New issues or messed something up tuning?

[Guest]

I'm at a bit of a loss. I'm not sure if the bike is having a new problem or if I messed something up with my carb tuning.

Background:
Last month, the bike started dripping gas from the airbox drain hose. Suspecting overflowing carbs, I tried to identify which leaked. None seemed to but when I tipped the rack over, Carb #3 dripped first. Assuming that meant it's fuel level was highest, I raised the float height to the upper end of the spec 23.40 to lower the fuel level. Turns out my problem was my cam timing so I corrected that and the airbox stopped dripping. The bike was ridable but there was midrange hesitation and when the bike got hot it would idle rough and stall.

Attempt to correct
My likely incorrect theory was: I suspected a lean condition was causing the hesitation and possibly making the bike overheat and that this was causing the stalling at idle. Since I had lowered the fuel level before which wasn't the cause of a problem, I pulled the carbs and reset all the float heights to 22.15-22.40. I also bought a Colortune and Carbtune. I attempted to tune the bike with the new tools on Saturday. I was able to take a long ride the next day but I had the same hesitation and stalling at idle when hot. Once the bike got hot, it got pretty bad. By the time I got home, the bike would die immediately as soon as I came to a stop. Now the bike seems to be running very poorly. I made another attempt to use the Carbtune today but I'm not having much success.

Some comments / questions:

• I only tried it the first time but the Colortune showed almost nothing - always blue but not completely steady (blinking off from time to time). If I turn the mixture screws all the way in, the flame goes out. If I turn the mixtures screws WAY out eventually I get an explosion of yellow. Other than that, it doesn't seem to change much. Then again, I've never really been able to get much of a reaction attempting the highest idle either.
  
  
• At best I get the Carbtune to register 20 Hg cm. Bwringer's guide mentions it should be 25-28 or higher. For some reason, now it barely reaches 15 Hg cm. What does this mean? Should I just ignore that and synch anyway?
  
  
• I'm having a very hard time getting the bike to idle around 1750 RPM (the Clymer recommends this for synch on the 550). I have to turn the idle screw a lot now to get above 1500 RPM and then it shoots to 2100 or so.
  
  
• The carbs seem to be going out of synch today without me changing anything. I'll let the bike cool down and come back for another try and things are off (sometimes by quite a bit). I can adjust the synch screws again to get them close but something seems wrong.
  
  
• It's running so poorly, I feel like I'm missing something obvious. Have a developed a new air leak? Have I developed a compression problem (never checked this)? Would gaskets be causing problems? I haven't replaced the valve breather cover gasket (haven't noticed leaks), valve cover gasket (may be a slight leak), or head gasket (not sure where the head gasket is but there does seem to be some oil around the "middle" of the engine)

For reference:
* new petcock
* carbs stripped / dipped / new o-rings
* new intake boots / o-rings
* valves adjusted / new tach cable seals
* airbox sealed / filter cleaned (airbox boots NOT replaced but seem ok)
* cam timing adjusted
* spark plugs replaced (maybe messed them up with all my tuning misadventures?)

[Nessism]

Not sure if this is related but where are the pilot screws set?

Edit: another thing to check is coil voltage. Less than 11.5 volts and I'd do the coil relay mod.

[scott]

Not sure if this is related but where are the pilot screws set?

Since I wasn't confident in my Colortune results, I put them back to 3 turns out today and tried to tweak them a little from there before attempting the vacuum synch. Should I just set them to 3 turns out and stop messing with them? I still don't know whether I should be erring to the rich side of 3 turns or lean side of 3 turns. Another thing I thought of trying was doing the mixture screw adjustment with the Carbtune attached - seeing if I could do a Highest Vacuum instead of Highest Idle?

Edit: another thing to check is coil voltage. Less than 11.5 volts and I'd do the coil relay mod.

I checked that again today when I was having issues. The drop to one coil was 1.5V and the drop to the other coil was 0.5V. This is roughly what I was getting when I checked it a month or so ago.

[Steve]

I only tried it the first time but the Colortune showed almost nothing - always blue but not completely steady (blinking off from time to time). If I turn the mixture screws all the way in, the flame goes out. If I turn the mixtures screws WAY out eventually I get an explosion of yellow. Other than that, it doesn't seem to change much. Then again, I've never really been able to get much of a reaction attempting the highest idle either.

