idle and sync issues?

[luvmy40]

I mentioned this in another thread started by oldfailthful but didn't want to clutter his line up, so...

 

I have been working on getting my pilot mixture and synchronization perfect. I've gone several different routes on the pilot mix. I first went with a color tune which I have used for years with great success on my XJ bikes. I didn't get the same level of feedback with the Venture so my results were only so-so. I then just tuned by ear with very poor results. So back to the color tune. Then I tuned to vacuum. BTW, My sync is always tight. That's never a problem.

 

So here's the deal. No matter how I set the pilot circuits, I always either have a lot of popping on deceleration or sluggish throttle response off idle. Right now i'm getting both. She pops like crazy on decel and takes forever to warm up. Once warm, the throttle response is good.

 

She's also developed a lope at idle. An intermittent "miss". I haven't investigated the miss as yet.

 

Ok, so here's the strange thing. Tuned as is with the popping, slow warm up and lope at idle, I'm getting the best fuel economy I have gotten to date. My last tank ran 39.5 MPG as close as I can figure by filling to the same level in the neck visually. Up till now I'd been getting 33-35 mpg and before the carb rebuild I was getting 28-29 mpg.

 

On a possibly related note; My voltage meter is showing 12v at idle and sits solid at 14v while riding but when not rolling, in neutral or with the clutch in at a light it will not rise above 12v at any rpm. This is a new bug. I just noticed a couple days ago and it went away for a short time but is back now.

 

 

:confused::confused:

 

ETA. She pulls strong once warmed up. Plenty of power and no detectable miss at speed.

Edited June 29, 2018 by luvmy40
added note

[cowpuc]

As I mentioned before and maybe what got you looking at your volt gauge in the first place .40 , if your stator or regulator is acting up (and what you are describing is exactly what I had issues with on mine, those issues being irractic running/popping too = that being the reason that I suggested checking that in the first place) running strange at idle or under a load just off idle can be symtomatic.. All that said, I would definitely pull the side cover and ohm out the three white stator wires, do a voltage test at the battery to double check your dash meter.. In the end, unless the stator shows absolute signs of problems after testing and cleaning those terminal leads (suggest hard wiring those leads = that terminal has always given me fits) - I would give that regulator an evil eye close look,, replacing that puppy seems to have fixed my similar issues with popping/sluggish off idle/idle.

On another note,,, I have found that a lot of decel popping/backfiring/little fartish type noises can and usually are attributabul to air leaks in my exhaust system.. It is amazing IMHO how one little hole or loose gasket can cause so much ruckus. Personally, because I am always running over stuff and/or even seem to find myself changing back tires so the gasket on my right side muffler never really seals correctly,,,,,,, my bikes always pop and snarl at people on decel and will even do the big bang thingy (fun if timed perfectly and done next to a person driving a car while on the cell phone ) as the fresh air thru the leak meets those hot gasses inside the system.. Maybe check your exhaust system for air leaks.....

Lots and lots of things like pin holes in diaphrams, poor sync and poor tune up or even sticky brake calipers can cause poor MPG IMHO,,,, but I think you got a handle on all that....

And even on another note yet, Maybe its time to check out dropping your metering rods on the slides by shimming them down. IMHO, the down draft design of our carbs with the side mount slides (and the constant "bounce" of those slides cause we are talking CV carbs) is a little more susceptible to emulsion tube (or what ever ya wanna call that brass tube that the metering rod slides into) oblonging/wear. I have a theory that when this happens, as the metering rod is closing off the main jet to allow only pilot/idle jet circuit to operate - if its oblonged,,, raw gas can enter thru the wear area and BINGO = running fat,,,,, getting poor MPG can result.. I dropped those metering 65 thou worth of nylon shims on Tweeks instantly got my fuel economy back and also lost the heavy exhaust odor and dark coloring on her pipes..

