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Too Lean, Reason for Concern? (See photos)
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TOPIC: Too Lean, Reason for Concern? (See photos)
#1019891
MidnightRide (User)
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Too Lean, Reason for Concern? (See photos) 6 Months, 1 Week ago  
My '01 XV1600ASN Roadie has the Hyper Charger, Cobra (or similar) pipes, and associated jetting. Before I made any adjustments I pulled a single plug and described its condition as 'clean', not white. I had just bought the bike.

But the reason I found RSC to begin with was to deal with deceleration backfire issues. I turned in the PMS screw to 2.5 turns and it solved the backfire problem and purred like a kitten at idle. But it just sounded too lean at speed so I started working the pilot screw back out. I'm now at about 3.33 turns out and it runs awesome, though some of the deceleration backfiring has returned which I'm fine with now that I know the cause.

But we just returned from a 400+ mile run up into the desert mountains, followed by a flat desert run of about 45 miles in about 100* temps, and I pulled all four plugs to have a look because it was crapping out a couple of weeks ago when climbing a mountain pass in 5th gear at 75-80 MPH.

The plugs are all 'whitish' rather than the 'clean' that they were before. I'm beginning to think that's why the previous owner had the pilot screw turned so far out before I bought it. I didn't count what he had it at but I'm guessing it was at least 4+ turns out.

I'm going to open the pilot screw back up a bit and run it to see if it affects the plugs at all.

In looking at the pics do you think I have need for concern on our mountain runs at altitude? I haven't pulled the main needle out yet but have the carb partially out right now to replace the throttle cables. Should I pull that needle up a bit? I have no idea where it's set right now because I've never had a reason to pull the top of the carb apart, though I did pull the bowl off a few weeks back. We've clearly put things to the test on the open road and without issue, but I know that valves can fry if running too lean for extended lengths.

Hopefully the pics show enough info. I wiped one off a bit with my finger when I pulled it out, I think it's the second from the left.








UPDATE: I may have just answered my own questions after a quick online search. It appears that I'm in the 'optimal' range because the terminal insulators themselves are still white rather than toasted.

That pic is below:

 
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Last Edit: 2017/08/15 18:15 By MidnightRide.
 
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#1019892
Tug (User)
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Re:Too Lean, Reason for Concern? (See photos) 6 Months, 1 Week ago  
Too lean means it will run hot and can burn a hole in the top of your piston. Do you still have the AIS on it? That is generally the cause of decel backfiring
 
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#1019943
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Re:Too Lean, Reason for Concern? (See photos) 6 Months, 1 Week ago  
That's a good looking plug. Just the right amount of carbon on the ring and the timing mark is in the right place. Take a strong light and look down in the plug where the insulator meets the metal. There should be a dark ring there that indicates the mixture. Mine's stock and that's what my plugs look like.

The dark spots are caused by the accelerator pump spray.
 
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#1019944
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Re:Too Lean, Reason for Concern? (See photos) 6 Months, 1 Week ago  
Remove the AIS and ditch the hypercharger. AIS causes deceleration back fire and the HC causes lean at higher speed.
 
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#1019949
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Re:Too Lean, Reason for Concern? (See photos) 6 Months, 1 Week ago  
MidnightRide wrote:
My '01 XV1600ASN Roadie has the Hyper Charger, Cobra (or similar) pipes, and associated jetting. Before I made any adjustments I pulled a single plug and described its condition as 'clean', not white. I had just bought the bike.

But the reason I found RSC to begin with was to deal with deceleration backfire issues. I turned in the PMS screw to 2.5 turns and it solved the backfire problem and purred like a kitten at idle. But it just sounded too lean at speed so I started working the pilot screw back out. I'm now at about 3.33 turns out and it runs awesome, though some of the deceleration backfiring has returned which I'm fine with now that I know the cause.

