Carb issue - Slow to return to idle, rough idle - RESOLVED

[Jersey]

Hey everyone.  I could use some advice.  Due to a hand injury I had to stay off the bike for about 2 wks, then when I rode it would not idle unless it was full choke.  Did a few tanks of Berryman's  and only very slight improvement. Also, it would not return to idle quickly, but delay for about 15 secs and then slowly decrease.  Figured it was the Pilot jets, so I pulled the carb bellies off and 4 of the 6 were clogged with the last two almost clogged.

Bike History: 99 I/S with about 75k.  Is Desmogged. Had carbs rebuilt about 18 months ago by the local shop and bike ran great. Regularly used either Seafoam or Berrymans with an occasional mix of MMMO.  I ride daily doing about 70 miles commuting. Only use 87 octane. My lady has always ran well until it sat for this 2week period.

Took the opportunity to replace the stock PJ #35 with #38.  Reset the Idle Screws to 2 turns out of from seat. Warmed it up and did a sync.  UNFORTUNATELY, the idle issue continues... almost like it was unaffected by the change in PJs.  I did do a propane test around the intakes with no effect.

Here's the video. At 18 sec point is were I let go of the throttle and it doesn't drop to idle until 35 sec point.  https://youtu.be/eEqWsCdNkxc

Thoughts on what to check next?


UPDATE #1 Oct 8,2018: Rode into work this morning about 35 miles. While the bike has power I can tell the fuel flow is rough except for WOT.  Unable to obtain a proper idle level despite adjustments to the main Idle control.  Will idle around 750rpm despite slow increase and then after about 2-3 full turns with jump to about 2200rpm.  This happened before as well with the OEM PJs before I did anything. Thinking about the clogged PJs and all these sudden issues... it's possible I got some dirty gas.  IF that's the case could the decel device (forget its name) also be clogged?

Somewhat unrelated to the core issue, but noticed she ran about 10F degrees hotter than normal and probably running lean.  Will run through the Idle screw procedure for each carb tonight.  See what impact that has.

UPDATE #2 Oct 9,2018:  Tried the suggestions given today and no luck.  Here's what I did.
1. pulled PJs and blew out the area with compressed air
2. Reset PJs following the procedure posted on the forum... or tried to.
3. Had great difficulty get it to idle at 900 rpms.  The idle adjust flange when turned only 90 degrees would take the rpms from 750 to 2000. it would do one or the other with nothing in between.
4. tried the choke about halfway and was able to dial in 900 rpms. so figured I needed more idle mix
 adjustment. eventually got to 3+ turns on each carb with only slight improvement but still rough.  Figured something wasn't right since these are new #38 PJ
5. tried reducing the choke while I increased the idle mix screws and it would die.
6. bike runs kinda ok with partial choke, but again still rough
7. at more than 1/4 throttle it sounds like a screaming bear, but I still tell it's not as smooth as a few weeks ago.

I'm thinking whatever clogged the OEM #35 PJs has clogged other things in the carbs.


UPDATE #3 Oct 10,2018:
I took all the great advice and check that the linkage, butterflies, and pump seem to be working as they should.  I was able to get rid of the slow return to idle; however, I have to run with full choke.  Also, the idle is very rough as if one of the carbs isn't keeping up with the rest.  I did notice on the ride home today that she was much more peppy from 1/4 to WOT.  She took off when I blipped it while cruising 75 and went to 90 is a flash.  I guess the #38's helped with that!  A moment later I was at 110. Yeah. It was like that!  But at idle it's still rough.
Next steps:
-check the spark plugs and see if any are not running
-bought an ultrasonic cleaner to recondition the OEM PJs and reinstall as a test
-bought a full RedEye Carb kit... just in case I have deep dive.
Thanks again to all the great advice and don't hesitate to add more!!