I know it's not much consolation, but I got similar results last year when I tried a Colortune. It worked GREAT on a set of VM carbs, so I tried it on my wife's CV carbs and saw exactly what you did.

At best I get the Carbtune to register 20 Hg cm. Bwringer's guide mentions it should be 25-28 or higher. For some reason, now it barely reaches 15 Hg cm. What does this mean? Should I just ignore that and synch anyway?

When synchronizing the carbs, numbers don't mean a thing. What you are looking for is the relationship of all the levels.
The level will change a bit, based on engine speed.

I'm having a very hard time getting the bike to idle around 1750 RPM (the Clymer recommends this for synch on the 550). I have to turn the idle screw a lot now to get above 1500 RPM and then it shoots to 2100 or so.

Can you get it to idle lower than that? I had done many, many sets of carbs before I knew that the recommended speed was anything above normal idle. I still sync carbs at about 1200 RPM.

The carbs seem to be going out of synch today without me changing anything. I'll let the bike cool down and come back for another try and things are off (sometimes by quite a bit). I can adjust the synch screws again to get them close but something seems wrong.

Are you locking the adjustment screws into place with the locknuts? No "gorilla-torque" necessary, but they should not move.

It's running so poorly, I feel like I'm missing something obvious. Have a developed a new air leak? Have I developed a compression problem (never checked this)? Would gaskets be causing problems? I haven't replaced the valve breather cover gasket (haven't noticed leaks), valve cover gasket (may be a slight leak), or head gasket (not sure where the head gasket is but there does seem to be some oil around the "middle" of the engine)

The breather cover and valve cover gaskets will not affect how the engine runs, they will just make it messy with a bit of oil leakage. To see if your head gasket is leaking, clean your engine well, then look for telltale signs after a ride.


.

[tom203]

So bike starts easy, you go for long ride , have dead spot in mid range, and fully warmed up, it stalls at idle? How about the idle after 15 minutes- is it stable or heading further south?
You're implying the bike gets too hot - these things get wicked hot, but tolerate it as long as they keep moving. I think you need to hold off on the fancy gauges and redo the bench sync and correct the sinking idle problem. How many miles have you put on in last couple of weeks?

[scott]

I know it's not much consolation, but I got similar results last year when I tried a Colortune. It worked GREAT on a set of VM carbs, so I tried it on my wife's CV carbs and saw exactly what you did.

Well, at least I know it's not indicative of a problem. If I get another bike with carbs, maybe it'll be useful.

When synchronizing the carbs, numbers don't mean a thing. What you are looking for is the relationship of all the levels.
The level will change a bit, based on engine speed.

I was worried it meant my carbs were too rich (bwringer's guide said something about a carb being too rich causes it not to create enough vacuum).

Can you get it to idle lower than that? I had done many, many sets of carbs before I knew that the recommended speed was anything above normal idle. I still sync carbs at about 1200 RPM.

I think I can get it to idle at 1500 RPM. Since I've been having midrange issues, I was trying to synch at a higher RPM. I was able to synch between 1750-1900 this weekend but now it doesn't seem to want to cooperate.

Are you locking the adjustment screws into place with the locknuts? No "gorilla-torque" necessary, but they should not move.

Before taking a ride I've been tightening them (I haven't been able to get the middle 2-3 locknut very tight since it's not easily reached). While I was tweaking yesterday and letting it cool off, I didn't tighten the locknuts.

The breather cover and valve cover gaskets will not affect how the engine runs, they will just make it messy with a bit of oil leakage. To see if your head gasket is leaking, clean your engine well, then look for telltale signs after a ride.

I wasn't able to get the oil off the middle of the engine easily so I just left it (in other areas it just wiped off) - I'll need to try a scrub brush / cleanser.

[scott]

So bike starts easy, you go for long ride , have dead spot in mid range, and fully warmed up, it stalls at idle? How about the idle after 15 minutes- is it stable or heading further south?
You're implying the bike gets too hot - these things get wicked hot, but tolerate it as long as they keep moving.

The bike seems to start okay. I think it was after my tuning this weekend that the choke doesn't seem to be working as it should (the RPMs are not shooting up to the 2K - 3K range). It hasn't stopped the bike from starting though and it has been hot weather so maybe the bike isn't that cold to start with.

