Need advice on repairing a torn slide diaphragm


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extremeodd
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Need advice on repairing a torn slide diaphragm

Post by extremeodd »



I've been working on getting my new to me $150 84 gl1200 up and running the last few days. After bypassing the fuel cutoff relay to get the pump running and replacing a blown float bowl gasket, I got the bike to start up and idle quite nicely. However, whenever I would try to open the throttle more than 10% it would choke out and die. This was screaming "main jet issues" and despite the PO telling me it was running only a few months prior, my mind immediately went to the main being gummed up with varnish (completely forgetting the pilot has a far smaller orifice and would probably plug up first). So while waiting on my carb cleaning tools to arrive in the mail I figured that I'd try the lazy man's approach: drain all the gas, dump in a can of seafoam, start it up to get the seafoam into everything and let it sit for a day.

After doing that I realized that by pulling the top cap and slides out I'd be able to possibly dislodge anything in the main from the top using compressed air. The first carb I popped the top off of, I found a torn diaphragm. The tear is U shaped and is about 1/4in wide. The diaphragm has been patched before with something that was brushed or smeared on and that patch is still holding just fine so I'd like to try and emulate that.

Some quick googling showed that quite a few people have had varying amounts of success using either plastidip or liquid electrical tape. Before I get the stuff and go wild I figured I'd ask you guys for your opinion on this.



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shevik
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Re: Need advice on repairing a torn slide diaphragm

Post by shevik »

Personally I haven't tried it, but I don't see what you have to lose in either case-- if the patch fails you're not worse off then you started.

My only advice would be to try and use whatever the PO used to do the original patch, especially because it's holding, but moreover because you don't know how different resins might react to eachother over the life of the repair.

I'd love to see some photos of the bike, sounds like a serious project!
If I just work hard enough I should be able to get her out and about before riding season is over.

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extremeodd
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Re: Need advice on repairing a torn slide diaphragm

Post by extremeodd »

The one downside to the previously done repair is that I have no idea what was used and based on the latest PO's (lack of) knowledge on the bike, I don't think he ever had the carbs off or apart.

It appears like it was brushed or smeared on which eliminates sprayed on plastidip (but doesn't eliminate the brush on version) however, considering most fuel resistant flexible sealants are black and look the same, I'll just have to try something and hope for the best.

Worst case I end up buying a K68 diaphragm from http://jbmindustries.com/index.html for $20, a generic diaphragm from china for $20 (ugh, shipping times), or a generic diaphragm/piston from china for $30 (ugh, shipping times). Hopefully, I don't discover any more torn diaphragms when I get the front 2 carbs opened, wasn't able to get my long (only) JIS screwdriver in there with the fairing in the way and am being lazy about pulling out the carbs again.

Here are a couple of pics

About 10 mins after getting the bike:


Picture from the listing


My diaphragm showing the tear at 12 oclock and the repair at 9 oclock


Better view of the tear


Side shot of that booty


Rear booty view as it currently stands. Bonus 66cc 2 stroke motorized bike in the backround (for a bicycle it's scary fast)


Brief video of it starting up (on 100% seafoam)


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I probably should start a thread on here documenting everything I do on this bike. Where would be the best place on these forums for that? I've noticed there aren't many build threads and these forums seem to be primarily for specific questions or topics of interest.

With the diaphragm, I'm going to try out plastidip after cleaning it really good and see how well it works.

EDIT: Got the front 2 carb's caps off and found another torn diaphragm that was on the same side as the first one and it had also been repaired like the first one. Sadly, the repair had failed on the 2nd one despite being the same material. Upon further inspection, the repair made on the first carb actually wasn't holding very well and I was easily able to peel it off.
With that in mind, I picked up a tub of liquid electrical tape and am going to try using a nitrile patch from a glove. But it's starting to really look like I get to buy 2 diaphragms. At the very least, I've figured out why the PO had some bad running issues that he was blaming on the carbs being out of sync.

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dingdong
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Re: Need advice on repairing a torn slide diaphragm

Post by dingdong »

My vote is on the JBM diaphram. Just did the same on my1500. Quality product. Do you really want to have to pull the carbs again if the patch doesn' t work. And odds are it won't considering it is in the place where the most movement is. How many glues are really gas "proof"?

