Vacuum Leak? Maybe?...UPDATE

[Steve K (IA)]

Got some idle issues that have come on kind of suddenly.  Bike won't return to idle when shifting.  No matter what rpm I shift at, instead of the rpm's dropping to idle, the rpm's jump 1000 to 1500 rpm's when closing the throttle and pulling in the clutch.  It can take almost a minute for the rpm's to come back down to idle when I wait to see what happens.
Had a milder version of this a few years ago and was told to look for a vacuum leak.  At that time I got new vacuum lines from Redeye because that stuff was all original.  Even with the age, the tubing looked and felt new.  I changed them anyway.  Didn't fix the problem.  Took the petcock off and the diaphram was torn.  Problem fixed.

I've looked and the vac lines and caps...they are in place and look like new.  I won't bother yet looking at the petcock since I rebuilt using the Honda Cover Set parts.  The band clamps above and below the carbs are tight.  Only one other place to look.  Intake runner o-rings.  I've never changed these.  Picked up 6 at Advance Auto and hope to change them out in the next day or 2.  I hope that's where my problem is.  I don't want to have to take the carbs off because my working conditions aren't ideal anymore.

PS,  The idle adjust screw between the carbs is non responsive.
Has anyone else experienced this and what did you find?

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[MnM Valk 97]

Did you check to see if your second throttle (return) cable is intact? And is the throttle linkage contacting the idle screw to do it's job?

[Steve K (IA)]

Did you check to see if your second throttle (return) cable is intact? And is the throttle linkage contacting the idle screw to do it's job?

Ahhh.  No.  I'll look tomorrow.  Thanks for the idea.

[Ricky-D]

Temporarily remove the throttle linkages at the carburetors and spray the whole assembly with copious amounts of a lubricant while working the throttle.

Probably one of the most neglected area on the bike when it comes to "maintenance".

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[RWhitehouse]

A hanging idle and non-responsive idle adjust do sound like signs of a vacuum leak, but rule out the easy stuff (sticking cable/linkage) first.

Slowly wave an unlit torch around the intakes with the engine running. If the RPMs pick up, you've found the leak.

[Steve K (IA)]

All good ideas, Thanks. 
Opened the clam shell on the handlebar and using a needle nose pliers got a hold of the cables and both are tight.  I have a Vista Cruise and had to swing the arm of that out of the way because it goes across the clam shell clamp.  The throttle seemed to free up a bit.  So put some WD-40 on the chrome band...hope that wasn't a mistake.  Put it all back together and the throttle will now snap back by itself. Started it up and just sitting there seems to be better, never took the bike out.  Will do that a little later.  When I go back to the garage....it's down at the end of my street, a storage garage.  I'll stuff some rags under the carbs and spray that throttle assembly with WD-40 before going for a ride.
If that is the fix, I will still change out those o-rings since I have them and they have never been changed.  And because I have to go to the trouble of taking the pods and spark plug valances off to remove the intake runners, will replace the spark plugs also.  60,000+ miles, changed the plugs at 18,000 miles and remember they still looked new.
I'll let everyone know what I found.
Again, thanks for the ideas.  I was fixated on vacuum because of similar symptoms in the past, but this time the symptoms are worse.
 

[Chrisj CMA]

I'm glad you may have solved it.  However, why in the world would you grab throttle cables with needle nose pliers?  I cringed when you said that.  Second, I doubt those 0-rings from the auto parts store are the ones you need.  I tried all the stores including Advanced, they had some that were very close but I didn't like the fit, they seemed to be too thick and wouldn't allow the runner to sit on the head, it was up sitting on the 0-ring instead.  The Viton 123 ones fit perfect.

Third maybe it was wording, but do you actually close the throttle when you shift or just back off a tad?

[Ramie]

Use a cable lube not WD-40.

[Steve K (IA)]

I'm glad you may have solved it.  However, why in the world would you grab throttle cables with needle nose pliers?  I cringed when you said that.  Second, I doubt those 0-rings from the auto parts store are the ones you need.  I tried all the stores including Advanced, they had some that were very close but I didn't like the fit, they seemed to be too thick and wouldn't allow the runner to sit on the head, it was up sitting on the 0-ring instead.  The Viton 123 ones fit perfect.

Third maybe it was wording, but do you actually close the throttle when you shift or just back off a tad?

The pliers I used some people may have never seen.  Each jaw is round, tapered and smooth.  They are made for working with stranded wire.  They didn't/wouldn't cause any damage.
I worked building aircraft avionics for several years with a needle nose pliers in my hand most of the day.  Rockwell Collins.  I bet your familiar with the Collins Radio name.