UPDATE #4 Oct 23,2018:
Since all other efforts failed it was time to pull the carbs and do a complete rebuild with new parts from RedEye and long soaks in the ultrasonic cleaner.  In the process I discovered that one of Air Control Valve (ACV Part #16510-MAL-600) was faulty.  Waiting on it to arrive and anticipate this will resolve the issues.  Considering the many observations that there might be an leak somewhere, this failed part makes sense.  Unfortunately, this kind of leak is internal and not traceable with the standard propane test.

UPDATE #5 RESOLVED Oct 25,2018:
The new Air Valve came in today and installation was normal... the airbox was a PIA!
Setup the DigiSync and dialed in the new #38's without a problem.  Waiting on an accurate Tach so I can finetune the Idle screws. In the meantime, a 1 3/4 turn out seems to be working so far.  The girl now idles so smooth with a well sync' punch when I blip it.  Did a quick run up the driveway and seems to pull a bit harder than before.
It appears there where TWO causes to this problem:
- 4 of the 6 Pilot Jets (#35) were clogged
- 1 of the 6 Air Valves was leaking

UPDATE # TEST RIDE Oct 27,2018:
OMG!  Night/Day difference from before. Smooth. Noticeable increase in power. Quicker off the line. Gonna need to invoke additional self-control during the first few weeks.

Want to thank everyone for all of the great feedback and encouragement!  If things start going wrong don't forget to check those Air Valves.

[Avanti]

Simple things first. Are all the throttle linkage and cables working free.

[Jersey]

Simple things first. Are all the throttle linkage and cables working free.

Thanks Avanti.  Yep, the linkage and cables are free.

[Valkrocket]

Sounds like a similar problem that I had. Check your sync springs(there's 1 for each carb) to see if they are in the correct position. the spring on right had migrated down and was preventing my throttle to return to idle.

[Jersey]

Sounds like a similar problem that I had. Check your sync springs(there's 1 for each carb) to see if they are in the correct position. the spring on right had migrated down and was preventing my throttle to return to idle.

Thanks! I'll check that.  Which side did that happen to you?  It looks like the left in the photo.

[Jims99]

If the air fuel mixture screws are off, it will cause the slow return to idle. With it running hotter, I would say it’s lean. Try backing screws out to 2 1/2 from seat. Sometimes when it’s not set right, causes slides to come down slower.

[Jersey]

If the air fuel mixture screws are off, it will cause the slow return to idle. With it running hotter, I would say it’s lean. Try backing screws out to 2 1/2 from seat. Sometimes when it’s not set right, causes slides to come down slower.

Thanks Jims99!  That's good to know.  Hopefully the adjustment will solve it all.  I really do NOT want to pull the carbs and get into all that.  Too much on my plate already to get done.

[Paladin528]

clogged pilot jets will cause a slow drop to idel and rough idling if they are really bad.  Also look for a vacuum leak

[Jersey]

clogged pilot jets will cause a slow drop to idel and rough idling if they are really bad.  Also look for a vacuum leak

I replaced the #35 PJs with #38's and it didn't change the slow idle drop or difficulty maintaining a 900rpm.  I did the propane test throughout the entire intake area and didn't seem to show any leaks.  Also, last night I tightened all the exhaust nuts, many were on the looser side. Unfortunately that didn't make a difference.

[WintrSol]

The fuel/air adjustment screws go into a pretty small hole, too. Are you certain you blew all the little ports clear?

[Jersey]

The fuel/air adjustment screws go into a pretty small hole, too. Are you certain you blew all the little ports clear?

Actually I did not. Was trying to be gentle with all of that. Thank you! Will do that first as part of the procedure.

[Bob D]

Letting the bike sit for only 2 weeks after running great doesn’t seem near long enough to plug the carbs. I had a similar issue that was caused by bad carb diaphragms. The bike ran fine it just took a long time to get back to 900 rpms after deceleration. Changed the diaphragms and the problem went away. I bought the bike used (2001 Standard) so they were probably the originals Good luck with diagnosis.....