But we just returned from a 400+ mile run up into the desert mountains, followed by a flat desert run of about 45 miles in about 100* temps, and I pulled all four plugs to have a look because it was crapping out a couple of weeks ago when climbing a mountain pass in 5th gear at 75-80 MPH.

The plugs are all 'whitish' rather than the 'clean' that they were before. I'm beginning to think that's why the previous owner had the pilot screw turned so far out before I bought it. I didn't count what he had it at but I'm guessing it was at least 4+ turns out.

I'm going to open the pilot screw back up a bit and run it to see if it affects the plugs at all.

In looking at the pics do you think I have need for concern on our mountain runs at altitude? I haven't pulled the main needle out yet but have the carb partially out right now to replace the throttle cables. Should I pull that needle up a bit? I have no idea where it's set right now because I've never had a reason to pull the top of the carb apart, though I did pull the bowl off a few weeks back. We've clearly put things to the test on the open road and without issue, but I know that valves can fry if running too lean for extended lengths.

Hopefully the pics show enough info. I wiped one off a bit with my finger when I pulled it out, I think it's the second from the left.








UPDATE: I may have just answered my own questions after a quick online search. It appears that I'm in the 'optimal' range because the terminal insulators themselves are still white rather than toasted.

That pic is below:



I'm not sure of the thought process used in this pic but the plug marked as lean is not lean. Also is the white plug in the pic from a air cooled carbed vehicle or a water cooled injected vehicle. IMO they have the labeling ass backward. To me your plugs look to be on the "very" lean side of OK and not gonna damage the engine in normal temps but may cause the issues you have mentioned. If turning the PMS out helps then you probably need to install a larger pilot jet that will aid in eliminating decell backfire and richen the mid range just a bit. IMO the plugs should have a light grey to tan color on the insulators. We are not trying to race grand prix cars so getting too in depth with plug reading isn't necessary. Crapping out climbing a mountain pass under a load indicates a bit of a lean main as also indicated by your plug color. If I was running in 100º heat I would want to be a little richer than you are. After all lean adds heat, richer cools.
 
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Re:Too Lean, Reason for Concern? (See photos) 6 Months, 1 Week ago  
What Dave said about the bottom pic. The lean and optimal pics should probably reversed. Especially on an air cooled motor
 
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#1019955
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Re:Too Lean, Reason for Concern? (See photos) 6 Months, 1 Week ago  
Shores wrote:
Remove the AIS and ditch the hypercharger. AIS causes deceleration back fire and the HC causes lean at higher speed.

Why would I ditch the HC? This bike runs terrific and I couldn't be happier with the way it runs at speed, which I do plenty of! Acceleration off the light is fun as well...
 
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#1019957
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Re:Too Lean, Reason for Concern? (See photos) 6 Months, 1 Week ago  
I'm going to have to disagree fellas. If you look at the lean plug you'll see that there are no carbon deposits on the metal ring and the threads look burned. The insulator is probably glazed which means the deposits seen there can never be burned away.

The insulator is designed so it can get hot enough to self clean as the optimal plug shows. The optimal plug also shows carbon deposits on the metal ring which is a good indication of what the combustion chamber looks like.
 
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Re:Too Lean, Reason for Concern? (See photos) 6 Months, 1 Week ago  
davej wrote:

I'm not sure of the thought process used in this pic but the plug marked as lean is not lean. Also is the white plug in the pic from a air cooled carbed vehicle or a water cooled injected vehicle. IMO they have the labeling ass backward. To me your plugs look to be on the "very" lean side of OK and not gonna damage the engine in normal temps but may cause the issues you have mentioned. If turning the PMS out helps then you probably need to install a larger pilot jet that will aid in eliminating decell backfire and richen the mid range just a bit. IMO the plugs should have a light grey to tan color on the insulators. We are not trying to race grand prix cars so getting too in depth with plug reading isn't necessary. Crapping out climbing a mountain pass under a load indicates a bit of a lean main as also indicated by your plug color. If I was running in 100º heat I would want to be a little richer than you are. After all lean adds heat, richer cools.


