Diaphragm repair update

[motoman]

Totally agree with U James. If the diaphrams on mine had had more than that one little pin-hole in one(BTW, it hadn't had any effect on slide position.........yet) of the diaphrams, I would of replaced them all. As it was with what I used the last time I had it out IS stuck there for good with that one teeny drop of the product. If all of them eventually need replacing, I would use the OEM ones not worrying bout the cost. That way I know for sure the slide movement with varrying vacuum loads would be the same as when new. But that's just me, and unlike some others can't afford to do that. I understand fully that others are not able to do that as I BTDT with raising a family and such years past. These scoots and any others similar with age are NOT cheap to CORRCTLY keep operational! Guess they can be purchased on the cheap at times, but that IS were that notion ends if intended to be fixed properly.

[clcorbin]

In fact the slide doesn't control anything at all; it responds to changes in partial vacuum when the butterfly valves are opened. The rate of opening of the throttle is controlled by the butterflies. I was referring to the possibility of a throttle slide sticking in the open position due to ingress of bits of RTV or whatever it was that flaked off the diaphragm mentioned.

What I meant by that is it controls the airflow in the sense that when you wack open the throttle, the slide moves slower and is only raised as the vacuum across the venturi increases with increasing airflow through the carb. So in that sense it does "control" the air flow into the engine, but only when the butterflies are open a decent amount. And the butterfly will control the air flow when you close the throttle as it will be blocking pretty much all the airflow, so even if a slide does stick open, it still has no effect on the engine returning to idle as that is only "controlled" by the butterfly and not the slide.

[clcorbin]

A breakdown in Poland due to a 'repair' that saved me a measly few dollars is not something I want. I need to feel that the bike is reliable and trustworthy.... you don't get that with makeshift repairs. Having said that, they are no doubt up to relatively low mileage, local riding, where there's a support structure if you break down...

Of course, even if all four slide froze completely closed (as far as a slide can close at any rate), you would STILL be able to ride the bikes. You just have about 1/3 your power or so. Not fun, but you would still get home.

But I do have to agree with you on one point: If I am taking my bike into the back country of some country where I could not get parts if something goes wrong, I would want the bike to be as close to 100% reliable as possible. And because of that, I would NOT be taking a 30+ year old bike even if I thought it was 100% reliable. There are just TOO many little things that can go wrong with these old beasts.

[Schming]

Extra weight? Have you weighed the slide assembly? The TINY bit of extra weight caused by the sealing pin holes in the diaphragm is absolutely trivial. You are talking about less than 1/100 of a percent of the total weight! (estimate based on what the rubber weights, it's volume and the total weight of the slide assembly).

Extra stiffness falls in the exact same category. When I repaired mine, I dabbed the material on both sides of each pin hole and worn spots to reinforce them. That diaphragm has over 3 square inches of area in total. At 2 inches of vacuum (this is venturi vacuum, not manifold vacuum), you would have around 6 pounds of force operating against the diaphragm. That tiny bit of extra stiffness in the diaphragm will make no difference in the operation of the slide. None.

I guess these concerns would be valid if you where to try and build up the whole diaphragm to a 1/4" thickness or some equally crazy. But they simply don't matter when the diaphragm is simply repaired.

Yes you're right about using a minute bit of sealer.
I saw "dipping can" in your first post and envisioned just that.
Still, if your going to repair instead of replace why are'nt you guys using the fuel and oil resistant gasket sealer ?

[James England]

But I do have to agree with you on one point: If I am taking my bike into the back country of some country where I could not get parts if something goes wrong, I would want the bike to be as close to 100% reliable as possible. And because of that, I would NOT be taking a 30+ year old bike even if I thought it was 100% reliable. There are just TOO many little things that can go wrong with these old beasts.

I would agree on that.... I used to do long tours on XS11's but they weren't old at that time. I do know of a German XSive who's done 250,000 on them but one never knows what it's taken to do that. Having said that, some XS riders continue to do large mileages on tours, as far as I understand. I did 5,000 miles on mine in jumps of 150-300 miles last year with no problems at all though (maybe because I do proper repairs? )

Ironically, I went to the south of France on a brand-new Kawasaki GT750. I left Scotland and reached Aix-en-Provence.... where the gear linkage (similar to the XS11 linkage on the European spec bikes) snapped a ball joint. I coasted to a stop, heart in my mouth, and looked around me. There was a great big green K sign! A Kawasaki dealer. He had the part, fitted it and I was off again. So, whilst even a new bike can break down, as you say the spares were readily available. I doubt a Yamaha dealer would have a single part for an XS1100.