Bottom line I reckon,,,,, keep playin with the thing,,, you'll get it!!!!! just dont let er wear ya down in the process..

[luvmy40]

I used Skydoc's needle shims when I rebuilt the carbs.

 

I have had the popping tuned out almost completely but it was definitely a rich mix.

 

I'm going to pull the plugs later and see what they tell me.

 

Right now the pilot circuits are tuned to highest vac reading then synced at 1000 rpm.

[MiCarl]

Popping on decel can be exhaust leaks or a problem with the air cut off valves.

[luvmy40]

I got some pics of the spark plugs and I decided to play around and do some vid clips. The popping and stumble doesn't come through in the audio as well as I'd like but here goes.

 

The plugs all look way lean to me.

 

N0.1

 

No.2

 

No.3

 

N0.4

 

I re tuned the pilot mix to best highest vac and ended up enriching all 4 cylinders a good bit. After bI got them tweaked to the highest vac. I opened them up 1/4 turn further, Then synchronized.

Here's the result.

 

[luvmy40]

Tried to get the popping on video.

 

 

And when I got back from that ride she was stumbling at idle again.

 

[GaryZ]

Here is what I have heard you say;

Popping during deceleration

Poor running when cold

Best MPG ever

 

This list is all pointing at a lean closed throttle condition.

With the vacuum idle set perfect, the needles on the slides are possibly too low.

Add spacers to the slides and to raise the needles. See if that helps . . .

[luvmy40]

I just swapped the needle shims for Skydoc's shim set that is supposed to stop the popping.

[Marcarl]

I'd be checking for an intermittent miss on one cylinder.

[Patch]

So Luv

 

I'm not hearing crisp acceleration.

 

Not impressed by the plugs.

 

I'm not sure how you are trying to adjust, pilot screw by vacuum, although I think I get what you are saying, vacuum is a result of jug and throttle plate position.

 

1st thing we need to know compression numbers. The idle circuit needs the compression for heat.

 

can you put together an unclolorful list of all changes to the carbs.

 

Are there any vacuum leaks at the intakes, you read how I check.. When checking is there ever any back pressure up the intake. even though you have mentioned popping at the carbs.

 

What checks did you do to the coasting enrichment circuit times 4?

[luvmy40]

Here are the compression test results from 3/9/2018

 

Compression test results:

 

#1 190psi

#2 185psi

#3 190psi

#3 190psi

#3 190psi

#3 190psi

#4 180psi

 

I ran #3 multiple times as that cylinder was giving me grief at the time.

 

The only change to the carbs other than new OEM gaskets and o rings are Skydoc's needle shims. No other modifications.

 

I'm not sure what you mean when you say you are not impressed with the plugs. The plugs are new this season and have approx. 1700 miles on them.

 

I checked for vacuum leaks around the same time I ran the comp test but I'll do it again tomorrow. Didn't find any leaks then.

 

The main diaphragms and the coast diaphragms looked good from a visual inspection. I stretched them looking for pin holes and found none.

 

If the acceleration was much more crisp, I'd have whip lash.

Edited June 30, 2018 by luvmy40
spelling/typo

[Chaharly]

Here are the compression test results from 3/9/2018

 

Compression test results:

 

#1 190psi

#2 185psi

#3 190psi

#3 190psi

#3 190psi

#3 190psi

#4 180psi

 

I ran #3 multiple times as that cylinder was giving me grief at the time.

 

The only change to the carbs other than new OEM gaskets and o rings are Skydoc's needle shims. No other modifications.

 

I'm not sure what you mean when you say you are not impressed wit the plugs. The plugs are new this season and have approx. 1700 miles on them.

 

I checked for vacuum leaks around the same time I ran the comp test but "ill do it again tomorrow. Didn't find any leaks then.

 

The main diaphragms and the coast diaphragms looked good from a visual inspection. I stretched them looking for pin holes and found none.

 

If the acceleration was much more crisp, I'd have whip lash.