Well my main concern is whether I'm going to melt the bike down or toast the valves, neither of which I've accomplished to date hehehe. The weather is actually starting to cool down here a bit, not even reaching 100* yesterday.

Opinions obviously vary on these plugs and if you search the web you'll see a myriad of plug conditions and associated labeling. I cut my teeth with some hard core racers who took some serious studies of their plugs after each little carb or engine tweak and test run. They ran the AMA Grand National dirt track circuit and some occasional road racing (and a LOT of motocross), and mostly raced Harley's. I remember them even noting how tough it was to balance the cylinders because the rear cylinder ran hotter than the front due to the nature of air cooling. Seems to me they ran a different plug in each cylinder to compensate. But I was just thinking that the electrodes on my plugs may be a bit on the white side so I needed to richen things up.

However at this point in time I really don't want to get into the jetting of this carb, particularly since I'm so pleased with the way it's running. LOL I'm frankly already tired of pulling that carb out of the bike and want to give it a rest for a while now that I've got the new throttle cables on it. The plugs are already back in the bike and everything's back together or I'd take a couple more pics of them.

When I first pulled the carb's float bowl, the phillips screw that held the float in place was locked solid (frozen) so I just left it there. I'm concerned that I'm going to run into a lot more of that if I get deeply into the carb and I don't want to open that can of worms right now if it's really not needed. Not sure what jetting's in it right now but I'm assuming that the HC jet kit was installed with the HC and pipes. The main needle is metal, not plastic. Haven't pulled it out to see if it's adjustable.

Thanks for your input! I like a bike that runs a bit on the lean side anyway. I may back the pilot out a bit more now that I'm more familiar with the bike. There is a NOTABLE change in performance from 2.5 to 3.5 turns out, from a very clean and lean running range to a much throatier richer sounding motor under acceleration.

I'm going to ride on for now...
 
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Last Edit: 2017/08/16 12:24 By MidnightRide.
 
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#1019973
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Re:Too Lean, Reason for Concern? (See photos) 6 Months, 1 Week ago  
The PMS, is designed to adjust the mix at idle. If you back it out more then needed for the idle, to compensate for a lean condition elsewhere, now you're richer then needed at idle. Also, when you get closer to 3.5 out, you increase the chances of losing the little rascal. It's happened to others.
With the more open intake and exhaust on a 1600, a 37.5 or even 40 Mikuni Pilot is a nice choice.

Scott is liking the whiter insulators, and seeing some other stuff he's happy about on the rest of the plugs. In certain circumstances, especially water cooled, I'd think that was a good idea.
Normally here, most of us recommend a nice tan on the insulator. When jetted properly, you can run richer then stock settings because of intake and exhaust mods. Get a nice tan on the insulators which generally indicates less heat, and keep your mileage in the low to mid 40's or even better with easy driving at speeds around 70. Which is pretty decent, considering Yamaha has them spec' in the mid 30's with mixed driving.
Another plus about running slightly richer, is the cooling benefits.
If you can run slightly richer jetting that creates a bit of tan on the insulator, keeps things cooler and help or certainly not hurt your mileage, why not?
We have had people attempt to lean the bikes down as much as possible, and they generally end up running worse, the closer you get to lean. We had one particular "lean is mean" advocate who got to redo his heads.
You can get it to where it runs okay, but is right on the cusp of lean. I'd encourage you not to. They'll run better and cooler, if they tend more towards the rich side. Roadies are big sloppy pigs. Spoil them. Don't starve them.


Several years ago we had several members, one of whom is Davej, who did a lot of real time testing using AFR gauges on their bikes. The general consensus was if you jet to lean, the AFR would get worse towards the lean side the faster you went. Prior to that, a lot of people were trying to lean their bikes out in pursuit of some minuscule fraction of performance gain or fuel savings.
 
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