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extremeodd
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Re: Need advice on repairing a torn slide diaphragm

Post by extremeodd »

The beauty of how Honda built these goldwings (at least the gl1200) is you can easily service the diaphragm, slide, and needle without removing the carbs. Plenty of people have success repairing diaphragms, a quick google search will reveal this. It's fairly common on older bikes where replacement parts are super hard to locate. Any patch materials used like plastidip, electrical tape, vulcanizing liquid, don't need to be gas proof, they just need to resist gas vapors.

Ended up patching both of the torn diaphragms with liquid electrical tape and patch pieces of a nitrile glove. I'm not entirely certain that both repairs held but I was able to take the bike for a spin around the block for the first time. Admittedly I wasn't able to quickly open the throttle or get above approx 2500rpm in gear but it is significantly better than it was the other day.

Later tonight I'm going to pop the tops on the 2 carbs I addressed and see how the patches held up. I'd bet money on the 2nd one I patched having failed, I missed a small spot when cleaning and I don't think the liquid tape got good purchase on the rubber.

When I get paid again I'll probably order some of the JBM parts if I don't have any luck with my repair attempts. Not like it hurts anything trying to not spend money on parts if I don't have to, especially when working on a $150 bike.

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Charlie1Horse
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Re: Need advice on repairing a torn slide diaphragm

Post by Charlie1Horse »

My thought would be to replace all four of them as all the rubber is as old as what was torn and will likely tear again. It would be best to replace them all instead of taking a chance on an unknown repair process. So, it costs a little more to replace them but on a nice looking bike like that for only $150.00, what a deal.
Russell

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extremeodd
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Re: Need advice on repairing a torn slide diaphragm

Post by extremeodd »

Welp, I'm just going to get new diaphragms. Not because I believe that they are unfixable but because I fractured my damn rib pushing the bike home and that pisses me off. Of all the stupid ways to get hurt, I get hurt PUSHING a goldwing. Not it falling on me, noooo, but from pushing it. I blame working behind a computer screen for the last 6 years for this happening.

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shevik
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Re: Need advice on repairing a torn slide diaphragm

Post by shevik »

First of all, I'm so sorry. That **** sucks dude. I'm sorry you're hurt but I'm glad you're ok. I really hope the medical bills dont set you back. But as someone who is also going through the drama getting an old goldwing running again I'm also laighing a little out of sympathy for the BS you're going through. Feel better dude and heal quick.
If I just work hard enough I should be able to get her out and about before riding season is over.

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extremeodd
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Re: Need advice on repairing a torn slide diaphragm

Post by extremeodd »

No worries on the medical bills, I don't go to the doctor unless absolutely necessary. There isn't anything they can do for a rib anyways.
EDIT: I never explained what happened. On the test ride the battery died about a 1/4 mile from the house because I had the lead from the alternator off (the load was causing it to stall at idle) so I pushed it back without taking any breaks. What did me in was the final hard push to make it up the driveway incline, I felt it pop then and about dropped the bike. Honestly, I didn't even think I had actually hurt anything until a few hours later when I sneezed and nearly passed out from the pain.

Changed out the plugs since it seemed to not be firing on all cylinders at idle and now it's idling like a champ. It also made it so I can have the alternator hooked up without it wanting to stall. It's also far more willing to rev up which is giving me hope that only one of the repairs failed and I might simply be able to repatch the failed one. Before when I would go WOT from idle, it would stall. Now the rpms increase to 1500-2000, it hesitates for a full second, then revs up to 5500 fairly quickly before I cut the throttle. It really feels like only one of the slides isn't opening and it's revving up on 3 cylinders vs before where it would barely be able to climb to 5k. If I hold the choke open when I do this it seems to skip the hesitation somewhat.

Also discovered why the rear tire keeps going flat, has a nail in the dead center of the tread. Now I no longer have to replace the tire, hooray!

It's looking like once I run up to walmart for a tire patch kit, get the tire patched/aired up and zip tie the choke full open, I'll be able to take it for a spin around the block again.

I've already made sure to have the alternator plugged in this time so I won't have to push the so and so back (not that I am currently capable :/) this time.