 

 

Heres what I'd do. Take a Bic lighter and run it around anywhere on the exhaust that there could possibly be a leak and go real, real slow. Check where the headers go into the motor, and check where your slip on exhaust goes on. Go real, real slow and if you see a draft moving the flame, well there's where you're getting air into the exhaust. I also believe these exhausts have a drain hole on each side to let out accumulated moisture. I'll go check in a second, but if those drain holes are rusted out to bigger than what they should be then you can assume your exhaust is sucking too much cold air and causing backfiring and popping and blubbing. That's what it sounded like to me, but of course I am NOOO expert! I only know what I know from the fellas here!

[Patch]

OK Luv;)

 

So your tests read high and this is going to present a challenge.

Not having them right in front of me I remember pairs of 190.

Why do you think they are up so high? I think I know.

The 1300 limits at 192.

 

Look at the 1st pic what is different about it?

 

After see the numbers 1st I would deal with that, but move away from setting pilot with vacuum _ we know they are going to be different.

 

The vacuum will also mislead when you jump over to the next circuit because of drag (another conversation) use a tach.

 

Let me know after you look up the compression specs if you want to try and lower psi

[Chaharly]

Have you checked the float levels on the carbs at all?

[Patch]

So fill some time in while Luv checks his specs.

 

Who knows the consequences of the high compression, assuming standard is 170 pis?

 

Visualize what is going on- in or on?

 

Or what causes the compression to rise? When we expect compression to weaken with ware?

[cowpuc]

IMHO,,, Go down and buy new plugs - NGK DPR8EA-9's, get 4 of them and gap them at 32 thou so they have room to expand to grow into high spec, look at your plug caps carefully for carbon tracking and ohm em out/do a resistance check, clip 1/4 inch off the end of each plug wire and screw it back on the caps if they are good. I am far from any form of an expert in the stuff but to my untrained eye looking at the blackened edge of those plugs,,, I am gonna guess that at some time or another they got a good over choking... Plugs are cheap,,, dont bother trying to clean em,,, opt for new IMHO... That may help a lot in your bikes stumbling.

I am with MiCarl and Cha,, look that exhaust system over very carefully for holes and leakin gaskets - a tiny little bit of air leak can cause a lot of snortin!!!!

[luvmy40]

Have you checked the float levels on the carbs at all?

 

Yes, The float levels have been checked and are good.

 

The compression spec from the service manual is 128-156 psi. It would appear that I am quite high. I will run another test ASAP just to make sure I wasn't reading the gauge wrong. I have been told since I ran that test that you should only cycle 4 times and I'm sure I chugged it much more than that. That may account for the high readings.

[luvmy40]

I'll snag new plugs tomorrow as well. Any befit in going up a point in heat?

[Chaharly]

So fill some time in while Luv checks his specs.

 

Who knows the consequences of the high compression, assuming standard is 170 pis?

 

Visualize what is going on- in or on?

 

Or what causes the compression to rise? When we expect compression to weaken with ware?

 

I was told that over cranking would wash away the oil on the rings and possibly lower compression, but i would assume higher compression is from carbon on pistons and valves

[Patch]

I was told that over cranking would wash away the oil on the rings and possibly lower compression, but i would assume higher compression is from carbon on pistons and valves

 

Well Chaharly you are right.

 

Lets brake it down: Luv mentioned engine seems to not get warm or warm slowly. Idle circuit prefers heat and so do the plugs.

 

Some things have changed while others have stayed the same: Lift, duration and stroke unchanged

Volume - what do you think Chaharley?

Compression is up through build up of carbon covering the combustion chamber and piston top.

Carbon insulates.

Heat transfers of 40 plus % through piston rings, usually higher.

This heat then dispersed through water jackets. Same for head combustion area.

Valves are not suppose to be insulated so the cool by exhaust on one side and fresh air/fuel the other

Carbon can glow in spots which cause pre ignition.