An average ride for me is in the morning (so typically < 80 degrees) somewhere around 45 min / 25 mi. Other than a few stop signs and a pretty short light or two, I don't think the bike gets HOT. I've had it rough idle / stall a few times like this but setting the idle adjustment to around 1500 RPM gets me through it okay (not always).

On anything outside my usual ride (getting a little bored doing the same loops), I almost always have to go through long lights (can be sitting at red lights for several minutes). At this point, I assume the bike is now HOT and I will tend to have problems if I have to stop (this could start happening 15-20 mins into the ride). I tend to plan my routes where I don't have a lot of lights / traffic but it's pretty unavoidable in my area.

How long should the bike be able to sit at idle? Is there a big difference to the bike between 80 degrees and 90+ degrees? I've actually considered turning off the bike at a light but that would be dangerous and I'd worry it wouldn't start when the light changed.

I think you need to hold off on the fancy gauges and redo the bench sync and correct the sinking idle problem. How many miles have you put on in last couple of weeks?

I've put roughly 430 miles on it since the cam timing adjustment. So the sinking idle / stalling is not related to the carbs? Or do you mean I've got the settings so far off I need to start with a baseline again?

[tom203]

scott said..."I've put roughly 430 miles on it since the cam timing adjustment. So the sinking idle / stalling is not related to the carbs? Or do you mean I've got the settings so far off I need to start with a baseline again? "

430 miles should have cleaned things up! A 4cyl bike should have no trouble idling at 1000 rpm,especially warmed up. 80 or 90 degrees is nothing to an engine running in low 200's waiting for a red light to change. I don't think you got settings so far off, but these carbs are tricky at idle-that's why there's so much emphasis on cleaning out the little tiny passages. I hope the PO did not modify jet needles/ position to compensate for the poor running due to cam errors- this might explain mid range hesitation, but leaves me clueless as to inconsistent idling.

[scott]

A 4cyl bike should have no trouble idling at 1000 rpm,especially warmed up. 80 or 90 degrees is nothing to an engine running in low 200's waiting for a red light to change.

That's what I would expect. If something was causing the engine to overheat, would that even cause it to stall at idle?

I don't think you got settings so far off, but these carbs are tricky at idle-that's why there's so much emphasis on cleaning out the little tiny passages. I hope the PO did not modify jet needles/ position to compensate for the poor running due to cam errors- this might explain mid range hesitation, but leaves me clueless as to inconsistent idling.

I haven't looked at the jet needles yet. When I was setting the float heights this past weekend, I did confirm the main jets were 92.5 which is stock. As far as I can tell, everything major seems to be stock but you never know. I did notice that the float needle valves in there don't look identical to the Suzuki needle valve I put in Carb #4 so those may be from a rebuild kit.

[tom203]

That's what I would expect. If something was causing the engine to overheat, would that even cause it to stall at idle?


I haven't looked at the jet needles yet. When I was setting the float heights this past weekend, I did confirm the main jets were 92.5 which is stock. As far as I can tell, everything major seems to be stock but you never know. I did notice that the float needle valves in there don't look identical to the Suzuki needle valve I put in Carb #4 so those may be from a rebuild kit.

As I said a while back, your next bike will be alot easier after all the work you've done on this one! Anyways, I have to suspect carb low speed circuits being partially blocked- I know you cleaned them correctly, but you had fuel spitting back thru carbs after that cleaning. Personally, and at the risk of ridicule, I would try a Seafoam treatment. Half a can into low fuel tank, run 15 minutes to ensure stuff gets to all fuel bowls and shut off and leave overnight. Sorta worked on my son's ninja- other folks claim miracles using it- for $10 it's worth a shot.
For your own safety, you need to be confident that the bike will idle well at all times, so you can focus on other stuff.

[scott]

As I said a while back, your next bike will be alot easier after all the work you've done on this one! Anyways, I have to suspect carb low speed circuits being partially blocked- I know you cleaned them correctly, but you had fuel spitting back thru carbs after that cleaning. Personally, and at the risk of ridicule, I would try a Seafoam treatment. Half a can into low fuel tank, run 15 minutes to ensure stuff gets to all fuel bowls and shut off and leave overnight. Sorta worked on my son's ninja- other folks claim miracles using it- for $10 it's worth a shot.
For your own safety, you need to be confident that the bike will idle well at all times, so you can focus on other stuff.