Of course, down the road, I will replace the diaphragms but I'd like to get past this part so I can figure out what else this thing needs to be a solid bike.

EDIT: Redid the failed patch without the nitrile glove to see if that helps or hurts. Managed to plug the tire and with the diaphragms, back in place I took her for a ride around the block. It'll idle without the choke but currently doesn't have enough power to move unless you have the choke full open. During the ride around the block it didn't have much power but it had enough to get to 25mph without much issue. There was a constant irregular carb backfire which tells me my patch failed yet again, but it was better than before. I'm thinking that the badly damaged plastic carb box lid isn't helping matters allowing air past the filter. Time to pull that diaphragm again and try patch attempt #3

EDIT 2: I lied, BOTH PATCHES HELD!

Now I just gotta work on balancing these carbs, I have very little power and a constant but infrequent backfire out of one of the carbs. It will eventually get up to high rpm if you keep the throttle open but it feels like the pistons are fighting each other.

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shevik
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Re: Need advice on repairing a torn slide diaphragm

Post by shevik »

Ok, so I just finished getting intimately familiar with the carbs on my gl1100 and had to troubleshoot a lot to make them perfect so for once in my life I feel somewhat qualified to comment :o What do your float bowls look like? Are your jets clogged? Are the floats themselves set to factory or are they all at different levels?

It seems like the big hint that your jets are filled with crud is that opening the chokes helps a little. If I were you I'd clean the carbs before bothering with a sync.
If I just work hard enough I should be able to get her out and about before riding season is over.

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extremeodd
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Re: Need advice on repairing a torn slide diaphragm

Post by extremeodd »

When I had the carbs off last week to replace a bowl gasket the bowls looked surprisingly clean considering the age of the 'wing. However, like all great fools, I didn't bother to tear into the carbs and clean them while I had them off.

After my last edit, I lost the ability to edit the post (I've noticed it locks that out after an hour or two unless you leave a tab open on the post) but discovered that the left rear cylinder isn't getting any fuel. Tried taking the pilot screw out to blast some air through but it appears the pilot circuit is completely plugged on that carb. Even with the screw out and the bike started no fuel would leak out of that opening. Weirdly the mains should be open but I wouldn't be shocked if my seafoam treatment broke up some crud that plugged them up.

Thankfully I already have 4x rebuild kits on hand since that was the same price as a 4 pack of bowl gaskets.

Today's project is to pull the carb box (again) and to do a light rebuild. Mainly going to pull all the soft bits, clean out every orifice with carb cleaner and tools and rebuild using the bits I actually trust from the kits (never trust a cheap kit's jets).

While I'm in there I'm going to see what I can do to fix the airbox lid as it's in pretty rough shape.

I'm willing to bet by the end of the day that I'll have her firing on all 4 which isn't too bad for only "investing" $45 or so on this $150 bike.

EDIT: Thought about it some more and it seemed fishy that I was getting no firing even with open throttle on that dead cylinder so I double checked my patch and it had totally failed. So I'm attempting to patch it again without using a piece of glove as that made it a touch stiff. It doesn't help that this liquid electrical tape is super thick and starts drying immediately. If I can scare up some acetone I'll see if I can water it down some so I can apply it in thinner coats if this attempt doesnt work. However, despite the liquid electrical tape being a PITA to work with, it sticks to the diaphragm really well and is sturdy. All of my failures have been from trying to use a patch layer of nitrile instead of letting the liquid tape handle that. An ideal solution might be thinning out the liquid tape, dipping a patch piece of nitrile in it then using that to patch the diaphragm. In theory that would stick well, resist retearing and be thin enough to not throw off carb balancing too much. We might have to try that if this fails. I'd just order new diaphragms but I'm broke and am willing to waste a bunch of time trying stuff.

EDIT 2: Turns out the diapgragm being super flexable is an important issue so I redid one of the repairs. Now they both are fixed and move almost as easily as the untouched ones.

Next is the fun of balancing carbs with a DIY manometer since no local places sell one (that I could return after use) or to cough up the $45 since I'll probably be fixing more than just this bike in my future.