I'm reminded of someone I know.... they got married and went on a European tour for their honeymoon. On a brand new Harley. It broke down in Germany and came back on a low-loader. Surprised?

Maybe I'm being unfair re the goop solution to holed diaphragms. In the USA though, you can buy those diaphragms at a lot less than they cost here (I bought some from the USA) and you don't pay the unreasonable postage costs that the seller charges for international. I just prefer to do the job properly and as permanently as possible. Otherwise, the bodge philosophy means that there is always something that one is doing again

[clcorbin]

Yes you're right about using a minute bit of sealer.
I saw "dipping can" in your first post and envisioned just that.

Given some of the, shall we say, "silly" things I have seen people do, I would have to say that is a perfectly valid thought! The reason I mentioned the dipping can is that people were taking the spray cans, shooting a bit into a cup and then using a brush to apply it to the holes.

To be honest, I went with the plasti-dip as that is the product mentioned in the repair section of this web site. I didn't even think about using other products.

[clcorbin]

Ironically, I went to the south of France on a brand-new Kawasaki GT750. I left Scotland and reached Aix-en-Provence.... where the gear linkage (similar to the XS11 linkage on the European spec bikes) snapped a ball joint.

<snip>

I'm reminded of someone I know.... they got married and went on a European tour for their honeymoon. On a brand new Harley. It broke down in Germany and came back on a low-loader. Surprised?

That's the nature of things built by man: they break. I would still have more faith that the probability that a new bike (and by "new" I mean one that has been properly broken in and sorted out!) will break on any given ride is much less than the probability that a 30 year old bike will break on the same ride.

Maybe I'm being unfair re the goop solution to holed diaphragms. In the USA though, you can buy those diaphragms at a lot less than they cost here (I bought some from the USA) and you don't pay the unreasonable postage costs that the seller charges for international.

Normally I agree with you 100% on this. Unfortunately, in these times, I am more willing to spend a few hours of time and $7 to see if a fix will work than I am willing to spend the same time and $80 or so for a fix that SHOULD work just fine. Hopefully, the $7 fix will get me and my bike through "these times" into more economically friendly times!

[James England]

I would still have more faith that the probability that a new bike (and by "new" I mean one that has been properly broken in and sorted out!) will break on any given ride is much less than the probability that a 30 year old bike will break on the same ride.

Actually though, I would trust my last XS1100 as much as any other bike because it was low mileage, impeccably maintained and had been properly looked after. I regularly did 300 miles round trip to visit my mother and it worked perfectly. The problem with the 30 year old side of things is that, usually, they've had lots of PO's... some good, some bad, and at least one person will have maintained them poorly (eg gooping the diaphragms). Let's say you do, for entirely understandable financial reasons, do the goop trick with the diaphragms. Then, later on, you sell the bike. The bike will not be as reliable as one which had the proper replacement diaphragms used and the next owner will not know the cause of any problems which the 'fix' may cause. The goop drops off, the bike misfires and as far as he's concerned, he has an 'unreliable' bike..... whereas in fact, the bike has suffered what people on this forum refer to as being "PO'd"... ie a bodged repair. In a sense, you have become the PO often alluded to on this forum when pix of poor quality repairs are posted with corresponding comments.

Inherently, there's nothing per se wrong with a bike being 30 years old.... it's the history of it during that time and what people have done (and not done) during that period. I've seen many, many bikes that were 1/3rd the age of my XS1100 and I wouldn't trust them one bit.

Having said all that.... yes, I understand the financial reasons behind nursing an older bike along on a shoestring budget.

[skids]

I used RTV Ultra Black on a couple of tiny holes. It is plyable and somewhat fuel resistant (fumes should be no problem). That was a long time ago and the bike runs great. I can't tell you if it is still adhering, but I figured what the hell... it is on the top side of the diaphragm anyway! You know, tiny holes really shouldn't affect operation much. The losses through those holes is quickly replaced anyway.

[clcorbin]

Actually though, I would trust my last XS1100 as much as any other bike because it was low mileage, impeccably maintained and had been properly looked after.

But that still won't address any of the hidden demons of old vehicles. When is the last time you borescoped the inside of the frame tubes? The outside of your frame might appear 100% perfect, but it could very well be almost completely rusted out from the inside. Without visual, ultrasound or x-ray inspection, you really don't know. And 30 years is a LONG time for rust to grow in hidden places.

The other demon that you will never see until it is too late is metal fatigue. There is a lot of aluminum on these bikes and aluminum does not have a lower fatigue limit like steal does. It WILL fail from fatigue eventually, no matter how low the stress is. And without x-ray inspection, you can not see it until it breaks. Not a failure mode I am worried about, but it IS working on our bikes every single time we ride them.