[Jersey]

Letting the bike sit for only 2 weeks after running great doesn’t seem near long enough to plug the carbs. I had a similar issue that was caused by bad carb diaphragms. The bike ran fine it just took a long time to get back to 900 rpms after deceleration. Changed the diaphragms and the problem went away. I bought the bike used (2001 Standard) so they were probably the originals Good luck with diagnosis.....

Agreed. I didn't think 2 weeks would do it, but 4 of 6 OEM PJs were clogged. Now whether that happened during the two weeks I don't know.  I think it's possible I got a bit of dirty gas.  I don't have a fuel filter between the tank and carbs.  My goof. Some of the carb bowls did have some small particles sitting in the bottom.

[sixlow]

Simple things first. Are all the throttle linkage and cables working free.

Thanks Avanti.  Yep, the linkage and cables are free.

Check that the barrels/butterfly plates are closing as fast as you back off the throttle. I have a high mileage carb bank that is junk because the pivot of the brass rods for the butterflies are sticky and are leaking fuel or sucking in air at the felt seal/washer it pivots in. Also make sure the enricher pistons are fully depressed once you take the choke off.

[Jersey]

Simple things first. Are all the throttle linkage and cables working free.

Thanks Avanti.  Yep, the linkage and cables are free.

Check that the barrels/butterfly plates are closing as fast as you back off the throttle. I have a high mileage carb bank that is junk because the pivot of the brass rods for the butterflies are sticky and are leaking fuel or sucking in air at the felt seal/washer it pivots in. Also make sure the enricher pistons are fully depressed once you take the choke off.

Ok. Good to know.  I'm assuming I'd have to pull the tank/air box to see the butterflies.  Not sure what you mean by the enricher piston... do you mean the Air control Valve or the starter valve?
 https://www.cmsnl.com/honda-gl1500cf-valkyrie-interstate-1999-x-usa-california_model1082/valve-set-starter_16046kbh000/#.W71TkGhKiUk

I'm asking because since the PJs were clogged it's likely that other things were infected as well.   

[Jersey]

Letting the bike sit for only 2 weeks after running great doesn’t seem near long enough to plug the carbs. I had a similar issue that was caused by bad carb diaphragms. The bike ran fine it just took a long time to get back to 900 rpms after deceleration. Changed the diaphragms and the problem went away. I bought the bike used (2001 Standard) so they were probably the originals Good luck with diagnosis.....

Wanted to clarify what you meant by the diaphragms... you mean the vacuum rubber that the needle jet sits in?  Those are expensive!

[sixlow]

you should be able to tell butterflies are closing by watching where those springs are in the photo above and all the arms are resting at the same time. push on them with your finger to see if they are hitting the stop. The enricher piston is what moves in and out when you apply the choke. 

[SPOFF]

Wanted to clarify what you meant by the diaphragms... you mean the vacuum rubber that the needle jet sits in?  Those are expensive!

That's the biggest problem with Valk carbs, everything is $$ times six. I don't know if you had the top of the carbs off and the needles out. If so, make sure all the diaphrams were sitting in the groove and installed correctly. It's easy to pinch the edge of the diaphram. If you didn't touch them and the bike was running great a few weeks ago, the diaphrams probably aren't your issue. It's the tiny passages further down in the carbs that get ethanol poisoning.

[Jersey]

Wanted to clarify what you meant by the diaphragms... you mean the vacuum rubber that the needle jet sits in?  Those are expensive!

That's the biggest problem with Valk carbs, everything is $$ times six. I don't know if you had the top of the carbs off and the needles out. If so, make sure all the diaphrams were sitting in the groove and installed correctly. It's easy to pinch the edge of the diaphram. If you didn't touch them and the bike was running great a few weeks ago, the diaphrams probably aren't your issue. It's the tiny passages further down in the carbs that get ethanol poisoning.

That's what I'm thinking. Dirty gas clogged the ports. I'm sure a good soak in the ultrasonic will fix it. It's a job, but that's ok. I did liked the high end effect I noticed today, so maybe once all clean I'm hoping the #38s work.
Thanks!

