. That worked out great BTW. If I can pull the head off this bike and get the valves fixed for $300 or so I'll probably do it but if it's gonna be more than that I may have to give priority to other projects.

As always, any insight is appreciated.

 

[Jim]

It would seem that there's a serious problem with compression, probably due to burnt valves.

These engines aren't known for burning valves... but you do get stuck piston rings from years of sitting. If I was a betting man, that's where I'd put my chips.

No, you don't need to split the cases to do a top end refresh on these bikes. If you look in Tech, the very first article is the top end buildup. Just reverse the order to tear it down. These engines are a bit harder than a 2 stroke, but a relatively easy engine to work on as far as 4 strokes go. From what I've seen of your work so far, I'd say it's well within your wheelhouse.

Saw a thread where Jim, DFA had done a mod to increase longevity & maybe I'll try that or Gary at HoosRacing.com had a mod he was selling for a very reasonable $30. I might try that if he still has them available.

Yes, by all accounts the Hoos guides are as good as the originals.
DFA?

If I can pull the head off this bike and get the valves fixed for $300 or so I'll probably do it but if it's gonna be more than that I may have to give priority to other projects.

You won't know 'till it's apart. If the cylinders are good and don't need an oversize bore, you can come in well under that. If they need bored and oversize pistons, you'll be pushin' your $300 limit. Only way to know is a teardown.

 

[gggGary]

Spray carb cleaner in the plug holes let it sit overnight RIDE it. I won't tear down a motor with low compression that runs till I've put a 100 or 200 miles on it and rechecked, doesn't always "fix it" but worth a shot.
Umm make up your mind and get the other two bikes together, stored neatly, or gone before starting in disassembling a third.

 

[650Skull]

https://www.xs650.com/threads/compression-test-results.52684/#post-558105

 

[bul_racer]

These engines aren't known for burning valves... but you do get stuck piston rings from years of sitting. If I was a betting man, that's where I'd put my chips.

No, you don't need to split the cases to do a top end refresh on these bikes. If you look in Tech, the very first article is the top end buildup. Just reverse the order to tear it down. These engines are a bit harder than a 2 stroke, but a relatively easy engine to work on as far as 4 strokes go. From what I've seen of your work so far, I'd say it's well within your wheelhouse.

Yes, by all accounts the Hoos guides are as good as the originals.
DFA?

You won't know 'till it's apart. If the cylinders are good and don't need an oversize bore, you can come in well under that. If they need bored and oversize pistons, you'll be pushin' your $300 limit. Only way to know is a teardown.

Jim, sorry about the DFA. Guess I got you confused with someone from another thread. Thanks for your input. I think I can figure out how to pull off the head and check things out. I wouldn't expect any damage to the cylinder walls/pistons but a stuck ring is certainly possible.

 

[bul_racer]

Spray carb cleaner in the plug holes let it sit overnight RIDE it. I won't tear down a motor with low compression that runs till I've put a 100 or 200 miles on it and rechecked, doesn't always "fix it" but worth a shot.
Umm make up your mind and get the other two bikes together, stored neatly, or gone before starting in disassembling a third.

Thanks Gary! I can certainly give that a shot. Maybe I'll get lucky.

[/QUOTE]Get the other two bikes together before starting in disassembling a third.[/QUOTE]

Yeah, too late. I've actually got THREE other bikes apart now. [74 Husqvarna 400CR, 71 Bultaco 250 Matador, 2017 KTM 250XC]. What can I say? Depending on how you look at it I'm either an ambitious multi-tasker or a complete scatterbrain. The good news is I'm just doing a top end on the KTM.

 

[gggGary]

too late

 

[bul_racer]

https://www.xs650.com/threads/compression-test-results.52684/#post-558105

Thanks Skull! A real interesting thread. So, if I understand correctly since differences in atmospheric pressure vary approximately 3.5% per 1000 feet of elevation and since I'm at 7700 feet my adjusted compression would be 89 Left, 114 Right.

Of course, since the 2 sides are supposed to be close I still have a problem.

 

[Raymond]

The biggest part of the job is taking the engine out, and putting it back in. It's a heavy lump so you're going to need some assistance with lifting it. Or a pulley system.

But with the engine out it's all pretty straightforward spannering. Agree with all the comments above. gggGary's suggestion of riding it and see if it improves, maybe a stuck ring frees up, seems there's not a lot to lose?

 

[5twins]

When you did the compression test, were you holding the throttle wide open or better yet, were the carbs removed? If you don't at least hold the throttle open, you can get low readings. A warm engine usually tests better than a cold one too.

 

[bul_racer]

The biggest part of the job is taking the engine out, and putting it back in. It's a heavy lump so you're going to need some assistance with lifting it. Or a pulley system.

But with the engine out it's all pretty straightforward spannering. Agree with all the comments above. gggGary's suggestion of riding it and see if it improves, maybe a stuck ring frees up, seems there's not a lot to lose?

So I need to take out the engine to remove the head? Or just if I need to remove the cylinder?