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shevik
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Re: Need advice on repairing a torn slide diaphragm

Post by shevik »

Hell yeah dude keep the updates coming. As far as I can tell you're going to end up the go-to thread for people who can't replace diaphragms when they're out of production or too expensive so keep the experimentation up in the interests of science lol.

As for your plugged jets sounds like you need some carb and choke cleaner. NAPA sells a generic for like 3-4$. If that won't do the trick you might need to soak the assembly in some kind of detergent. Just be careful with those brass jets, soft as butter. They'll bend before the crud breaks if you dont do a thorough job.

I'm interested in what you figure out for your airbox lid because even though mine is in tact it doesn't close all the way. Probably because my air filter is a touch large. I've thought about taping it but I'm not sure what kind of mess that would make in the long run.
If I just work hard enough I should be able to get her out and about before riding season is over.

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extremeodd
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Re: Need advice on repairing a torn slide diaphragm

Post by extremeodd »

For the airbox using some moldable plastic putty mashed onto the bottom of the air filter box made it so I got a good seal against the carb box lid. Before it had a chance to cool down I quickly tossed in the filter and screwed on the lid, then went around the outside pressing the plastic into the grooves to ensure I had no air leaks.

Unfortunately, this bike had more surprises for me than I was expecting and financial needs are rearing their ugly head so I'm probably going to sell it if I can get a decent price.
The cylinders on the left side dont seem to be firing under any circumstances other than when your pressing the start button. Pulling the wires or swapping them once its running doesn't change anything.
The previous owner parked it because the left side timing belt cover came loose and the gasket got pulled in which caused the belt to jump a couple of teeth. He replaced the belt and reset the timing but was unable to get it started (I found a bad fuel pump cutoff relay, shorting it got the pump working and the bike to start) so he suspected bent valves. I'm starting to think he might have been onto something there. I've yet to rent a compression tester tool to confirm or debunk this suspicion. Then again the plug wires gave me weird readings on the (admittedly crappy) harbor freight multimeter so those could be suspect despite the plugs sparking quite vigorously when removed and grounded since I've read that the spark is hotter while starting. Or it's simply the diaphragms not actually working, and the pilots are clogged. So many possibilities...

Also, there might be a bad head gasket as it would start to boil the water every time after just a short trip around the block. Not to mention the 2ish quarts of really thin oil that came out of the dipstick hole when I put it on the center stand and tried to check the oil. I'll have to check to see if the water separated out but the oil weirdly wasn't milky, just really watery. It didn't smell like gas at all and when I hit it with a torch it wasn't flammable.

It really does bum me out to have to sell the bike since most of these problems could be fixed with, at most, an ebay head ($60-100), top end gasket kit (includes head gaskets $69.95), maybe timing belts ($15) and maybe a new water pump gasket ($26). However, maybe I'll be able to set aside most of this money to buy a slightly less rough example of a GW. This one is beyond beat up and is a better base for a naked wing or something along those lines since it's missing a lot and what it does have is severely UV damaged. Plus I have no clue how many miles it truly has on the bottom end and I really don't want to deal with splitting the case for a spun bearing or something after addressing these other issues.

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shevik
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Re: Need advice on repairing a torn slide diaphragm

Post by shevik »

Yeah if you're looking at an engine build it's not worth your time anymore, it will just be too expensive. Bent valves don't have to be, but opening up the heads on these things gets seriously hairy. The upside at least for my GL11 is that if I have to do this, and I might, the engine doesn't have to come out.

But look at how much you learned and so quickly about the bike! If you can find the thing a home you've already done the next owner the favor of having diagnosed or begun to diagnose most of the bikes issues. I wouldn't be surprised if it sold relatively quickly on that fact alone. There are a lot of people out there that want to rebuild old bikes just to learn and if someone knows exactly what they're signing up for with yours they might spring for it.
If I just work hard enough I should be able to get her out and about before riding season is over.

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extremeodd
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Re: Need advice on repairing a torn slide diaphragm

Post by extremeodd »

After looking at the oil some more, I realized it was just overfilled.
Played around some more and it's really looking like the carbs need rebuilding. Good thing the bike comes with 4x rebuild kits (don't trust the jets without measuring them, they are cheap kits).