[saddlesore]

I didn't read the entire post but I had a problem with not coming down to idle speed after a stop.   I replaced the vacuum hoses.  When they get old they dry out. That includes the plugs on the intakes.     

[Jersey]

I didn't read the entire post but I had a problem with not coming down to idle speed after a stop.   I replaced the vacuum hoses.  When they get old they dry out. That includes the plugs on the intakes.    

So true!  I did notice the petcock hose was not that good at the carb connection, so I cut off an inch and tested the remainder with a vacuum pump.  All good there for now, but ordered a replacement. The caps are new already and verified then you still be good. Thanks for the advise!  

[Ricky-D]

It wouldn't hurt to remove the linkage covers and slather the linkage with ample mounts of spray lubricant or spray silicone.

***

[Jersey]

Bad Air control valve seems to be the problem.

[sixlow]

Did you use the mighty vac and the procedures from the Redeye kit to test the air valves ? Also did you get some popping on hard deceleration, I think that is another symptom of a bad air valve. Thanks for following up on this post.

[Avanti]

I am glad you found the problem.   
Thank you for posting the results. 
Let us know how it runs out after it is up and running.

[Jersey]

Did you use the mighty vac and the procedures from the Redeye kit to test the air valves ? Also did you get some popping on hard deceleration, I think that is another symptom of a bad air valve. Thanks for following up on this post.

I did have popping on the one side only and used the redeye vacuum test procedure, which actually showed the failure. Son glad I went with that kit. Tomorrow the part comes in!

[Avanti]

Aircut Valve

https://www.motorcycleproject.com/text/keihin_idle_circuits_white_paper.swf

[Jersey]

Final DigiSync.  Can't get too much better than that!!!

[Avanti]

Gotta like that  Digi Sync

[Forge]

Final DigiSync.  Can't get too much better than that!!!

Looking good.  Waiting on the ride report!

[Jersey]

Test Rode it today after the rain stopped.  OMG!  What a difference. Major increase in power from idle to 3500prm.  Interesting though, I didn't feel as much pull as before in the 4-6k RPM range.  Maybe it's just because the lower end has increased?  

I'm going to do some research on tuning the upper end.  I didn't touch the needle settings, so maybe increasing one step up might be something to consider.  Any suggestions on that?  I'd be interested in hear from those who've used the DynaJet Stage 1 on an I/S.

[Ricky-D]

If you have stock throughout the carburetors you will find the needles are not adjustable. Now, some have taken the small washer that sits on the top of the needle and put it under the needle to raise the needle a bit.

If you are looking for some real help in the fuel area you should consider the Dial-A-Jet system for a great improvement in performance.

https://thunderproducts.com/dial-a-jet-automatic-fuel-induction-system/

***

[Red Ballz]

That digisync looks great! I bought one recently and it is currently my favorite tool!

[Jersey]

If you have stock throughout the carburetors you will find the needles are not adjustable. Now, some have taken the small washer that sits on the top of the needle and put it under the needle to raise the needle a bit.

If you are looking for some real help in the fuel area you should consider the Dial-A-Jet system for a great improvement in performance.

https://thunderproducts.com/dial-a-jet-automatic-fuel-induction-system/

***

That looks like an interesting system.  Maybe a bit overkill for me though.  Thanks!

[98valk]

Test Rode it today after the rain stopped.  OMG!  What a difference. Major increase in power from idle to 3500prm.  Interesting though, I didn't feel as much pull as before in the 4-6k RPM range.  Maybe it's just because the lower end has increased?  

I'm going to do some research on tuning the upper end.  I didn't touch the needle settings, so maybe increasing one step up might be something to consider.  Any suggestions on that?  I'd be interested in hear from those who've used the DynaJet Stage 1 on an I/S.

your mpg will tank with the dynajet.  the needles are too rich unless u have pipes, airbox mods and just looking for max race track power.

suggest factorypro.com kit, which has needles and jets.

[Blackduck]

What small washer ON TOP of the needles?
All I have seen the washer is already under the needle.
You can add another washer but it cannot be too thick or the needle does not sit in the piston correctly