Also, when is the last time you replaced the whole electrical harness on that 30 year old bike? The insulation has hardened and cracked in places due to oxidation (I'm fairly sure this bike hasn't been stored in an oxygen free environment these last 30 years). Corrosion that has started at the ends of wires has worked it's way back several inches in many wires causing increased electrical losses and decreases mechanical strength. Plus, the plastic that forms the connector housings (and keeps the pins lined up and prevents them from shorting out) are brittle due to age (oxygen and UV exposure). Stresses caused by vibration and movement as you ride your bike can potentially break one of these housings and cause a potential short that will bring your bike to a dead stop.

So which do I consider more reliable? My 30 year old motorcycle that I have tried to take care of (but perhaps not to your standards) or my 6 year old Mustang? The car wins hands down. It has proven it is reliable AND it is not so old or high mileage that things are reaching the end of their service lives. I can't say that about my bike.

Let's say you do, for entirely understandable financial reasons, do the goop trick with the diaphragms. Then, later on, you sell the bike.

Not going to happen! I've owned this bike since 1989 and I have no plans on selling it now or any time in the future. Plus, being single, I don't have to worry about my wife forcing me to sell it either...

Personally, I think there is more worry about this repair than is justified. How many of these bikes have tanks that have been repaired with liners due to rust? I would not consider that a "proper repair". When I went through my tank (in more ways than one...) a few years ago and used electrolysis to clean it out, I found several pin holes in the normal problem areas. How did I fix it? I pulled out an awl and started probing around every suspect area and opened up each and ever soft spot in the tank as far as I could. Then I fire up the TIG welder and welded everything back up solid. NOTE: this was after electrolysis, so there was NO gas fumes in the tank! No more leaks and I have more metal down there now than I did 20 years ago... But, the epoxy liners have worked just fine for a lot of people...[/QUOTE]

Having said all that.... yes, I understand the financial reasons behind nursing an older bike along on a shoestring budget.

Ditto! Hopefully, these budgets will improve for everyone in the next few years!

[Geezer]

It's amazing how often this discussion pops up... Several years ago I covered repairing carb diaphragms with Yamabond #5. Back then the 80 1/2 special 1/2 standard Mongrel I rode only had 2 good diaphragms. I looked through all my spares and found 4 more that were bad.

I washed all the bad ones with dish soap and water and let dry. After that I applied Yamabond #5 to the holds. After they were dry it was hard to tell the repaired ones from the ones that were OK to begin with. I ended up putting in all repaired ones since they looked fine. The bike was still running great when I sold it a few years later.

Geezer

[James England]

30 years is a LONG time for rust to grow in hidden places.

The other demon that you will never see until it is too late is metal fatigue. There is a lot of aluminum on these bikes and aluminum does not have a lower fatigue limit like steal does.

Ditto! Hopefully, these budgets will improve for everyone in the next few years![/QUOTE]

True. 30 years is a long time for rust. I suppose I may have an unrealistic view of XS1100's, clouded in nostalgia. I do agree with what you've said re age related problems (as opposed to mileage), in that I sold my last XS1100 because it was worth such a lot of money over here. I did so because of the possibility of it blowing up (and therefore being scrap value). So I took the $8,500 and bought a modern Yamaha XJR1300 for regular use with lots of money left over. I must say, in many ways, it's a relief not to be driving an old classic regularly and wondering what would happen if it dropped a valve etc. So, forgive my hypocrisy! I just think if one is going to run them and repair them, do it right though........but again, that's budget permitting. Better a goop repair than no repair and a dud bike.

Incidentally, I thought the XS1100 was fast. The XJR1300 is incomparable in terms of just about everything (except appearance). I feel like a bit of a traitor to my beloved XS11's but a modern bike does have a lot going for it.

[clcorbin]

I sold my last XS1100 because it was worth such a lot of money over here.

This might get me banned, but if someone offered me $8500 for my XS, it would be GONE!!!!

Incidentally, I thought the XS1100 was fast. The XJR1300 is incomparable in terms of just about everything (except appearance). I feel like a bit of a traitor to my beloved XS11's but a modern bike does have a lot going for it.

That new Aprilla RSV4 Tuono has got me lusting as well, so I sure can't claim new bikes don't also have a lot of appeal to me!

Enjoy your Yamaha!

[skids]

Your aren't banned, but maybe you should be committed to a mental hospital! =8-)

[clcorbin]

Your aren't banned, but maybe you should be committed to a mental hospital! =8-)

I've got plenty of friends and relatives that would agree with that last statement!