This thread is now documentation for the new owner haha. I'm fairly certain that the bike has found a new home with someone who is excited to bring her back to life and sees the fact that this is a solid base to work with. Once he comes by to pick up the bike tommorow, I'll send him a link to this thread.

In hindsight not cleaning off the storage grime probably wasn't a great sales tactic and might have been scaring away some folk.

On a side note, I Michael J Fox'd some oil all over the exhaust so it's going to smoke like the dickens. I did my best to clean it off with carb cleaner but there is only so much you can do with oil/dust-coated pipes other than to let it burn off.

UPDATED DIAPHRAGM REPAIR INFO FOR FUTURE PEOPLE USING GOOGLE
The liquid tape method WORKS, BUT you must perform an extra step.

1: Clean the diaphragm using starter fluid (denatured alcohol should work too).
--There must be no oil or dirt anywhere near the repair area.

2: Line up the edges of the tear on the pressure side (engine side) using a small piece of masking tape or used electrical tape on the backside (cap side) to keep everything in place, but the tape must NOT be overly sticky or you risk tearing the diaphragm when removing it.

3:Coat the tear in a thin layer of liquid tape.
--Do NOT use the brush that comes in the can, personally I used the end of a small zip tie but a cheap artists brush would work better.
--You must work fast as the liquid tape drys extremely quickly.
Make sure that some gets into the tear to ensure maximum adhesion. You do not need to worry about it being smooth or looking pretty.

4: Inspect your first coat. Did it fill up the tear completely, or can you see a visible impression?
--If it's not completely filled, use a 2nd thin coat to ensure it's filled in.
Even if you feel that it is filled in, still use a second coat.
--If this seems like too much, do not worry as we are going to address this later.

5: Carefully remove the tape from the backside.
--If you used electrical tape you may find that the liquid tape has adhered to it quite strongly, if you are careful it should come free without causing any damage.

6: Repeat steps 3 and 4 ensuring the tear is completely filled and the surrounding area has a light coat of liquid tape on it.
Do not worry about over application or smoothness.

7: Once the liquid tape has fully cured (10 mins) you will notice that the diaphragm is fairly stiff where you repaired it.
This has rendered it all but completely useless.
Congratulations, you've completely ruined your diaphragm and it's now garbage

7.5: Oh... Yeah, this is where the new part of the technique comes into play. Pull the diaphragm out of the garbage (or back out of your carb if you jumped the gun) and keep on reading.

8: Grab a can of carb cleaner, I used the cheap Walmart brand.
--If you're unsure if your carb cleaner will work, spray some on any cut you can find on your body.
--If that was less than pleasant, it should do the job.
--If it didn't hurt, you've either built up a tolerance to solvents or you have some "eco-friendly" fake cleaner on your hands.
--Go to the store and get the toxic stuff.
Use this to soak the corner of a rag.

9: Using the wet rag corner, carefully rub the liquid tape repair to remove the excess liquid tape.
Ensure that you are stopping every few seconds to blow off the diaphragm to keep the carb cleaner from completely destroying it.
--You should be able to carefully massage off the excess liquid tape without damaging your diaphragm until you are left with only the sealed tear and 3-4mm around it.
If you are unsure if you have removed enough, stop and let it completely dry for 10-20 mins then check for flexibility. if the repaired spot isn't nearly as supple as the rest, you need to remove more of the liquid tape.

10: Once you're confident that the repaired area is as flexible as you can get it without exposing the tear, reinstall and let her rip!

11: If the repair fails on you, repeat the above but leave a bit more material on the engine side of the repair.
Last edited by extremeodd on Tue Oct 22, 2019 10:44 pm, edited 2 times in total.

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Charlie1Horse
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Re: Need advice on repairing a torn slide diaphragm

Post by Charlie1Horse »

I had a carb, (RF), that wasn't getting any fuel and after cleaning it ran well for a couple of days. Then it quit getting fuel again. I took them off again and cleaned them again and the same happened a second time. Nothing was wrong with float level and fuel was at the carb inlet. I found that the float valve was sticking closed and every time I cleaned it, it would be good for a few days. So I went on ebay and found someone with new aftermarket valves and replaced them. Then I never had any more trouble.
Russell

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Those who say it cannot be done should try not to interrupt those who are doing it.