For reference... https://www.amazon.com/Aven-10306-Technik-Stainless-Overall/dp/B001J0NQ5G/ref=sr_1_24?crid=31CBR118HMCH9&keywords=smooth+needle+nose+pliers&qid=1559353473&s=gateway&sprefix=smooth+needle+nose+%2Caps%2C341&sr=8-24

I've used the o-rings from Advance Auto on the '97 Std that I had for 12 years with no problems at all.  They are the exact dimensions called for...28mmx34mmx3mm.  I do remember using 3 or 4 tiny dabs of black RTV in the groove so the new rings would stay in place during re-assembly.  The runners should set up off the heads slightly so when you tighten the bolts, the o-ring will squish and fill the groove.
 
I've worked with o-rings as a Toolmaker/Machinist calculating the width and depth of the groove needed when given only the dimensions of the o-ring more times than I could ever remember....but I can't remember anymore how to do the calculations.      The engineers would bring me an o-ring and say "this is what I want to use".  That's where Machinery's Handbook came into play.
 
So, lubing the throttle assembly/linkage didn't work.  Guess I'll change the o-rings.  Keeping my fingers crossed because I DON'T want to have to take the carbs off in a dark garage.  I've run plenty of cleaners through it so that would be the next step. 

And yes, when I shift, I back the throttle off all the way. 

[Chrisj CMA]

Thanks for the reply. Glad you have the right tools and knowledge on them cables. Just hope no one takes normal needle nose pliers and try’s to unhook the cables from the handlebars it will be messy.

Try learning how to back off the throttle just enough so the rpms don’t rev up when you pull the clutch lever. Shifts will be smoother, quicker and easier on the clutch and transmission.

One night we were on a ride and I lost a valve stem. We had to leave my bike at a gas station. My friend gave me a ride home to get my truck. He shifts like you do. I couldn’t believe how much harsher it sounded for his engine doing that. Really there is a big difference.

[Steve K (IA)]

Well, the o-rings looked like they were ready to be changed.  Replaced the spark plugs while I was at it....there was 42,000 miles on the ones in there, they looked new. 
Still have the problem but it is a little different.     Now when shifting above or below 2500 rpm, the engine rpm goes to 2500 between shifts.  I've checked everything I can think of.  The symptom still tells me vacuum leak, but it will sit there and idle fine before starting to ride.  About ready to pull my hair out. 
Got a little less than 1/2 a tank of gas that has some B-12 in it...1oz per 1Gal.  Than means I have a half can of B-12 sitting on the shelf.  Wondering if I should dump that in and go do a slow putz around. 

[The emperor has no clothes]

Well, the o-rings looked like they were ready to be changed.  Replaced the spark plugs while I was at it....there was 42,000 miles on the ones in there, they looked new. 
Still have the problem but it is a little different.     Now when shifting above or below 2500 rpm, the engine rpm goes to 2500 between shifts.  I've checked everything I can think of.  The symptom still tells me vacuum leak, but it will sit there and idle fine before starting to ride.  About ready to pull my hair out. 
Got a little less than 1/2 a tank of gas that has some B-12 in it...1oz per 1Gal.  Than means I have a half can of B-12 sitting on the shelf.  Wondering if I should dump that in and go do a slow putz around. 

It can't hurt. But, it sounds to me your throttle linkage or cables are binding slightly.

[gordonv]

Got a little less than 1/2 a tank of gas that has some B-12 in it...1oz per 1Gal.  Than means I have a half can of B-12 sitting on the shelf.

To actually see what it should be, the can is 15 oz. That to half a tank of fuel is about 3 gal to 7.5 oz., making a ratio if 2.5 oz B-12 per 1 gal.

I've an IS, so my ratio is a little lower, someone else with a std/T would be higher. I think the most important thing after having a stronger dose in there, is to have the engine in the rpm range that is giving you the trouble. Usually this means low rpm. So drive in the highest gear at a slow speed, something like 40 mph in 5th on a long hwy type road somewhere. A country type ride, stop and goes thrown in there, gets some idle, some higher rpm too. Multiple rides to, letting it sit in between.

[Steve K (IA)]

Got a little less than 1/2 a tank of gas that has some B-12 in it...1oz per 1Gal.  Than means I have a half can of B-12 sitting on the shelf.

To actually see what it should be, the can is 15 oz. That to half a tank of fuel is about 3 gal to 7.5 oz., making a ratio if 2.5 oz B-12 per 1 gal.

I've an IS, so my ratio is a little lower, someone else with a std/T would be higher. I think the most important thing after having a stronger dose in there, is to have the engine in the rpm range that is giving you the trouble. Usually this means low rpm. So drive in the highest gear at a slow speed, something like 40 mph in 5th on a long hwy type road somewhere. A country type ride, stop and goes thrown in there, gets some idle, some higher rpm too. Multiple rides to, letting it sit in between.