If carbon builds past piston edge it becomes abrasive to the cylinders, and clogs the ring landings.

 

 

Carbon crazing on plugs cause misfires.

[Patch]

Good day Luv my shoulder is keeping me up so I thought I’d put together my thoughts on how to resolve the issues.

 

“So here's the deal. No matter how I set the pilot circuits, I always either have a lot of popping on deceleration or sluggish throttle response off idle. Right now i'm getting both. She pops like crazy on decel and takes forever to warm up. Once warm, the throttle response is good.

 

She's also developed a lope at idle. An intermittent "miss". I haven't investigated the miss as yet. “

 

So here’s the deal, you can not properly tune the CV carbs under these parameters.

 

When I read Carls post I could see what he was thinking and I agree, she is pumping unburnt fuel into the collector.

 

In part because of the crazing however the bigger picture is she is choked with carbon and as mentioned the carbon is keeping the combustion temp down even though the compression is high! The reasons for this ise as stated in my earlier post.

 

Here is somethings to remember moving forward, it is because you took the compression you have already begun to turn this around. If the compression had been taken long ago when the carbs were misbehaving, you, the forum could have reached a corrective decision long ago.

 

I believe you need to decarbonize the cylinders. There are risks you should know up front. I assume the 1200 is also a standard 170 psi you are between 180 low & 190 high. This is not a Seafoam in the tank fix. You could try a 50/50 mix but I doubt it? It’s easy and cheap if you want to, get 2 cans and give it a try. Below is how I would attempt it.

 

You will need to cool the engine with a fan or 2 both blowing across the rad - we don’t want to melt her down!

 

You’ll need to find the sweet spot with the rpm as the pistons will need pressure, guessing between 15 and 1800 rpm. With the odd twist of the throttle. Keep your eye on the temp gauge keeping it below the red area is all you need concern over. Blow it out with compress air and a rag around the nozzle to catch any debris. Then retest

 

The risks: well you might end up below standard or the high ones might end up lower then the low ones now. This is due to the abrasive nature of the carbon and it rubbing on the walls! Again this is firsthand experience. But I have had them level very close, within couple of pis more often than not but with use of more aggressive chem's! We can’t put back the ware!

 

I wrote up a carb check list if you want but, it's possible your rebuild corrected the issue?

 

This says a lot right: :"My last tank ran 39.5 MPG as close as I can figure by filling to the same level in the neck visually. Up till now I'd been getting 33-35 mpg and before the carb rebuild I was getting 28-29 mpg."

 

PS:\ that's a 50/50 bypass the tank, container to the pump

Edited June 30, 2018 by Patch

[cowpuc]

You will need to cool the engine with a fan or 2 both blowing across the rad - we don’t want to melt her down!

 

You’ll need to find the sweet spot with the rpm as the pistons will need pressure, guessing between 15 and 1800 rpm. With the odd twist of the throttle. Keep your eye on the temp gauge keeping it below the red area is all you need concern over. Blow it out with compress air and a rag around the nozzle to catch any debris. Then retest

 

 

Please pardon my interuption here Steven but I am a bone head and gotta ask,,, where exactly should 45 be "blowing it out" at to decarbonize the heads/pistons during this process and exactly what "nozzle" should be covered to catch debris.. If you would not mind, please clairify for an old slowpoke.

Thanks

[Chaharly]

Good day Luv my shoulder is keeping me up so I thought I’d put together my thoughts on how to resolve the issues.

 

“So here's the deal. No matter how I set the pilot circuits, I always either have a lot of popping on deceleration or sluggish throttle response off idle. Right now i'm getting both. She pops like crazy on decel and takes forever to warm up. Once warm, the throttle response is good.

 

She's also developed a lope at idle. An intermittent "miss". I haven't investigated the miss as yet. “

 

So here’s the deal, you can not properly tune the CV carbs under these parameters.