Gord
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Re: Need advice on repairing a torn slide diaphragm

Post by Gord »

I would not play with back yard fixes. Buy new. $99.00 for a set of new.
https://www.carburetordiaphragms.com/sh ... arburetor/

Papamark
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Re: Need advice on repairing a torn slide diaphragm

Post by Papamark »

So... i am the new owner of this bike. I have ro say a few things and hopefully not slam on the p.o. that started this thread.
First of all. You cannot fix a torn diaphragm well not one torn that badly. Pin holes yes. With nail polish. I replaced the attempted repaired ones and solved that problem. Now it gets plenty of fuel to all 4 carbs.
Second. For anyone else that is having similar problems, do not unplug the bank angle sensor unless you absolutely know how to rewire it. What it will cause is the left coil to not fire this causing the bike to only run on 2 cylinders and the stalling he was talking about.
Now the bike runs like a champ! All i need to do is some cosmetic repair and she will be good to go.
Like i said. Sorry if this offends anyone or upsets them. I just needed to put the correct repair solutions out there.

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shevik
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Re: Need advice on repairing a torn slide diaphragm

Post by shevik »

Thanks for the follow up! Glad to hear the update.
If I just work hard enough I should be able to get her out and about before riding season is over.

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extremeodd
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Re: Need advice on repairing a torn slide diaphragm

Post by extremeodd »

Papamark wrote:
Sat Nov 09, 2019 9:34 am
So... i am the new owner of this bike. I have ro say a few things and hopefully not slam on the p.o. that started this thread.
First of all. You cannot fix a torn diaphragm well not one torn that badly. Pin holes yes. With nail polish. I replaced the attempted repaired ones and solved that problem. Now it gets plenty of fuel to all 4 carbs.
Second. For anyone else that is having similar problems, do not unplug the bank angle sensor unless you absolutely know how to rewire it. What it will cause is the left coil to not fire this causing the bike to only run on 2 cylinders and the stalling he was talking about.
Now the bike runs like a champ! All i need to do is some cosmetic repair and she will be good to go.
Like i said. Sorry if this offends anyone or upsets them. I just needed to put the correct repair solutions out there.
It was just a sensor?! Awh man, awesome find! Had a feeling it was something really dumb keeping it from running. There is a reason that the bike triggered my "gut instinct" to buy it. Glad it's working out for you!

Honestly, I wasn't sure if the repair would hold. It was something I figured I'd do between paychecks to keep the amount I spend on fixing stuff as low as can be. Also, I should note that this was the 2nd bike I have ever touched with the first being just 2-3 months ago. Again, I'm somewhat bothered I didn't discover the bank angle sensor before selling it, however, that doesn't appear to be a common failure so it didn't come up on any of the "look for this not working on your gl1200" lists I had seen.

Once you get it running at full power, you gotta let me know and bring it by just so I can experience what that is like just once.

Papamark
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Re: Need advice on repairing a torn slide diaphragm

Post by Papamark »

No problem. The bank angle sensor was hanging and not in the "proper " place. It had tripped and once it was put in the holder it reset.
The carb diaphragms were a simple fix. But i do have to give you props for trying. I would have done the same in your situation.
For future reference, Bobs motorcyle has tons of used parts on hand and quite a few new on the shelf. Thats where i got the parts.
I will definitely bring it by and let you take it for a ride. I havent put it on the street yet, still have some cosmetics to take care of. But i will let you know and figure out when i can stop by.

Papamark
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Re: Need advice on repairing a torn slide diaphragm

Post by Papamark »

So.....
After chasing a bunch of demons i finally tracked down the major problem with the old girl.
Turns ot that when the timing belt came off it bent both intake valves causing it to not fire on the left side.
You were almost there when you pulled the valve covers and exhuast.
Now it runs like new. Almost scary the power it has!

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shevik
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Re: Need advice on repairing a torn slide diaphragm

Post by shevik »

Glad to hear you pulled it off!

What was finding new valves like?


If I just work hard enough I should be able to get her out and about before riding season is over.

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