I picked up some Seafoam but haven't tried it yet. I think I'll do that tonight.

Side note: I had read a post about measuring secondary resistance of the spark plug caps and that it should be around 35K ohms on 1-4 and 2-3. My 2-3 was around 35K but my 1-4 was very high (not measurable on my meter). I had picked up new caps a while back but never got around to replacing them. I switched them all out and now my secondary resistances are around 25K. I'm not sure it will help with my current issue but it can't hurt.

I was able to take it for a ride today to get it warmed up without issue (didn't seem to pull strong but didn't stall at a few brief stops at least). I'm sure I didn't get the bike too hot so I'm not sure that's a good test. Then I tried doing the mixture screw / vacuum synch tuning again.

If I synch it around 1800 and then lower it to a more normal idle, Carb #1 and Carb #2 (especially 2) drop lower than Carb #3 and Carb #4. I think the left exhaust also smells richer than than the right (very scientific test, I know). Since I'm having problems with stalling at idle, I wonder if I should just synch below 1500 and not worry about the upper range. I was thinking that would likely make my mid-range hesitation worse and maybe overheat things too.

I also feel like I was seeing signs of an air leak during my synch a few times (hanging idle). I'll probably take it for a spin as is (synched around 1800) and see how it behaves. I haven't noticed a hanging idle before.

[tom203]

If you tried the Seafoam last night, prepare for scary fun- make sure you start up outside to thrill the neighbors. And remember, no cursing at northerners who make these suggestions!

[scott]

If you tried the Seafoam last night, prepare for scary fun- make sure you start up outside to thrill the neighbors. And remember, no cursing at northerners who make these suggestions!

I actually didn't notice much difference with the Seafoam today. It was very hard to start - it took several tries of just holding down the start button. The choke still seemed to have no effect (or made it idle even worse / lower). I adjusted the idle up to about 1400 using the idle screw. During the ride it seemed be pretty jerky in the midrange. When I got back from a 40 min ride, it was idling at 1600 RPM. I adjusted it back down to 1300-1400 RPM and let it idle for a while. It did drop some and get a little rough but didn't stall. I'm pretty sure if I adjust it to normal (1200) and let it still, it may stall. It may just be the new spark plug caps are keeping it from completely stalling just by having a stronger spark. So it's ridable but doesn't seem to be running well.

Also, I don't think this is a new symptom but my oil level goes up after a ride and then seems to go back down after a while. Previously, I had the oil below the Full line so that it would be around the Full line after a ride. After the bike would cool, the oil level would be below the Full line. Yesterday when the bike was cold, I put more oil in up to the Full line. I figured having the most amount of oil possible would help keep the bike cool. After my ride today, the oil level is now over the sight glass. I'm guessing in a while it will be back down to the Full line but is this an issue? I can't tell whether it smells like gas+oil or not - it may. Since my carbs don't seem to be leaking, what else would cause this?

[scott]

Also, I don't think this is a new symptom but my oil level goes up after a ride and then seems to go back down after a while. Previously, I had the oil below the Full line so that it would be around the Full line after a ride. After the bike would cool, the oil level would be below the Full line. Yesterday when the bike was cold, I put more oil in up to the Full line. I figured having the most amount of oil possible would help keep the bike cool. After my ride today, the oil level is now over the sight glass. I'm guessing in a while it will be back down to the Full line but is this an issue? I can't tell whether it smells like gas+oil or not - it may. Since my carbs don't seem to be leaking, what else would cause this?

Okay - reading up, the expansion while hot is normal. I think I knew that and is why I filled it below the Full line while cold. I guess I should try to get some of that extra oil out.

[tom203]

Okay - reading up, the expansion while hot is normal. I think I knew that and is why I filled it below the Full line while cold. I guess I should try to get some of that extra oil out.

I'm disappointed - no white smoke! After seafoam soak, hard start is normal, but I like that you had to drop idle stop screw. Find a nice long downhill, get up to 60 mph, drop down a gear and close throttle completely- high vacuum in throttle plate area just might coerce crap out of those nasty little holes.
I run my bike with oil above window cold on centerstand- I check it by putting on kickstand and rotating it to verticle.