 

When I read Carls post I could see what he was thinking and I agree, she is pumping unburnt fuel into the collector.

 

In part because of the crazing however the bigger picture is she is choked with carbon and as mentioned the carbon is keeping the combustion temp down even though the compression is high! The reasons for this ise as stated in my earlier post.

 

Here is somethings to remember moving forward, it is because you took the compression you have already begun to turn this around. If the compression had been taken long ago when the carbs were misbehaving, you, the forum could have reached a corrective decision long ago.

 

I believe you need to decarbonize the cylinders. There are risks you should know up front. I assume the 1200 is also a standard 170 psi you are between 180 low & 190 high. This is not a Seafoam in the tank fix. You could try a 50/50 mix but I doubt it? It’s easy and cheap if you want to, get 2 cans and give it a try. Below is how I would attempt it.

 

You will need to cool the engine with a fan or 2 both blowing across the rad - we don’t want to melt her down!

 

You’ll need to find the sweet spot with the rpm as the pistons will need pressure, guessing between 15 and 1800 rpm. With the odd twist of the throttle. Keep your eye on the temp gauge keeping it below the red area is all you need concern over. Blow it out with compress air and a rag around the nozzle to catch any debris. Then retest

 

The risks: well you might end up below standard or the high ones might end up lower then the low ones now. This is due to the abrasive nature of the carbon and it rubbing on the walls! Again this is firsthand experience. But I have had them level very close, within couple of pis more often than not but with use of more aggressive chem's! We can’t put back the ware!

 

I wrote up a carb check list if you want but, it's possible your rebuild corrected the issue?

 

This says a lot right: :"My last tank ran 39.5 MPG as close as I can figure by filling to the same level in the neck visually. Up till now I'd been getting 33-35 mpg and before the carb rebuild I was getting 28-29 mpg."

 

PS:\ that's a 50/50 bypass the tank, container to the pump

 

Could running seafoam through the intake ports get rid of some of that carbonation? Or even pouring some down the intake side of the carbs.

[bongobobny]

I remember from back in the 60's an old trick for decarbonizing old car engines was to keep the rpm's up there and with an eyedropper slowly drop water through the carb throat. The water, through compression, would literally send shock waves in the combustion chamber and bust loose the carbon! No, I am not recommending this procedure, I'm just reminiscing!

 

So far I see two possibilities, an exhaust leak, and excessive raw gas coming from the engine, both are very plausible! I am leaning towards the exhaust leak as the primary culprit as even with some raw gas/unexploded vapors with no source of oxygen they would possibly not ignite, and the only way to get oxygen to them before they exit the exhaust is from a leak.

 

Now, as far as the intermittent stumble, where do you want to look first? Valve adjustment? An intermittent ignition failure? A partially plugged orifice somewhere? A vacuum leak somewhere? Speaking of that, are you still using your plastic YCIS box?? Although in theory, they do help balance the vacuum, they also develop a crack on the seam of the body and can (and do) develop a vacuum leak. All that YCIS box does is to form a collector tank for all 4 carburetor vacuums to balance out. In reality, the gain of the system is pretty much insignificant and many people eliminate them! To properly test them, submerge the tank in a bucket of water, plug off 3 of the 4 ports, and apply air pressure to the 4th port and watch for bubbling for several minutes. You can sometimes fix them by applying a bead of glue or sealer to the seam which is where they usually leak. Just something else to check out...

[BlueSky]

Running too lean can cause it to pop back.

 

I recommend you put a bottle of Chevron Techron or Gumout with PEA in the gas tank to clean the cylinders (and carbs). Those compression numbers are not all that high in my opinion. When I bought my Kawasaki, it had 1k miles on it, not enough miles to build up a lot of carbon on the pistons. The compression checked 178 to 180 psig in all four cylinders with a cold engine. We are also assuming the gauge is correct. I would be happy with those compression readings. The V4 does have a high compression ratio.