I have an I/S.  To clarify, I put a half can of B-12 in a full tank...last week.  The tank was less than half full now.  Dumped the rest of the B-12 in and went for a 3 mile slow ride followed by 40 mile ride never getting above 50 mph.  I've noticed some improvement.  I'd say about 60 - 70% better.  Going to let it sit and soak for a day or 2.  I think it's going to clear up.

So, as Paul Harvey would say, here's the rest of the story...
A year and a half ago I went through a divorce.  So as usual in Iowa, the bike was in storage during the winter.  I did start it last spring, but that was it.  I didn't know it, but one of my doctors told me I was suffering from depression.  I had no desire to ride the I/S last summer...and I sold my Std which I now regret.  By the time I started feeling better the riding season was close to being over.  By this time, the bike ran like crap.  Coughed, spit, choked, puked....at slow speed.  Ran fine at highway speeds. I did the slow ride thing, 5th gear between 1000 & 1500 rpm's with SeaFoam in the tank.  Wasn't clearing up, so more SeaFoam    I honestly don't know how much of that stuff I put in.  After riding around and no results, I'd come home and pour more in the tank.  I had so much in there I had white smoke coming out the exhaust.  It took 148 miles of putzing around this industrial area close by before it seemed to come around.  Well now it's time to put it up for winter.  Topped off the tank, didn't add anymore SeaFoam as I thought there was plenty in there.  This spring, it started on the second try.   Hadn't ridden much this spring because the weather hasn't been good at all.  It. Won't. Stop. Raining!
What I experienced today after new o-rings and with a higher dose of B-12, I'm hoping I'm on the right track.
Keeping my fingers crossed.

[Steve K (IA)]

Thanks for the reply. Glad you have the right tools and knowledge on them cables. Just hope no one takes normal needle nose pliers and try’s to unhook the cables from the handlebars it will be messy.

Try learning how to back off the throttle just enough so the rpms don’t rev up when you pull the clutch lever. Shifts will be smoother, quicker and easier on the clutch and transmission.

One night we were on a ride and I lost a valve stem. We had to leave my bike at a gas station. My friend gave me a ride home to get my truck. He shifts like you do. I couldn’t believe how much harsher it sounded for his engine doing that. Really there is a big difference.

I'm sure if we rode together you would see/hear my shifting is fine.  I may have overstated how I shift or wasn't too good at describing it.  It all comes natural as I have been riding 53 years and don't really think about it so trying to describe it, well...  I do back off the throttle between shifts, but of course the rpm's don't go all the way back to idle when everything is good.  I was doing that when I experienced this problem to see how long it took to go back to idle.  Because the rpm's weren't dropping and sometimes increasing. It was like I was speed shifting.  I use T-6 oil and most times the only time I hear the trans shift is when initially putting it in 1st gear.  Most times when shifting I usually hear a little click and not a clunk.  As you know there can be a lot of factors involved when shifting.  The best rpm range for me is anywhere between 2000 and 4500.  Depends on how quick I'm getting on it. 

[gordonv]

Someone also recommended fueling up at Chevron, with their Techron additive in their fuel, so that's what I TRY to do as much as I can. I won't go out of my way, but when I see fuel, and I can choose, then I do.

Seafoam is good for storage, to stabilize the fuel so it will function next year. 2 years might be too much for any stabilizer.

So with the above, after trying the B-12 twice, try something else, anything (I'd use the Techron), and see if it gets better still.

It sounds like it's working, and only time and riding will tell.

Good Luck, let us know how it works out.

[Steve K (IA)]

Someone also recommended fueling up at Chevron, with their Techron additive in their fuel, so that's what I TRY to do as much as I can. I won't go out of my way, but when I see fuel, and I can choose, then I do.

Seafoam is good for storage, to stabilize the fuel so it will function next year. 2 years might be too much for any stabilizer.

So with the above, after trying the B-12 twice, try something else, anything (I'd use the Techron), and see if it gets better still.

It sounds like it's working, and only time and riding will tell.

Good Luck, let us know how it works out.

I doubt there is a Chevron station in this State.  I have used Techron in cars in the past with good results.  That will be my next try since I'm out of B-12 and getting low on gas.  Won't hurt to try it.

[Steve K (IA)]

Okay!    
After running 1 can each of SeaFoam, Berryman's and now half of a large bottle of Techron (20oz size) through my I/S, I think I've seen a 95% improvement.  Dodged a bullet as far as having to remove the carbs.  Next tank will get the other half bottle of Techron.,,that should finish clearing it up.  And the rest of the summer I'll add half a can of SeaFoam to every other tank.

[Ricky-D]

SeaFoam is probably the least effective additive of the three you mentioned.

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